Intergovernmental Panel on Climate Change (IPCC) currently estimates temperature increases of 3.0°C for doubled CO2. Recent findings refute this fundamental IPCC projection, demonstrating that the risk of a much hotter future is significantly greater than conventional models estimate. Furthermore, the decadal rate of CO2 increase is increasing in an exponential and not linear manner.
Based on historical records (ice; ocean and lake sediment; bore holes into the earth’s crust; and cave deposits), when CO2 levels double, the Earth’s temperature rises an average of 4.8°C (ranging from 3.6°C to 6°C). Oxford Open Climate Change, Volume 3, Issue 1, 2023: Global warming in the pipeline. James E. Hansen, Makiko Sato, Leon Simons, et al. https://academic.oup.com/oocc/article/3/1/kgad008/7335889
“Climate sensitivity is substantially higher than IPCC’s best estimate (3°C for doubled CO2), a conclusion we reach with greater than 99 percent confidence.”) “Seeing the Forest for the Trees,” James E. Hansen and Pushker Kharecha, August 6, 2025. Dr. Hansen points out that the IPCC’s best estimate of 3.0°C is inconsistent with multiple lines of scientific evidence. The “greater than 99 percent confidence” is based on an analysis of multiple and combined data sets and concludes that the probability of climate sensitivity being as low as 3.0°C or less is extremely small.”
The CO2 level in 1750 was 280 parts per million (ppm). In May 2025, the CO2 level at Mauna Loa Observatory reached a high point of 428 ppm. The 2023 to 2024 increase of atmospheric CO2 was 3.54 ppm. Assuming future annual CO2 ppm increases do not exceed the 2023-2024 increase, the Pre-Industrial level of 280 ppm will double in 37.7 years (2062), baking in temperature increases of approximately 4.8C (ranging from 3.6°C to 6°C).
To learn more about this important finding, access Roger Hallam’s January 2026 Report here: ______________________What this means to you: A fundamental way to approach the question of “how fast is our planet overheating” is to project, as best possible, temperature increases based on the increase of current CO2 levels above pre-industrial levels of CO2. Because conventional climate models continue to use discredited sensitivity information, their projections significantly underestimate the speed of collapse. As a result of this misinformation, we are losing valuable time to address and develop effective responses to the collapse that is coming.
