Tuesday December 4, 2007
There is now a broad scientific consensus that we need to prevent temperatures from rising by more than 2C above their pre-industrial level. Beyond that point, the Greenland ice sheet could go into irreversible meltdown, some ecosystems collapse, billions suffer from water stress, and droughts start to threaten global food supplies.
The government proposes to cut the UK's carbon emissions by 60% by 2050. This target is based on a report published in 2000. That report was based on an assessment published in 1995, which drew on scientific papers published a few years earlier. The UK's policy, in other words, is based on papers some 15 years old. Our target, which is one of the toughest on earth, bears no relation to current science.
Over the past fortnight, both Gordon Brown and his adviser, Sir Nicholas Stern, have proposed raising the cut to 80%. Where did this figure come from? The last G8 summit adopted the aim of a global cut of 50% by 2050, which means that 80% would be roughly the UK's fair share. But the G8's target isn't based on current science either.
In the new summary published by the Intergovernmental Panel on Climate Change (IPCC), you will find a table that links different cuts to likely temperatures. It suggests that to prevent global warming from eventually exceeding 2C, by 2050 the world will need to cut its emissions to roughly 15% of the volume in 2000.
I looked up the global figures for carbon dioxide production in 2000 and divided it by the current population. This gives a baseline figure of 3.58 tonnes of CO2 per person. An 85% cut means that (if the population remains constant) the global output per head should be reduced to 0.537 tonnes by 2050. The UK currently produces 9.6 tonnes per head and the US 23.6 tonnes. Reducing these figures to 0.537 means a 94.4% cut in the UK and a 97.7% cut in the US. But the world population will rise in the same period. If we assume a population of 9 billion, the cuts rise to 95.9% in the UK and 98.3% in the US.
The IPCC figures might also be out of date. In a footnote beneath the table, the panel admits that "emission reductions...might be underestimated due to missing carbon cycle feedbacks". What this means is that the impact of the biosphere's response to global warming has not been fully considered. As seawater warms, for example, it releases carbon dioxide. As soil bacteria heat up, they respire more, generating more CO2. As temperatures rise, tropical forests die back, releasing the carbon they contain. These are examples of positive feedbacks. A recent paper (all the references are on my website) estimates that feedbacks account for about 18% of global warming. They are likely to intensify.
A paper in Geophysical Research Letters finds that even with a 90% global cut by 2050, the 2C threshold "is eventually broken". To stabilise temperatures at 1.5C above the pre-industrial level requires a global cut of 100%. The diplomats who started talks in Bali yesterday should be discussing the complete decarbonisation of the global economy.
It is not impossible. In a previous article I showed how by switching the whole economy over to the use of electricity and by deploying the latest thinking on regional supergrids, grid balancing and energy storage, you could run almost the entire energy system on renewable power. The major exception is flying (don't expect to see battery-powered jetliners), which suggests that we should be closing rather than opening runways.
This could account for around 90% of the necessary cut. Total decarbonisation demands that we go further. Preventing 2C of warming means stripping carbon dioxide from the air. The necessary technology already exists: the challenge is making it efficient and cheap. Last year Joshuah Stolaroff, who has written a PhD on the subject, sent me some provisional costings, of £256-£458 per tonne of carbon. This makes the capture of CO2 from the air roughly three times as expensive as the British government's costings for building wind turbines, twice as expensive as nuclear power, slightly cheaper than tidal power and eight times cheaper than rooftop solar panels in the UK. But I suspect his figures are too low, as they suggest this method is cheaper than catching CO2 from purpose-built power stations, which cannot be true.
The Kyoto protocol, whose replacement the Bali meeting will discuss, has failed. Since it was signed, there has been an acceleration in global emissions: the rate of CO2 production exceeds the IPCC's worst case and is now growing faster than at any time since the beginning of the industrial revolution. It's not just the Chinese. A paper in the Proceedings of the National Academy of Sciences (the US institute's journal), finds that "no region is decarbonising its energy supply". Even the age-old trend of declining energy intensity as economies mature has gone into reverse. In the UK there is a stupefying gulf between the government's climate policy and the facts it is creating on the ground. How will we achieve even a 60% cut if we build new coal plants, new roads and a third runway at Heathrow?
Underlying the immediate problem is a much greater one. In a lecture to the Royal Academy of Engineering in May, Professor Rod Smith of Imperial College explained that a growth rate of 3% means economic activity doubles in 23 years. At 10% it takes just seven years. This we knew. But Smith takes it further. With a series of equations he shows that "each successive doubling period consumes as much resource as all the previous doubling periods combined". In other words, if our economy grows at 3% between now and 2040, we will consume in that period economic resources equivalent to all those we have consumed since humans first stood on two legs. Then, between 2040 and 2063, we must double our total consumption again. Reading that paper I realised for the first time what we are up against.
But I am not advocating despair. We must confront a challenge that is as great and as pressing as the rise of the Axis powers. Had we thrown up our hands then, as many people are tempted to do today, you would be reading this paper in German. Though the war often seemed impossible to win, when the political will was mobilised strange and implausible things began to happen. The US economy was spun round on a dime in 1942 as civilian manufacturing was switched to military production. The state took on greater powers than it had exercised before. Impossible policies suddenly became achievable.
The real issues in Bali are not technical or economic. The crisis we face demands a profound philosophical discussion, a reappraisal of who we are and what progress means. Debating these matters makes us neither saints nor communists; it shows only that we have understood the science.