We are living in strange times. One exceptionally warm winter is enough – irrespective of the fact that in the course of the 20th century the global temperature increased only by 0.6 per cent – for the environmentalists and their followers to suggest radical measures to do something about the weather, and to do it right now.

In the past year, Al Gore’s so-called “documentary” film was shown in cinemas worldwide, Britain’s – more or less Tony Blair’s – Stern report was published, the fourth report of the United Nations’ Intergovernmental Panel on Climate Change was put together and the Group of Eight summit announced ambitions to do something about the weather. Rational and freedom-loving people have to respond. The dictates of political correctness are strict and only one permitted truth, not for the first time in human history, is imposed on us. Everything else is denounced.

The author Michael Crichton stated it clearly: “the greatest challenge facing mankind is the challenge of distinguishing reality from fantasy, truth from propaganda”. I feel the same way, because global warming hysteria has become a prime example of the truth versus propaganda problem. It requires courage to oppose the “established” truth, although a lot of people – including top-class scientists – see the issue of climate change entirely differently. They protest against the arrogance of those who advocate the global warming hypothesis and relate it to human activities.

As someone who lived under communism for most of his life, I feel obliged to say that I see the biggest threat to freedom, democracy, the market economy and prosperity now in ambitious environmentalism, not in communism. This ideology wants to replace the free and spontaneous evolution of mankind by a sort of central (now global) planning.

The environmentalists ask for immediate political action because they do not believe in the long-term positive impact of economic growth and ignore both the technological progress that future generations will undoubtedly enjoy, and the proven fact that the higher the wealth of society, the higher is the quality of the environment. They are Malthusian pessimists.

The scientists should help us and take into consideration the political effects of their scientific opinions. They have an obligation to declare their political and value assumptions and how much they have affected their selection and interpretation of scientific evidence.

Does it make any sense to speak about warming of the Earth when we see it in the context of the evolution of our planet over hundreds of millions of years? Every child is taught at school about temperature variations, about the ice ages, about the much warmer climate in the Middle Ages. All of us have noticed that even during our life-time temperature changes occur (in both directions).

Due to advances in technology, increases in disposable wealth, the rationality of institutions and the ability of countries to organise themselves, the adaptability of human society has been radically increased. It will continue to increase and will solve any potential consequences of mild climate changes.

I agree with Professor Richard Lindzen from the Massachusetts Institute of Technology, who said: “future generations will wonder in bemused amazement that the early 21st century’s developed world went into hysterical panic over a globally averaged temperature increase of a few tenths of a degree, and, on the basis of gross exaggerations of highly uncertain computer projections combined into implausible chains of inference, proceeded to contemplate a roll-back of the industrial age”.

The issue of global warming is more about social than natural sciences and more about man and his freedom than about tenths of a degree Celsius changes in average global temperature.

As a witness to today’s worldwide debate on climate change, I suggest the following:

■Small climate changes do not demand far-reaching restrictive measures

■Any suppression of freedom and democracy should be avoided

■Instead of organising people from above, let us allow everyone to live as he wants

■Let us resist the politicisation of science and oppose the term “scientific consensus”, which is always achieved only by a loud minority, never by a silent majority

■Instead of speaking about “the environment”, let us be attentive to it in our personal behaviour

■Let us be humble but confident in the spontaneous evolution of human society. Let us trust its rationality and not try to slow it down or divert it in any direction

■Let us not scare ourselves with catastrophic forecasts, or use them to defend and promote irrational interventions in human lives.

The writer is President of the Czech Republic