Climate slowdown means extreme rates of warming

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

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.

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

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.

Reports  in 2007 said 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.

Ice The report suggests that warming in the near term will be less than forecast.

"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 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. Scientists said that climate sensitivity was in the range of 2.0-4.5C

This latest research, including the decade of stalled temperature rises, produces a range of 0.9-5.0C.

The researchers say the difference between the lower short-term estimate and the more consistent long-term picture can be explained by the fact that the heat from the last decade has been absorbed into and is being stored by the world's oceans.

The authors say there are ongoing uncertainties surrounding the role of aerosols in the atmosphere and around the issue of clouds.

Source:BBC

N.H.Khider