Our planet is likely to experience as much as 20 percent more warming by the end of the century than previously estimated, according to a study released this week in the scientific journal Nature Climate Change.
Despite the recent slowdown in global warming, during which surface temperatures worldwide since 2000 have risen much more slowly than in previous decades, the study found that Earth's climate system may have a higher sensitivity to greenhouse gas emissions than a wide range of past estimates indicate.
The study looked primarily at two things: how aerosols both cool and warm the atmosphere, and the sensitivity of the Earth's transient climate response to changes in the level of carbon dioxide and other greenhouse gases (GHG) in the atmosphere.
How sensitive the planet is to changes in GHG concentrations has been the subject of significant debate in recent years, especially as Earth's average surface temperatures have warmed by only about 0.05°C (0.09°F) per decade since about 2000, after rising by about 0.12°C (0.22°F) per decade since the 1950s.
During this time, emissions of carbon dioxide and other GHGs in the atmosphere have only increased, a fact that has prompted suggestions that Earth's climate system may not be as sensitive to increasing GHG emissions as once thought.
Research studies and the Intergovernmental Panel on Climate Change have weighed in with their own estimates on the temperature rise we can expect from the Earth's transient climate response, from a high of about 1.4°C (2.52°F) by recent research to a low of about 1°C (1.8°F) by the IPCC.
Drew Shindell, a climatologist at NASA's Goddard Institute for Space Studies who led the study, studied how the airborne particles known as aerosols – which emanate from both natural sources like volcanoes as well as man-made sources like industrial manufacturing plants and cars – impact this response.
If his study is correct, over the long term the planet is actually more sensitive to increasing GHG emissions than previously thought, which means that a doubling of greenhouse gases in the atmosphere will cause temperatures to rise by 1.3°C to 1.7°C (2.34°F to 3.06°F).
The conclusions he reaches, Shindell said in a NASA news release, mean that the world's industrial nations need to move much more aggressively to reduce emissions than they have so far in order to avoid the most damaging impacts of climate change.
"I wish it weren't so," Shindell added. "But forewarned is forearmed."
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