Critical report

UN scientists settle the argument on climate change

The evidence is “unequivocal”. It’s mostly our fault, the situation is getting worse, and the consequences are potentially devastating. There is still a lot we can do to stop climate change getting out of hand, but that means reversing the upward trend in greenhouse gas emissions within a decade or so. Take heart, though, because “mitigation actions” need not be prohibitively pricey – especially when set against “near-term co-benefits” such as improved health due to reduced air pollution.

That’s the gist of the findings of the uniquely authoritative Fourth Assessment of the UN’s Intergovernmental Panel on Climate Change (IPCC). Shortly before Bali the IPCC delivered the final synthesis of this work, wrapping up the science, the impacts of climate change and – crucially – what to do about them. As UN secretary-general Ban Ki-Moon said: “Today the world’s scientists have spoken clearly and with one voice. In Bali I expect the world’s policymakers to do the same.”

World temperatures rose on average by 0.7°C last century, and are set to go up another 1.3°C just from the greenhouse gases already released into the atmosphere. Alarmingly, 20-30% of the species the IPCC scientists examined could face extinction if temperatures rise by more than 1.5-2.5°C – and a worst case scenario sees increases possibly as great as 6.4°C.

Other potential impacts:

• Water scarcity hitting between 75 million and 250 million people;
• Yields from rain-fed agriculture halved;
• Widespread damage to coral reefs;
• More extreme weather, from droughts to torrential rainstorms;
• More tidal flooding, as global sea levels rise by 3.1mm a year, mostly due to warm water expansion;
• Much of Spain, Italy and Greece turned into deserts; and
• Britain and northern Europe facing more floods, heatwaves and stronger storms.
  

– Roger East

7 January 2008

Roger East