The Intergovernmental Panel on Climate Change (IPCC) publishes, every 3 to 4 years, their version of the science supporting their theory of global warming. Laboratory tests would indicate that for every doubling of CO2 in the atmosphere, the Earth’s temperature should rise about 1C. That is not really very threatening. Their theory says that a doubling will bring about a 3C temperature increase. The theory postulates that the temperature rise caused by CO2 would increase the amount of water vapor (H2O) in the atmosphere. This increase in water vapor, the major so called greenhouse gas, would result in an additional 2C rise— thus when added to the 1C from the CO2 effect would give the 3C rise for a doubling of atmospheric CO2. This is their view of climate sensitivity. The warmer’s climate models are programmed with this sensitivity. And if you follow this topic at all, you know that the models have predicted much higher temperatures than the real, measured temperatures. And the gap between actual temperature measurements and the climate model forecasts keeps growing.
A 20 June 15 posting on Niche Modeling titled “Published measurements of climate sensitivity declining has a chart that compares the current research versus older research into climate sensitivity. From that posting:
” Scientists made numerous estimates of climate sensitivity over the last few decades and have yet to determine the correct value. The figure shows the change in published climate sensitivity measurements over the past 15 years (from here). The ECS and TCR estimates have both declined in the last 15 years, with the ECS declining from 6C to less than 2C. While one cannot extrapolate from past results, it is likely that the true figure is below 2C, and may continue to decline. Based on this historic pattern we should reject the studies that falsely exaggerated the climate sensitivity in the past and remember that global warming is not the most serious issue facing the world today.
Frow Wiki, an expanded definition of ECS andTCR:
The equilibrium climate sensitivity (ECS) refers to the equilibrium change in global mean near-surface air temperature that would result from a sustained doubling of the atmospheric carbon dioxide concentration. The transient climate response (TCR) is defined as the average temperature response over a twenty-year period centered at CO2 doubling in a transient simulation with CO2 increasing at 1% per year. The transient response is lower than the equilibrium sensitivity, due to the “inertia” of ocean heat uptake.
Over the 50–100 year timescale, the climate response to forcing is likely to follow the TCR. With atmospheric CO2 now at a level of about 400 ppm and some experts claiming that the amount of CO2 will never rise to 800 because fossil fuels will be depleted by then. I don’t know how to assess that but getting to 800ppm is a long way off into the future.