The IPCC's "Climate Bible" relies on the HadCRUT (HC) global temperature dataset for its analysis - the last 100 years of HC data reveals the weak CO2 and global warming relationship
A previous 'C3' post regarding CO2 and NOAA / NCDC global temperatures generated a lot of interest, especially the second chart titled: "The Case Against CO2." That chart revealed that CO2's impact on global temperatures was essentially very weak over the last 50 years, ending 2011, versus the prior 50 years ending 1961.
We received questions as to how the famous HadCRUT (the IPCC's favorite global temperature dataset) compared to the previously used NOAA/NCDC dataset. The adjacent chart shows the result of switching to the all important HC data.
As one can discern from this chart, the result is essentially the same for the two datasets (see previous NOAA/NCDC chart).
- The 50-year period ending 1961 had little CO2 growth, yet global temperatures increased significantly more than the "unprecedented" and "accelerating" global warming of the 50-year period ending 2011.
- The growth of CO2 levels has an inconsistent effect on global temperatures suggesting the CO2 and temperature relationship is not robust - it is actually frail
- Global temperatures are not "accelerating" because of CO2 during the last 50 years
- Modern global warming over last 50 years was not "unprecedented" versus earlier periods
- Other climate dynamics and inputs primarily drive temperature and climate change - the trace gas CO2 has only a trace impact in comparison