According to a statement on the study from NASA, researchers developing warming estimates by calculating the Earth’s “transient climate response.” This measure determines how much global temperatures will change as carbon dioxide’s atmospheric presence grows at about 1 percent per year until the total amount of atmospheric carbon dioxide has doubled. Transient climate responses have range from near 2.52 degrees in recent research, to the Intergovernmental Panel on Climate Change’s (IPCC) estimate of 1.8 degrees. Shindell’s study estimates a transient climate response of 3.06 degrees. He says it is unlikely values would cool below 2.34 degrees.
The global mean temperature change estimates from a new NASA report. The dashed line shows estimates assuming uniform sensitivity to all forcings, while the solid line shows results including the enhanced sensitivity to the inhomogeneous aerosol and ozone forcings. Graphic credit: Nature Climate Change journal
His study also considers how aerosols, or airborne particles contribute to climate change in the Northern Hemisphere. Aerosols are produced by both natural sources like volcanoes and wildfires, as well as by manufacturing, driving automobiles, producing energy and more. Some aerosols cause warming, depending on their components, while some create a cooling effect. According to NASA, it is necessary to account for atmospheric aerosols in order to understand the role carbon dioxide emissions have on global warming.