Global Warming Pause: Who Pressed the Button?


The Earth's surface temperature upsurge at a rate of 0.04°C between 1998 and 2013, a rate which is way slower than the 0.18°C increase in the 1990s. At the same time, the release of carbon dioxide increases on and on. This delay in global warming has increased ambiguity about the climate change. A few cynics say firmly that global warming has ended.

But many still argue that scientists' perception of the climate is so imperfect that their understanding about it cannot be assumed with any assurance. It needs a persuasive clarification of the pause both to the proper understanding of the climate and to the credibility of climate science - and papers released for the past few weeks did their best to provide one, which almost did a good job if all were right.

As information compiled revealed that temperatures were not rising much, some scientists discharged it as minor shock. The temperature, they said, had fallen for much longer periods twice in the past century or so, in 1880-1910 and again in 1945-1975. Variability is part of the climate system and a 15-year hiatus, they suggested, was not worth getting excited about.

A possible way of looking at the pause's significance was to declare that there had been a gradual decrease but not a big one. Some records do not add calculations from the Arctic, which has been warming faster than any place in the world.

Kevin Cowtan of the University of York in Britain and Robert Way of the University of Ottawa in Canada used satellite data to fill in the missing Arctic numbers. They set the overall rate of global warming at 0.12°C a decade between 1998 and 2012 - not far from the 1990s rate.

But remember that the average warming is not only the way to calculate the climate change. According Sonia Seneviratne of the Institute for Atmospheric and Climate Science, the number of hot days, the number of extremely hot days and the length of warm periods all rise up during the pause in 1998-2012.

The causes of the global warming pause maybe aerosols, solar cycle, ocean winds and currents. But then again, the solar cycle is already revolving. Most of the situations put the planet's temperature rise on "pause" look temporary. Global warming will be back.

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