本世纪地球气候将持续变暖

A new NASA study shows Earth's climate likely will continue to warm during this century on track with previous estimates, despite the recent slowdown in the rate of global warming. This research hinges on a new and more detailed¹ calculation of the sensitivity of Earth's climate to the factors that cause it to change, such as greenhouse gas emissions². Drew Shindell, a climatologist at NASA's Goddard Institute for Space Studies in New York, found Earth is likely to experience roughly 20 percent more warming than estimates that were largely based on surface temperature observations during the past 150 years.

 

Shindell's paper on this research was published March 9 in the journal Nature Climate Change.

 

Global temperatures have increased at a rate of 0.22 Fahrenheit³ (0.12 Celsius) per decade since 1951. But since 1998, the rate of warming has been only 0.09 F (0.05 C) per decade -- even as atmospheric⁴ carbon dioxide continues to rise at a rate similar to previous decades. Carbon dioxide is the most significant greenhouse gas generated by humans.

 

Some recent research, aimed at fine-tuning long-term warming projections⁵ by taking this slowdown into account, suggested Earth may be less sensitive to greenhouse gas increases than previously⁶ thought. The Fifth Assessment⁷ Report of the Intergovernmental Panel on Climate Change (IPCC), which was issued in 2013 and was the consensus⁸ report on the state of climate change science, also reduced the lower range of Earth's potential for global warming.

 

To put a number to climate change, researchers calculate what is called Earth's "transient climate response." This calculation determines how much global temperatures will change as atmospheric carbon dioxide continues to increase -- at about 1 percent per year -- until the total amount of atmospheric carbon dioxide has doubled. The estimates for transient climate response range from near 2.52 F (1.4 C) offered by recent research, to the IPCC's estimate of 1.8 F (1.0 C). Shindell's study estimates a transient（短暂的） climate response of 3.06 F (1.7 C), and determined⁹ it is unlikely values will be below 2.34 F (1.3 C).

 

Shindell's paper further focuses on improving our understanding of how airborne particles, called aerosols¹⁰（气溶胶）, drive climate change in the Northern Hemisphere. Aerosols are produced by both natural sources -- such as volcanoes, wildfire and sea spray -- and sources such as manufacturing activities, automobiles¹¹ and energy production. Depending on their make-up, some aerosols cause warming, while others create a cooling effect. In order to understand the role played by carbon dioxide emissions in global warming, it is necessary to account for the effects of atmospheric aerosols.

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