Worst-case global warming is upon us - scientists

The IPCC and UNU estimated 150 million environmental refugees in a +2ºC scenario, most of them women and children. There are already almost 50 million. See UN maps of threatened areas shown at Bonn in June 2009.
photo courtesy Edouard Stenger
Latest scientific data exceed worst-case IPCC scenarios. At the Copenhagen Climate Congress, 10-12 March 09, scientists say the tipping points for +5 to +6ºC have been passed. The 2007 report of the IPCC said that average temperatures could rise by up to 6ºC this century if no action were taken to curb greenhouse gas emissions. Many scientists say this understates impacts, because emissions are rising faster than the old BAU (Business As Usual) trend line.

BAU is no longer an option, they told governments and business lobbies who have been delaying action for 15 years. Prepare for at least +4ºC, says Bob Watson of DEFRA, a former head of the Intergovernmental Panel on Climate Change (IPCC). Steven Sherwood of Yale and British science advisor Sir David King warned of "runaway" warming above 4ºC from Arctic methane hydrate release. Research is scurrying to keep up with such changes. By the time all the data are collected it will be too late.

More quotations: Said King, "We begin to have to talk about ordered retreat from some areas of Britain... There's no choice here between adaptation and mitigation [the UNFCCC term for prevention], we have to do both." Prof Neil Adger of the Tyndall Centre countered that we must focus on mitigation, keeping to the previous 2ºC target. "There is no science on how we are going to adapt to 4 degrees warming.... the only real adaptation strategy is to avoid that at all cost because of the pain and suffering." Watson, a former science adviser to President Clinton and ex-chief scientist at the World Bank, urged support on the scale of the US space program, for the (largely unproven) "clean coal" CCS system promoted by the UK and US government and the Bank. However, he admitted that if coal plants scrub sulphur pollution (with the only proven technology so far), dimming would lessen and climate change worsen.

Sir Nicolas Stern admits his 2006 report understated impacts. It said BAU (in the old +4ºC scenario) would risk flooding between 7 million and 300 million in coastal areas every year, reduce water availability 30-50% in southern Africa and the Mediterranean, lower crop yields 15%-35% in Africa, and threaten 20%-50% of animal and plant species with extinction. To which we must now add the probable loss of 85% of the Amazon rainforest, another "runaway" impact, predicted by scientists yesterday.

Stern's original scenario said +5ºC would drown major cities such as New York, London and Tokyo. Increased ocean acidity would destroy marine ecosystems and fisheries, major source of protein for the world's poor. Rising sea levels, droughts and extreme weather would "lead to major disruption and large-scale movement of population". The effects would be "catastrophic" and "far outside human experience".

Stern's original report gave governments a business argument to invest in climate mitigation: GDP would be barely affected, and the losses avoided would be far greater. His argument is now even stronger. See Wikipedia on mitigation and adaptation; UNESCO world water report 16 Mar 09, and the water shortage map above (click to enlarge) from Globe and Mail 12 Mar 09; Norwegian Refugee Council, Future Floods of Refugees (2008); UN Office for the Coordination of Humanitarian Affairs (OCHA) and CARE, Humanitarian Implications of Climate Change (2008).