Since then, the demand to know whether emissions from burning fossil fuels are exacerbating climate and weather extremes has risen, and climate scientists are responding.
Since then, the demand to know whether emissions from burning fossil fuels are exacerbating climate and weather extremes has risen, and climate scientists are responding.

Global warming put on ice?

By FIONA MACRAE Time of article published Sep 27, 2013

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London - Global warming has been put on ice, the world’s leading experts are expected to confirm on Friday.

The United Nations’ Intergovernmental Panel on Climate Change is set to reveal world temperatures have barely risen in the past 15 years, despite growing amounts of greenhouse gases being pumped into the atmosphere.

Critics say this shows carbon dioxide is not as damaging as had been claimed. Indeed, the report is expected to admit that computer models of climate change were too pessimistic.However, some scientists insist the slow-down is temporary – and warn that global warming remains a pressing threat.

The IPCC report – the first in six years – has been compiled by more than 250 scientists. It will be used to inform government policy around the world.

Officials from 195 countries have spent this week behind closed doors in Stockholm, Sweden with UN scientists, hammering out a 30-page summary document due to be released today.

It is expected to give the strongest warning yet that climate change is man-made and will cause more heatwaves, droughts and floods unless governments take action.Drafts say it is “extremely likely” – with at least 95 percent certainty – that the burning of fossil fuels and other human activities are the main cause of rising temperatures since the Fifties.

That level of certainty is up from 90 percent in the last report in 2007, and 66 percent in 2001.

The IPCC, led by Rajendra Pachauri, will also give new estimates of the effect of global warming on sea levels, glaciers and ice sheets.

But its explanation of why the rise in global average surface temperatures has “paused” will be the most contentious passage. After the IPCC’s last major report was criticised for a string of errors – including the since-withdrawn claim that Himalayan glaciers would vanish within 25 years – confidence in the new document’s conclusions will be crucial.

The report is expected to say that temperature rises have dropped from 0.12C per decade since 1951 to just 0.05C per decade since 1998. The slowdown is great enough to be termed a “pause” or “hiatus” by scientists.

Climate change sceptics argue this means that the heating effect of carbon dioxide has been greatly exaggerated. Controversially, several governments have called for the references to the slowdown to be amended or even removed from the report.

Germany has asked for the passage to be deleted, saying a timespan of 10 to 15 years is misleading in the context of climate change, which takes its toll over longer periods.Belgium objects to using 1998 as a starting year for the statistics, as it was exceptionally warm.

Climate scientists say such pauses in warming occur regularly throughout history and can last for up to 20 years – but cannot be predicted. In addition, the IPCC is expected to say that much of the ‘missing’ heat is being stored deep beneath the sea, preventing it from contributing to temperatures at surface level.

Volcanic eruptions and changes in the sun’s activity are also thought to have contributed to the slow-down.

However, the summary is also likely to acknowledge that some of the computer programmes used to predict changes to the climate over-estimated the effect of carbon dioxide. Ed Hawkins, a climate expert from Reading University’s department of meteorology, said: “The current ‘pause’ in global surface temperatures certainly does not mean climate change has stopped.

“Surface temperatures have continued to rise more slowly than before – but other measures, such as rises in sea levels and melting snow and ice, show the climate has continued to change.

“Greenhouse gases are continuing to build up in the atmosphere and are warming the climate, but we believe temporary factors such as small volcanic eruptions and a decline in solar activity, alongside extra heat being absorbed into the deep ocean, are acting to temporarily cool the climate.

“When these temporary factors subside, we should see a return to warming.” The IPCC report is also expected to say that the world has already burned through half the amount of fossil fuel that will bring about dangerous levels of climate change, and that many of the changes that have already occurred to the atmosphere, land and sea are “unusual or unprecedented on time-scales of decades to millennia”.

Two more IPCC reports will be issued shortly, covering the impact of the changing climate and how to limit the damage, ahead of treaty talks in Paris in 2015.. - Daily Mail

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