The choice may be global warming or a new Ice Age, say scientists
For many of us, the debate over the reality of climate change never goes beyond wondering if it can explain a recent bout of freakish weather.
Yet for many of the hundreds of thousands of Filipinos living in the UAE the debate has taken a tragically personal turn.
Yeb Sano, leader of the Philippines delegation to November’s UN climate conference in Warsaw, doubtless spoke for many when he implicated global warming for the Super Typhoon Haiyan, which has so far claimed more than 5,000 lives and left 500,000 homeless.
Mr Sano’s speech was made all the more poignant by the fact that exactly a year ago, his delegation appealed for action to combat global warming while his nation was being battered by another typhoon, causing a then-unprecedented disaster on the southern island of Mindanao.
He was close to tears as he called on those still sceptical about climate change to “get off your ivory tower and away from the comfort of your armchair” to witness the evidence. “We can stop this madness”, he said.
There can be no doubting his sincerity. Yet while he is not alone in seeing the disaster as proof of the reality of calamitous climate change, few scientists have been happy to make the connection.
They are all too aware of falling for the notorious fallacy known to logicians as post hoc, ergo propter hoc (after this, therefore because of this).
Many, perhaps most, scientists are convinced that global warming is taking place, and it seems that more violent storms are a natural consequence.
Higher temperatures mean more thermal energy being packed into the oceans, and more powerful convective currents, resulting in more powerful storms.
Yet scientists have long recognised that climatic phenomena are rarely that simple. In the case of tropical storms, the processes are still too poorly understood to make sense of the latest spate of severe storms.
Indeed, there is no clarity even about so basic a fact as whether such storms are becoming more common. While tropical cyclone intensity has increased since the 1970s, the trend is within the normal range of long-term historical records.
It does seem that such storms are causing more damage, but that could reflect the fact that there are just more people and buildings in harm’s way. The population of the Philippines has doubled since the mid-1970s, with some predicting it will exceed 100 million in the next year.
Yet whatever the reality of a link between climate change and Typhoon Haiyan, the chances of Mr Sano’s conference plea to combat global warming leading to action are low to zero.
Barely had he sat down 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.
The cause of the calamities that have struck the Philippines is no more certain.
But when it comes to climate change, both science and history suggest adaptation is the surest route to safety.
Robert Matthews is visiting reader in science at Aston University, Birmingham, England
Updated: November 30, 2013 04:00 AM