Forgive me for going on, but once again the consensus over man-made climate change is looking more and more threadbare. This background piece for the Times after chief scientist Peter Ewins here, objected to ministers' 'simplistic' comments on climate change.
MONDAY APRIL 16 2001
All change over the climate
ANALYSIS BY MARK HENDERSON
FEW mainstream climate scientists dispute that the world is getting warmer. Over the past two centuries, all the evidence suggests that atmospheric temperatures have risen significantly, by about 2C. This year the United Nations Intergovernmental Panel on Climate Change predicted that global average temperatures would rise by up to 5.4C over the next 100 years.
Neither is there much contention over the claim that concentrations of greenhouse gases such as carbon dioxide have increased in the atmosphere since the industrial revolution. What this means for the weather and, by extension, the future of the planet, is far less certain. While orthodox opinion holds that human activity and climate change are inextricably linked, many researchers remain unconvinced. There are also great differences over the best strategies for dealing with the problems of a warmer world.
There is good evidence that a warmer climate in Britain will bring with it more extreme weather, such as floods and storms of the sort that struck the country last November. Much of that evidence comes from the Met Office’s Hadley Centre, the world’s leading long-term forecasting unit.
However, Peter Ewins, the Met Office’s chief executive, picks up ministers for putting two and two together and making five. Just because we have had floods and the climate is warming, he says, does not necessarily mean that the former is caused by the latter.
The ease with which such statements can be countered can call into question the trustworthiness of other, more robust, evidence that a politician such as John Prescott, the Environment Secretary, presents in support of the Kyoto treaty. Climate science, as the Met Office accepts, is inexact, and overclaiming on limited evidence might be said to detract from one’s case. For example, evidence for rises in sea levels, a favourite of global warming activists, is mixed. They are rising in some parts of the world, but not in others.
Scepticism about the impact of human beings on the warming process also has a basis in science. The Earth, it is accepted, is emerging from a “Little Ice Age” that struck in the middle of the last millennium. Average temperatures in Europe in 1200 were 2C higher than now. In the 17th century they were lower, as shown by a frozen Thames.
Although most scientists accept that greenhouse gases have accelerated this cyclical change, the view is far from universal. Even the Inter- Governmental Panel on Climate Change admits that, of 12 important factors thought to affect climate, nine are incompletely understood.
Another debate surrounds the usefulness of the Kyoto treaty — President Bush recently announced his refusal to ratify it — in cutting greenhouse gases. Even scientists who accept the arguments for global warming are divided as to its merits. It demands average cuts of 5.2 per cent in carbon dioxide and other greenhouse gas emissions from developed countries by 2012. Yet a Hadley Centre model has shown that the net effect of this on world temperatures will be negligible when overall predictions hold that by 2100 average temperatures will have risen by as much as 6C.
Most scientists accept Kyoto as a first step towards more radical measures to cut greenhouse emissions. Others who agree that man-made global warming is happening believe that money would be better spent on learning to adapt. Mr Ewins believes in a precautionary approach to climate change, but one in which the uncertainty is admitted. “I think the UK approach is correct. It makes sense to go ahead with Kyoto, but don’t let’s kid ourselves it’s going to have a big impact. Holding back some of the effects might be plausible. Reversing it is beyond our ability.
“The US approach personally irritates me, but we must be very careful we don’t rubbish it. Their belief is that it’s probably real, and might be man-made, but that it’s uncertain and there’s no need to act. The scientific underpinning is not that different.”
-- James Heartfield