Magny et al. utilizing advanced scientific techniques, reconstructed 1,000 years of past summer (July) temperatures for the Swiss Jura Mountains region. Unequivocally, they found that July temperatures during the Medieval Period were significantly warmer than modern summer temps.
"Working at Lake Joux in the Swiss Jura Mountains...employed a multi-proxy approach with pollen and lake-level data to develop a 1000-year history of the mean temperature of the warmest month of the year (MTWA), which was July...based on the Modern Analogue Technique. This work revealed what they describe as an "MWP between ca. AD 1100 and 1320," during which time the MTWA at Joux Lake exceeded that of the 1961-1990 reference period by fully 2.0°C....Thus, it would appear that the peak warmth of the MWP at Lake Joux exceeded that of the CWP at that location by something on the order of 0.4-1.0°C." [Michel Magnya, Odile Peyrona, Emilie Gauthiera, Boris Vannièrea, Laurent Milleta, Bruno Vermot-Desroches 2011: Quaternary Research]
Read here. In peer-reviewed research published by the influential Proceedings of the National Academy of Sciences (PNAS), scientists reconstructed 5,600 years of climate conditions in Greenland. This new reconstruction confirmed the warm and optimum climate conditions of the Medieval Warming and the rapid onset of the frigid Little Ice Age.
In the case of Greenland's flourishing Viking settlements, the climate change to a cold phase meant total destruction of their existing society and settlements.
This new PNAS study totally refutes Michael Mann's entirely bogus 'hockey stick' portrayal of climate being benign and unchanging prior to the 20th century.
"What climate scientists have been able to ascertain is that an extended cold snap, called the Little Ice Age, gripped Greenland beginning in the 1400s. This has been cited as a major cause of the Norse’s disappearance. Now researchers led by Brown University show the climate turned colder in an earlier span of several decades, setting in motion the end of the Greenland Norse...The Vikings arrived in Greenland in the 980s...The arrival coincided with a time of relatively mild weather, similar to that in Greenland today. However, beginning around 1100, the climate began an 80-year period in which temperatures dropped 4 degrees Celsius (7 degrees Fahrenheit), the Brown scientists concluded...“You have an interval when the summers are long and balmy [Editor: yes, Greenland summers "long and balmy" during the Medieval period] and you build up the size of your farm, and then suddenly year after year, you go into this cooling trend, and the summers are getting shorter and colder and you can’t make as much hay. You can imagine how that particular lifestyle may not be able to make it,”...[William J. D’Andreaa, Yongsong Huanga, Sherilyn C. Fritz, N. John Anderson 2011:Proceedings of the National Academy of Sciences]
As so many past studies have documented, the Medieval Warming Period was indeed hotter than our current climate, especially in the extreme north and polar regions, such as Greenland and Iceland. The empirical evidence from past research, using a wide variety of scientific techniques, confirms the anecdotal information that was written in the historical past. A newly published study again confirms both the past scientific efforts and historical writings.
Ran et al. performed a diatom-based reconstruction of sea surface temperatures from waters of northern Iceland. Their analysis found that temperatures were approximately 0.6°C higher during the AD 940-1300 period versus modern temperatures. In addition, a strong solar radiation influence was noted in the data. (click on image to enlarge)
"Ran et al. reconstructed summer sea surface temperature (SST) on the North Icelandic shelf for the period AD 940-2006, based on their high-resolution and precisely dated diatom records, along with the help of "a modern diatom-environmental dataset from around Iceland...In the words of the four researchers, their diatom-based SST record indicates that the sea surface on the North Icelandic shelf "was not as warm during the last century as during the Medieval Warm Period (MWP)." More specifically, they write that "warm and stable conditions with relatively strong influence of the Irminger Current on the North Icelandic shelf are indicated during the interval AD 940-1300, corresponding in time to the MWP," and that "a considerable cooling at ~AD 1300 indicates the transition to the Little Ice Age (LIA) with increased influence of Polar and Arctic water masses deriving from the East Greenland and East Icelandic currents."...they end by stating that "the data suggest that solar radiation may be one of the important forcing mechanisms behind the palaeoceanographic changes."" [Lihua Ran, Hui Jiang, Karen Luise Knudsen and Jón Eiríksson 2011: Palaeogeography, Palaeoclimatology, Palaeoecology]
Read here. Map source here. (click on images to enlarge)
Newton et al. analyzed sediment cores from the Makassar Strait between the Indian and Pacific Oceans and confirmed that the hottest sea-surface temperatures took place some 800+ years ago, during the Medieval Period. These scientists noted that Medieval Warming took place during a solar activity maximum.
"Based on Mg/Ca ratios of the planktonic foraminifer Globigerinoides ruber that they obtained from a sediment core that was extracted from the seabed at the southern end (~5.3°S, 117.8°E) of the Makassar Strait...as they describe it, that "the warmest sea surface temperatures of the past 2000 years occurred between 1000 and 800 years ago," which period, they say, "is broadly coincident with the Medieval Warm Period as reflected in Northern Hemisphere temperature anomaly reconstructions."
"...used to reconstruct surface-water temperature (SST), sea-surface salinity (SSS), and seawater density variability over the past 2000 yr. Maximum SST and SSS occurred at both sites between 850 and 700 yr ago, coinciding with the Medieval Solar Maximum and Medieval Warm Period (ca. 1000–700 yr ago). SST and SSS declined at both locations after 700 yr ago and reached minimum values during the Little Ice Age, between 300 and 100 yr ago." [Alicia Newton, Robert Thunell and Lowell Stott 2011: Geology]
Abrupt and massive climate change, as represented by temperatures, has been a natural phenomenon for eons. Despite the claims of IPCC activists, pundits, celebrities, reporters, and some politicians, our current climate change is not unequivocally unprecedented and accelerating faster than previous occurrences. In fact, as the below charts depict, the current climate change is kind of wimpy compared to its ancestors.
It's important to recognize that scientists within the physical science realm concur that the climate can change abruptly with great severity, and that it has taken place with regularity over the last 10,000 years. Their proof? It's the ice cores pulled from the Greenland ice cap, which reveal incredibly large temperature changes as the graph immediately adjacent reveals. (And the Antarctic ice cores provide even more proof.)
As the experts will tell you, there is absolutely no scientific dispute regarding this historical evidence that was laid down by the climate for thousands of years.
While analyzing the ice core data, the scientists additionally determined several undisputed scientific facts:
1. Temperatures have been both hotter and colder than modern temperatures over the last 10,000 years.
2. There has been a cycle of warmer and cooler temperature swings over the last 10,000 years.
3. The modern increase in temperatures since the Little Ice Age represents #19 in the count of climate change swings over the last 10,000 years.
4. Major temperature swings of at least a 1 degree change may take anywhere from 220 years to 1000+ years before ending.
5. The recent past temperature increase has been both modest (below 1 degree) and relatively slow (750+ years) to warm since the initial plunge to the Little Ice Age levels.
These scientific facts are depicted in the visual representation of ice core data below (click on image to enlarge):
The #1 bar is this chart is that of a warming period that started around 10,000 years ago, lasting 840+ years with a temp increase of 1.23 degrees. The #2 bar represents the subsequent cooling period, which lasted some 850 years with temps cooling a huge 3 degrees. The rest of warm/cool climate change swings are represented all the way down to the present period, which is bar #19. (Each bar lists the associated temperature change and the length of the cooling/warming period, from peak to trough or vice versa.)
The modern bar (#19) is especially revealing. Since the initial plunge of the Little Ice Age temperatures about 750 years ago, the natural warming rebound has yet to even cross the 1 degree finish line that would denote this most recent climate change as a major one. Based on historical, natural precedents that the ice core evidence provides, our modern period should be expecting to reach the 1 degree mark in the near term future, regardless of any human influences - that's what nature and the climate does, naturally.
One final note: the ice core data only extends to 1905. To estimate the temperature change from 1905 to 2010, 'C3' used a really useful graphing service provided by Global Warming Science. Using this invaluable service, we found 4 arctic area weather stations (above 65N) that had fairly complete temperature records from 1905. The chart below is the end result, including a linear trend for the 4 stations: 0.55 degrees per 100 years.
Read here. Scientists analyzing maximum latewood density (MXD) datasets from Scandinavia determine that the Medieval Warming was unprecedented in its duration, at least 100 years in length.
In contrast to the modern era, this study, by Gunnarson et al., revealed that there were similar temperature increases from 1910 to 1940's, and one that started in the late 1990's. Neither of these very short-term warmings have MDX temperature reconstructions exceeding the Medieval Period.
"Working in the same general area, researchers combined these older historical MXD data with "recently collected MXD data covering AD 1292-2006 into a single reconstruction of April-September temperatures for the period AD 1107-2006,".....report "there is a steep increase in inferred temperatures at the beginning of the twelfth century, followed by a century of warm temperatures (ca. 1150-1250)," which falls within the temporal confines of the Medieval Warm Period; and they state that "the record ends with a sharp increase in temperatures from around 1910 to the 1940s, followed by decreasing temperatures for a few decades," after which they indicate that "another sharp increase in April-September temperature commenced in the late 1990s," during what is commonly known as the Current Warm Period. Thus, they say that "the two warmest periods are the mid to late twentieth century and the period from AD 1150-1250," and they emphasize that the temperatures of both of these periods have been so similar that "it is not possible to conclude whether the present and relatively recent past are warmer than the 1150-1250 period."" [Björn E. Gunnarson, Hans W. Linderholm, Anders Moberg, 2011: Climate Dynamics]
Read here. Map source here. (click on images to enlarge)
There are multiple factors that affect both regional and global temperatures, but the most important source of long-term temperature change is solar activity. Using data from the Norwegian Sea and multiple solar proxies, the peer-reviewed research by Sejrup et al. confirms a robust and synchronous correlation between solar activity and temperatures.
Note: This research was conducted and completed without the use of magical "hockey stick" science and statistics, perfected by Penn State University personnel.
"...worked with two sediment cores they extracted from the seabed of the eastern Norwegian Sea, developing a 1000-year proxy temperature record "based on measurements of δ18O in Neogloboquadrina pachyderma, a planktonic foraminifer that calcifies at relatively shallow depths within the Atlantic waters of the eastern Norwegian Sea during late summer," which they compared with the temporal histories of various proxies of concomitant solar activity.....This work revealed, as the seven scientists describe it, that "the lowest isotope values (highest temperatures) of the last millennium are seen ~1100-1300 A.D., during the Medieval Climate Anomaly, and again after ~1950 A.D." In between these two warm intervals, of course, were the colder temperatures of the Little Ice Age, when oscillatory thermal minima occurred at the times of the Dalton, Maunder, Sporer and Wolf solar minima, such that the δ18O proxy record of near-surface water temperature was found to be "robustly and near-synchronously correlated with various proxies of solar variability spanning the last millennium," with decade- to century-scale temperature variability of 1 to 2°C magnitude." [Sejrup, H. P., S. J. Lehman, H. Haflidason, D. Noone, R. Muscheler, I. M. Berstad, and J. T. Andrews 2010: J. Geophys. Res]
Read here. Map source here. (click on image to enlarge)
As coastal elites and MSM reporters remain on the 'stuck-on-stupid' belief that current temperatures are"unprecedented," climate researchers continue to establish a scientific database that documents the unprecedented warmth of the Medieval Warming Period.
The newest addition to the database is a peer-reviewed study by Mullins et al. that reveals the New York region being both warmer and wetter than the present climate.
"Working with two sediment cores extracted from the extreme southern end of Cayuga Lake in central New York researchers "found paleolimnological evidence for the Medieval Warm Period (~1.4-0.5 ka), which was warmer and wetter than today." This evidence included weight percent total carbonate, total organic matter, non-carbonate inorganic terrigenous matter, carbonate stable isotopes, carbon isotope values of total organic matter and fossil types (gastropods, ostracods, bivalves, oogonia) and amounts, all of which were used to interpret past climate based on their relationship to modern climate data for the Finger Lakes region of the state. And to make their findings perfectly clear, they repeat that the "data for central New York suggest a warmer, wetter climate than today."" [Henry T. Mullins, William P. Patterson, Mark A. Teece and Adam W. Burnett 2011: Journal of Paleolimnology]
Read here. Map source. (click on images to enlarge)
The IPCC and global warming alarmists have attempted to convince policymakers and the public that modern global warming is unprecedented. In addition, the Climategate scientists claimed that prior climate warming periods only took place in North Atlantic/European regions. Peer-reviewed study after study clearly documents that actual empirical evidence does not support the IPCC and alarmist sceintists claims, as this Chinese data reveals.
"Working with a sediment core extracted from the northern East China Sea...the authors [Li et al.] employed the alkenone paleotemperature index Uk'37...to construct a sea surface temperature history of that region covering the past 3600 years..."the highest temperature was 22.7°C which was recorded at 1.01 cal ka BP," about three-fifths of the way through the Medieval Warm Period...calculate that the peak warmth of the MWP was 2.9°C greater than the mean warmth of the first decade of the 21st century..."[GuangXue Li, XiaoYan Sun, Yong Liu, Torsten Bickert, YanYan Ma 2009: Chinese Science Bulletin]
Read here. Map source here. A new peer-reviewed study (Clegg et al.) firmly establishes that modern global warming is significantly less than the global warming experienced in the high latitudes, during the summers of multiple periods over the last 3,000 years. Specifically, historical global warming is still unprecedented, and modern warming is a blip in comparison. (click on images to enlarge)
"The authors conducted a high-resolution analysis of midge assemblages found in the sediments of Moose Lake in the Wrangell-St. Elias National Park and Preserve.....The results of the study are portrayed in the accompanying figure, where it can be seen, in the words of Clegg et al., that "a piecewise linear regression analysis identifies a significant change point at ca 4000 years before present (cal BP)," with "a decreasing trend after this point." And from 2500 cal BP to the present, there is a clear multi-centennial oscillation about the declining trend line, with its peaks and valleys defining the temporal locations of the Roman Warm Period, the Dark Ages Cold Period, the Medieval Warm Period, the Little Ice Age.....and, finally, the start of the Current Warm Period, which is still not expressed to any significant degree compared to the Medieval and Roman Warm Periods." [Benjamin F. Clegg, Gina H. Clarke, Melissa L. Chipman, Michael Chou, Ian R. Walker, Willy Tinner, Feng Sheng Hu 2010: Quaternary Science Reviews]
Read here, here and here. The IPCC and Climategate scientists, such as Michael Mann, teamed up to rid the world of the Medieval Warming Period and the Little Ice Age in an effort to convince the world's politicians and mainstream press that the modern warming was "unprecedented." Literally, Mann and his colleges presented a temperature history that had erased the warming and cooling extremes prior to the modern era.
The result of that effort was two fold: one, the infamous 'hockey stick' portrayal of historical temperatures as being a time of little temperature variation was blatantly contrary to known history and evidence; and two, the recognition by other scientists and a minority of the public that climate science had become the complete victim of the governing elites' political agenda.
Subsequent to the 'hockey stick' revelations of politics and fabricated temperature histories, many scientists pushed harder to examine the historical past, in attempts to reconstruct paleo-climate temperatures and climate.
This new study, by Büntgen et al., was able to identify the significant warming periods and the resultant civilization prosperity of a warmer climate, as represented by the known Roman warming and Medieval periods. The tree rings also identified both the Dark ages and Little Ice Age extreme coolings and the associated disease, famine and death of those natural cold periods.
"Climate variations have influenced the agricultural productivity, health risk, and conflict level of preindustrial societies.....Wet and warm summers occurred during periods of Roman and medieval prosperity. Increased climate variability from ~AD 250 to 600 coincided with the demise of the Western Roman Empire and the turmoil of the Migration Period." [Ulf Büntgen, Willy Tegel, Kurt Nicolussi, Michael McCormick, David Frank, Valerie Trouet, Jed O. Kaplan, Franz Herzig, Karl-Uwe Heussner, Heinz Wanner, Jürg Luterbacher and Jan Esper 2010: Science]
"Der Spiegel presents the most important results, which I myself think are not a surprise. The bulk of the Der Spiegel piece focuses on the hunger and misery precipitated by the climatic cold periods throughout the 2500-year period. One really gets a sense of how temperatures in Europe by no means followed the hockey stick shape proposed by Mann, and went from cold to warm, and vice versa. Numerous other proxies show the same applies globally."
Read here. Another peer-reviewed study proves the IPCC speculative claim that modern temperatures are "unprecedented" is bogus.
Although the infamous Climategate scientists attempted to force the false "hockey stick" caricature of historical temperatures on the public, the on-going scientific research continues to discover that Medieval Period temperatures were, on average, higher than our present temperatures.
Per a new study, a lake in Switzerland provides evidence from sediment cores that refutes IPCC's propaganda that modern temperatures are warmer than past temperatures. (click on image to enlarge)
"Based on their analysis of fossil chironomids that were identified and quantified in four sediment cores extracted from the bed of Lake Silvaplana in the eastern Swiss Alps, plus a previously developed 101-lake transfer function, Larocque-Tobler et al. constructed a detailed history of that region's mean July air temperature over the last millennium.....it can be seen that the peak mean warmth of the Medieval Warm Period exceeded that of the Current Warm Period by approximately 0.5°C in the case of 20-year averages and 1.2°C in the case of 50-year averages." [Larocque-Tobler, I., Grosjean, M., Heiri, O., Trachsel, M. and Kamenik, C. 2010 Quaternary Science Reviews29: 1940-1949]
Other than a handful of discredited tree-ring studies, the vast accumulation of scientific evidence indicates that modern warming has not been as great as that experienced during the Medieval Warming span.
Another peer-reviewed research study confirms the unprecedented warmth of the MWP from data collected at a lake on Baffin Island, Canada. (click on images to enlarge)
"Sediment cores collected from Donard Lake, Baffin Island, Canada were analyzed to produce a 1240-year record of average summer temperature for this region based on clastic varve thickness..... And in the words of Moore et al. who did the work, "the most prominent feature of the record is a period of elevated summer temperatures from AD 1200-1375," the peak 10-year mean value of which was approximately 0.9°C warmer than the peak 10-year mean value in the vicinity of 1960 (the highest of the last hundred years), 1.2°C warmer than the peak 10-year mean value in the vicinity of 1980, and fully 2.0°C warmer than the last 10-year value of the record, which was centered on approximately 1987." [Moore, J.J., Hughen, K.A., Miller, G.H. and Overpeck, J.T. 2001.]
IPCC Climategate scientists and alarmists claim that modern temperatures are "unprecedented." In another example of just how bogus this claim is, a new peer-reviewed study documents that eastern Finland's temperatures during the Medieval Warming were significantly warmer and extended over a 700-year span, not just a 25-year span that the modern warming represents. (click on images to enlarge)
"Working with a sediment core from Lake Pieni-Kauro in eastern Finland, Luoto and Helama identified and quantified various midge assemblages that were dominated by chironomids, after which they reconstructed a 1500-year history of mean July air temperature from the Finnish multi-lake calibration model of Luoto (2009). The results, shown in the accompanying figure, delineate a Medieval Warm Period stretching from about AD 580 to 1280, the peak temperature of which was approximately 0.3°C greater than the peak temperature at the end of the record, which concludes near the end of 2008. [Luoto, Tomi P. and Helama, Samuli 2010]
'Big Green' and its comrades have proven themselves capable of some the most outlandish lies in their incessant promotion of global governance, regulation and taxation of CO2 emissions. Possibly the biggest of lies is the one that today's modern temperatures are "unprecedented," never before warmer.
This big lie is the linchpin for all the associated hysterical, non-empirical, over-the-top, catastrophic predictions that are made by Big Green. Of course, when the actual, empirical, scientific data is actually considered, the big lie of "unprecedented" is shown to be a blatant falsehood.
As the graphs below reveal, there has been a general decline in polar temperatures over the last 10,000 years. Modern temperatures at both poles are well below their historical peaks.
Simply put, this means both humans and polar bears survived and adapted to warmer temperatures in the recent geological past. In addition, ice sheets outlasted extended periods of significantly higher temperatures in the past. (click on images to enlarge)
The other lie that the empirical evidence exposes as pseudo-science is that CO2 is the primary driving force of climate and temperature change. The ice core evidence is a stunning record of climate and temperature changing regardless of CO2 levels. Obviously, there are other natural forces in play that are the primary "climate disruptors."
That's not to say that human CO2 emissions have no part in modern warming, but it is more likely that a trace gas, like CO2, only has a trace affect on global temperatures and climate.
Notes: The average daily Vostok temperature (1958-2010) is the 2010 data-point for the Antarctica chart. The 2010 Greenland Summit temperature data point is average temperature of recent January through December monthly temperatures (added for modern context). The light gray columns in both charts represent CO2 levels, with 2010 estmated level (added for modern context) being the black column on far right.
YBP (years-before-present) figures were adjusted accordingly with use of year 2010 as end point.
Read here and here. Fredrik Charpentier Ljungqvist, a Stockholm University scientist recently published a peer-reviewed study that found there were previous warming periods that produced a warmer climate than our current climate, over the past 2,000 years . As a followup to that study, Ljungqvist has published additional information for the past 1,200 years that examines paleo-reconstructed temperatures for specific Northern Hemisphere regions.
This new data clearly reveals that both the Medieval Warming and the Little Ice Age cooling were significant climate events across the entire northern portion of the globe. In the majority of regions, modern temperatures are yet to reach the level and extent of the MWP.
"The presently available palaeotemperature proxy data records do not support the assumption that late 20th century temperatures exceeded those of the MWP in most regions.....Previous conclusions (e.g., IPCC, 2007) in the opposite direction have either been based on too few proxy records or been based on instrumental temperatures spliced to the proxy reconstructions. It is also clear that temperature changes, on centennial time-scales, occurred rather coherently in all the investigated regions – Scandinavia, Siberia, Greenland, Central Europe, China, and North America.....Assumptions that, in particular, the MWP was restricted to the North Atlantic region can be rejected."
This new data, combined with his other recent research, establishes without any doubt the existence of substantial climate change prior to 20th century's large emission of CO2. This research completely invalidates the UN's IPCC attempt to falsify historical climate change via the Climategate team of scientists. (click on images to enlarge)
Note: Original graphs had instrumental temperatures superimposed on top of proxy reconstruction during 20th century period. The instrumental data was removed and a reconstruction of the proxy reconstruction was done in order to make them visible - our re-do is close enough for NASA/GISS government work. ;-)
Read here. Map source here. Using sediment cores from lakes, researchers identified distinct periods of climate change, including the Dark Ages, Medieval Warming Period and the Little Ice Age. This peer-reviewed study, like so many, is contrary to the speculative comments by IPCC Climategate scientists who claimed that the MWP was only a northern European phenomenon.
"...the authors measured a number of sediment properties, among which were sulfur content and coarse mineral grains, the former of which served as a proxy for paleo-Asian summer monsoon activity and the latter of which served as a proxy for paleo-Asian winter monsoon activity. This work revealed the presence of a cold/dry interval stretching from AD 1 to 750, a warm/humid interval stretching from AD 750 to 1200, and another cold/dry interval stretching from AD 1200 to the present, which periods they associated, respectively, with "the Dark Ages Cold Period, the Medieval Warm Period and the Little Ice Age ." [Yamada, K., Kamite, M., Saito-Kato, M., Okuno, M., Shinozuka, Y. and Yasuda, Y. 2010]
Read here and here. As is well known by now, the IPCC, the MSM and Hollywood wildly (and foolishly) celebrated the "Hockey Stick" caricature of past temperatures when it was first introduced, which portrayed the Medieval Warming and Little Ice Age as non-existent. Subsequent expert analysis by McIntyre and McKitrick found the hockey stick portrayal of past temperatures to be bogus and without scientific merit.
Recently, paleo-climate experts from around the world confirmed that the hockey stick caricature was dead by holding a major Medieval Warming Period (MWP) symposium in Lisbon, Portugal titled "The Medieval Warm Period - Where and when was it warm?". [Archived home web page here.]
Obviously, holding a MWP conference means there is no MWP "consensus" yet, and the IPCC Climategate-style of science is definitely not "settled." Additional confirmation of the MWP existence (pouring salt into Michael Mann's wound) is the symposium's prominent use of a graph from a peer-reviewed study that depicts MWP temperatures matching or exceeding modern warming temperatures. The symposium graph is an ensemble of paleo proxy reconstructions [Jansen et al., 2007]; and, by focusing solely on the ensemble's temperature ranges of the proxies, as depicted in the 'C3' chart below, the Jansen et al. research clearly is more supportive of, and similar to, the McIntyre & McKitrick results instead of the infamous hockey stick results. (click on image to enlarge)
This range of ensemble temperatures is also very similar to the results of multiple other peer-reviewed studies in the paleo-climate science field.
Read here. Map source here. Numerous temperature reconstructions indicate that during the Medieval centuries, two distinct warming intervals happened. New research from a Scottish loch's sediment core analysis identified the two separate, extended warming periods between 900 and 1600AD.
In addition, the new peer-reviewed research clearly reveals the wide climate variation experienced prior to the large industrial CO2 emissions of the 20th century. The modern warming was found not to be unusual or out of the ordinary. (click on image to enlarge)
"“The Loch Sunart reconstruction for the late MCA suggests temperatures from AD 916 to 1035 were similar to those recorded over the late twentieth century.”..... Cage and Austin [Cage, A.G. and, W.E.N. Austin. 2010] point out “perhaps the most distinctive feature of the Loch Sunart temperature record is the short-lived event between AD 1540 and1600, which is characterized by a very abrupt warming transition at AD 1540. This period had an average temperature anomaly of 1.1ºC above the long-term mean, which is higher than most of the 20th century and the late MCA.”....."“The Loch Sunart temperature reconstruction exhibits a gradual cooling trend that continues from AD 1608 to 1941, with the coldest temperature anomalies (~0.75ºC) of this period occurring between the early 1930s and 1940s.” So in the last 400 years, the sea bottom of Loch Sunart cooled, the coldest period over the past 400 years occurred 70 years ago, and then the water warmed up to levels that were typical during the beginning of the 400-year period."
Read here and here. Map source here. A peer-reviewed study utilizing high resolution data from a peat bog sediment core, analyzes 6,000 years worth of a temperature proxy. The researchers determined that both Roman and Medieval Periods experienced temperatures that were significantly higher than those of the current period. (click on image to enalrge)
"Working with cores extracted from a peat bog west of Jinchuan, China the authors developed "a 6000-year high-resolution δ18O record of peat plant cellulose," which they interpret as "reflecting changes in regional surface air temperature." And from their results, which are depicted in the figure [adjacent], it can be seen that the Medieval Warm Period (which was preceded by the Dark Ages Cold Period and followed by the Little Ice Age) was considerably warmer than the Current Warm Period (which followed the Little Ice Age) has been to date"
Read here. Map source here. Another peer-reviewed study provides high resolution evidence that the world's climate is impacted by an oscillation that occurs approximately every 1,500 years. This oscillation produces rapid climate change, which most likely explains the global warming rebound experienced since the Little Ice Age.
"On the southern coast of the English Channel, Billeaud et al. (2009) studied offshore-derived sediments in the macrotidal setting of Mont-Saint-Michel Bay, France, where they conducted a high-resolution sequence stratigraphy analysis of the intertidal to subtidal wedge, utilizing juvenile shells, peat and organic-rich bulk sediment.....The work revealed that "rapid climate changes, with ~1500-year periodicity, are recorded in the sedimentary successions.....Such results add to the overwhelming evidence provided by other paleoclimate records that have shown, in their words, that "Holocene climate was punctuated by widespread cooling events, recurring every ~1500 ± 500 years (Bond et al., 1997; Bianchi and McCave, 1999; Broecker, 2000; Mayewski et al., 2004; Debret et al., 2007; Allen et al., 2007)."...And since this periodicity suggests that the world was fully ripe for a recovery from the last of these coolings (i.e., the Little Ice Age), 20th-century global warming is seen to be neither unusual, unnatural nor unprecedented..."
Read here. Peer-reviewed research documents the glacier retreat that happened during the Medieval Warming period for the Antarctica peninsula area. Despite Climategate scientists and alarmists claims, this evidence confirms that Antarctica (and the Southern Hemisphere) experienced the climate change of the Medieval era.
"Hall et al. examined organic-rich sediments exposed by recent retreat of the Marr Ice Piedmont on western Anvers Island, where glaciers have been undergoing considerable retreat in response to the well-documented warming of the Antarctic Peninsula..... This work revealed, in their words, that "peat from the overrun sediments dates between 707 ± 36 and 967 ± 47 cal. yr B.P.," which led them to conclude that "ice was at or behind its present position at ca. 700-970 cal. yr B.P," which they interpret as implying that "the present state of reduced ice on the western Antarctic Peninsula is not unprecedented," which means that this period was at least as warm as, or likely even warmer than, the peak warmth of the Current Warm Period."
Read here. Map source here. For eons, Earth's climate and temperatures have changed in a cyclical pattern. In a peer-reviewed study, researchers analyzed a cave speleothem that produced a 17,000 year temperature record. The results clearly show that the climate changes naturally, and significantly, while atmospheric CO2 levels remained at levels well below current levels. They also confirmed that Roman and Medieval period temperatures equaled or exceeded modern temperatures.
"Working with stalagmite SV1 from Grotta Savi -- a cave located at the southeast margin of the European Alps in Italy.....This work revealed -- among several other things -- the occurrence of the Roman Warm Period and a Medieval Warm Period.....the five researchers say they were "characterized by temperatures that were similar to the present," while with respect to the Roman Warm Period, they say its "temperatures were similar to those of today or even slightly warmer.....we have here yet another example of the millennial-scale oscillation of climate that has characterized the earth throughout glacial and interglacial periods alike; and we note that it provides three good examples of times when temperatures were equally as warm as they are presently, or even warmer, in spite of the fact that the air's CO2 content was much lower at those earlier times than it is today."
Read here and here. A new study reconstructs 2,000 years of temperature variation from 30 datasets. The authors eliminated the discredited data and techniques utilized by Michael Mann (of Climategate fame) for multiple studies, and also used by his close paleo research comrades. For example, this study totally avoids the bristlecone pine and foxtail pine data that so miraculously produced the fake hockey-stick blades of temperatures in the 20th century.
This new study's findings demonstrate that climate change has been very active over 2,000 years, with pronounced changes in temperature being one of the results. This past climate change and temperature variation happened in a atmosphere of low CO2 levels. These results also reveal Roman and Medieval temperatures that exceed modern temperatures derived from the same 30 datasets. (click on image to enlarge)
This chart shows the modern global warming, as do so many paleo studies, but confirms that both warming and cooling are natural cyclical events.
Read here. McKay et al. research PDF download. Peer-reviewed study analyzing 9,000 years of sediment core data (two different types of sediment cores) from the west Arctic Ocean area confirms what was learned from the Greenland ice cores: the Medieval and Roman periods experienced higher temperatures than the world's present climate. See top chart, Fig. A. (click on image to enlarge)
[Note: Blue bars on y-axis of both figures indicate range of modern measurements. The open and closed markers for both figures represent the results from the two sediment cores. The red-shaded areas represent warming periods as found within the sediment cores. The authors contend the red-shaded areas are associated with an evident 2,500 year period of oscillation that naturally occurs.]
Ice-core charts and other historical temperature charts here. Additional climate history postings.
In addition, this study was able to determine the approximate sea ice coverage (see bottom chart, Fig. B) over the last 9,000 years. As one would expect, and the bottom chart data reveals, the actual sea ice coverage would be less over the term of a calendar year when the sea-surface temperatures were higher.
Obviously, the "death spiral" of Arctic sea ice that big-government paid scientists like to frighten MSM reporters with (about the current Arctic conditions) has happened multiple times before. These "death spirals" are solely due to natural climate variation - literally, humans don't cause these sea-ice death spirals and humans can do nothing to stop them from happening.
The final conclusion of authors: Modern surface temperatures of west Arctic are well below historical/ancient temperatures. Modern sea-ice coverage is well above the 9,000 year average of the past. Neither modern measurement is "unprecedented" as claimed by global warming alarmists.
The readers can also conclude the following from both this new evidence and the previous Greenland ice core data: Polar bears and walruses are not at risk since both species survived much warmer temperatures and significantly less ice in the past.
Read here. Map source here. Brand new peer-reviewed study that analyzes subfossils from a Swiss lake confirms what hundreds of previous peer-research have found: that the Medieval Warming had temperatures significantly warmer than modern ones.
"Thousand years of climate change reconstructed from chironomid subfossils.....Based on their analysis of fossil chironomids (non-biting midges) -- which were identified and quantified in four sediment cores extracted from the bed of Lake Silvaplana -- the authors constructed a detailed history of that region's mean July air temperature.....Larocque-Tobler et al. report that "at the beginning of the record, corresponding to the last part of the 'Medieval Climate Anomaly' (here the period between ca. AD 1032 and 1262), the chironomid-inferred mean July air temperatures were 1°C warmer than the climate reference period (1961-1990)," which would also make them warmer than most subsequent temperatures as well. And in looking at their graphs of 20- and 50-year running means, it can be seen that the peak mean warmth of the Medieval Warm Period exceeded that of the Current Warm Period by approximately 0.5°C in the case of 20-year averages and 1.2°C in the case of 50-year averages."
Read here. Map source here. Japanese scientists working with historical data and documents determine that the extended Medieval Warming had temperatures exceeding current temps by at least one-half degree in Kyoto. Their research also confirms that the Medieval Warming was global in nature, not just a northern Europe climate condition as speculated by IPCC Climategate scientists.
"The authors investigated documents and diaries from the ninth to the fourteenth centuries to supplement phenological data series pertaining to the flowering of Japanese cherry trees in Kyoto, Japan, "to improve and fill gaps in temperature estimates based on previously reported phenological data," after which they "reconstructed a nearly continuous series of March mean temperatures based on 224 years of cherry flowering data, including 51 years of previously unused data, to clarify springtime climate changes.".....The resulting temperature reconstruction "showed two warm temperature peaks of 7.6°C and 7.1°C, in the middle of the tenth century and at the beginning of the fourteenth century, respectively," and they say that "the reconstructed tenth century temperatures are somewhat higher than present temperatures"...[Yasuyuki Aono, Shizuka Saito 2009: International Journal of Biometeorology]
Read here. Map source here. More research from China confirms Medieval temperatures were significantly warmer than current ones. The study also provides direct evidence that the Medieval Warming was a global phenomenon, not just a European regional climate condition, as the IPCC speculates.
"...the authors extracted cores of peat from a location close to Hani Village, Liuhe County, Jilin Province, China; and they used them to develop, as they describe it, "a peat cellulose δ18O temperature proxy record proximately existing for 14,000 years.""....."Their efforts revealed, first of all, that the MWP had indeed held sway on the Chinese mainland over the period AD 700-1400, peaking at about AD 900......they say MWP temperatures were as much as "0.9-1.0°C higher than modern temperatures "....."with respect to the last 14,000 years, Hong et al. write that "sudden cooling events, such as the Older Dryas, Inter-Allerod, Younger Dryas, and nine ice-rafted debris events of the North Atlantic are almost entirely reiterated in the temperature signals of Hani peat cellulose δ18O."....."indicating that the recurring warming and cooling did indeed occur "outside the European region" and that it truly was "a common phenomenon.""
Read here. Map source here. Those "wild and crazy" Norwegians decided to conduct some home-grown, intimate fjord research. Their up close and definitive findings? Amazingly, they discovered temperatures appear to oscillate from warm-to-cold-to-warm over extended periods, naturally.
Isn't that just incredibly, freaking amazing? (Are leftists/Marxists/liberals/progressives/Democrats aware of this yet?)
"Just as has been discovered numerous times and throughout the entire world, northern Norway has experienced alternating multi-century periods of relative cold and warmth over prior millennia. And this pervasive natural phenomenon appears to be totally sufficient to explain 20th-century warming (there has been no more so far this century) without any need to invoke the help of the greenhouse effect of CO2 or any of the atmosphere's other greenhouse gases."
Read here. Scientists confirm that Northern Hemisphere temperatures during the Medieval Period exceeded those of recent years of the 20th and 21st centuries. The Greenland ice sheet scientific evidence is clear about this, as the chart depicts. (click on image to enlarge)
"The authors say their data "show clear evidence of the Medieval Warm Period and Little Ice Age in agreement with documentary evidence," and those data clearly show that the Medieval Warm Period was at times considerably warmer than the Current Warm Period has been to date, and that even the Little Medieval Warm Period was considerably warmer than it was over the last decades of the twentieth century, as well as the first decade of the 21st century. Thus, there is no compelling reason to believe that the 20th-century increase in the air's CO2 content (a 100-ppm rise above what it was during the warmer Medieval Warm Period) was the cause of 20th-century global warming, especially when climate alarmists claim that such warming, when it occurs, should be most evident and earliest expressed in high northern latitudes..."
Read here. Map source here. Climate scientists have previously proposed that a 1,500 year oscillation driven by solar activity changes affects the climate, causing periodical warming and cooling cycles. A new study analyzing lake sediment cores from Bolivia confirms the existence of the approximate 1,500 year cycle.
"The five researchers report that their work "shows clear evidence of millennial-scale climate variation between ~60 and 20 ka BP," which was driven by variations in the degree of regional wetness; and they say that this climatic oscillation is well correlated with the stadial/interstadial oscillation of the North Atlantic region. More specifically, they write that "the correlation between the Lake Titicaca and NGRIP records suggests that the major cold periods in the North Atlantic region were synchronous with wet periods on the Altiplano.".....And this combined set of findings suggests that the approximate 1500-year climatic oscillation that alternately brings century-long periods of relative cold and warmth to the Northern Hemisphere impacts the hydrologic climate of the Southern Hemisphere on approximately the same time scale."
Read here. Scientists from Germany and Russia conducted extensive research and reconstructed past temperatures from tree rings. Using tree samples of Scots pine in the Khibiny Low Mountains of the Kola Peninsula in Arctic Russia, they found the following:
"The reconstructed summer temperature on Kola in the months of July and August has varied between 10.4°C (1709) and [peaking at] 14.7°C (1957), with a mean of 12.2°C. Afterwards, after a cooling phase, an ongoing warming can be observed from 1990 onwards.....The temperature fluctuated between 10.4°C and a peak of 14.7°C in 1957 , and then cooled until 1990. The scientists say it correlated very well with solar activity until 1990.....What stands out in the data from the Kola Peninsula is that the highest temperatures were found in the period around 1935 and 1955, and that by 1990 the curve had fallen to the 1870 level, which corresponds to the start of the Industrial Age.....The reconstructed summer temperatures of the last four centuries from Lapland and the Kola and Taimyr Peninsulas are similar in that all three data series display a temperature peak in the middle of the twentieth century, followed by a cooling of one or two degrees......What is conspicuous about the new data is that the reconstructed minimum temperatures coincide exactly with times of low solar activity. The researchers therefore assume that in the past, solar activity was a significant factor contributing to summer temperature fluctuations in the Arctic."
The above scientific evidence reveals little, if any, correlation between growth of human CO2 emissions and Arctic temperatures. The scientists conclude that there was a past relationship between solar activity and temperatures.
During the 1990's, the scientists find that warming resumes in the Arctic. And what was solar activity like during the 90's and later? Well solar activity increased, as documented in this Watts Up With Thatarticle. (click on image to enlarge)
Read here. Our modern world is experiencing natural climate change, but scientists are now telling us that it doesn't rival the destructive force of ancient climate change that took place during Medieval times.
When true unprecedented climate change occurs, it can be devastating to cultures and civilizations that are not prepared to adapt to different environmental conditions.
In the case of the Central American Mayans, their civilization was destroyed because they chose to follow the hope of mitigation, through human sacrifice and prayer to their gods, instead of pursuing the practical adaptation needed to survive the natural Medieval Warming drought conditions.
How bad was the climate change for the Mayans during the Medieval Warming period?
"Escobar et al. state that their findings "confirm the interpretations of Hodell et al. (1995, 2007) and Curtis et al. (1996) that there were persistent dry climate episodes associated with the Terminal Classic Maya Period." In fact, they find that "the Terminal Classic Period from ca. AD 910 to 990 was not only the driest period in the last 3,000 years, but also a persistently dry period." And in further support of this interpretation, they note that "the core section encompassing the Classic Maya collapse has the lowest sedimentation rate among all layers and the lowest oxygen isotope variability.".....that "double whammy" of persistent warmth and persistent dryness appears to have been just a bit too much for the Mayans of that trying time to endure.""
Read here. A peer-reviewed study documents the extremely warm temperatures of the Medieval Period that occurred in the California Sierra Nevada range. Scientists, working with dead tree trunks located above the current treeline, affirm California's Medieval extreme warm temperature history, which still remains unprecedented.
"Working with dead tree trunks located above the current treeline on tephra-covered slopes of Whitewing Mountain and San Joaquin Ridge.....the five researchers say "the Medieval forest on Whitewing was growing under mild, favorable conditions (warm with adequate moisture)," as indicated by "extremely low mean sensitivities [to stress] and large average ring widths." More specifically, they conclude, as reported in their abstract, that annual minimum temperatures during the Medieval Climatic Anomaly in the region they studied were "significantly warmer" (+3.2°C) "than present,".....Once again, we have another example of a paleoclimate study in which the Medieval Warm Period is determined to have been significantly warmer than it is currently....."
Read here and here. A peer-reviewed study confirming that Medieval Warming temperatures were considerably warmer than those experienced during modern era. The research reveals that modern temperatures are not "unprecedented" as claimed, and that significant natural warming does happen without the influence of human CO2 emissions. (click on image to enlarge)
"The Jämtland multi-millennial tree-ring width chronology is comprised of living and subfossil Scots pines (Pinus sylvestris L.) sampled close to the present tree-line in the central Scandinavian Mountains.....Several periods of anomalously warm and cold summers were noted throughout the record: (1) 550 to 450 BC (Roman Warm Period), when summer temperatures were the warmest of the entire record, exceeding the 1961-1990 mean by more than 6°C, (2) AD 300 to 400 (Dark Ages Cold Period), which was "the longest period of consecutive cold summers," averaging 1.5°C less than the 1961-1990 mean, (3) AD 900 to 1000, a warm era corresponding to the Medieval Warm Period, and (4) AD 1550 to 1900, a cold period known as the Little Ice Age..... With respect to the latter portion of the tree-ring record, which encompasses the period of modern global warming, Linderholm and Gunnarson declare that this phenomenon "does not stand out as an anomalous feature in the 3600-year record, in fact other periods show more rapid warming and also higher summer temperatures." What should be even more embarrassing to the world's climate alarmists is the fact that the last half of the 20th century actually experienced cooling."
Read here. Map source here. Scientists studied the extended warm period (interglacial) prior to the last major ice age. That prior warm period happened some 125 thousand years ago. Using a sediment core from a German lake, the scientists analyzed the quantity of pollen grains found in the core. Approximately every 1,500 years during the ancient interglacial, the climate changed from a warming phase to a cooling phase. The current interglacial, since the end of the last ice age about 15 thousand years ago, shares this same, every 1,500 year oscillation of warming-to-cooling climate changes.
The scientists involved in the study suggest this natural 1,500 year oscillation, found in both the ancient interglacial and the one we live in, is likely due to solar forces.
"The results of the authors' analysis revealed the presence of 11 major cold events having an average recurrence time of approximately 1450 years over the course of the last interglacial, which periodicity is essentially identical to the millennial-scale oscillation of climate throughout the current interglacial (Bond et al., 1997, 2001; deMenocal et al., 2000; McDermott et al., 2001; Gupta et al., 2003; Hu et al., 2003).....This study adds to the growing body of evidence that earth's climate oscillates in a well-defined manner on a timescale of approximately 1500 years. This knowledge is very important, for it suggests that something other than the historic buildup of carbon dioxide in the atmosphere may be responsible for 20th-century warming..... Indeed, there is absolutely no evidence for any concomitant oscillation in the air's CO2 content accompanying the 1500-year oscillation of climate that was responsible for the warmings that produced the prior Medieval Warm Period and the still earlier Roman Warm Period,"
Read here. Map source here. Using sediment cores and two different techniques of analysis, scientists confirm in a peer-reviewed study that Medieval Warming peak sea surface temperatures adjacent to Greenland were some 3°C higher than modern temperatures, both in the winter and summer. No wonder Erik the Red found Greenland so agreeable and attractive.
"The authors developed a high-resolution record of ocean and climate variations during the late Holocene in the Fram Strait.....based on detailed analyses of a sediment core recovered.....sea surface temperature (SST) histories were "nearly identical and show oscillations between -1°C and 5.5°C in winter and between 2.4°C and 10.0°C in summer,".....the mean SSTs of summers were warmer than those of the present about 80% of the time, while the mean SSTs of winters exceeded those of current winters approximately 75% of the time.....The highest temperatures of all were recorded in the vicinity of 1320 cal. years BP, during a warm interval that persisted from about AD 500 to 720 during the very earliest stages of the Medieval Warm Period"
Read here. In the broad realm of empirical evidence for Medieval Warming, there is one unique indicator that does not require a Phd to appreciate and understand - that would be tree lines. In general, if the climate is warmer, the tree line will move farther north and/or to higher elevations. As scientists discovered in the Ural Mountains, the modern tree line is at a much lower elevation than the Medieval tree line.
"Most importantly, Mazepa reports that "a large number of well-preserved tree remains can be found up to 60-80 meters above the current tree line, some dating to as early as a maximum [our italics] of 1300 years ago," and that "the earliest distinct maximum in stand density [our italics] occurred in the 11th to 13th centuries, coincident with Medieval climatic warming.".....Noting that "dead trees located above the current tree-line ecotone provide evidence of the dynamic behavior in the location of the tree line in the recent past (Shiyatov, 1993, 2003)," Mazepa reports that "previous studies have concluded that increases in tree-line elevation, and associated increases in tree abundance within the transient tree-line ecotone, are associated with extended warm periods"
Read here. Map source here. Government funded climate scientists and Gore-led warming alarmists constantly attempt to mislead the public by implying that any present climate change is "unprecedented." Unfortunately for the alarmistas, the preponderance of peer-reviewed research documents significant climate change shifts over the last 5,000 years, with many of the shifts being of far larger magnitude. From this study of Alberta, Canada sediment cores, comes more irrefutable evidence of natural climate change prior to human CO2 emissions.
"Periods of both increasing and decreasing grain size (moisture availability) were noted throughout the 4000-year record at decadal, centennial and millennial time scales. The most predominant departures included several-centuries-long epochs that corresponded to the Little Ice Age (about AD 1500-1900), the Medieval Warm Period (about AD 700-1300), the Dark Ages Cold Period (about BC 100 to AD 700) and the Roman Warm Period (about BC 900-100).....The Pine Lake sediment record convincingly demonstrates the reality of the non-CO2-induced millennial-scale climatic oscillation that alternately brings several-century periods of dryness and wetness to the southern Alberta region of North America during concomitant periods of relative hemispheric warmth and coolness, respectively. It also demonstrates there is nothing unusual about the region's current moisture status"
Read here. As common sense science would surmise, the Antarctic region follows a natural cycle of cooling and warming. As the scientists have now found, new peer-research confirms these type of dominant Antarctic warming/cooling cycles - and human CO2 emissions are found not to be the relevant driving force.
"Historical records for the western Antarctic Peninsula (WAP) show that it is particularly prone to rapid climate change—change that occurs in cycles of ~200 years and ~2500 years.....ice in the Antarctic region undergoes periodic episodes of rapid melting—and it is all entirely natural, not because of human activity. The new paper echos these findings: “Paleo-records show that analogous climate variations have occurred in the past 200 to 300 years, and over longer 2500-year cycles, with rapid (decadal) transitions between warm and cool phases in the WAP."....."Their conclusion was that “variability of these parameters demonstrates the significance of both short-term cycles, which recur approximately every 200 yr, and longer term events (~2500 yr cycles) that are most likely related to global climatic fluctuations.”"
Read here. Map source here. Scientists construct temperatures over the last 1,000 years from Scottish fjord sediment cores. The past temperatures of some 500 years ago reveal a rate of change warming and absolute temp levels that equal those of the late 20th century. Again, another peer-reviewed study confirms the natural state of constant temperature and climate change regardless of low/high CO2 atmospheric levels.
Summary: Today's temperatures are not unusual, nor unprecedented.
"The results of the two researchers' most recent efforts revealed that the most distinctive feature of the Loch Sunart temperature record was an abrupt warming at AD 1540 that led to a temperature anomaly of 1.1°C above the long-term mean from AD 1540-1600.....Noting that "the rate and magnitude of the inferred warming at AD 1540... is similar to the rate of change and magnitude observed during the late twentieth century," Cage and Austin concluded that "changes in twentieth century marine climate cannot yet be resolved from a background of natural variability over the last millennium," which is another way of saying that late 20th-century warming was not unusual enough to validly ascribe it to the concomitant increase in the air's CO2 content."
Read here. IPCC scientists still claim that the Medieval Warming was limited to the northern European region despite all the evidence otherwise. Adding to that 'otherwise,' researchers documented a confirmed Medieval warming and associated dry precipitation levels within the Panama region, near the Equator.
"The authors conclude that "the correspondence between warm medieval temperatures and dry hydrologic anomalies in Panama supports a large-scale Medieval Climatic Anomaly that may have been global in extent, and involved atmospheric circulation reorganizations that are linked to ENSO.".....noting that such reorganizations of earth's climate system are not dependent on rising atmospheric CO2 concentrations to trigger them, and, therefore, that the development of the Modern Warm Period likely was largely unrelated to the concomitant increase in the air's CO2 concentration"
Read here. Map source here. Scientists, using sediment cores, determine that all the historical, major climate changes have impacted the Southern Hemisphere at approximately the same times as impacting the Northern Hemisphere.
"Signy Island [in Southern Ocean, near Antarctica] is seen to have experienced the relative warmth of the last vestiges of the Roman Warm Period...Then comes the Dark Ages Cold period...after which the Medieval Warm Period appears at the same point in time and persists for the same length of time that it does in the vicinity of Ireland, whereupon the Little Ice Age sets in just as it does in the Northern Hemisphere. Finally, there is an indication of late 20th century warming, but with still a long way to go before conditions comparable to those of the Medieval Warm Period are achieved..... it demonstrates that the global warming of the past century, which led to the demise of the Little Ice Age, is but the most recent phase of a natural climatic oscillation that is totally unrelated to the increase in the air's CO2 content that just happened to coincide with its occurrence."
Read here. The research keeps being conducted, providing further scientific evidence that the Medieval Warming was considerably warmer that the current period warming of the late 20th and early 21st century. The irrefutable climate data continues to mount regarding the extreme variation in historical temperatures, as this chart indicates. (click on image to enlarge)
"Kobashi et al. (2010)constructed a history of the last thousand years of central Greenland surface air temperature, based on values of isotopic ratios of nitrogen and argon...from air bubbles trapped in the GISP2 ice core that had been extracted from central Greenland...results reveal that the latter part of the Medieval Warm Period was approximately 1.67°C greater than the temperature of the last decades of the 20th century, which climate alarmists claim to have been the warmest of the past millennium."
Read here. Map
Why do we say "huge" for the post-Roman period? Climate alarmistas are in
an existential panic about a global temperature change of 0.7°C since
1880, per the National Climate Data Center (NCDC) data. A fair amount of that
increase in temperatures since 1880 is natural versus the small AGW
increase since 1970; and, the total 0.7 temperature change is significantly less
than the post-Roman 2.0 degree change - 2.0 is huge versus 0.7.
The historical evidence
points to past periods experiencing much greater temperature variation
and associated climate change, and the South China Sea is yet another
Sr/Ca ratios of two Porites corals from the coast of Leizhou
Peninsula in the northern South China Sea were measured.....From the
Dark Ages Cold Period portion of the coral record, Wei et al. determined
that the average annual SST was approximately 2.0°C colder than that of
the last decade of the 20th century (1989-2000), while from the Roman
Warm Period portion of the record they obtained a mean annual
temperature that was identical to that of the 1989-2000 period as
measured at the Haikou Meteorological Station.....As has been
demonstrated many times before in a number of places throughout the
world, these data indicate that the last decade of the 20th century did
not display unusual or unprecedented warmth. Indeed, there were prior
times within both the Medieval Warm Period and Roman Warm Period when
temperatures were equally as warm as, or actually warmer than, what
they have been recently; and all of these earlier warm periods occurred
at times when the air's CO2 concentration was fully 100 ppm less than
what it is today"
Map source here. Read here. Anderson et al. used sea core sediments to reconstruct temperatures of the Norwegian Sea surface over the last 3,000 years. Research clearly identified the Roman warming, Dark Ages cooling, Medieval warming and the Little Ice Age cooling. Research also showed historical temperatures warmer than those experienced in the Norwegian Sea during the modern era.
"The climate history derived from this study is remarkably similar to that derived by McDermott et al. (2001) from a high-resolution speleothem ð18O record obtained from a stalagmite discovered in a cave in southwestern Ireland. At the beginning of the 3000-year-long Voring Plateau record, both regions were clearly in the end-stage of the long cold period that preceded the Roman Warm Period...both regions begin their descent into the Dark Ages Cold Period, which held sway until the increase in temperature that produced the Medieval Warm Period...Last of all, the Little Ice Age is evident, with cold periods centered at approximately 400 and 100 years BP.....Andersson et al. report that "surface ocean conditions warmer than present were common during the past 3000 years."
Read here. Scientists who base their livelihoods on global warming research funding claim that late 20th century warming was "unprecedented." This specific claim is embarrassingly false, and more peer-research science (study of fossil dinoflagellate cysts and pollen from sediment cores) from the Chesapeake Bay waters confirms that.
"The authors report that "several dry periods ranging from decades to centuries in duration are evident in Chesapeake Bay records." The first of these periods of lower-than-average precipitation, which spanned the period 200 BC-AD 300, occurred during the latter part of the Roman Warm Period,.....The next such period (~AD 800-1200), in the words of the authors, "corresponds to the 'Medieval Warm Period',..... First, it [Willard et al. research] demonstrates the reality of the millennial-scale hydrologic cycle that accompanies the millennial-scale temperature cycle that is responsible for producing alternating warm and cold intervals such as the Roman Warm Period, Dark Ages Cold Period, Medieval Warm Period, Little Ice Age and Modern Warm Period. Second, it [research] demonstrates that the global warming of the 20th century has not produced unusually strong wet and dry periods, contradicting climate-alarmist claims that warming will exacerbate extreme climate anomalies."
Read here. Scientists using the latest analysis techniques, conducted a high resolution analysis of the ice core retrieved from Antarctica's Dome C station. The Dome C is located on the eastern half of Antarctica, on the polar plateau with an elevation of 10,607 feet. (The more well-known Vostok polar station is located on the same plateau at a similar elevation, ~ 3,200 meters.)
What did this new high resolution analysis determine?
The Medieval Warming period had temperatures that approached 1°C higher than current temperatures, in spite of lower CO2 levels.
The Minoan Warming period had temperatures that possibly exceeded current temperatures by 1°C, in spite of lower CO2 levels.
The previous interglacial period, approximately 130,000 years ago, had temperatures in excess of 4°C versus current temperatures, in spite of lower CO2 levels.
Clearly, the new ice core data indicates that natural climate variations caused huge temperature variations in the past. Based on this empirical climate science, it would be safe to conclude that current climate changes are predominantly driven by natural forces (see this chart and post also), not human CO2 trace gas emissions. (click on image to enlarge)
This high resolution ice core data ends at the year 1912. The similarly situated Vostok polar station temperature record was used as proxy to assess polar plateau temperature increase/decrease over the last 60 years. As the Vostok temperature data reveals, current temperatures may actually be lower than what the Antarctica plateau experienced during the 1950's. In addition, peer-reviewed studies indicate Antarctica temperature change to be minimal over last two centuries.
Download this newest Dome C ice core research, source here.
Read here. Much has been made by global warming alarmists about the warming of Alaska since the 1970's and thus inferring it is due to human CO2 emissions. What they conveniently fail to mention is that most of the warming was due to a major PDO (Pacific Decadal Oscillation) shift to a warming phase that took place during the late 70's.
And, they always fail to point out that peer-reviewed research shows that the Alaskan climate was both warmer and cooler than the current climate over the last 2,000 years. (click on image to enlarge)
"In commenting on these findings, Hu et al. remark that "the warmth before AD 300 at Farewell Lake coincides with a warm episode extensively documented in northern Europe whereas the AD 600 cooling is coeval with the European 'Dark Ages'." They also say that "the relatively warm climate AD 850-1200 at Farewell Lake corresponds to the Medieval Climatic Anomaly, a time of marked climatic departure over much of the planet." And they say that "these concurrent changes suggest large-scale teleconnections in natural climatic variability during the last two millennia, likely driven by atmospheric controls.""....."Noting that "20th-century climate is a major societal concern in the context of greenhouse warming," Hu et al. conclude by reiterating that their record "reveals three time intervals of comparable warmth: AD 0-300, 850-1200, and post-1800," and they say that "these data agree with tree-ring evidence from Fennoscandia, indicating that the recent warmth is not atypical [it's not unusual] of the past 1000 years,"
The U.S. has sponsored much climate research over recent decades, including the study of ice cores from Greenland. The National Climate Data Center (NCDC), a NOAA organization, maintains the Greenland ice core temperature data, which can be downloaded from their web site.
Fortunately, this Greenland ice core temperature data allows for an analysis of temperature change from minimum (trough) temperature to maximum temperature (peak) over extended time spans. Likewise, temperature change from maximum to minimum can also be analyzed. Sooo, what does that NCDC ice core temperature data actually indicate about temperature change?
1. Huge temperature swings have occurred naturally over thousands of years, prior to any human CO2 emissions.
2. The Modern warming increase (see pink arrow/dot on chart) since the bottom of the Little Ice Age (around 1840) has been minuscule versus all previous warming period temperature changes when compared to their respective cooling period trough that preceded.
3. Over the 9,000 years, the average temperature increase from the trough of the preceding cooling period to the next temperature peak has exceeded 2.0°C. In contrast, the Modern warming has barely reached a 0.7°C increase since the Little Ice Age cooling trough.
4. There have been nine significant warming trends leading to temperature peaks over last 9,000 years; and, all exceed the Modern warming trend in terms of absolute degree change (increase).
5. There have been nine significant cooling periods over the same time span. Many cooling periods have seen temperatures decline by over 2.0°C.
6. The average number of years between temperature warming peaks is approximately 990 years. Since the last peak around 1040 A.D., it has now been 970 years, which suggests the current warming period is close to peaking before the next natural cooling period dominates.
7. All scientists agree that all extreme temperature changes prior to the 20th century were of natural origin. In contrast, it's only climate alarmist scientists who believe that the temperature change since the Little Ice Age is all man-made (see pink arrow/dot).
(click on image to enlarge)
Note: The Greenland ice core data ends in early 20th century; the pink arrow and dot have been added to indicate the "consensus" temperature increase through 2009 since the LIA end mid-19th century.