SCIENTISTS of the Intergovernmental Panel on Climate Change (IPCC) are quite certain: by using fossil fuels man is currently destroying the climate and our future. We have one last chance, we are told: quickly renounce modern industrial society – painfully but for a good cause.

For many years, I was an active supporter of the IPCC and its CO2 theory. Recent experience with the UN's climate panel, however, forced me to reassess my position. In February 2010, I was invited as a reviewer for the IPCC report on renewable energy. I realised that the drafting of the report was done in anything but a scientific manner. The report was littered with errors and a member of Greenpeace edited the final version. These developments shocked me. I thought, if such things can happen in this report, then they might happen in other IPCC reports too.

Good practice requires double-checking the facts. After all, geoscientists have checked the pre-industrial climate, over the past 10,000 years: this isolates natural climate drivers. According to the IPCC, natural factors hardly play any role in today's climate so we would expect a rather flat and boring climate history.

Far from it: real, hard data from ice cores, dripstones, tree rings and ocean or lake sediment cores reveal significant temperature changes of more than 1°C, with warm and cold phases alternating in a 1,000-year cycle. These include the Minoan Warm Period 3,000 years ago and the Roman Warm Period 2,000 years ago. During the Medieval Warm Phase around 1,000 years ago, Greenland was colonised and grapes for wine grew in England. The Little Ice Age lasted from the 15th to the 19th century. All these fluctuations occurred before man-made CO2.

Based on climate reconstructions from North Atlantic deep-sea sediment cores, Professor Gerard Bond discovered that the millennial-scale climate cycles ran largely parallel to solar cycles, including the Eddy Cycle which is – guess what – 1,000 years long. So it is really the Sun that shaped the temperature roller-coaster of the past 10,000 years.

But then coal, oil and gas arrived: from the 1850s onwards, Man pumped large amounts of carbon dioxide into the atmosphere and the CO2 level today stands at 0.039%,compared to 0.028% previously.

With our empirically proven natural pre-industrial pattern, however, we would predict that solar activity had risen since 1850, more or less in parallel with an increase in temperatures. Indeed, both timing and amount of warming of nearly 1°C fit nicely into this natural scheme. The solar magnetic field more than doubled over the past 100 years.

Remember, there are three climate parameters that go up at the same time: solar activity, CO2 and temperature. Modern climate is likely to be driven by both anthropogenic and natural processes, so CO2 will undoubtedly have contributed to the warming, but the question is just how much?

Yet the IPCC's computer models consider the solar-forcing as negligible, requiring an unknown amplifying mechanism to explain the observed temperature variations. A promising model is proposed by Danish physicist Henrik Svensmark but is still under research.

Whether this mechanism is understood or not, the IPCC's current climate models cannot explain the climate history of the past 10,000 years. But if these models fail so dramatically in the past, how can they help to predict the future?

Furthermore, what is little known is that CO2 also requires a strong amplifier if it were to aggressively shape future climate as envisaged by the IPCC. CO2 alone, without so-called feedbacks, would only generate a moderate warming of 1.1°C per CO2 doubling. The IPCC assume in their models that there are strong amplification processes, including water vapour and cloud effects which, however, are also still poorly understood, like solar amplification. These are the shaky foundations for the IPCC's alarming prognoses of a temperature rise of up to 4.5°C for a doubling of CO2.

In the last 10 years the solar magnetic field dropped to one of its lowest levels in the last 150 years, indicating lower intensity in the decades ahead. This may have contributed to the halt in global warming and is likely to continue for a while, until it may resume gradually around 2030/2040. Based on the past natural climate pattern, we should expect that by 2100 temperatures will not have risen more than 1°C, significantly less than proposed by the IPCC.

Climate catastrophe would have been called off and the fear of a dangerously overheated planet would go down in history as a classic science error. Rather than being largely settled, there are more and more open climate questions which need to be addressed in an impartial and open-minded way.

Firstly, we need comprehensive research on the underestimated role of natural climate drivers. Secondly, the likely warming pause over the coming decades gives us time to convert our energy supply in a planned and sustainable way, without the massive poverty currently planned.

In the UK and Germany, for example, power-station closures and huge expenditure for backup of volatile wind or solar energy or harmful ethanol production will raise energy prices massively and even threaten power cuts: the economic cost will be crippling, all driven by fear.

We now have time for rational decarbonising. This may be achieved by cost-improved and competitive renewable technologies at the best European sites, through higher energy efficiency and by improving the use of conventional fossil energy.

The choice is no longer between global warming catastrophe and economic growth but between economic catastrophe and climate sense.

Professor Fritz Vahrenholt is one of the fathers of Germany's environmental movement and the director of RWE Innogy, one of Europe's largest renewable energy companies. Last Wednesday, he delivered the 3rd Global Warming Policy Foundation Annual Lecture at the Royal Society, London