06 December, 2011

Global warming not slowing down: study

Global warming is showing no signs of slowing down and further increases are to be expected in the next few decades, shows a new study published today, in the Environmental Research Letters.

They tried to capture “the true global warming trend” by analyzing the five leading global temperature data sets, covering the period from 1979 to 2010, to factor out three of the main factors that account for short-term fluctuations in global temperature: El Niño, volcanic eruptions, and variations in the Sun’s brightness.

Removing these short-term fluctuations, the researchers from Tempo Analytics and the Potsdam Institute for Climate Impact Research showed that the global temperature has increased by 0.5°C in the past 30 years. In all of the five global data sets, 2009 and 2010 were the two hottest years. In the average over all five data sets, 2010 is the hottest year on record.

“Our approach shows that the idea that the global warming trend has slowed or even paused over the last decade or so is a groundless misconception. It shows that differences between the five data sets reside, to a large extent, in their short-term variability and not in the climatic trend. After the variability is removed, all five data sets are very similar,” said co-author Stefan Rahmstorf.

By bringing together and analyzing the five records – three surface records and two lower-troposphere records – the researchers were able to clarify the discrepancies between each one and, when factoring out the naturally occurring variability, show the excellent agreement between all five data sets.

The three surface temperature data sets analyzed by the researchers were from NASA, the National Oceanic and Atmospheric Administration (NOAA) and the Hadley Centre/Climate Research Unit in the UK. Data representing the lower troposphere temperatures was based on satellite microwave sensors.

“The unabated warming is powerful evidence that we can expect further temperature increase in the next few decades, emphasizing the urgency of confronting the human influence on the climate,” says, lead author Grant Foster.

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