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Warming Slows but Greater Impact Is Inevitable: Study May 24, 2013
Satellite Image
Since 1880, the average global surface temperature of Earth has risen by about 1.5 degrees Fahrenheit. The oceans have absorbed far more heat than that.
Global warming is occurring at a slower rate than previous models have predicted, according to a study published in the science journal Nature Geoscience.

Authored by an international team of climatologists from eight countries, the article argues that in light of this slowing trend current projections of extreme climate change in the near future should be revised.

But the report argues that over the longer term, global temperatures are still expected to ratchet upward in the absence of significant reductions in greenhouse gas emissions.

Though the ten warmest years on record have all been since 1998, the year-over-year increase in average temperatures has actually slowed in the last two decades compared to the 1980s and 1990s. 

Building a climatological forecast based on this more recent slowdown, the report estimates that a doubling of the atmospheric concentration of carbon dioxide above pre-industrial levels will raise temperatures by 1.6 to 3.6 degrees over a 50-to-100-year period.

This is a somewhat less extreme impact than the 2007 projection published by the United Nations panel on climate science, which linked a doubling of carbon dioxide to a short-term temperature increase of between 1.8 to 5.4 degrees Fahrenheit.

The more muted warming response to a steady uptick in greenhouse gas emissions is likely due to the absorption of excess atmospheric heat by the world’s oceans, the new report says.

Reto Knutti, a Swiss climatologist and one of the authors of the study, tells Reuters that the ocean’s moderating influence will only be temporary. 

“We are still looking at warming well over the two degree goal that countries have agreed upon if current emission trends continue,” he said.

Graphic: NASA