What You Won’t Find in the New National Climate Assessment
Guest essay by Dr. Pat Michaels
Under the U.S. Global Change Research Act of 1990, the federal government has been charged with producing large National Climate Assessments (NCA), and today the most recent iteration has arrived. It is typical of these sorts of documents–much about how the future of mankind is doomed to suffer through increasingly erratic weather and other tribulations. It’s also missing a few tidbits of information that convincingly argue that everything in it with regard to upcoming 21st century climate needs to be taken with a mountain of salt.
The projections in the NCA are all based upon climate models. If there is something big that is systematically wrong with them, then the projections aren’t worth making or believing.
Here’s the first bit of missing information:
The chart shows predicted and observed tropical (20⁰N-20⁰S) temperatures in the middle of the earth’s active weather zone—technically the mid-troposphere, roughly from 5,000ft to 30,000ft elevation. The predicted values are from the 102 climate model realizations from 32 different base model groups. These models are from the most recent science compendium of the UN’s Intergovernmental Panel on Climate Change (IPCC), and is the most comprehensive set available. Data for the chart were recently published in the Bulletin of the American Meteorological Society.
The squares are the average of the three extant datasets for satellite-sensed global temperatures in the same zone, the circles are the average of the four weather balloon records, and the diamonds are the fancy new “reanalysis” data, which uses a physical model to compensate for the fact that not all three-dimensional “soundings” of the atmosphere are from the same stations every day.
The difference between the predicted changes and observed is striking, with only one model, the Russian INCM4, appearing realistic. In its latest iteration, its climate sensitivity (the net warming calculated for a doubling of the atmosphere’s carbon dioxide concentration) is 1.4⁰C (2.5⁰F) compared to the average of 3.2⁰C (5.8⁰F) in the family of models used in the National Climate Assessment. In fact, the temperature trajectory the earth is on, along with an expected large-scale shift from coal to gas for electrical generation (already underway in the U.S. and Canada) will keep total human-caused warming to less than 2.0⁰C (3.6⁰F) between 1950 and 2100, which is the goal of the Paris Climate Agreement.1
That’s a far cry from the extremism of the National Assessment.
The second bit of missing information is sufficient to invalidate most of the Assessment’s predictions. It’s a bit more complicated than the first one.
The vertical axis is height (as measured by barometric pressure) and the horizontal axis is temperature change, in degrees C per decade. The solid green line is the observed average of our four sets of vertical sounding data from balloons. You can see that the observed warming rate at the surface (given as the “1000 hPa” on the left axis) is a bit above 0.1⁰C/decade, while the predicted value (1979-2016) is smidge below 0.2⁰C. In other words, in this region, which is extremely important to global climate, almost twice as much warming is being predicted compared to what is measured. This is figure S-2 in the recent Bulleting of the American Meteorological Society report on the climate of 2016.
But the situation gets truly horrific as one goes up in the atmosphere. The models predict that there should have been a huge “hot spot” over the entire tropics, which is a bit less than 40% of the globe’s surface. Halfway up through the atmosphere (by pressure), or at 500 hPa, the predicted warming is also twice what is being observed, and further up, the prediction is for seven times more warming than is being observed.
