Colin Challen, a member of Parliament and chair of the All Party Parliamentary Climate Change Group, has a good editorial in the latest issue of Science (sub. rqd). He makes a key point that is often missed in the debate:
Not only must we reduce anthropogenic greenhouse gas emissions, we need a timetable that reduces the risk of positive feedbacks and sink failures that could lead to runaway catastrophic climate change.
We are "playing climate change poker," as Challen says, fighting not just to avoid the consensus prediction for climate change, but the plausible worst-case scenario, which is far worse. That’s why even a 60 percent cut in emissions by mid-century may not be enough, and many are pushing for an 80 percent cut.
The entire editorial is reprinted here:
Targets can be troublesome things. If they’re set for some distant future date, the target setter may not live long enough to see if they’ve been met. Interestingly, much discussion about tackling climate change anticipates having achieved something by the middle of this century. What’s the target? Both the European Union (EU) and, at a national level, the United Kingdom have focused on a CO2 emissions cut of at least 60%, which is intended to reduce average global warming by 2°C. (The June G8 summit also spoke of an emissions cut of 50% globally, but only in the context of exploring such a goal and with no greenhouse gas stabilization target in mind.)
What are the chances of meeting the 2° objective? Not likely, according to Malte Meinshausen of the Swiss Federal Institute of Technology, who presented the scientific evidence in a report of the 2005 Exeter climate change conference and who’s been quoted since, both by UK government economic advisor Sir Nicholas Stern and the Intergovernmental Panel on Climate Change. His analysis of 11 climate sensitivity studies of the effect of global CO2 atmospheric concentrations on temperature shows that settling for a 60% cut in atmospheric CO2 (which corresponds to 550 parts per million by volume) leaves a probability between 63 and 99% of missing the 2°C target. Both the UK and EU proposals indicate that their emissions reduction targets might be toughened. Perhaps, like an athlete attempting the high jump, we are warming up at lower heights first. But scant evidence supports that luxury. Not only must we reduce anthropogenic greenhouse gas emissions, we need a timetable that reduces the risk of positive feedbacks and sink failures that could lead to runaway catastrophic climate change.
In a democracy, it is difficult to convince voters that they should take actions, especially expensive ones, to avoid an as yet largely unseen and unquantifiable danger. How do you base a policy that is likely to have significant economic impacts on model data and forecasts that some might regard as guesswork? We only need to recall the false economy of not spending taxpayers’ dollars on building up the New Orleans levees to realize how actions taken today could avert a long-range problem. Delay, combined with the risk that skeptics may accuse the Al Gores of this world of "crying wolf," could make tougher policies harder to adopt later.
In setting a UK target, the government must also ask what the United Kingdom’s share of the burden is. Its national target must necessarily relate to reductions in other countries, including the developing world, where industrial growth to alleviate poverty is increasing emissions, as foreshadowed in 1992 by the United Nations Framework Convention on Climate Change. We cannot make a random national calculation and throw it into the global pot of targets; rather, we have to determine what the global need is and figure out how to distribute it — a calculation that must combine science with justice. A successful global climate change framework will have to pay as much attention to the latter as to the former; countries such as China and India will be more inclined to budge if developed countries fully embrace their own responsibilities. Why should anyone sign an agreement that cements their own disadvantage?
The UK government is the first to take on this challenge, with publication of the draft Climate Change Bill in March of this year. Its leadership carries the responsibility to get emissions targets right. The final bill needs to make explicit the formula used to arrive at any target that government sets. That formula should tell us not only the size of the cake but also how we calculate our share of it. The draft bill proposes a figure that cannot be explained in terms of either criterion. If it did, that would surely boost confidence that the result is designed to solve the problem faster than we’re creating it. I suspect I have set myself a target of living until I’m 97 to see what transpires.