Few scientists or rational politicians doubt that global warming is a serious issue that poses long-term dangers to the planet. The scientific evidence that the world’s climate has changed and that this change is accelerating is convincing. But it is also beyond doubt that the world is in danger of being held captive by powerful lobby groups that have distorted data, made unjustified extrapolations and attempted to stifle debate on one of the most important issues of our time.

The warnings issued by the Intergov-ernmental Panel on Climate Change (IPCC) in Brussels yesterday are a collection of worst-case scenarios. The report, approved by 130 governments and endorsed by 2,500 scientists (few of whom probably had any hand in writing it), makes scary reading. It predicts a catastrophic future for millions of humans and other species. Global warning will bring hunger, floods and water shortages. Greenhouse gases will change rainfall patterns, intensify tropical storms, accelerate the melting of Arctic ice and mountain glaciers. Africa faces starvation, coastal cities will be swamped and China will see the rapid advance of the desert.

Some of these dangers may well be real. But many are deliberate exaggerations, as the IPCC’s mandate was to highlight the dangers if global temperatures were to rise by up to 4C (7.2F). That assumption is far from proven. But it is enough for some environmental groups to speak of “an apocalyptic future”, a “nightmare vision” and a “humanitarian catastrophe”.

Every group is entitled to lobby hard for its cause. But to jump on a band-wagon and blame everything on climate change is neither good science nor sound lobbying. China’s deserts have been threatening its cities for hundreds of years. Africa cannot be simultaneously threatened by endless droughts and by a rapid increase in malaria. Children are threatened by global warming, but they have also been helped by the economic development that some lobbyists seem to regard as a criminal activity. Tens of millions of children in India and China who would have died 30 years ago are not dying because increased wealth has brought better food, cleaner water and improved access to healthcare.

Companies and individuals have a responsibility to examine their behaviour and reduce their impact on the planet. But that self-examination should be rational and real and not debased by left-leaning fear-mongers, whose social agendas are recipes for impoverishment and hardship.

The real danger of the zealots is that they brook no argument. This does not mean that scientists should take a myopic view of figures that point to danger, such as the rise in carbon dioxide levels to about 380 parts per million, far exceeding the “natural” range for the past 650,000 years. But even to ask what is the natural range is regarded as some sort of heresy, and to ask questions about the precise contribution of anthropogenic influences is to commit a thought crime. There have already been examples of environmental scientists hounded out of their jobs for daring to question the prevailing orthodoxy. The IPCC summary is inevitably a political narrative, one in which each word and phrase will be endlessly and selectively parsed by the likes of Greenpeace and friends.

The planet deserves the benefit of the doubt. Climate change is serious and must be a political priority. But the arguments must be subject to free and rigorous debate and the facts separated from fanciful predictions — the environment is too important to be bequeathed to the hysterical.