The extreme anti-CO2 jihadists, and the green-fundamentalists at the UN's IPCC, claim that modern warming has been historically unusual, unique and statistically "significant" due to human CO2 emissions - yet, when the UK's HadCRUT4 global temperature dataset is examined, it is readily apparent that modern temperature change is primarily a repeat of the past natural climate patterns
(click on chart to enlarge; data sources)
Recently, the UK's MetOffice was forced to admit to Parliament that global warming since the 1850's has not been statistically significant - read here, here and here.
In essence, for the recent modern warming to be statistically significant, then there should be no earlier periods exhibiting a similar warming trend and monthly variation that occurred when CO2 levels were low.
So, exactly how hard was it to find an earlier warming period that took place under a low atmospheric CO2 regime that had similar traits? Hmmm.....not so hard, as it turn out.
Despite the previous statistical gyrations the MetOffice utilized to convince both lawmakers and the public that human CO2 emissions caused modern global warming to be "statistically" unique, in fact, upon analysis, the recent modern warming is typical of past natural climate variation.
Without conducting the type of statistical analysis that forced the MetOffice admission of being wrong (you can read about at those above article links), one can easily recognize earlier periods exhibiting similarity. The adjacent chart depicts such a similar period.
As can be discerned visually from the chart, the modern warming over the last 60 years (green data plots) ending April 2013 has obvious similarities to the 60-year climate period ending November 1949 (blue data plots). These two 720-month periods look very similar with the exception of atmospheric CO2 growth.
With that said, what else can be discerned from the above chart?
One, the modern atmospheric CO2 levels (top line of black dots) versus the earlier atmospheric CO2 level (bottom line of blacks dots) are, materially and real-world speaking, significantly larger - indeed, the grey 2nd order fitted trends indicate a dramatic modern CO2 growth rate since the 1950's (likely due to the post-WWII consumer/industrial/population/wealth expansion).
Two, yet despite the immense magnitude of the modern CO2 change, the 2nd order polynomial global temperature trend fits (green for modern and blue for past) are almost identical for the two 60-year datasets.....in linear trend-speak, the 60-year modern warming exceeds the past 60-year period by a ludicrously small, insignificant and a definite immaterial +0.38°C per century (yep, barely a third of a degree greater difference after all those modern CO2 emissions).
Simply put, natural variation easily explains any change of +/-0.38 degree per century trend.
Three, not only are the 60-year linear temperature trends similar, but visually, the monthly variation of the two datasets are strikingly similar (more on that in a later post).
Four, although more difficult to discern visually, the earlier 60-year period had many very large month-to-month warming incidents. How large? Multiple pre-modern monthly warming increases that were larger than any such warming incidents during the supposed "accelerating" and "dangerous" modern warming.
Below, is a chart comparing the top 20 monthly warming increases for the earlier 60-year period versus the modern period. In fact, of the the top 20 warming increases for both periods, the pre-modern period would claim 15 of the top 20 spots if the two lists were combined.
Conclusions:
The recent modern global warming was hardly much different than the previous warming(s). Certainly, referring to the modern warming as "statistically significant" is significantly misleading, if not an outright falsehood.
- The 60-year impact of the immense modern human CO2 emissions has had an insignificant impact on the global temperature trend - CO2 is not a global "thermostat" as claimed by green-ideologues
- The 60-year impact of higher CO2 levels on the climate/temperature monthly variation is not at all evident when compared to the older 60-year dataset
- The large monthly increases of modern global temperatures occurred with less frequency and less severity during a span of much greater CO2 atmospheric levels - again, there now exists less frequent, less severe climate change
- Although the modern 60-year period started at a higher anomaly point, the recent global temperature increases never, ever approached the mythical "runaway, climate tipping point" that anti-CO2 alarmists have long predicted was just around the corner (remember "boiling oceans," "climate refugees," "submerged islands and coasts" and other hysterical, tipping point fearmongerings)
- And, as a previous analysis of the HadCRUT global dataset revealed, the actual modern global temperature changes have "unexpectedly" morphed from warming to a growing cooling phase, much to the chagrin of the world's consensus-loving climate "scientists"
One last comment - as the UK's HadCRUT global temperature dataset used for this analysis is considered the IPCC's gold-standard, it is available to all for analysis. Thus anyone can use this same dataset to discover what taxpayer-funded climate agencies really don't want discovered - the fact that many of the past natural 10-year, 20-year, 30-year and 60-year climate periods share similar traits and attributes to modern climate patterns. If modern climate patterns and variations were in real-world science terms, materially "statistically significant," then this would not be the case.
Additional modern, regional and historical temperature charts.