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The Choice May Be Global Warming Or A New Ice Age, Say Scientists

Robert Matthews, The National

Whatever the reality of a link between climate change and Typhoon Haiyan, the chances of Mr Sano’s UN climate conference plea to combat global warming leading to action are low to zero.

Barely had he sat down [at the UN climate summit in Warsaw] than the government of Japan announced a new greenhouse gas emission target that allows an increase rather than a drastic cut over coming years. Other governments, most recently Australia and Canada, have made their lack of enthusiasm for drastic action no less clear.

So are we now condemned to seeing ever more climate-related tragedies? If so, the blame will certainly lie with mankind alone – at least, that is what environmentalists would have us believe. By disturbing the balance of nature, they argue, disaster will surely follow.

Once again, however, climate science is revealing a more complex reality. Evidence increasingly suggests that man-made global warming may actually be preventing a worldwide calamity, in the form of a new Ice Age.

Despite its pejorative image, the “greenhouse effect” of our atmosphere is all that stands between us and our being plunged into the bitter cold of the space around the Earth.

It keeps us warm by trapping the sun’s heat using molecules of certain gases – notably carbon dioxide and methane – in the atmosphere.

The heat we get from the sun ebbs and flows over millennia according to changes in the Earth’s orbit and orientation in space.

And calculations suggest we should have been heading back into a terrible Ice Age for the past few thousand years.

Fortunately this hasn’t happened – but why not?

Around a decade ago, a team of climate scientists led by Prof William Ruddiman of the University of Virginia suggested that humans may have been holding off the next Ice Age through our wilful production of greenhouse gases.

These are usually thought of as products of the Industrial Revolution. But Prof Ruddiman and his colleagues pointed out that basic agricultural practices, such as crop planting and deforestation, generate hefty amounts of carbon dioxide and methane – and perhaps even enough to cancel out the Big Chill that should have set in over the past few thousand years.

The idea has received a predictably frosty reception from environmentalists. But studies have since shown that greenhouse gases did indeed rise about 5,000 to 8,000 years ago – in line with the origins of large-scale agriculture in Asia and extensive deforestation in Europe.

Now fresh evidence that we humans are holding off an Ice Age has emerged. The journal Science has just published research by a team led by geochemist Prof Logan Mitchell at the University of Utah, Salt Lake City, who have compared methane levels trapped in ancient ice cores from Greenland and Antarctica.

The significance of the two locations is that human population growth has been different over the northern and southern hemisphere. So if methane levels have risen as the result of human activity – as Prof Ruddiman originally claimed – the ice cores from each hemisphere should show a different rate of increase in methane levels.

The team has now confirmed a substantial rise in methane in ice-core samples dating back up to 2,800 years. Crucially, however, the rise was bigger in the northern hemisphere, and could only be explained by including human activity – such as rice cultivation.

All this serves to underline the dangers of simplistic thinking in our approach to climate change. Trying to prevent it through drastic reduction of greenhouse gases may have disastrous consequences.

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