If Earth heats by four degrees Celsius the planet we call home would become a very unwelcoming place. Even as some world leaders tamp down expectations for the 7-18 December UN climate conference, experts say the threat of a 4°C warming over pre-industrial times is all too plausible.
Once that threshold is crossed, what might a four-degree world look like?
Oceans have risen by at least a metre, drowning several island nations and driving hundreds of millions of people in Bangladesh, Thailand and Vietnam and other delta nations to scramble for higher ground.
Polar bears are a folk memory, starved to extinction in an Arctic where temperatures have soared by 15°C, nearly four-fold the global average.
Australia is routinely swept by white-hot fires of the kind that claimed 170 lives last February.
A third — perhaps more — of the Amazon forest has been reduced to desolate shrubland, its treasure chest of flora and fauna decimated.
Asia’s eternal fountain, the Himalayan glaciers, are running dry.
South Asia’s precious monsoon, once reliable as clockwork, has become fickle, dumping too little or too much rain.
A quarter of the planet’s mammals are on a downward spiral toward extinction.
Hardly science fiction…
“A 4°C increase in global mean temperatures has the potential to threaten human security and quality of life in a manner unprecedented in recent history,” says Arizona State University professor Pamela McElwee.
Francois Gemmene, a researcher at France’s Institute for Sustainable Development and International Relations (IDDRI), adds: “At 4°C, climate-driven migration redraws the map of population distribution across the surface of the globe.”
Science fiction? If only.
On 16 November, an international team of scientists, the Global Carbon Project, said carbon emissions had surged by 29 percent from 2000 to 2008.
This places Earth on track with the worst-case warming scenario put forward by the UN’s Nobel-winning Intergovernmental Panel on Climate Change (IPCC), it said.
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