A post on Nature’s blog In the Field, reports that Martin Parry, who co-chaired the Intergovernmental Panel on Climate Change’s Task Group on Scenarios for Climate Impact Assessment, has again reiterated that the international community’s goals for CO2 emissions reductions are two low and unlikely to achieve the desired effects.
As blogger Jeff Toleffson points out:
One of the ongoing debates in Poznan is whether to enumerate some kind of goal for emissions reductions, at least in the short term. The usual number that comes up for Annex I countries – the industrialized world – is 25-40 percent below 1990 levels by 2020, and the EU has been pushing for a 50-percent reduction by mid-century in order to limit global warming to 2 degrees Celsius. The scientific basis for this, however, is unclear at best.
Parry has long maintained that the 50% reduction by 2050 is insufficient. He also maintains that mitigation efforts alone will be insufficient and that we also need to be planning adaptation strategies. Back in July 2007 at the meeting to introduce the latest IPCC report Parry stated:
“We are all used to talking about these impacts coming in the lifetimes of our children and grandchildren. Now we know that it’s us.”
First, a 50 per cent reduction of global emissions below 1990 levels by 2050, widely considered to be the most stringent achievable target, will not avoid major global impacts. At this level of emissions, there is a good chance in 2050 of avoiding a temperature rise of 2 °C above pre-industrial levels (equivalent to 1.6 °C above 1990 global temperatures; see Fig. 1), which is the European Union’s target. That misleadingly appears to be a satisfactory outcome, but it omits that, even with further reductions after 2050, we would be locked into a warming trend until at least 2100 owing to inertia in the climate system, and damages would therefore accumulate beyond mid-century. By 2100 there would be a greater than 50 per cent chance of exceeding the 2 °C target — assuming the same percentage reductions in emissions continue annually from 2050 through to 2100.
Parry crunched some numbers before the conference and determined that the odds of staying under 2 degrees of warming are only slightly better than 50/50 even if emissions peak in 2015 and then decrease to 60 percent below 1990 levels by mid-century.
If you want to increase the odds of coming in under 2 degrees and avoid the most serious impacts of global warming, you need an 80-percent reduction by 2050.
Individually, some nations are looking at 80-percent figure. The United Kingdom’s climate plan shoots for 80 percent, and US President-Elect has called for 80 percent in his climate plan. But there’s another twist in Parry’s numbers: Each decade that the global peak is delayed, the temperature increase goes up by .4 to .5 degrees. According to this model, an eighty percent reduction by mid-century delivers 1.4 degree of warming with a peak in 2015; 1.8 degrees if the peak is in 2025; and 2.4 degrees with a peak in 2035. In other words, there is a penalty for delayed action.
Chart is from the following article:
Martin Parry, Jean Palutikof, Clair Hanson & Jason Lowe
Nature Reports Climate Change , 68 – 71 (2008) Published online: 29 May 2008
As Parry concluded in an earlier article in Nature this year:
We have lost ten years talking about climate change but not acting on it. Meanwhile, evidence from the IPCC indicates that the problem is bigger than we thought. A curious optimism — the belief that we can find a way to fully avoid all the serious threats illustrated above — pervades the political arenas of the G8 summit and UN climate meetings. This is false optimism, and it is obscuring reality. The sooner we recognize this delusion, confront the challenge and implement both stringent emissions cuts and major adaptation efforts, the less will be the damage that we and our children will have to live with.
It is worth nothing that while Parry generally regards the views of the governments attending the Poznan conference as overly conservative, his own views seem conservative by comparison with those of Nasa’s James Hansen. Parry’s goal of holding atmospheric CO2 at less that 450 parts per million according to the latest IPCC report will require emissions cuts of 80% to 95% by 2050 compared to 1990 levels. Hansen is calling [PDF] for an initial target of cutting CO2 emissions to 350 parts per million (they are currently at 387ppm).
There is debate among climatologists whether 350 or 450 is the better target scientifically, but whichever target is correct, it is pretty clear that the targets being proposed by most governments are inadequate.
“The 50-percent pathway won’t do what they think it will, and that’s a pity,” Parry said after his presentation this afternoon. “The problem is they are working with old information.”
Related post: China and India Say Obama Climate Plan Not Ambitious Enough