To achieve the IPCC’s 3˚ “best estimate” of warming from doubled CO2 since the Industrial Revolution by the end of this century, GAT would have to rise another 2.593˚ in the remaining 63.5 years, a rate of 0.41˚ per decade, which is 3.7 times as fast as the observed rate so far. To achieve the 2˚ lower bound claimed for over 20 years, GAT would have to rise two-and-a-quarter times as fast as the observed rate. Even to reach the 1.5˚ the IPCC now claims is the lower bound, GAT would have to rise one-and-a-half times as fast as the observed rate.

And there is no empirically driven reason to think warming will accelerate in coming decades. On the contrary, because the warming effect of rising carbon dioxide concentration is logarithmic, warming attributable to it should slow, not accelerate, as CO₂ continues its steady rise.

Look at it another way:

• On average the computer models on which the IPCC relies simulate twice as much warming as observed over the relevant period.
• Over 95% simulate more warming than observed, meaning their errors are not random but driven by bias built into the models (probably incorrectly assuming that many climate feedbacks, such as clouds, are strongly positive that are instead either only weakly positive or actually negative).
• None simulated the complete absence of statistically significant warming for the last 17 to 27 years, depending on the database—18 years and 8 months according to the satellite data.

For it to make sense to try to slow anthropogenic (human-induced) global warming (AGW), particularly when the only way to do so is to slow or stop economic development in the world’s poorer countries and reverse it in the richer ones, AGW must pose grave danger. It does so only if we have good reason to believe it will be rapid and sustained, that is, if “climate sensitivity” (warming in response to added CO₂) is high. These facts are extremely difficult to reconcile with that idea.

You might have seen news recently that a study from the National Oceanic and Atmospheric Administration (NOAA) proved that, contrary to that last point, global warming has continued throughout the time that many call “the pause.” I happen to think, along with many climate scientists, that that study was fatally flawed. But even assuming that the dataset NOAA constructed in that study is right and all the others, which do show “the pause,” are wrong, the implication for the rapidity of AGW is incompatible with the alarmist case.

As Dr. Roy W. Spencer, a NASA award-winning scientist and now Principal Research Scientist in Climatology at the University of Alabama in Huntsville and U.S. Science Team Leader on NASA’s Advanced Microwave Scanning Radiometer (AMSR) on the Aqua Satellite—the source of the satellite data—points out:

Even if it has warmed in the last 15 years, the rate of surface warming (and deep-ocean warming) we have seen in the last 50 years still implies low climate sensitivity.

If you read Spencer’s complete article you’ll see why he concludes that even if NOAA is right about “the pause,” climate sensitivity is low—only about 1.5˚ for every doubling of atmospheric CO₂ concentration.

That’s a good reason to sign An Open Letter on Climate Change to the People, their Local Representatives, the State Legislatures and Governors, the Congress, and the President of the United States of America.