Lord Chris Smith, BBC Green Room 16 Mar 10;
Climate-related controversies and the outcome of the Copenhagen summit widely regarded as a failure have left a sense of hopelessness in climate policy, says Lord Chris Smith. In this week's Green Room, he stresses the soundness of the fundamental climate science and the need to continue pushing for meaningful climate deals.
The myth fostered by some parts of the media in recent months - that somehow the scientific evidence for climate change is deeply flawed - needs to be laid to rest, and soon.
Sloppily expressed e-mail exchanges involving researchers from the University of East Anglia's Climatic Research Unit (CRU), and a blithe assumption that the Himalayan glaciers may melt by 2035, were both irresponsible and damaging.
But we cannot allow a few errors to undermine the overwhelming strength of evidence that has been painstakingly accumulated, peer-reviewed, tested and tested again.
That evidence shows overwhelmingly that our emissions of greenhouse gases are having a serious impact on the Earth's atmosphere, and that - as a result - climate change is happening and will accelerate.
The damage that has been done by the glee with which sceptics have seized on one or two scientific mistakes and attempted to use them to undermine the whole consensus about the evidence for climate change cannot be underestimated.
Not if but when
In recent years, the public here in the UK, and across much of Europe, had come to accept the reality and the urgency of climate change.
There were still debates about what precisely to do to counter it, but at least the fundamental recognition was there.
I think that is probably less true now than it was four months ago - and that is a tragedy.
We need to take the argument back to the sceptics, and make the powerful, convincing and necessary case about climate change much clearer to everyone.
There may still be a degree of uncertainty, and we need continuously to test the scientific evidence with rigour.
But the uncertainties are not primarily about whether or not climate change is happening, but about how fast the change will come and how bad it will be.
The evidence of change is indeed there.
The glaciers of the Alps and the Himalayas are retreating. Weather patterns around the world are becoming more erratic and more extreme.
The most intensive rainfall ever experienced in one location over a 24-hour period in England fell on Cumbria last November, and caused the tragic consequences of the severe flooding that we saw in Cockermouth, Keswick and Workington.
We cannot say for certain that these things - or indeed the intense heat recently experienced in Australia, or the droughts in Kenya - were caused by climate change.
But we can see with our own eyes that climatic, weather and temperature trends are changing, and we know that these hitherto exceptional events are likely to become more frequent over coming years.
Here in England and Wales, the Environment Agency works at the very point where people's lives intersect with environmental change.
We help people prevent and cope with flooding, environmental degradation, water depletion, and pollution.
In our day-to-day work, we can see small things that are happening all around us.
Damselflies and dragonflies are being found much further north than before, as they move with the warming climate.
The rare vendace fish is disappearing from its former stronghold in the Lake District, and is having to be re-introduced into the colder waters of Scotland.
Our yearly water testing over 20 years has shown an average rise in temperature in our rivers of 0.6C (1.1F). These are small signals, but like the canary in the mine, they foretell greater danger in the future.
'Disappointing outcome'
If we can hold the average global air temperature increase to 2C (3.6F) since pre-industrial times, we have a chance of surviving more or less intact.
But if it ends up being 4C or more, the impacts on population, water resources, sea levels, agriculture, weather patterns, biodiversity, and the quality of human life across the world, will be severe.
That is why the international discussions on climate change at Copenhagen were so important, and why the outcome was so disappointing.
We always knew that we would not emerge from Copenhagen with a full signed-and-sealed treaty with firm commitments for specific emissions reductions from everyone around the world.
But I did hope that we might emerge with rather more than we did, with at least a set of in-principle commitments and some target dates and a map charting where we were heading.
Instead, we have the Copenhagen Accord, drawn up by the US, China, India, Brazil and South Africa, with some aspirations and agreements, and an earnest of intent to build on this during the coming year.
Build on it we must. The worst response to Copenhagen would be to throw up our hands in horror and say nothing was achieved and therefore we should give up on the search for international commitments and agreement.
We need to continue the drive for an international treaty, and do so with renewed urgency.
There are some useful fundamentals in the Copenhagen Accord - the acknowledgment of a 2C limit on the global average temperature increase; the principle of north-south flows of aid and support in order to ensure that the developing world can grow more sustainably than those of us who have largely caused the problem up to now; and commitments to help combat deforestation.
We should now work as hard as we can to build these up into more specific commitments over the coming months.
Lord Chris Smith is chairman of the UK's Environment Agency
The Green Room is a series of opinion articles on environmental topics running weekly on the BBC News website
