Climate change scientists warn of 4C global temperature rise


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COP15 3C Environmental Destruction Threatens Kenya
Nomadic pastoralists Turkana tribesmen herd goats and sheep to a almost dry dam on the outskirts of Gakong, in northwestern Kenya on 13 December 2009. Photograph: Stephen Morrison/EPA





Rachel Warren, at the University of East Anglia, described a 4C world in her research paper: "Drought and desertification would be widespread ... There would be a need to shift agricultural cropping to new areas, impinging on [wild] ecosystems. Large-scale adaptation to sea-level rise would be necessary. Human and natural systems would be subject to increasing levels of agricultural pests and diseases, and increases in the frequency and intensity of extreme weather events."



In sub-Saharan Africa, "the prognosis for agriculture and food security in a 4C world is bleak", according Philip Thornton, of Kenya's International Livestock Research Institute, who led another research team. He notes there will be an extra billion people populating the continent by 2050.

"Croppers and livestock keepers in sub-Saharan Africa have in the past shown themselves to be highly adaptable to short- and long-term variations in climate. But the kind of changes that would occur in a 4C+ world would be way beyond anything experienced in recent times. It is not difficult to envisage a situation where the adaptive capacity and resilience of hundreds of millions of people could simply be overwhelmed by events," Thornton's team concludes.

Another team tackled another complex question: what would happen to humid tropical forests in a 4C world? There was the risk of forest die-off in the Amazon, central America and parts of Africa, but some regions, eg around the Congo basin, would have the potential for forest expansion. The scientist noted, however, that in practice deforestation might be the most important factor.

The speed – as well as the size – of the temperature rise is crucial too, warned scientists from Oxford University, as faster rates of global warming could outpace the ability of human civilisation and the natural world to adapt. "Dangerous climate change depends on how fast the planet is warming up, not just how hot it gets," said Myles Allen of Oxford University's department of Pphysics. "It's not just how much we emit, but how fast we do so."