Climate scientists insist global warming hasn’t stopped

Shari Miller — Daily Mail Sept 22, 2013

Global warming has not stopped – it’s just on a ‘hiatus’ and likely to return with ever more heatwaves, droughts, floods and rising sea levels – according to a draft report from leading scientists.

The 127-page United Nations report, and a shorter summary for policymakers due for release in Stockholm on September 27, suggests a slowdown in Earth’s rising temperature can be explained by volcanic ash and a cyclical dip in energy emitted from the sun.

While likely to attract opposition from sceptics – who say climate change is not man-made – the UN’s Intergovernmental Panel on Climate Change is likely to stand by the bold claims as the body attempts to salvage its reputation following the publication of its last report in 2007.

In that report, scientists erroneously claimed the Himalayas would melt by 2035

Now six years on, the IPCC must convincingly explain why temperatures have risen more slowly in the past 15 years despite rising emissions of greenhouse gases – something that has emboldened sceptics who question the need for urgent action.

The IPCC is seen as the world authority on the extent of climate change and what is causing it.

Governments around the world, including Britain, largely base their green policies on the report.

Just on Friday, France called for bolder EU cuts in greenhouse gases and said it would halve its own energy consumption by 2050.

While the IPCC draft report acknowledges the slow rise in temperature, scientists predict this is simply a ‘common break’ in global warming – and it will resume once more.’Barring a major volcanic eruption, most 15-year global mean surface temperature trends in the near-term future will be larger than during 1998 to 2012,’ reports the Technical Summary, dated June 7. Temperatures are likely be 0.3 to 0.7 degree Celsius (0.5-1.3 Fahrenheit) higher from 2016-35 than from 1986-2005, it adds.

The reports by the IPCC, updating an overview of climate change from 2001, are the main guide for government action.’Fifteen-year-long hiatus periods are common’ in both historical records and in computer models. But scientists were caught out – in one computer model, 111 of 114 estimates over-stated recent temperature rises.

The drafts predict that temperatures could rise by up to 4.8C (8.5F) this century – far above a ceiling set by governments of 2C (3.6F) above pre-industrial times to avoid dangerous changes to nature and society.

However, the report suggests that with deep cuts in greenhouse gas emissions, the rise could be kept to just 0.3C (0.5F), the draft says.

Many experts agree that natural variations in the weather, caused by factors such as shifts in ocean currents or winds, can mask a warming trend even with a continued build-up of carbon dioxide in the atmosphere.

The hiatus ‘is not a sign that the warming trend has gone,’ said Guy Brasseur, director of the Climate Service Center in Germany.

He said the climate was comparable to Wall Street – there were often long-term trends with unpredictable daily swings.

Brasseur and other experts contacted were stating their own views, not referring to details of the coming report.

‘There are a number of explanations (for the hiatus), any one of which might be correct,’ said professor Myles Allen of Oxford University, who contributed to the IPCC draft.

‘That is very different from saying: ‘We have no idea what’s going on’.’

The drafts say that a reduction in warming for 1998 to 2012 compared to 1951 to 2012 is ‘due in roughly equal measure’ to natural variations in the climate and factors such as ‘volcanic eruptions and the downward phase of the current solar cycle.’Volcanoes spew ash into the air that can dim sunlight and so cool the surface of the planet. The sun was in a downward cycle of output – meaning that it was emitting less energy – during most of the period.

The technical summary says that warming from 1998 to 2012 slowed to 0.05 degree C (0.09F) per decade, against 0.12 (0.2F) per decade from 1951-2012.

But the decade to 2012 was the warmest since records began in the mid-19th Century.

It says another factor could be that computer models consistently over-estimate warming.

Some experts argued that near-term projections of temperature rises should be cut by 10 percent, it said.

Other theories include that more heat is going into the oceans or that air pollution is dimming sunlight.

An academic report last month said a cooling of the Pacific Ocean, linked to natural La Nina events that bring cooler waters to the surface, was the main explanation.

The IPCC draft also says the planet may be somewhat less sensitive than expected to a build-up of carbon dioxide in the air.

A doubling of atmospheric carbon dioxide levels from pre-industrial times is likely to mean an eventual temperature rise of between 1.5 and 4.5 C (2.7-8.1F), down from 2.0 to 4.5 (3.6-8.1F) estimated in 2007, the report adds.

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