The distinctive global warmings during the modern era and the Medieval Period share similar causes - our solar system's sun, per China's climate scholars...
(click on image to enlarge)
Researchers around the globe continue to build on the mountain of scientific evidence that the Medieval Period had warmer temperatures than the modern era.
And the evidence for a powerful solar influence on temperatures and climate change is substantial and growing.
====> "Here we present[Editor: Chinese scientists] decadally-resolved, alkenone-based, temperature records from two lakes on the northern Tibetan Plateau. Characterized by marked temperature variability, our records provide evidence that temperatures during the MWP were slightly higher than the modern period in this region. Further, our temperature reconstructions, within age uncertainty, can be well correlated with solar irradiance changes, suggesting a possible link between solar forcing and natural climate variability, at least on the northern Tibetan Plateau."
Peer reviewed studies continue to be published, adding to the unequivocal evidence that climate change was common in the past, often with temperatures higher than modern averages.
The evidence confirms that modern temperatures are not unprecedented nor that human CO2 emissions are required for climate change to happen.
A new study:"A paper published today in Global and Planetary Change reconstructs temperatures in Northern Fennoscandia [within the Arctic circle] over the past 1,600 years.....demonstrating that the Arctic was warmer than the present during the Medieval Warm Period. The paper adds to over 1,000 peer-reviewed published non-hockey-sticks finding the Medieval Warm Period was global, as warm or warmer than the present, and that there is nothing unusual, unnatural, or unprecedented about the current warm period.....Furthermore, the authors find a natural 70-80 year oscillation of temperatures, similar to the 60-70 year oscillation of the natural Pacific Decadal Oscillation [PDO]." (paper abstract)
A new peer reviewed study based on an analysis of megafossil tree remains documents the indisputable conclusion: it was warmer during both the Roman and Medieval periods - ergo, extreme climate change can happen without human involvement.
The above plots (click each plot to enlarge) of ancient tree lines from previous research provides ample evidence that indeed climates were warmer prior to human CO2 emissions. This new research examines 455 radiocarbon-dated mega-fossils from Scandinavian region.
that mega-fossil analysis is the only methodology that can "accurately document the existence of a certain tree species at a certain spot and at a certain point of time in the past."
indicates that "summer temperatures during the early Holocene thermal optimum may have been 2.3°C higher than present,"
that "the pine tree line was about 100 m higher than today (i.e., early 21st century) c. 1940 and 1300-930 cal. years BP," while noting that "the same applies to birch by c. 1700 and 1300 cal years BP," which clusters "represent the Medieval and Roman times."
that "these temperature anomalies were succeeded by a distinct tree line/temperature dip, broadly corresponding to the Little Ice Age."
that "the emergence during the past two millennia of at least two short-term tree line and thermal excursions to higher than present levels (i.e. early 21st century) indicates that the current performance of the ecological and climatic systems is well within the envelope of the natural variability
that "the pine tree line (and summer temperature) was consistently higher than present ... during the Roman and Medieval periods, c. 1900 and 1000 cal years BP."
Note: Doing a search of the internet did not result in finding a definition for 'megafossil' yet a definition for 'microfossil' was readily available. For purposes of this posting, megafossil refers to fossilized material that can be viewed with the naked eye.
Steve McIntyre analyzed the Southern Hemisphere historical temperature information contained in the recent IPCC AR5 report and documents an amazing discovery.
Extreme, absurd cherry-picking that defies objective, impartial science.
In essence, the IPCC's representation of Southern Hemisphere temperature changes is biased with unrelated Northern Hemisphere paleo-temperature datasets; the IPCC ignores established, widely accepted Southern datasets such as Antarctica's ice core evidence, as displayed here (click on image to enlarge).
Not only does the IPCC avoid utilization of the the inconvenient Vostok ice core temperatures that reveal the Medieval Warming period for the Southern latitudes, they chose to use Northern datasets that have been widely criticized for being error-filled and massively manipulated via questionable, non-standard statistical techniques.
Like previous IPCC reports, the AR5 edition obviously shares the agenda-science traits of absurd cherry-picking, gross misrepresentations and ludicrous fabrications, which confirms the accusations that green-alarmists have completely corrupted climate science.
Note: As the chart depicts, the polar region of the Southern Hemisphere has exhibited an overall cooling trend over the last 5,000 years, with multiple peaks and valleys. This persistent cooling trend is also evident from the Greenland ice core dataset. While the polar regions share many temperature change similarities, their warming/cooling phases occur during different years/decades with different amplitude - i.e., narrowly speaking, perfect synchronization of polar climates does not exist.
Back in 2008, Climate Sanity did an article about Arctic warming, creating the adjacent top graphic that highlights 14 different peer reviewed studies. (click to enlarge image)
The light pink areas represent large geographical areas where the past Arctic climate, over the last 3,000 to 9,000 years, was warmer than today's.
Recently, 'C3' posted an article regarding 15 studies that determined the Medieval Arctic warming was greater than the current warming.
In addition, the adjacent bottom graphic depicts both past and modern tree lines and permafrost boundaries. This inconvenient empirical evidence confirms that in the past trees were able to grow farther north (due to a warmer northern climate) than our modern period; also, today's permafrost boundary stretches farther south due to a modern climate that is cooler.
Despite this preponderance of empirical evidence and multiple peer reviewed studies about the present and past Arctic climate, a new moss (lichen) study by Miller et al. 2013 makes a bogus claim that today's Arctic temperatures are warmer than the past 44,000 to 120,000 years.
This bogus claim has all sorts of scientific lameness, falsehoods and wild misrepresentations associated with it, as described by experts here, here, here and here.
The criticisms of this study are extensive. But the obvious criticism of blatant cherry-picking is indisputable. As one expert pointed out, this research focused on just four moss sample sites on Baffin Island and ignored the island's 135 other moss sites' samples that completely discredit the bogus "warmer than the last 44,000 to 120,000 years" claim.
latest study's bogus science affirms, anti-science cherry-picking
remains alive and well in "scientific" circles pushing the discredited catastrophic global warming hypothesis. Just another example of 'the ends justify the means' style of agenda-science.
And BTW, the top graphic does not include the recent Baffin Island icecap study and another Island study using lake sediment cores, which both confirm that the modern Arctic temps are cooler than the past.
Climate history is replete with peer reviewed research and historical anecdotal evidence that both the Roman and Medieval warming eras were likely warmer than current modern temperatures.
This new study (see adjacent plot) adds to the cornucopia of empirical evidence that natural climate change (warming & cooling) is a powerful force, taking place constantly. This research also confirms the likelihood that our modern warming is more a result of natural forces than greenhouse gases.
Those stubborn facts of natural climate change are without mercy to those who espouse anti-scientific, anti-empirical claims, especially the bogus "unprecedented" claim, no?
New research discovers ancient tree stumps that existed under an Alaskan glacier for thousands of years.
The retreating glacier confirms that climate temperatures were much warmer from at least the Minoan period to the Medieval era.
At some point, the climate became cooler and the actual trees were snapped at the stump level, then buried in the glacier's ice for centuries. Finally, the stumps were revealed as the climate returned to warmer temperatures in the rebound from the Little Ice Age.
This actual climate evidence is corroborated by the empirical ice core dataset from Greenland. As the ice core empirical evidence depicts, the ancient periods of the Minoans, Romans and the Medieval era were warmer than the present.
This Greenland evidence also reveals that temperatures have been in an overall cooling phase for the last some 3,500 years, which eventually led to the global glaciers' growth that ultimately would bury trees and forests, such as Alaska's Mendenhall glacier described in this article.
This new research adds to the mountain of empirical evidence and studies that refutes the IPCC's claim that modern temperatures (i.e., global warming) are "unprecedented".
Hmmm...the IPCC climate "science" always seems to be contradicted by those stubborn facts, no?
The empirical evidence is irrefutable, no longer debatable.
These 20 studies confirm that the known Northern Hemisphere natural climate change periods, referred to as the Little Ice Age, the Medieval Warming, the Dark Ages and the Roman Period, also had significant impacts on the Southern Hemisphere.
In all cases, across both hemispheres, the large, natural climate changes took place without any human CO2 influence.
This means that natural climate change is caused by other factors that are of either earthly or (and) cosmic/solar origins.
Using sediment cores from two lakes in the Qaidam Basin of the northern Tibetan Plateau, Chinese researchers reconstructed temperatures back some 2,000 years.
Their research was unequivocal: modern warming has been cooler than past warming periods. They also confirmed that the climate naturally made shifts between warm/cool regimes. Plus, the climate shifts appear to be associated with solar activity.
Note: Historical temperature charts and previous climate-history articles.
Anti-science alarmists and pro-global warming ('AGW') scientists are very enamored with multi-proxy temperature reconstructions, which allows "researchers" to statistically blend and torture different forms of data to force a "confession" that modern warming has been "unprecedented" - however, as expert skeptics have discovered, these studies are often found to be empirically and statistically-challenged garbage and end up being a cornucopia of unintended contradictions...the new PAGES2K paleo-torture study is the latest example
The new Kaufman et al. study (aka as the 'PAGES2K' research) is getting its initial web-wide forensic review in multiple articles across the web, including here, here, here, here and here.
The two images above are derived from one of the study's own charts (see the Bob Tisdale article).
The chart on the left depicts those areas of the world that experienced modern warming supposedly greater than any warming over the last 2,000 years; and, the chart on the right represents those areas where modern warming was less than that of certain periods during the past 2,000 years. Both charts have the past 2,000 year atmospheric levels superimposed (the pinkish curve) on them.
It is from the Tisdale analysis that it first becomes apparent that the law of unintended consequences has interestingly come into play - the study's authors have actually built a case (be it likely an unforced error) that supports the views of the majority of catastrophic global warming skeptics/lukewarmers.
From the study itself, and a close review of the above images, we now know the following:
First, as even the New York Times points out, this study determined that the Arctic was warmer during the 1940s to 1970s than during years of the late 20th century. (Sidebar: If the approximate modern instrumental global warming increase of 0.85°C since 1850 is added to the Greenland ice core data, modern warming is still below peaks of the Medieval & Roman periods.) Confirms view of skeptics, check.
Second, the study determined that periods prior to 1000AD had warmer temperatures in Europe. Confirms view of skeptics, check.
Third, this study finds Antarctica was warmer, from the 2nd through 13th centuries, than during our modern era. (Sidebar: If the approximate modern instrumental global warming increase of 0.85°C since 1850 is added to the Vostok ice core data, modern warming is still below the peak temperature between 1AD and 1000AD.) Confirms view of skeptics, check.
Fourth, this study points out that true global warming has not taken place in the modern era, but regional strong warming has. Of the 7 regional areas analyzed, only 3 exhibit a strong warming (more likely only 2, see point #11 below). The other four regions, not so much. Confirms view of skeptics, check.
Fifth, the study clearly indicates that major climate change is taking place at all times, in different manners, across the globe. Climate change is not some new modern phenomenon. Confirms view of skeptics, check.
Sixth, the study shows atmospheric CO2 levels are not a cause of past major climate change. Throughout most of the last 2,000 years, CO2 levels are stable yet climate change is constantly happening. Confirms view of skeptics, check.
Seventh, the study documents that unprecedented regional warming takes place regardless of low/high atmospheric CO2 levels.Confirms view of skeptics, check.
Eighth, this study, in combination with the known recent global temperature trend (subsequent to this study's ending date of 2000AD), clearly makes an indisputable case that recent modern global warming is not as claimed: unprecedented; unequivocal; irrefutable; irreversible; nor dangerously accelerating. Confirms view of skeptics.
Ninth, this study affirms that periods of "unprecedented" warming do not cause the IPCC's urban legend of "runaway," "tipping point," dangerous global warming. Of course, the hottest period ever recorded (Minoan era) in the ice cores over the last 4,000 years already proved that the mythical "tipping point" is just that. Confirms view of skeptics, check.
Tenth, this study again provides proof that the AGW-alarmist researchers will use each and every attempt to remove and/or minimize the exceptional Medieval Warming Period that the vast majority of local/regional paleoresearchstudies, and the historical literature, have well documented. It is simply freaking amazing that this group of researchers would present an analysis of Europe's past warming without the extreme and extended warming of the Medieval era (see chart onright). Confirms view of skeptics, check.
Eleventh, this study clearly proves to the public that the proponents of AGW-alarmism will utilize excessive cherry-picking ofempirical paleo research to fabricate their "scientific" claims of modern "unprecedented" warming. Not only did this study exclude the preponderance of paleo-scientists' research that documents past extreme warming, but this study was brazen enough to include paleo temperature reconstructions that even a peer-reviewed science journal ultimately rejected because of its statistical flim-flam. Without the infamous, widely discredited Gergis et al. study, it is highly likely that the "Australasia" region of the above chart on the left would have to be moved to the chart of the right, above - thus leaving just 2 regions of the world that may have had modern "unprecedented" warming in the 20th century, and only a single region of the world that had "unprecedented" warming since 1970 (recall that this study confirmed the Arctic was warmer from the 1940s to the 1970s). Confirms view of skeptics, check.
Conclusion: This multi-cherry-picking proxy study has many claiming that modern temps are the "hottest" across the globe, over the last 1,400 years. In fact, as the above information clarifies, some regions of the world had strong modern warming (that is, supposedly), while the majority did not. As this study itself determines, global warming, cooling and climate change are not done in some lock step manner across the world in a monotonous cause and effect relationship with CO2. Skeptics of both the IPCC's catastrophic global warming hysteria and the elites' CO2-kills fanaticism have pointed this out for years (if not decades). The geological and historical records/datasets support the essentials of the non-hysterical skeptic/lukewarmers' analysis of climate change, and now this study suggests the alarmist community has inadvertently accepted many of the same views.
The bogus "unprecedented" modern warming claims by the IPCC and catastrophic global warming 'hystericals' takes another body blow - newly released Arctic region empirical evidence (from Svalbard) confirms that Medieval Period was robustly warmer than the world-ending, hypothetical CO2-induced modern warming feared by alarmists
The Climate Audit blog has another article regarding the amazing "scientific" attitudes/methods of paleo-climate "scientists" who embrace the IPCC's left-green-alarmist propaganda.
The 'CA' article includes the adjacent temperature reconstruction chart of an Arctic region, spanning the time period of 800AD to 1997AD.
Clearly, the Medieval Period was significantly warmer than the recent modern warming. The MWP climate warmth took place during an era of low atmospheric CO2 levels and minuscule human CO2 emissions. The evidence reveals the extended, unprecedented polar temperatures experienced prior to the Little Ice Age cooling.
The anti-science Democrats and left-wing greens absolutely hate the Medieval Warming Period (MWP), due to its invalidation of the modern CO2 global warming-climate change hypothesis - no matter their extraordinarilylame corrupted/bogus attempts to prove otherwise, the objective empirical evidence continues to confirm the MWP was an uniquely extended warm era
In another fascinating exposé of climate science flim-flam produced by yet another group of academia climate-quacks, Steve McIntyre has the adjacent chart embedded in his article.
This chart represents a 5,000 year span of temperature variation in the Arctic region (Ellesmere Island) per peer-reviewed research . To add context, we superimposed the atmospheric CO2 levels (mauve curve) from the last 2,000 years.
Several very obvious conclusions can be drawn that gut claims by anti-science alarmists and quacks:
1. Climate change is a science-proven constant.
2. Periods of global warming and global cooling happen frequently
3. The Medieval and Roman periods were warmer than the modern era
4. Temperatures changed regardless of CO2 levels
5. CO2, be it natural or human, is not the globe's "thermostat"
Finally, per the HockeySchtick blog, it is known that the essentially barren Ellesmere Island had temperatures some 2 to 3 degrees higher than current temps, despite the gigantic CO2 emissions of our modern consumer/industrial era.
The UN's IPCC claims that modern global warming is "unprecedented" continues to be robustly discredited by the newest scientific research - another peer reviewed study confirms that the Medieval Warming (plus the Roman and Minoan) periods had significantly warmer summers (Kamchatka, Siberia) than our current period, which has atmospheric CO2 levels exceeding 350 ppm
Read here. Scientists from Europe and Russia reconstructed temperatures from a Kamchatka Peninsula sediment core that contained chironomids. As the chart on the right depicts, the scientists determined that there were extended periods, well before CO2 atmospheric CO2 levels of 350 ppm and greater, when summer temperatures were well above modern temps.
"A paper published in Quaternary Science Reviews reconstructs Arctic temperatures in Kamchatka, USSR over the past 4,500 years and finds the highest reconstructed temperatures were about 3.8°C warmer than modern temperatures. The authors find "the highest reconstructed temperature reaching 16.8 °C between 3700 and 2800 years before the present," about 3.8°C above "modern temperatures (∼13 °C)." In addition, the data shows temperatures between 2500 - 1100 [during the Medieval and Roman warming periods] were about 1-2°C above modern temperatures of ~13°C." [Larisa Nazarova, Verena de Hoog, Ulrike Hoff, Oleg Dirksen, Bernhard Diekmann 2013: Quaternary Science Reviews]
The IPCC's "consensus agenda" has produced a lot of non-scientific climate garbage over its history - new Antarctica study debunks the claim that the Little Ice Age was non-global and restricted only to the Northern Hemisphere - another IPCC 'factlesstoid' has became official 'toast' for the anti-science ash bin file
Read here. The U.S. has a research station located at the WAIS divide where scientists associated with the Scripps Institution of Oceanography conducted an analysis to determine the Little Ice Age impact on the southern polar region.
"The authors (Orsi et al.) write that "the Northern Hemisphere experienced a widespread cooling from about 1400 to 1850 C.E., often referred to as the Little Ice Age (hereafter LIA)," which they describe as "the latest of a series of centennial scale oscillations in the climate,"...three researchers, all from the Scripps Institution of Oceanography, report determining that "the WAIS Divide was colder than the last 1000-year average from 1300 to 1800 C.E.," and they say that "the temperature in the time period 1400-1800 C.E." - which meshes well with the chronology of the LIA in the Northern Hemisphere - "was on average 0.52 ± 0.28°C colder than the last 100-year average."...stating that their result "is consistent with the idea that the LIA was a global event, probably caused by a change in solar and volcanic forcing..." [Anais J. Orsi, Bruce D. Cornuelle, Jeffrey P. Severinghaus] 2012: Geophysical Research Letters]
Climate change and global warming/cooling are the constant factors of Earth's history regardless of human CO2 emissions - a new study confirms that unprecedented Medieval and Roman period temperatures in the New Mexico area were significantly warmer than current
(click on image to enlarge)
Read here. The empirical research for the unprecedented temperatures during the Roman and Medieval periods continues to build.
As this chart depicts, the New Mexico region of the southwest U.S. experienced considerably warmer temperatures than those of the modern era.
As can be seen, extreme climate change took place frequently in the past, well before any influence of humans on the landscape and the atmosphere from CO2 emissions.
A paper published in Palaeogeography, Palaeoclimatology, Palaeoecology reconstructs climate change in central New Mexico, USA over the past 12,800 years and finds mean annual temperatures were ~1°C warmer than the present during
the Roman Warming Period 2,000 years ago, the Medieval Warming Period
1,000 years ago, as well as during other unnamed warming periods in the
past. The paper also shows cold periods were relatively wet, and warm
periods relatively dry, the opposite of the claims of climate alarmists.
Furthermore, the paper shows that mean annual precipitation today is
neither dry nor wet in comparison to the precipitation extremes over the
past 4,000 years. [Stephen A. Hall, William L. Penner 2012: Palaeogeography, Palaeoclimatology, Palaeoecology]
UK and U.S. left-wing agenda "scientists," associated with the IPCC fraudulent hockey-stick affair, attempted to dictate to other scientists that the Medieval Warming Period was an isolated phenomenon only experienced by the Europe/North Atlantic region -- most paleo-climate researchers rejected the lame arguments of the IPCC authors and continued to find non-European regions that experienced the Medieval Climate Anomaly (MCA), including Obama's birthplace
Nope, we're not speaking of Obama's first birthplace, the one before he decided to run for U.S. president, although Kenya does have a warm and humid climate.
Instead, the research was done in the Hawaii area, the newer birthplace of Obama after his U.S. Senate election. Specifically, the study was done at the scenicKealia Pond, Maui.
These scientists wanted to determine what impact the MCA had on the tropical island, where the UN's IPCC scientists had claimed there was no impact. As scientists dedicated to the scientific truth, they ignored the IPCC's dictates (i.e., flimsy reasoning) and pursued their research.
"Based on "high-resolution palynological, charcoal, and sedimentological analysis of a sediment core from Kealia Pond, Maui, coupled with archaeological and historical records,"... Pau et al. developed "a detailed chronology of vegetation and climate change since before human arrival."...Most pertinent was the three researchers' finding that "a shift from dry to wet climate conditions marked the beginning of the Medieval Climate Anomaly (MCA) as evidenced by a precipitation reconstruction based on a pollen abundance index." They note, for example, that over the 2500 years of their record "there have been two major climatic events: first the MCA (AD 800-1300), followed by the Little Ice Age (AD 1400-1850)."...In the case of the early inhabitants of Maui, Pau et al. write that "an increase in forest resources during this wet climate interval coincided with rapid Polynesian population growth," which suggests that the Medieval Warm Period was a time of prosperity for them..." [Stephanie Pau, Glen M. MacDonald, Thomas W. Gillespie 2012: Annals of the Association of American Geographers]
Regardless of which falsehood of Obama's birthplace one chooses to believe, there is no choice concerning the truth regarding the Medieval Climate Anomaly. Its impact has been substantiated by reams of empirical research and peer reviewed articles. The Medieval Warming Period impact was immense, stretching across the entire world, even touching the tropical islands of Hawaii.
The statistical fabrication known as the "hockey stick" has been thoroughly discredited as being proof that modern global warming is unprecedented - adding to the growing empirical evidence that the "hockey stick" was bogus, a new study of Scandinavian temperatures reveals the greater warmth of both the Roman and Medieval Periods
Read here. As several new 2012 studies of the Arctic and Antarctic regions have determined, modern warming is not unprecedented versus the Medieval and Roman periods.
The current research coming out of the polar regions is confirmed by a group of European scientists utilizing the latest research technology in a non-polar region.
As can be seen, this new research from Esper et al. is depicted adjacent - clearly, summer temperatures during the Roman period, sans consumer/industrial human CO2 emissions, were significantly warmer than the current period.
"The authors developed 587 high-resolution wood density profiles from living and sub-fossil Pinus sylvestris (scots Pine) trees of northern Sweden and Finland to form a long-term maximum latewood density (MXD) record stretching from 138 BC to AD 2006, wherein all MXD measurements were derived from high-precision X-ray radiodensitometry...And in comparing their results with the earlier temperature reconstructions of others, they say that their MXD-based summer temperature reconstruction "sets a new standard in high-resolution palaeoclimatology,"...the four researchers state that their new temperature history "provides evidence for substantial warmth during Roman and Medieval times, larger in extent and longer in duration than 20th century warmth."[Jan Esper, Ulf Büntgen, Mauri Timonen, David C. Frank 2012: Global and Planetary Change]
Conclusions: As the irrefutable empirical research mounts, it is becoming untenable for politicians, regulating bureaucrats and taxpayer funded scientists to maintain the falsehood that modern global warming has been unprecedented. The latest objective, scientific research from across the world confirms that modern warming is not unusual, nor dangerous. In addition, the preponderance of new research indicates that both the Roman and Medieval Periods were warmer.
Over recent years, the Arctic has warmed much like it did during the natural Medieval Warming Period - during prior warm phases, mother nature melted the Northwest Passage sea ice completely, but not yet in the modern era
Read here. Canadian Arctic experts have conclusively determined that the Arctic's Northwest Passage has frequently been devoid of sea ice during summer months.
This lack of sea ice was the result of natural warming that produced excessive temperatures. They conclude that temperatures during the Medieval Period, and multiple earlier periods, were significantly warmer than modern temperatures - from 1 to 3 degrees warmer.
"Numerous sites have been surveyed along the length of the Northwest Passage. The eastern and western approaches have become reliably ice-free in summer under historical climatic conditions, whereas in the central part summer sea ice has been persistent. The radiocarbon-dated bowhead whale remains indicate that the whales were able to range along the length of the Passage during two intervals (centered on 9000 years ago and 1000 years ago) and that they were able to access the central part from the east about 4000 years ago. During the first of these intervals (9000 before present) ice cores indicate that summer temperatures were about 3°C warmer than mid 20th Century. Therefore, a warming of 3°C exceeds the opening threshold. Medieval Warm Period temperatures were probably about 1°C warmer than mid-20th Century, which is likely close to threshold conditions for an opening of the passage."
When compared to the historical and ancient past, the modern Arctic warming and subsequent summer sea ice melt is not unusual, and is likely the result of the same natural climatic patterns and oscillations that produced such conditions in the past.
As revealed in the adjacent series of images, the modern sea melt (image3 at the bottom) still has not freed the Northwest Passage of summer ice as the experts believe the earlier warming periods easily did (image1 and image2).
Conclusions: Modern Arctic warming is not unusual versus the Medieval Warming. Current Arctic and Northwest Passage sea ice melt is less than what occurred in the past, per the empirical evidence. Since both modern and historical Arctic warming, and sea ice melting, are similar, one can surmise that natural warming is the principal cause of today's Arctic conditions. Plus, anthropogenic black soot and greenhouse gases may have exacerbated the current sea ice melting.
The unprecedented Medieval Warming Period is again confirmed by new Switzerland research - the MWP and subsequent cooling are both products of natural forces and not a result of large human CO2 emissions
Read here. The vast majority of scientific research documents the major warming and cooling periods prior to the 20th century. These periods of climate change exhibited large temperature swings across many regions of the world, well before the growth of industrial/consumer CO2 emissions.
A new study by Larocque-Tobler et al. provides more evidence that the Medieval Warming was not only significant, but remains unprecedented in some regions. Likewise, the subsequent Little Ice Age cooling was significantly colder than experienced in the 20th century.
"Working with a lake sediment core extracted in AD 2005 from the deepest point of Seebergsee in the northern Swiss Alps,... mathematically analyzed the taxonomy of chironomid assemblages they identified in the sediments and used the results to reconstruct mean July air temperatures for the past 1000 years. This work revealed a Medieval Warm Period that began some time before AD 1000 (where their temperature history had its beginning) and lasted until about AD 1250, the peak temperature of which was approximately 0.9°C greater than the peak temperature near the end of their record..." [I. Larocque-Tobleration, M.M. Stewart, R. Quinlan, M. Trachsel, C. Kamenik, M. Grosjean 2012: Quaternary Science Reviews]
Conclusion: Natural climate variation can cause dramatic climate change, which the unprecedented Medieval Warming Period represents. This level of extreme climate change can happen regardless of the amount and growth of human CO2 emissions.
Greenland's recording of both natural cooling and warming climate change proves that modern global warming is modest at best - as the evidence indicates, in the scheme of past climate change, current warming is well within natural variation
The Little Ice Age (LIA) is a well documented climate change period that was a global phenomenon. For the Northern Hemisphere, the coldest temperatures were reached during the mid-to-late 1600's, and then a much needed warming rebound started.
The adjacent painting depicts London in 1677, which is almost the same moment when Greenland reached its coldest temperatures after some 600 years of cooling (per the Greenland ice core dataset).
For 337 years since the bottom of the LIA, the world has been slowly but surely warming. That rebound warming though has only amounted to an approximate 2.2C degree increase as indicated by the ice core temperatures (Kobashi et al. estimated a current ice core decadal temperature of -29.9C degrees).
So, in the scheme of climate change, how does this most recent warming compare to previous warmings (and coolings)?
Using the temperature reconstructions from the Greenland ice sheet, it can be determined what the temperature change and duration was for each of the last 10 cooling periods and the last 10 warming periods (including the period since the LIA). From this information we know the following:
Climate change warming periods ranged in duration from 240 to 680 years
Climate change warming periods ranged in temperature increases from +0.8 to +3.7 degrees
Climate change cooling periods ranged in duration from 205 to 690 years
Climate change cooling periods ranged in temperature increases from -1.1 to +3.1 degrees
In contrast to the previous 9 significant warming periods, the modern warming has lasted only 337 years (from trough to current peak) with a temperature rise of only 2.2C degrees. It has been the 5th highest warming of the 10 and is only average in duration.
In contrast to the previous 9 cooling periods, the Little Ice Age lasted 643 years (from peak to trough) with a temperature decrease of 1.6(C) degree. It was the 3rd coldest cooling of the 10 and is one of the longest in duration.
Conclusion: Over some 9,000 years, the ice sheets of Greenland have faithfully recorded natural climate change and the associated temperature changes. These past changes, both warming and cooling, have produced greater temperature changes and lasted longer than the current modern warming and the more recent Little Ice Age. Although increasing CO2 levels from human emissions may have enhanced our modern, modest global warming, the lion's share of the warming rebound is likely from natural forces, which produced the same in the long ago past, multiple times.
Note: We used a 200 year minimum span to identify significant duration periods of warming and cooling.
The IPCC's now discredited 'hockey stick' temperature record attempted to change paleo-climate history by finding modern temps to be unprecedented - another new study confirms Medieval Warming Period was hotter
Read here. Paleo-climate research continues across the world and the vast majority of new studies confirm that earlier periods were warmer than our current climate. And the newest research establishes the same for Canada's Yukon region.
""Bunbury and Gajewski obtained sediment cores from Jenny Lake that "yielded chironomid records that were used to provide quantitative estimates of mean July air temperature."... This effort revealed the existence of "relatively warm conditions during medieval times, centered on AD 1200, followed by a cool Little Ice Age, and warming temperatures over the past 100 years." And from the authors Figure 8, reproduced below, it can be estimated that the Medieval Warm Period at Jenny Lake extended from about AD 1100 to 1350, and that the most recent (AD 1990) of their temperature determinations was about 0.8°C cooler than the peak warmth of the Medieval Warm Period." [Joan Bunbury, Konrad Gajewski 2012: Quaternary Research]
Conclusion: The Medieval Period had the unprecedented global warming, not our modern period. The Medieval warming took place during a time of low atmospheric levels of CO2, well before the modern growth of CO2 emissions.
Climate doomsday scientists and mainstream media proclaimed that modern temperatures were "unprecedented" when in fact they were not - a new study (the Rockall Trough) confirms the global warming science facts: the Medieval Period warming had higher temps
Read here. The Copard et al. team, using gravity core empirical evidence, reconstructed past temperatures of the northeastern Atlantic region. Their research proves these waters off the coast of Ireland experienced higher temperatures during the Medieval Period than those of today.
"Working with pristine aragonite fragments of fossil deep-sea corals of the species Lophelia pertusa taken by gravity core from the southwestern flank of Rockall Trough in the Northeast Atlantic Ocean...authors extracted the rare earth element neodymium (Nd) and calculated its isotopic composition (ɛNd)...revealed that "the warm Medieval Climate Anomaly (1000-1250 AD) was characterized by low ɛNd values (-13.9 to -14.5) ... while the Little Ice Age (around 1350-1850 AD) was marked by higher ɛNd values."...And because the ɛNd value of modern seawater recirculating in the northern North Atlantic at surface and intermediate depths is only -13.1 [currently], it can cautiously be concluded that ocean temperatures during the Current Warm Period have not eclipsed those experienced during Medieval times."[K. Copard, C. Colin, G.M. Henderson, J. Scholten, E. Douville, M.-A. Sicre, N. Frank 2012: Earth and Planetary Science Letters]
The 'hockey-stick' pseudo science that the IPCC attempted to fool the public with takes another hit - a new study concerning East China Sea temperatures confirms the known global warming science facts - unprecedented ocean temperatures were prior to modern era
(click on image to enlarge)
Read here. The IPCC's known political agenda requires it to publish "science" that purportedly establishes modern warming as unprecedented. One of the results of this agenda was the infamous and now discredited study known as the 'hockey stick'.
Unfortunately for the IPCC, the vast majority of scientific research confirms that ancient and historical global/regional temperatures do not resemble a hockey-stick with modern warming being higher than earlier periods. And now new Chinese research by Wu et al. has determined the same - there is no hockey-stick.
"The East China Sea SST reconstruction was developed by 5 researchers with various affiliations with several Chinese universities...collected a sediment core from the sea floor in the Southern Okinawa Trough (SOT) over which the warm Kuroshio current flows...The researchers analyzed the top 10 meters of the sediment core, corresponding to 2,700 years of sedimentation and from it were able to resolve 25-yr averages...shows a significant degree of long-term temperature variability...were able to identify the well-recognized climate periods of the past several millennia, including the Little Ice Age (LIA), Medieval Warm Period (MWP), Sui-Tang dynasty Warm Period (STWP), Dark Age Cool Period (DACP), and the Roman Warm period (RWP) along with the Current Warm Period (CWP) beginning in the mid-19th century...the temperatures at the end of the Current Warm period (CWP), are not the highest of the entire reconstruction. In fact, there are indications that there were 25-yr periods during nearly all of the previously identified warm periods in which the reconstructed temperature exceeded the recent average." [Weichao Wu, Wenbing Tan, Liping Zhou, Huan Yang, Yunping Xu 2012: Geophysical Research Letters]
Conclusions: The actual global warming science facts are again confirmed by the newest research. The IPCC's discredited 'hockey stick' was indeed bogus science. Unprecedented ocean temperatures (and regional/global) occurred prior to the modern era of growing consumer/industrial CO2 emissions.
New research keeps being added to the global warming science facts as we know them - a new Siberian study finds that climate has had frequent severe changes in the past and that extreme warm periods can't be explained by greenhouse gases (CO2)
Read here. The image on the left is Lake El'gygytgyn in Siberia. Scientists have been able to extract high resolution sediment cores from the lake that have recorded climate changes over the last 2+ million years.
From their analysis, a team of scientists (Melles et al.) have documented at least 8 significant warming periods in the past, with some exceeding modern temperatures by 5 degrees. The research indicates these warming periods can last for thousands of years without the aid (ie, cause) of increased levels of atmospheric CO2.
"Furthermore, the paper states, "Climate [model] simulations show these extreme warm conditions are difficult to explain with greenhouse gas [CO2] and astronomical forcing [solar insolation] alone." The paper also finds the Arctic warming occurred simultaneously with Antarctic warming, indicating an interconnected, global phenomenon. Implications of the paper include: 1) The globe has been much warmer without human influence during multiple periods over the past 2.8 million years, 2) IPCC climate models are incapable of reproducing past temps and therefore unable to project future temps, and 3) global warming far exceeding alarmist IPCC projections has occurred several times in the past without triggering any "tipping points."" [Martin Melles, Julie Brigham-Grette, Pavel S. Minyuk, Norbert R. Nowaczyk, Volker Wennrich, Robert M. DeConto, Patricia M. Anderson, Anthony Coletti,Timothy L. Cook, Eeva Haltia-Hovi, Maaret Kukkonen, Anatoli V. Lozhkin, Peter Rosén, Pavel Tarasov, Hendrik Vogel, Bernd Wagner 2012: Science]
Conclusions: This research finds that past extreme warming and climate change were not CO2 caused - the empirical observations from the past don't support the IPCC's version of the AGW theory. Extended warming periods do happen naturally without human contribution. Natural warming can be very dramatic. Those are the global warming science facts.
The UN's IPCC and associated climate doomsday scientists attempted to convince policymakers and the public that extreme climate change was occurring in the modern world world and that it was "unprecedented" - the historical empirical evidence does not support that conclusion
(click image to enlarge)
Read here. The UN's IPCC is not a climate science research agency. Instead, it is a bureaucratic political agency charged with "proving" human greenhouse gases (ie, CO2 emissions) are causing "unprecedented" global warming and climate change.
It conducts no original research, instead relying on cherry-picked peer reviewed studies and non-peer reviewed reports from green activist organizations. It prefers research studies that happen to also rely on cherry-picked data and/or flagrantly absurd statistical methodoloiges that produce the infamous hockey-stick presentation of past temperatures. The classic case of this IPCC-style of science, that's since been discredited, is this study and the most recent hockey-stick fiasco that had to be withdrawn is this one.
Because of the easy access to knowledge and information that the internet now provides, we can also discover the past and more current peer reviewed studies that the IPCC chose to avoid, ignore or dismissed because they did not support the political objective of proving the climate evils of CO2 greenhouse gases. One such report from the past that was ignored was conducted by Japanese researchers, which confirmed that modern climate change was not unusual but part of a natural pattern.
"In the early 1990s, Japanese scientists Kitagawa and Matsumoto extracted eleven tree ring cores from cedars on the...Japan island of Yakushima. The cores contained tree-rings going back some 2000 years. The researchers determined the carbon 13 isotope values and found the delta-13-C values fluctuated in a characteristic manner...The results showed that temperatures over the previous 2000 years in South Japan fluctuated over a range of 5°C...A clear millennium cycle is depicted. The cold period of the Migration Period, the Medieval Warm Period, the Little Ice Age and the Modern Warm Period are clearly recognisable. Moreover, this climate development is well documented in Japanese historical records...They carried out a detailed frequency analysis of their data and found characteristic cycles with periods in the range of several decades and centuries. Among others, they discovered a period of 187 years, which coincides with the known Suess/de Vries solar activity cycle. In a similar manner the 70 and 89-year Gleissberg-cycle was identified." [Hiroyuki Kitagawa and Eiji Matsumoto 1995: Geophysical Research Letters]
Conclusion: Extreme climate change as represented by significant global cooling and global warming periods over the past 2,000 years, is a natural phenomenon. Thus, modern global warming that took place over the late 20th century is not "unprecedented."
Modern temperatures have been claimed to be "unprecedented" yet the global warming science facts keeps intervening - a new ice core analysis from Svalbard reveals the Medieval Period to be much warmer
(click on image to enlarge)
Read here. New study documents Medieval Period winter temperatures that are significantly higher than those of the modern global warming.
This latest evidence comes from the Svalbard archipelago - Longyearbyen is on the peninsula of Spitsbergen, the largest island of the Svalbard archipelago. It is the world's northern-most town, with all settlements further north being research or meteorological outposts.
From the Divine et al. research:
"Working with ice cores extracted from Svalbard at Lomonosovfonna in 1997 and at Holtedahlfonna in 2005,...used the δ18O data derived from them to reconstruct a 1200-year winter...the 11-year running-mean peak winter temperature of the Medieval Warm Period was approximately 9°C greater than the end-of-record 11-year running-mean peak winter temperature." ["Working with ice cores extracted from Svalbard at Lomonosovfonna in 1997 and at Holtedahlfonna in 2005,...used the δ18O data derived from them to reconstruct a 1200-year winter...the 11-year running-mean peak winter temperature of the Medieval Warm Period was approximately 9°C greater than the end-of-record 11-year running-mean peak winter temperature." [Dmitry Divine, Elisabeth Isaksson, Tonu Martma, Harro A.J. Meijer, John Moore, Veijo Pohjola, Roderik S.W. van de Wal, Fred Godtliebsen 2011: Polar Research]
Conclusion: Modern global warming is not "unprecedented." The Medieval Period was a hotter era than our current climate. These are the simple global warming science facts that the empirical evidence corroborates.
The evidence for natural causes of global warming, and cooling, far outweighs the empirical evidence for human CO2-induced warming - a remote Andes mountain region lake confirms an excessive natural warming of the climate during the Medieval Period
Read here. The IPCC continues to proclaim that modern warming (okay, the IPCC does concede that the "warming" has disappeared over last 15 years) is "unprecedented." This proclamation is made based on the UN's political agenda and not the actual empirical research and evidence.
A plethora of peer reviewed studies provide absolute confirmation that prior periods were indeed warmer than our modern era; that both warming and cooling affected the entire globe and not just the European/North Atlantic region; and, that the significant prior climate change was entirely natural, not from human CO2 emissions.
A new study by scientists Fletcher and Moreno provides proof from the Southern Hemisphere that natural global warming is a powerful climatic force that is empirically irrefutable.
"The authors did an analysis of pollen and charcoal from Laguna San Pedro, a small closed-basin lake located in the Andes of Chile. Their results reveal centennial-scale changes in vegetation, climate and fire regime since 1500 cal yr before present...According to the study’s abstract, they found periods of relatively low summer moisture and increased fire activity between 1500–1300 and 1000–725 cal yr BP. The period 1000–725 cal yr BP (i.e. Medieval Warm Period) is characterised by remarkably rapid bulk sediment accumulation, from which they infer prolonged annual sedimentation resulting from a decrease in the duration of lake freezing under a warmer climate. Before the Medieval Warm Period, i.e. 1300–1000, they found relatively moist conditions during summer and low fire activity. After the Medieval Warm Period, from 725–121 cal yr BP, there was slow bulk sediment accumulation implying a cool and wet climate." [Michael-Shawn Fletcher, Patricio Iván Moreno 2012: Quaternary Science Reviews]
Conclusions: Natural causes of global warming and cooling are well documented, not only by anecdotal evidence, but from global empirical research of peer reviewed studies, including evidence from the Southern Hemisphere. It is a scientific travesty that the IPCC rejects the findings of the vast majority of peer reviewed research and instead relies on a handful discredited hockey-stick papers that use the same proxies over and over, and then employ absurd statistical tecniques that can't withstand professional scrutiny. By denying the natural Medieval Warming, the IPCC clearly establishes that the UN political agenda supercedes the actual science.
The IPCC’s climate doomsday scientists claim the modern global temperatures are “unprecedented” - the global warming science facts are irrefutably that past climate was warmer than our modern temperatures with a much lower atmospheric CO2 level
(click images to enlarge)
Read here. Another study, another nail in the “unprecedented” AGW coffin. New scientific research keeps refuting the claims of IPCC and chicken-little pundits. The empirical evidence is robustly overwhelming: global temperatures were warmer thousands of years ago despite low CO2 levels.
The two images above reflect the evidence of the warmer climates some six to ten thousand years ago. The image on the left reveals the history of the northern treeline in Finland and the image on the right the same for Siberia. The simple fact of a more northern treeline in both cases requires earlier periods to be considerably warmer than the current climate.
Now, a new study reveals that the northern treeline in Rocky Mountains was at a much higher altitude from six to nine thousand years ago, which confirms the extra warm climate was not just limited to the Finland/Siberia areas.
“…finds that the elevation of the treeline in the Rocky Mountains of Wyoming was higher than the present from approximately 9000 to 6000 years ago, indicating the climate was warmer during that period as compared to present temperatures. The paper adds to thousands of others indicating that the current warming period is not unprecedented; nor unusual compared to natural warming in the past.” [Scott Mensing, Thomas Minckley, Robert Musselman 2012: The Holocene]
Conclusions: The global warming science facts are often inconvenient - Earth was warmer in the past versus modern temperatures. The empirical evidence refutes claims that our current climate is on "unprecedented" warmth. In addition, the empirical evidence well establishes that warmer climates of the past occurred during periods of low atmospheric CO2. Climate doomsday scientists can take solace that they will be able to continue to predict climate catastrophe without ever being held accountable.
With constant frigid temperatures, the idea of modern Antarctica "global warming" that is "unprecedented" seems rather ludicrous - indeed it is ludicrous, as latest research again confirms Medieval Warming Period was hotter
Read here. The reality is that climate change just happens normally as the world goes through its typical warming and cooling phases, including the Southern Polar regions. Yet climate doomsday scientists insist on claiming that modern Antarctica warming is "unprecedented" - but is that really true?
Another peer reviewed study, this one by Lu et al., has determined that present-day warming has not reached the levels of the Medieval Warming era, which confirms unprecedented warming is not happening.
"...if collected and maintained at low temperatures, preserve hydration waters and their intact crystal structures, both of which have the potential to provide isotopic constraints on past climate change," after which they report on what they describe as "the first downcore δ18O record of natural ikaite hydration waters and crystals collected from the Antarctic Peninsula (AP)," which they say were "suitable for reconstructing a low resolution ikaite record of the last 2000 years." This record, as they continue, "qualitatively supports that both the Medieval Warm Period and Little Ice Age extended to the Antarctic Peninsula."...and they importantly indicate that "this climatic signature is not yet as extreme in nature as the MWP," suggesting that even the dramatic recent warming of the AP may not yet have returned that region to the degree of warmth that was experienced there during the MWP." [Zunli Lua, Rosalind E.M. Rickaby, Hilary Kennedy, Paul Kennedy, Richard D. Pancost, Samuel Shaw, Alistair Lennie, Julia Wellner, John B. Anderson 2012: Earth and Planetary Science Letters]
Conclusions: The ruse of Antarctica "global warming" continues to be undercut by the empirical evidence, both historical and modern. As of 2012, the modern warming of the Antarctica Peninsula is not "unprecedented" no matter the claims of climate doomsday scientists.
The IPCC and related Climategate climate research agencies conveniently ignore empirical evidence that confirms today's temps are not unusual - data from the Penny ice cap is one such source
(click on image to enlarge)
Read here. Less than credible climate "science" sources, such as the IPCC, continue to claim today's temperatures are "unprecedented" or "unusual." These type of false statements firmly establish the anti-science stance of the political agenda the UN's IPCC agency is pursuing.
The recent global warming science facts from Canada's Baffin Island is another example of the overwhelming evidence that past global warming prior to industrial CO2 emissions was considerably higher.
A team of scientists, Zdanowicz et al., analyzing the summer water melt rate for the Penny ice cap determined its 2010 temperatures were consistent with temperatures of 3,000 years ago - meaning, that current temps are significantly below those of both the Roman and Minoan warming spans. [see their adjacent plot of ice core temps]
"A paper published today in the Journal of Geophysical Research shows that a large ice cap in the Canadian Arctic had surface temperatures higher than the present for the vast majority of the past 11,000 years. The paper also shows that the meltwater fraction in 2010 was slightly less than the vast majority of a 7000 year period from roughly 10,000 to 3000 years ago...At latitude 67°N, Penny Ice Cap on Baffin Island is the southernmost large ice cap in the Canadian Arctic, yet its past and recent evolution is poorly documented. Here we present a synthesis of climatological observations...Recent surface melt rates are found to be comparable to those last experienced more than 3000 years ago." [Christian Zdanowicz, Anna Smetny-Sowa, David Fisher, Nicole Schaffer, Luke Copland, Joe Eley, Florent Dupont 2012: Journal of Geophysical Research]
Conclusion: The global warming science facts are unforgiving - the actual empirical evidence refutes claims by the IPCC and its Climategate scientists that modern temperatures are unprecedented within the higher northern latitudes. To be factually correct, a startling large number of extended periods over the past 7,500 years had global warming in excess of modern warming.
Read here. The IPCC and Climategate scientists, such as Michael Mann, attempted to mislead the public and policymakers with claims that the Medieval Warming Period was an insignificant climate event only affecting the northern European areas. However, the empirical evidence continues to grow that the Southern Hemisphere experienced a global medieval warming climate also.
Analyzing sediment cores from the Merín Lagoon Basin, in the region of the ancient Uruguay 'Los Ajos' mound builders, it was determined from opal phytoliths that Uruguay's climate of 750 AD to 1350 AD was warmer and wetter than those of its current modern climate.
"Focusing on coastal lagoons within the Merin Lagoon Basin, which is located between 31-34°S and 52-54°W in the easternmost part of the South American plains, and working with phytoliths found within various sediment cores which they used to create a temperature index indicative of relative warmth, Bracco et al. discovered a period of time straddling the division of the last two millennia (AD 750-1350) that they identified as having "warmer and wetter conditions than those of the present."" [Roberto Bracco, Laura del Puerto, Hugo Inda, Daniel Panario, Carola Castiñeira, Felipe García-Rodríguez 2011: Quaternary International]
Conclusion: Medieval global warming was a significant climate phenomenon that empirically prevailed across the world and not just limited to the northern European/Atlantic region as fabricated by the IPCC.
The IPCC and Michael Mann claimed that modern Antarctica climate change is "unprecedented' - new polar research demolishes that myth
Read here. Without doing any scientific field research, the IPCC and Climategate's Michael Mann chose to promulgate a non-scientific position that the Medieval Warming Period and the Little Ice Age were only local European phenomena. Their political agenda was to establish the myth that Antarctica climate change was unaffected by the MWP and the LIA.
That myth is no longer sustainable.
The team of Lu et al. published new research conclusively proving that the Antarctica continent also experienced both the MWP and LIA. In essence, the climate of previous centuries is similar to the climate Antarctica now has (as depicted in the adjacent image) - the modern South Pole climate is not "unprecedented."
"At present the Intergovernmental Panel on Climate Change (IPCC) argues that the Medieval Warm Period was confined to Europe – therefore that the warming we’re experiencing now is a man-made phenomenon...However, Professor Lu has shown that this isn’t true – and the evidence lies with a rare mineral called ikaite, which forms in cold waters...The scientists were particularly interested in crystals found in layers deposited during the ‘Little Ice Age,’ approximately 300 to 500 years ago, and during the Medieval Warm Period before it...‘We showed that the Northern European climate events influenced climate conditions in Antarctica,’...They were able to deduce this by studying the amount of heavy oxygen isotopes found in the crystals." [Zunli Lu, Rosalind E.M. Rickaby, Hilary Kennedy, Paul Kennedy, Richard D. Pancost, Samuel Shaw, Alistair Lennie, Julia Wellner, John B. Anderson 2012: Earth and Planetary Science Letters]
Conclusion: Modern Antarctica climate change is not unusual; is likely to have nothing to do with CO2 emissions; and similar climate variation happened in the past.
The empirical evidence continues to mount that documents the Roman and Medieval unprecedented warming - dust storms from the Aral Sea is the latest empirical evidence
Read here. The adjacent image is a classic example of the extreme environmental devastation produced by progressive / left government regime scientists. Although scientific geo-engineering has destroyed the Aral Sea, its historical evidence still provides further proof that modern global warming is not unprecedented.
The Huang et al. peer reviewed research analyzed 2000 years of dust storm residue and unequivocally determined that both Roman and Medieval minimum temperatures were higher than modern minimum temperatures for this central Asia region - a clear indication of warmer climates during earlier historical periods.
"Noting that dust storms are common features adjacent to the Aral Sea, the authors investigated the grain-size distributions of wind-blown sediments found in a core retrieved from that water body...report that the history of dust deposition in central Asia can be divided into five distinct periods on the basis of their observations: "a remarkably low deposition during AD 1-350, a moderately high value from AD 350-720, a return to a relatively low level between AD 720 and AD 1400 (including the Medieval Warm Period), an exceptionally high deposition from AD 1400 to [the] 1940s and an abnormally low value since [the] 1940s."...coincides with the Roman Warm Period, the second with the Dark Ages Cold Period, the third (as Huang et al. make a point of noting) with the Medieval Warm Period, the fourth with the Little Ice Age, and the fifth with the Current Warm Period...with low/high annual temperature anomalies corresponding to high/low dust supplied in the Aral Sea sediments, respectively...the minimum value of this inverted measure of annual temperature during the Medieval Warm Period was approximately 13% more extreme than the minimum value so far experienced during the Current Warm Period, and that the minimum value during the Roman Warm Period was fully 70% more extreme than that of the present." [Xiangtong Huang, Hedi Oberhänsli, Hans von Suchodoletz, Philippe Sorrel 2011: Quaternary Science Reviews]
Conclusion: Historical climate change, as represented by the Roman and Medieval unprecedented warming documented in central Asia, was a global phenomenon that modern climate change has yet to rival.
Climate science and consensus evidence is now moving to a position that natural climate change causes unprecedented warming (global and/or regional) - a major refutation of IPCC's denial of natural climate impacts
Read here and here. The IPCC's political agenda requires a denial dogma that is built on the concept that natural climate change is minor, thus the recent warming of the 1980's and 90's is a result of human CO2 emissions.
Of course, the lack of global warming over the last 17 years has made a shambles of the AGW hypothesis, plus new research continues to bolster the climate science thesis that natural climate change actually drives unprecedented temperature change. New research by Chen et al. confirms the power of natural climate forcings.
"...they state, in this regard, that "one of the most intriguing questions within the climate debate is if the present temperature rise is unique in the late Holocene or if there have been pre-industrial time intervals where comparable climatic perturbations occurred," noting that "one of these time intervals where historical records suggest that climate conditions might have been similar to today is the so called 'Roman Warm Period' (~200 BC - AD 400)."...developed high-resolution climatic and environmental reconstructions "based on a dinoflagellate cyst record from a well dated site in the Gulf of Taranto located at the distal end of the Po River discharge plume." ...determined that the dinoflagellate cyst warm/cold ratio suggests that sea surface temperature (SST) was "relatively high and stable between 60 BC and AD 200," which they say is suggestive of "slightly higher SST than today." In fact, they say that the association that is observed between 60 BC and AD 90 is equivalent to modern regions that are characterized by higher SST than those in the present day Gulf of Taranto. And noting that "Versteegh et al. (2007) showed that SST in the region is strongly related to local air temperature," they go on to suggest that the region's air temperature "might have been warmer during the Roman Period as well."" [Liang Chen, Karin A.F. Zonneveld, Gerard J.M. Versteegh 2011: Quaternary Science Reviews]
Conclusion: Paleo-climate empirical evidence from the Roman Period indicates that natural climate change causes unprecedented warming, which also may have been the dominant causal factor the modern warming during the 1980-1990's period.
Climate 'urban myths' have plagued policymakers and the public for years - fortunately Michael Mann's "unprecedented" modern global warming myth is finally dying an empirical-death
(click on image to enlarge)
Read here. Urban myths of Hollywood celebrities, the mainstream press and coastal elites are often foisted on the public and policymakers as "consensus" science.
A recent example was the left/liberal urban legend that vaccines cause autism, which a scientist-fraud perpetrated. (As researchers have amazingly documented, scientific fraud is rampant.)
The classic climate "science" urban myth is that 20th century global warming was "unprecedented" when in fact empirical study after study proves that myth to be without scientific merit. And now a new study demolishes that myth conclusively - will the discredited 'hockey stick' caricature of past temperatures now finally die?
"Working with the GISP2 ice core from the Summit region of central Greenland, Kobashi et al. reconstructed Greenland surface snow temperature variability over the past 4000 years with a method that utilizes nitrogen and argon isotopic ratios..."The estimated average Greenland snow temperature over the past 4000 years was −30.7°C with a standard deviation of 1.0°C and exhibited a long-term decrease of roughly 1.5°C, which is consistent with earlier studies. The current decadal average surface temperature (2001–2010) at the GISP2 site is −29.9°C. The record indicates that warmer temperatures were the norm in the earlier part of the past 4000 years, including century-long intervals nearly 1°C warmer than the present decade (2001–2010). Therefore, we conclude that the current decadal mean temperature in Greenland has not exceeded the envelope of natural variability over the past 4000 years..."" [Takuro Kobashi, Kenji Kawamura, Jeffrey P. Severinghaus, Jean-Marc Barnola, Toshiyuki Nakaegawa, Bo M. Vinther, Sigfús J. Johnsen, Jason E. Box 2011: Geophysical Research Letters]
Arctic Greenland was warmer than modern warming during the Bronze, Roman and Medieval periods - ergo, modern warming not unprecedented
Despite massive industrial/consumer human CO2 emissions, modern warming is easily within natural climate variation
Scientists claiming that modern warming is "unprecedented" are simply lying (or, amazingly ignorant of the plethora of actual empirical evidence)
Experts reconstruct sea surface temperatures off of Norway - evidence confirms this subarctic region was warmer during Roman and Medieval times
Read here. It's another peer reviewed study published that refutes Mann's 'hockey stick' caricature of past temperatures over the last 2000 years. (click image to enlarge)
Modern warming is not unprecedented as claimed by the IPCC's Climategate "scientists."
"Sejrup et al established exceptionally accurate chronologies for two marine sediment cores raised from the same location on the Norwegian continental margin...they developed the δ18O history depicted in the figure [adjacent], which they use as a proxy for what they call "near surface water summer temperature." And as this history clearly shows, the peak warmth of the Medieval Warm Period was significantly greater than the peak warmth of the Current Warm Period has been to date." [H.P. Sejrup, H. Haflidason, J.T. Andrews 2011: Quaternary Science Reviews]
The NOAA under Lubchenco's control continues to make a mockery of empirical-based science as global warming fabrication continues unchecked
This is an update from the two previous posts, here and here. During the month of December, NOAA / NCDC revised their published historical temperature dataset at least 6 times - affecting monthly historical temperatures going back to 1880. These major revisions were not constrained to just a few recent months or a few recent years, but to all the historical empirical records.
If doing it 6 times in December wasn't bizarre enough, the NOAA "scientists" have already revised the entire dataset 3 times during January (the month isn't even over yet). [Ed. Good news: No new revised datasets in last 2 days, which means the incessant changes may be halted until next month]
Since the Obama administration takeover of NOAA / NCDC, it has been on a tear to fabricate global warming, conducting major temperature fabrication on an almost monthly basis, which has now culminated to producing multiple major revisions per month. (click to enlarge images)
(Above is a sample of revisions, including 2 (of 3) done in January 2012.)
Defenders of Lubchenco's empirical evidence revisionism refer to the constant revisions as "quality control" which is categorically one of the lamest piles of B.S. uttered in the debate on global warming. If the 'QC' defense had even an ounce of truth to it, it would mean every single previous revision had "quality control" issues even though each was a result of the same quality control process.
Plus, in contrast to the 7 major revisions done by NOAA / NCDC over the last 4 weeks, there has been only one major revision by GISS and zero for HadCRUT, UAH and RSS. (These other alphabet climate agencies do not do major revisions every single month, let alone multiple major revisions to the historical record within a month.)
Simply put, the 'big green' activist Lubchenco must have a political agenda that calls for the NCDC dataset exhibiting more "global warming."
Needless to say, her servile puppet-scientists have performed that task since 2008, month-in and month-out, as the change in the global warming trend exhibits (red is new trend; blue is old) in the adjacent chart.
[Bonus recommendation to NOAA/ NCDC: Publish only one set of numbers per month; avoid changing historical temperatures prior to 1990; and, make future changes random so that they don't appear to be purposefully warming specific periods while cooling others. Food for thought.]
BTW, this Excel chart represents the typical way that alarmists portray "runaway" global warming. That red trend line leaves the impression that global warming will go through the roof by 2100. In fact though, that red trend line indicates a "global warming" of about +0.5°C by year 2100. To mislead the public and policymakers, alarmist scientists and the mainstream press typically avoid putting numeric linear trend information on the chart, for very obvious reasons.
New Antarctica evidence conclusively refutes IPCC global warming scientists' speculation that modern temperatures are "unprecedented" and "accelerating" higher
Read here. The UN's IPCC attempted to convince the public and policymakers that there was a scientific "consensus" that the last 150 years have witnessed "accelerating" global warming that is "unprecedented."
Instead, the evidence now points to the IPCC and its Climategate scientists conspiring to mislead. Thankfully, the vast majority of the world's scientists do not believe in the IPCC's climate political-science proclamations and thus continue performing/producing empirical research to determine the science truth.
The non-IPCC research team of Thamban et al is an example of this and the adjacent chart (click to enlarge) is a product of their research: Antarctica's modern temperatures are not unusual, nor are they rapidly warming versus what has occurred naturally in the historical past. As the evidence clearly shows, a natural warming has been taking place over the last 400+ years.
"Working with an ice core (IND-22/B4) that had been extracted during the austral summer of 2003 from the coastal region of Dronning Maud Land, East Antarctica... -- the authors developed 470-year histories of δ18O and δD that "showed similar down core fluctuations with [an] excellent positive relationship (R2 = 0.9; n = 216) between the two."..."the estimated surface air temperature at the core site revealed a significant warming of 2.7°C with a warming of ~0.6°C per century for the past 470 years."..."...Thamban et al.'s results clearly indicate that all three of these climate-alarmist claims are false in regard to this portion of the planet's southern polar region." [Meloth Thamban, C. M. Laluraj, Sushant S. Naik and Arun Chaturvedi 2011: Journal of the Geological Society of India]
Latest scientific research completely debunks Michael Mann's bogus hockey stick chart - North Atlantic ocean temperatures warmer during Medieval Warming
Read here. As the adjacent chart reveals, both the Roman and Medieval periods included significantly warmer sea surface temperatures in the North Atlantic region.
Around 1250 AD, the Little Ice Age started a cooling process of the sea surface temperatures, which modern warming has yet to recover from.
There is no hockey stick as claimed by Michael Mann. There is no "unprecedented" and "accelerating" warming as claimed by the IPCC. The empirical evidence does not support the left / liberal / progressive / Democrat claim of dangerous climate change due to CO2 warming.
"A paper published today in the journal Paleoceanography finds that Atlantic Ocean surface temperatures have significantly cooled over the past millennium, since the Medieval Warming Period from about 950-1200 AD...Cooling by ∼0.5°C takes place between about AD 1250 and AD 1500; while this corresponds to the inception of the Little Ice Age (LIA), the end of the LIA is not reflected in our record and SST remains relatively low. This transition to cooler SSTs parallels the previously reconstructed shift in the North Atlantic Oscillation toward a low pre-20th century mean state and possibly reflects common solar forcing." [Henning Kuhnert, Stefan Mulitza 2011: Paleoceanography]
New research determines that South America did experience the Medieval Warming and temperatures were higher during MWP, contrary to Michael Mann's hockey stick "science"
Read here. As hundreds of scientists have discovered and published, the Medieval Warming (MWP) climate was global in nature, with temperatures that in many areas of the world were higher than today's temperatures.
Contrary to Michael Mann's now widely discredited hockey stick "science," the Neukom et al research found the MWP was a significant high temperature event in South America. This team of 18 highly qualified researchers came from 7 countries; they chose the best 22 climate proxies to reconstruct a thousand+ year temperature series. (click to enlarge chart)
"The international research team — composed of scientists from Argentina, Chile, Germany, Switzerland, The Netherlands, the United Kingdom and the United States — write that their summer temperature reconstruction suggests that “a warm period extended in SSA from 900 (or even earlier) to the mid-fourteenth century,” which they describe as being temporally located “towards the end of the Medieval Climate Anomaly as concluded from Northern Hemisphere temperature reconstructions.” And as can be seen from the figure below, the warmest decade of this Medieval Warm Period was calculated by them to be AD 1079-1088, which as best as can be determined from their graph is about 0.17°C warmer than the peak warmth of the Current Warm Period." [Neukom, R., Luterbacher, J., Villalba, R., Kuttel, M., Frank, D., Jones, P.D., Grosjean, M., Wanner, H., Aravena, J.-C., Black, D.E., Christie, D.A., D'Arrigo, R., Lara, A., Morales, M., Soliz-Gamboa, C., Srur, A., Urritia, R. and von Gunten, L. 2011: Climate Dynamics]
New research continues to break Michael Mann's discredited hockey stick - individual proxy studies invalidate Mann's claims
Michael Mann concocted the infamous hockey stick temperature chart in an attempt to overturn known, well established paleo-temperature history. His research was soon after discredited by expert statisticians when it was found that Mann had over-weighted a single American tree some 390 times in order to produce his desired result.
The hockey stick was so thoroughly discredited that the IPCC had to quit using it in their PR "science" literature.
Read here. Most individual climate proxy studies are unable to reconstruct a temperature series that resembles the infamous Mann research. The newest study unable to do so is the Liu et al peer-reviewed research.
(click on image to enlarge)
As the 2,485 year old tree ring chart depicts, modern warming is well within the natural variability that the Tibet Plateau has experienced. As with so many independent studies, the hockey stick statistical fabrication is non-repeatable - it solely exists in the bowels of the Climategate conspirators and their bizarre methodologies.
"A blockbuster Chinese study of Tibetan tree rings by Liu et al 2011 shows, with detail, that the modern era is a dog-standard normal climate when compared to the last 2,500 years. The temperature, the rate of change — it’s all been seen before. Nothing about the current period is “abnormal”...these climate cycles have nothing to with human civilization. Their team finds natural cycles of many different lengths are at work: 2-3 years, 100 years, 199 years, 800 years, and 1,324 years. The cold periods are associated with sunspot cycles...The results showed that extreme climatic events on the Plateau, such as the Medieval Warm Period, Little Ice Age and 20th Century Warming appeared synchronously with those in other places worldwide. The largest amplitude and rate of temperature change occurred during the Eastern Jin Event (343–425 AD), and not in the late 20th century..." [Yu Liu, QiuFang Cai, HuiMing Song, ZhiSheng An, Hans W. Linderholm 2011: Chinese Science Bulletin]
Despite the bogus claims of the UN's bureaucrats and the IPCC Climategate "scientists," the polar areas of the Northern Hemisphere have had warmer climates prior to the 20th and 21st centuries.
There is a vast body of research and empirical evidence confirming that the Arctic regions, and other parts of the globe, were indeed warmer during both the Roman and Medieval eras. In fact, global warming, cooling and climate change are natural events that never cease - that is irrefutable, unequivocal climate reality.
A peer-reviewed study by Perner et al. just added to that mountain of evidence confirming the robust warming of the Greenland area prior to the the modern era.
"The six researchers -- hailing from Denmark, Germany, Norway, Poland and the United Kingdom -- say that their new high-resolution benthic foraminiferal record from Disko Bugt "documents a marked long-term cooling trend over the last 3.6 ka BP," but they state that superimposed on this longer-term late Holocene cooling trend, there is evidence of millennial to centennial scale variability. This variability begins with what they describe as "a pronounced cooling event" at c. 2.5 ka BP, after which "a warm phase in bottom waters is recorded at c. 1.8 ka BP, which corresponds to the 'Roman Warm Period' and is seen to represent the warmest bottom water conditions recorded in Disko Bugt during the last 3.6 ka BP." This unique warm period was in turn followed by a cooler period (which would obviously be the Dark Ages Cold Period), after which they identify a warming of the subsurface waters during the 'Medieval Climate Anomaly'," which was followed (from 0.9 ka BP) by "pervasive and even harsher environmental conditions" that ultimately culminate at 0.3 ka BP in what they say is the Little Ice Age, and from which the region has yet to recover to Medieval Warm Period conditions." [K. Perner, M. Moros, J.M. Lloyd, A. Kuijpers, R.J. Telford, J. Harff 2011: Quaternary Science Reviews]
Another study disproves Penn State's Michael Mann global warming hockey-stick "science"
Read here. With the advancement of paleo-climate science in recent years, the empirical evidence clearly indicates that Penn State's Michael Mann 'hockey stick' temperature graph to be without merit. The hockey-stick scenario was so discredited that even the IPCC eliminated it from their 2007 report.
Yet the hockey-stick myth continues to survive as a green legend despite the mounting empirical evidence that the Medieval Global Warming remains unprecedented.
Indeed, as the adjacent chart indicates, the Medieval Warming was significantly higher than the current warming.
Abrantes et al. just published research revealing the persistent high Medieval temperatures of coastal waters off the Portugal coast. Their analysis (from 900 AD to year 2002) is based on a sediment core from the Atlantic Ocean seabed.
As can be seen, levels of atmospheric CO2 have had little, if any, impact on sea surface temperatures. And this specific research clearly indicates that as CO2 levels rose, the SSTs declined - opposite of IPCC's climate model predictions.
"Abrantes et al. reconstructed a sea surface temperature (SST) history for waters off the coast of Porto, Portugal covering the past thousand years...revealed the occurrence of the Little Ice Age, as well as what they describe as the "persistently higher temperatures registered in the AD 960-1300 interval that we identify as the MWP [ed: Medieval Warming Period]." And from a graph of their SST history, one can see that the peak warmth of the MWP was about 1.2°C greater than the peak warmth of the CWP during the late 20th century." [F. Abrantes, T. Rodrigues, B. Montanari, C. Santos, L. Witt, C. Lopes, A. H. L. Voelker 2011: Climate Research]
Read here. The Climategate scandal was the door opening that revealed a cadre of IPCC "scientists" conspiring to push their rendition of crop circle pseudoscience. A key component of that effort was the infamous "hockey-stick" that purported to show modern era temperatures to be unprecedented, and the climates of the Medieval Warming (MWP) and Little Ice Age (LIA) to be minor blips of no significance. The IPCC's crop circle scientists also claimed that the MWP and LIA only existed in the small regional area of the north Atlantic/European geography. Subsequent studies and a mountain of empirical evidence refutes the IPCC pseudoscience.
A new peer-reviewed paper by Bertler et al., using the latest deuterium and temperature-isotope science, constructed temperatures going back 1,100 years. The new temperature dataset (see adjacent chart - click to enlarge) clearly shows the LIA in Antarctica to be massively cooler than modern temperatures; the dataset establishes that the modern warming is not "unprecedented" as the MWP is slightly warmer.
"The researchers obtained new deuterium (δD) data from the Ross Sea region of Antarctica that they acquired via analysis of the top fifty meters of a 180-meter-long ice core that had been extracted from the ice divide of Victoria Lower Glacier...work revealed three climatically-distinct time periods: the last 150 years of the Medieval Warm Period (MWP, AD 1140 to 1287), the Little Ice Age (LIA, AD 1288 to 1807), and the Modern Era (ME, AD 1808 to 2000)...authors report that "the final 150 yrs of the MWP were ... about 0.35 °C warmer than the ME,"" [N.A.N. Bertler, P.A. Mayewski, L. Carter 2011: Earth and Planetary Science Letters]
Read here. Map source. The Mannian style of climate science was established to fabricate a scenario that the Medieval Warming (MWP) and Little Ice Age (LIA) periods were insignificant weather blips, primarily felt in the northern Atlantic/European region. A vast amount of both anecdotal and paleo-climate empirical evidence refutes Mann's contentions that the MWP and LIA were insignificant and only regional. Another peer reviewed study adds to the refutation.
Researchers Rivera et al. determined that the current terminus position of the Chilean glacier Jorge Montt is the same as the terminus position prior to the onset of the LIA, some 450 years before present (~1550 AD). Dendrochronology analysis established that the maximum extent of the glacier was achieved around 1750 AD.
"A team of scientists studied tree rings...recently exposed by the retreating Patagonian glaciers....trees were dated using radiocarbon methods, yielding burial ages between 460 and 250 years ago...study confirms that the Little Ice Age existed in Chile too. Now remember how the high-sticking hockey team kept trying to have us believe that the Medieval Warm Period-Little Ice Age thing was a local phenomena, and not global?...No misprint there. It’s correct. Before the LIA the Chilean glaciers were at the same spot as the present position. Send a copy of that paper to Michael Mann..." [A. Rivera, M. Koppes, C. Bravo, J. C. Aravena 2011: Climate of the Past]
Read here. Map source. Modern climate alarmists, such as Joe Romm, Michael Mann, Jeff Masters, Al Gore and Kevin Trenberth, commonly deny or lie about significant climate change that took place over the last 5,000 years. Reflecting on their denial of the overwhelming empirical evidence, if they were to admit to the reality of past climate change then that would be a tacit approval that abrupt climate change is natural and does not require high atmospheric levels of CO2. Adding to their woes of gross misrepresentation of past climate history, comes another new study that confirms the reality of past abrupt climate change, further denigrating the position of all past climate change deniers.
Larsen et al. performed multiple analysis of sediment cores of an Iceland glacial lake. The analysis clearly documents the robust climate change during the periods of the Dark Ages,the Medieval Warming and the Little Ice Age. The empirical evidence points to the extreme warmth of Iceland's climate during the MWP and the extreme cold of the LIA.
"A suite of environmental proxies in annually laminated sediments from Hvítárvatn, a proglacial lake in the central highlands of Iceland, are used to reconstruct regional climate variability and glacial activity for the past 3000 years...Varve thickness is controlled by the rate of glacial erosion and efficiency of subglacial discharge from the adjacent Langjökull ice cap...ice-cap expansion is punctuated by notable periods of rapid ice cap growth and/or landscape instability at ca 1000 BC, 600 BC, 550 AD and 1250 AD. The largest perturbation began ca 1250 AD, signaling the onset of the Little Ice Age and the termination of three centuries of relative warmth during Medieval times.Consistent deposition of ice-rafted debris in Hvítárvatn is restricted to the last 250 years, demonstrating that Langjökull only advanced into Hvítárvatn during the coldest centuries of the Little Ice Age." [Darren J. Larsena, Gifford H. Millera, Áslaug Geirsdóttirb, Thorvaldur Thordarsonc 2011: Quaternary Science Reviews]
Read here. The paleo-climate empirical evidence continues to grow that documents the unequivocal, unprecedented warming of pre-industrial periods in many parts of the world. Thousands of researchers have now demonstrably proven that the recent IPCC Climategate science flim-flam and hockey-stick statistical bogosity claims, purporting to prove that higher levels of CO2 during industrial times have led to "unprecedented" warming, are without empirical merit.
The new Stewart et al. research clearly shows (click on image to enlarge) that the Lake Silvaplana, Switzerland region had robustly higher temperatures well prior to the modern industrial/consumer atmospheric levels of high CO2. During Roman and the pre-Roman iron age eras, peak summer temperatures would be considered unnaturally extreme by today's global warming alarmists.
"Working with a piston core that was extracted during the winter of 2005-2006 from Lake Silvaplana in the eastern Swiss Alps, the authors developed a June-July-August (JJA) temperature history of the surrounding region...report that "temperatures reconstructed from ca. 570 BC to AD 120 were warmer than today (AD 1950-2000; 9.8°C)," with the JJA temperatures of the warmest portion of this interval (ca. 570-351 BC) being approximately 11.2°C, after which they say they also "found moderately warm temperatures for the Roman Period (11°C, ca. 15 BC to AD 120)."...which yields a peak Current Warm Period temperature of 10.3°C. And thus we see that the peak temperature of the Roman Warm Period (11°C) was about 0.7°C warmer than the peak temperature of the Current Warm Period, while the peak temperature of the earlier 570-351 BC period (11.2°C) was approximately 0.9°C warmer than the peak temperature of the Current Warm Period." [Monique M. Stewart, Isabelle Larocque-Tobler, Martin Grosjean 2011: Journal of Quaternary]
Read here. The vast majority of new scientific research continues to document that the modern era's warming barely rivals what was experienced during the Medieval Period.
Other than the widely discredited hockey-stick style of temperature reconstructions, the empirical evidence continues to expand, supporting the well known historical anecdotal information about the Medieval Warming.
A new peer-reviewed study by Kaniewski et al. provides important evidence of the Medieval Warming Period (MWP) in the Middle East region of the world. An analysis of pollen from a Syrian sediment core confirms an extended state of higher temperatures during the MWP's low atmospheric CO2 environment.
"Based on analyses of pollen found in a 315-cm-long sediment core retrieved from alluvial deposits within the floodplain of the River Rumailiah in the coastal Syrian lowland, Kaniewski et al. were able to identify key plant functional types that allowed them to construct pollen-derived Biomes (PdBs) similar to those employed by Tarasov et al. after which they were able to relate "the ratio of PdB warm steppe (WAST) divided by PdB cool steppe (COST) to local temperature...The end result of this endeavor was their identification of the timeframe of the MWP (AD 1000-1230) and their finding that at approximately AD 1130, the MWP exhibited "warmer temperatures compared to AD 2000,..." [D. Kaniewskia, E. Van Campoa, E. Paulissend, H. Weisse, J. Bakkerc, I. Rossignola, K. Van Lerberghef 2011: Global and Planetary Change]
Read here. It's been well documented that global warming ideologists will always make every attempt to slant paleo-climate research in such a way that modern warming appears to be "unprecedented." This built-in research bias is very prevalent in tree-ring studies, which the infamous 'hockey-stick' fraud is the classic example - e.g., over-weighting a single tree species by 390 times in the hockey-stick study revealed how desperate researchers have been to create a warming bias.
Despite the efforts of some researchers, more objective and impartial scientists are conducting peer-reviewed studies that avoid the significant problems (flim-flam) of tree-ring analysis. The vast preponderance of these studies reveal the wide natural variations in both temperatures and climates over thousands of years. In addition, most establish that the Medieval Warming Period (MWP) was indeed warmer than our modern warming (but not always).
As an example, the recent Moschen et al. German peat bog research confirms that area of the world had considerably higher temperatures for an extended period during the MWP.
Their research also provided a unique indicator for the extreme temperatures of natural climate - varying without any industrial/consumer CO2 emission impact. As the adjacent chart shows, there is a large, multi-century gap with no peat bog data recorded (where the bold blue curve goes missing). That's when the post-Medieval Warming era became so freaking cold the natives actually dug up (The 'Big Dig') the bog's empirical evidence to burn in their homes to keep warm.
"A new paper by Moschen et al appearing in the journal Climate of the Past presents a high resolution reconstruction of local growing season temperature (GST) anomalies at Dürres Maar, Germany over the last two thousand years...In 2007, a 5.5 m long core was recovered from the centre of Dürres Maar peat bog in the mountainous West Eifel Volcanic Field in southwestern Germany...I got a copy of the paper from a source, who wrote: “The ex-hockey team will hate it”. The paper’s Figure 6 tells quite the story. Indeed there was a lot of climate change in the past when CO2 was more or less stagnant." [R. Moschen, N. Kuhl, S. Peters, H. Vos, A. Lucke 2011: Climate of the Past]