preview.tinyurl.com/d6hgbt -> www.newscientist.com/article/mg20126971.700-how-to-survive-the-coming-century.html?full=true
Explore an interactive map of the world warmed by 4 C ALLIGATORS basking off the English coast; the mythical lost cities of Saigon, New Orleans, Venice and Mumbai; Welcome to the world warmed by 4 C Clearly this is a vision of the future that no one wants, but it might happen. Fearing that the best efforts to curb greenhouse gas emissions may fail, or that planetary climate feedback mechanisms will accelerate warming, some scientists and economists are considering not only what this world of the future might be like, but how it could sustain a growing human population. They argue that surviving in the kinds of numbers that exist today, or even more, will be possible, but only if we use our uniquely human ingenuity to cooperate as a species to radically reorganise our world. The good news is that the survival of humankind itself is not at stake: the species could continue if only a couple of hundred individuals remained. But maintaining the current global population of nearly 7 billion, or more, is going to require serious planning. Four degrees may not sound like much - after all, it is less than a typical temperature change between night and day. It might sound quite pleasant, like moving to Florida from Boston, say, or retiring from the UK to southern Spain. An average warming of the entire globe by 4 C is a very different matter, however, and would render the planet unrecognisable from anything humans have ever experienced. Indeed, human activity has and will have such a great impact that some have proposed describing the time from the 18th century onward as a new geological era, marked by human activity.
Intergovernmental Panel on Climate Change, whose conclusions are generally accepted as conservative, predicted a rise of anywhere between 2 C and 64 C this century. And in August 2008, Bob Watson, former chair of the IPCC, warned that the world should work on mitigation and adaptation strategies to "prepare for 4 C of warming". A key factor in how well we deal with a warmer world is how much time we have to adapt. When, and if, we get this hot depends not only on how much greenhouse gas we pump into the atmosphere and how quickly, but how sensitive the world's climate is to these gases. It also depends whether "tipping points" are reached, in which climate feedback mechanisms rapidly speed warming. According to models, we could cook the planet by 4 C by 2100. Some scientists fear that we may get there as soon as 2050. If this happens, the ramifications for life on Earth are so terrifying that many scientists contacted for this article preferred not to contemplate them, saying only that we should concentrate on reducing emissions to a level where such a rise is known only in nightmares. "Climatologists tend to fall into two camps: there are the cautious ones who say we need to cut emissions and won't even think about high global temperatures;
Peter Cox, who studies the dynamics of climate systems at the University of Exeter, UK. We have to accept that changes are inevitable and start to adapt now." Bearing in mind that a generation alive today might experience the scary side of these climate predictions, let us head bravely into this hotter world and consider whether and how we could survive it with most of our population intact. The last time the world experienced temperature rises of this magnitude was 55 million years ago, after the so-called Palaeocene-Eocene Thermal Maximum event. Then, the culprits were clathrates - large areas of frozen, chemically caged methane - which were released from the deep ocean in explosive belches that filled the atmosphere with around 5 gigatonnes of carbon. The already warm planet rocketed by 5 or 6 C, tropical forests sprang up in ice-free polar regions, and the oceans turned so acidic from dissolved carbon dioxide that there was a vast die-off of sea life. Sea levels rose to 100 metres higher than today's and desert stretched from southern Africa into Europe. While the exact changes would depend on how quickly the temperature rose and how much polar ice melted, we can expect similar scenarios to unfold this time around. The first problem would be that many of the places where people live and grow food would no longer be suitable for either. Rising sea levels - from thermal expansion of the oceans, melting glaciers and storm surges - would drown today's coastal regions in up to 2 metres of water initially, and possibly much more if the Greenland ice sheet and parts of Antarctica were to melt.
would be disastrous," he adds, "certainly leading to an ice-free planet, with sea level about 80 metres higher... Half of the world's surface lies in the tropics, between 30 and -30 latitude, and these areas are particularly vulnerable to climate change. India, Bangladesh and Pakistan, for example, will feel the force of a shorter but fiercer Asian monsoon, which will probably cause even more devastating floods than the area suffers now. Yet because the land will be hotter, this water will evaporate faster, leaving drought across Asia.
Bangladesh stands to lose a third of its land area - including its main bread basket. The African monsoon, although less well understood, is expected to become more intense, possibly leading to a greening of the semi-arid Sahel region, which stretches across the continent south of the Sahara desert. Other models, however, predict a worsening of drought all over Africa. A lack of fresh water will be felt elsewhere in the world, too, with warmer temperatures reducing soil moisture across China, the south-west US, Central America, most of South America and Australia. All of the world's major deserts are predicted to expand, with the Sahara reaching right into central Europe. Glacial retreat will dry Europe's rivers from the Danube to the Rhine, with similar effects in mountainous regions including the Peruvian Andes, and the Himalayan and Karakoram ranges, which as result will no longer supply water to Afghanistan, Pakistan, China, Bhutan, India and Vietnam.
latitudinal dry belts where human habitation will be impossible, say Syukuro Manabe of Tokyo University, Japan, and his colleagues. One will stretch across Central America, southern Europe and north Africa, south Asia and Japan; while the other will cover Madagascar, southern Africa, the Pacific Islands, and most of Australia and Chile (Climatic Change, vol 64, p 59). The high life The only places we will be guaranteed enough water will be in the high latitudes.
James Lovelock, who developed the "Gaia" theory, which describes the Earth as a self-regulating entity. "The rest of the world will be largely desert with a few oases." So if only a fraction of the planet will be habitable, how will our vast population survive? "Humans are in a pretty difficult position and I don't think they are clever enough to handle what's ahead. I think they'll survive as a species all right, but the cull during this century is going to be huge," he says. "The number remaining at the end of the century will probably be a billion or less."
John Schellnhuber of the Potsdam Institute for Climate Impacts Research in Germany is more hopeful. The 4 C warmer world would be a huge challenge, he says, but one we could rise to. "Would we be able to live within our resources, in this world? I think it could work with a new division of land and production." In order to survive, humans may need to do something radical: rethink our society not along geopolitical lines but in terms of resource distribution. "We are locked into a mindset that each country has to be self-sustaining in food, water and energy," Cox says. "We need to look at the world afresh and see it in terms of where the resources are, and then plan the population, food and energy production around that. If aliens came to Earth they'd think it was crazy that some of the driest parts of the world, such as Pakistan and Egypt, grow some of the thirstiest crops for export, like rice." Taking politics out of the equation may seem unrealistic: conflict over resources will likely increase significantly as the climate changes, and political leaders are not going to give up their power just like that. N...
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