A high climate sensitivity to growing human CO2 emissions is absolutely essential to the catastrophic anthropogenic global warming (CAGW or AGW) hypothesis - the climate empirical evidence refutes the high sensitivity claim though
(click image to enlarge)
In climate science reality, the actual global temperature observations over the last 15 years do not support the catastrophic anthropogenic global warming (CAGW) hypothesis.
Central to the CAGW hypothesis is that increasing human CO2 emissions will raise atmospheric levels of this greenhouse gas. Subsequent to the atmospheric CO2 increase, global warming will automatically and consistently increase.
Once the globe starts warming, the AGW hypothesis states that a high climate sensitivity to CO2 will initiate a dangerous positive feedback loop: the rising temperatures will increase water evaporation; the powerful atmospheric greenhouse gas water vapor will then increase; then global temperatures will increase even more, the melting of ice sheets occurs; thus, less solar energy will be reflected into space; and global temperatures will then increase even more; and etc., etc.
This powerful and relentless positive feedback loop will produce unequivocal, robust, significant, unprecedented, irrefutable, rapid and accelerating global warming. At least that is what every "expert" climate model based on the CAGW hypothesis predicted.
But did the above prediction/scenario/forecast happen? Nope, not even close. In fact, the opposite happened.
The adjacent chart depicts the last 30 years of increasing CO2 levels and global temperature trends. This actual climate evidence is sliced into two time periods: the 15 years ending July 1997 and the 15 years ending July 2012. The real world evidence reveals the following:
1. The far right column (grey) shows that CO2 levels were increasing at a 147 ppm per century rate by the end of July 1997. Actual CO2 levels were at the 364 ppm mark.
2. For the 15 years ending 1997, global temperatures were increasing at +1.08°C per century trend (red column).
3. Since July 1997, the growth of CO2 levels has increased to a 197 ppm per century trend, and now stands at the 395 ppm mark.
4. After 30 years of increasing human CO2 emissions and faster growing atmospheric CO2 levels, the last 15 years have witnessed the previous global warming morph into a global cooling tend (blue column) at a -0.24°C per century trend.
Conclusions: The climate scientist and climate models that have long predicted catastrophic global warming from CO2 emissions are proven to be undeniably incorrect. The AGW hypothesis does not reflect climate reality. The actual empirical evidence proves the CAGW hypothesis to be irretrievably wrong. The climate sensitivity to CO2 levels is, at best, tiny. The natural forces of the climate will produce negative feedbacks that completely overwhelm the hypothetical CAGW positive feedback loop. Thus, while CO2 emissions will likely induce a slight warming, the natural climatic forces will dictate and dominate our climate future.
Finally, any "science" association, journalist, politician, celebrity, weatherperson, bureaucrat and pundit who says that dangerous global warming is happening, is unequivocal, is rapid, is irrefutable, is unprecedented, is robust, is significant and is accelerating can only be one thing: he or she is a pathological liar.Data used: HadCRUT and CO2