Dr. John Christy gives testimony to the U.S. Committee on Natural Resources about his analysis of the impact of proposed U.S. regulation on climate. He shows comparisons of climate model projection versus satellite and weather balloon observation. Climate models on average over predict global warming by a factor of three, and by a factor of four in the tropics. Dr. Christy shows eliminating all U.S. emissions today would reduce global temperatures by 0.05 to 0.08 Celsius, assuming a climate sensitivity of 1.8 C per doubling of CO2. He says there is evidence that climate sensitivity is less than 1.8 C, which would reduce this estimate further.
Dr. Patrick J. Michaels, a climatologist and guest speaker at the 5th Annual Friends of Science Luncheon writes, "year after year, the hole that climate scientists have buried themselves in gets deeper and deeper. The longer that they wait to admit their overheated forecasts were wrong, the more they are going to harm all of science." Referring to a graph prepared by Dr. John Christy, climatologist and guest speaker at the 7th Annual Friends of Science Luncheon, Michaels says there is a "remarkable disconnect between predicted global warming and the real world."
John Christy presented the graph to the House Committee on Natural Resources on May 15, 2015.
Dr. William Gray, Professor Emeritus of Colorado State University, writes,
"There are many flaws in the global climate models. But the largest flaw is a result of the climate model’s inability to realistically deal with the small horizontal scale (and model unresolvable) changes brought about by the globe’s thousands of individual deep cumulonimbus (Cb) cloud elements. An increase in the totality of these deep Cb convective units adds drying to the upper troposphere. This is in contrast to the assumptions implicit in the General Climate Model (GCM) simulations which increase upper tropospheric water-vapor as a result of enhanced rainfall and Cb convection associated with rising levels of CO2." The upper-level drying leads to extra infrared radiation loss to space, resulting in a negative water vapor feedback.
Climate scientist Bob Tisdale published an open letter to three U.S. Senators. He asked "Why are taxpayers funding climate model-based research when those models are not simulating Earth’s climate?" and other related questions. Tisdale notes that modes of natural variability of the oceans "are now being blamed for suppressing global surface warming." This natural variability, much of which may ultimately be solar-caused, enhanced warming from the mid-1970 to the turn of the century. Climate models were aligned to that warming trend, falsely attributing almost all the warming to human causes.
High estimates of climate sensitivity to double CO2 determined from climate models rely on "highly negative aerosol forcing" to offset high CO2 forcing estimates so the forecasts approximately match the 20th century warming. A new study by Bjorn Stevens shows the aerosol forcing is much less negative than previously estimated. Climate scientist Nicholas Lewis has calculated new lower climate sensitivity estimates utilizing the new aerosol estimates. His best estimate equilibrium climate sensitivity is only 1.45 C with a likely range of 1.2 to 1.8 C, which is much less that the AR5 range estimate of 1.5 to 4.5 C.