Global Warming Pause ‘Settled’

The existence of a more than 15-year “pause” in average global surface temperatures has been “settled” but scientists remain split on what it means for the future.

While the level of carbon dioxide in the atmosphere has continued to rise, global surface temperatures have not increased at the same pace, causing speculation over what has happened to the “missing heat”.

Some leading climate scientists claim the missing heat has been absorbed by the world’s oceans and will return with rapid future warming. But new research has found the Earth’s climate is much less sensitive to carbon dioxide than previously thought.

Michael Asten from Monash University’s School of Earth ­Atmosphere and Environment said that, while opinions on causes differed, the existence of the pause was settled.

“Only activists dare claim the pause in global temperature does not exist,” Professor Asten said.

Australia’s leading public science organisation, CSIRO, has ­acknowledged the “hiatus” but says its existence does not detract from the urgency of addressing human carbon dioxide emissions.

CSIRO Oceans and Atmosphere Flagship director Helen ­Cleugh said measurements did show that the rate at which global mean surface temperature had warmed in the past decade was less than in the previous decade. But she said actual temperatures had remained at historic highs. She said that when the entire climate system was considered, the Earth had continued to warm.

“Measurements across the oceans and Earth system as a whole show that warming has continued unabated throughout this period,” Dr Cleugh said.

Climate Council chief executive Amanda McKenzie said her organisation, which includes Will Steffen and Tim Flannery, did not accept there had been a pause.

“No, 2013 marked the 37th year in a row that the yearly global temperature was hotter than the average,” Ms McKenzie said.

“Vested interests have been using the so-called pause to spread doubt and misinformation.”

Federal Environment Minister Greg Hunt said warming of the climate system was “unequivocal”.

“The climate system, which includes the atmosphere, oceans, land and ice, has continued to accumulate heat over the last 18 years,” he said. “The government fully accepts the science.”

Most research has focused on finding the extra heat elsewhere in the climate system. NASA has ruled out an early theory that it was hiding in the deep oceans below 2000m. Other papers have claimed it could be located in the north Pacific and Atlantic oceans.

Another paper says warming of the Southern Ocean has been underestimated in the past.

Dr Asten said he believed the pause in surface temperatures would force scientists to re-examine fundamental assumptions in climate science. “The hiatus demonstrates a disconnect between climate models up to 2013 and physical measurements on our ‘laboratory Earth’,” he said.

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The Australian, 18 October 2014

IF two of the world’s foremost institutions for climate research can engage in an open and rational discussion about the planet’s obstinate refusal to abide by the strictures of scientific modelling, then it should not be beyond the wit of our national debate.

Britain’s Met Office Hadley Centre bluntly refers to the “recent pause in warming” and recognises that average global surface temperatures have “been relatively flat” since 1998. In the US the National Aeronautics and Space Administration talks about the “global warming hiatus”, declaring that since 1998 the rate of global surface temperature increase has been “one-third of that from 1951 to 2012”. The debate in the science communities of the northern hemisphere is not whether there has been a pause but about the reasons and implications. This is the debate our readers are entitled to and that the nation ought to embrace. Informed scepticism is the essence of scientific endeavour, yet to raise these issues in Australia’s stultifying climate of political correctness and climate dogma too often triggers denunciation or alarmist claptrap. So it is with a breath of fresh air that Monash University’s Michael Asten states the obvious in our pages today. “While opinions on causes differ, existence of the pause is settled,” Professor Asten tells Graham Lloyd. “Only activists dare claim the pause in global temperature does not exist.”