糖心原创出品

A paper co-authored by Dr. John Christy is among the top 10% most downloaded in 2020 from the AGU journal Earth and Space Science.

Michael Mercier | UAH

A that found a significant warming bias globally in the newest climate models and was co-authored by the interim vice president for research and economic development at 糖心原创出品 (UAH) has been cited by the American Geophysical Union (AGU) as among the top 10% most downloaded in 2020 from its journal Earth and Space Science.

鈥淧ervasive Warming Bias in CMIP6 Tropospheric Layers鈥� was co-authored by Dr. John Christy, a distinguished professor of atmospheric science who is also Alabama鈥檚 state climatologist and director of the Earth System Science Center (ESSC) at UAH, a part of the University of Alabama System. The article 鈥渉elped raise the visibility of Earth and space sciences and inspired new research ideas,鈥� according to AGU.

鈥淭his is cool 鈥� no pun intended,鈥� says Dr. Christy, who was appointed to serve on the U.S. Environmental Protection Agency鈥檚 Science Advisory Board during the Trump administration.

鈥淭his was a pleasant surprise for Ross McKitrick and me,鈥� he says. 鈥淩oss is an econometrician at the University of Guelph in Guelph, Ontario, Canada, with terrific statistical skills. I worked on assembling the observational datasets and converting the raw climate model output into a metric that matched what is observed from satellites and balloons.鈥�

The scientists examined and updated historical data focusing on 1979-2014 from the newest Coupled Model Intercomparison Project Version 6 (CMIP6) climate model and found that what previously were excessive warming rates modeled only in the tropical troposphere are now being excessively modeled globally. All of their model runs warmed faster than observations in the lower troposphere and mid-troposphere, both in the tropics and globally.

They found that the temperature of the bulk atmosphere, as measured by satellites, is an ideal characteristic to monitor for the detection of climate change. As part of an ongoing joint project between UAH, the National Oceanic and Atmospheric Administration (NOAA) and NASA, Dr. Christy with ESSC Principal Research Scientist Dr. Roy Spencer publishes a monthly that uses data gathered by advanced microwave sounding units on NOAA, NASA and European satellites to produce temperature readings for almost all regions of the Earth.

鈥淭his is where the response to increasing greenhouse gases should be most noticeable,鈥� says Dr. Christy of the bulk atmosphere.

In earlier work focused on the tropical upper troposphere 鈥� the region about 30,000 to 40,000 feet in altitude in the tropics 鈥� Dr. Christy and collaborators found that the region is critical because it serves as a key 鈥渧ent鈥� for releasing heat to space.

鈥淲e found that when the Earth warms, the amount of heat escaping to space is about twice the amount that climate models release,鈥� he says. 鈥淚n other words, this 鈥榲ent鈥� region in the models does not open up enough to release the extra heat at the same rate as does the real world.鈥�

As a result, he says that in climate models the extra heat is retained and eventually warms up the entire atmosphere down to the surface.

鈥淭he effectiveness of this 鈥榲ent鈥� can be impaired if the models have too much water vapor and/or thin clouds in that region,鈥� Dr. Christy says. 鈥淭his is a simple hypothesis to explain why the models are warming up the atmosphere too fast.鈥�

The researchers conclude that the bulk atmospheric measurement also avoids the imperfections that influence scattered surface thermometers, such as lack of coverage, contamination by urban effects and frequent site and instrument changes.

鈥淥ne of the reasons for the popularity of the article is the policy implication,鈥� Dr. Christy says. 鈥淭oday, governments are putting into place expensive energy policies that are based on climate model projections.鈥�

Since energy touches every aspect of our lives, he says that such policies have significant impact on everything we buy and everything we do.

鈥淥ur work demonstrates clearly that these policies are based on exaggerated notions of climate change,鈥� Dr. Christy says. 鈥淚n other words, we show that the models are too sensitive to the extra greenhouse gases that humans are placing into the atmosphere as a result of enhanced economic development, and so are not dependable for major energy-policy initiatives.鈥�