近期全球变暖趋势将延缓

Scientists say the recent downturn in the rate of global warming will lead to lower temperature rises in the short-term.

科学家称，近期全球变暖趋势的暂缓将造成短期内气温升高的降低。

Since 1998, there has been an unexplained "standstill" in the heating of the Earth's atmosphere. 

Writing in Nature Geoscience, the researchers say this will reduce predicted warming in the coming decades. 

But long-term, the expected temperature rises will not alter significantly.

The slowdown in the expected rate of global warming has been studied for several years now. Earlier this year, the UK Met Office lowered their five-year temperature forecast. 

But this new paper gives the clearest picture yet of how any slowdown is likely to affect temperatures in both the short-term and long-term.

An international team of researchers looked at how the last decade would impact long-term, equilibrium climate sensitivity and the shorter term climate response. 

Transient nature

Climate sensitivity looks to see what would happen if we doubled concentrations of CO2 in the atmosphere and let the Earth's oceans and ice sheets respond to it over several thousand years. 

Transient climate response is much shorter term calculation again based on a doubling of CO2. 

The Intergovernmental Panel on Climate Change reported in 2007 that the short-term temperature rise would most likely be 1-3C (1.8-5.4F).

But in this new analysis, by only including the temperatures from the last decade, the projected range would be 0.9-2.0C.

"The hottest of the models in the medium-term, they are actually looking less likely or inconsistent with the data from the last decade alone," said Dr Alexander Otto from the University of Oxford. 

"The most extreme projections are looking less likely than before."

The authors calculate that over the coming decades global average temperatures will warm about 20% more slowly than expected. 

But when it comes to the longer term picture, the authors say their work is consistent with previous estimates. The IPCC said that climate sensitivity was in the range of 2.0-4.5C.