For years the Intergovernmental Panel on Climate Change of the United Nations has warned us that greenhouse gas emissions from our fossil fuel consumption threaten the world's climate in ways we will regret. This year it won the Nobel Peace Prize for its efforts.

You don't have to be a true believer in human-caused climate change to take the IPCC's opinion seriously. We are contributing to a change in the chemistry of the global atmosphere by increasing its carbon dioxide concentration at an appreciable rate. Even a sceptical person must accept that there is a risk associated with altering the balance of greenhouse gasses on a global scale. And there is no doubt that the most effective way to limit this risk is to reduce our dependence on fossil fuels.

It is the IPCC that my former colleagues in Greenpeace, and most of the mainstream environmental movement, look to for expert advice on climate change. Environmental activists take the rather grim but measured language of the IPCC reports and add words such as "catastrophe" and "chaos", along with much speculation about famine, pestilence, mass extinction and the end of civilisation as we know it.

Until the past couple of years, the activists, with their zero-tolerance policy on nuclear energy, have succeeded in squelching any mention by the IPCC of using nuclear power to replace fossil fuels for electricity production. Burning fossil fuels for electricity accounts for 9.5 billion tonnes of global carbon dioxide emissions while nuclear power emits next to nothing. It has been apparent to many scientists and policymakers for years that this would be a logical path to follow. The IPCC has now joined these growing ranks advocating nuclear energy as a solution.

In its recently issued final report for 2007, the IPCC makes a number of unambiguous references to the fact that nuclear energy is an important tool to help bring about a reduction in fossil fuel consumption. Greenpeace has already made it clear that it disagrees. How credible is it for activists to use the IPCC scientists' recommendations to fuel apocalyptic fund-raising campaigns on climate change and then to dismiss the recommendations from the same scientists on what we should do to solve it?

Already, the 442 nuclear reactors worldwide are producing 16% of our electricity. It follows that 1000 reactors would produce 36% and so on, with negligible greenhouse gas emissions, replacing fossil fuel plants. But Greenpeace's policy is that we should not only build no new reactors but that we should shut down all the existing ones, thus inevitably forcing us to replace them with fossil fuel power plants. Oh no, says Greenpeace, we can replace the fossil fuel plants with wind and solar power. Here it is at its most deceitful.

Greenpeace is deliberately misleading the public into thinking that wind and solar energy, both of which are inherently intermittent and unreliable, can replace baseload power that is continuous and reliable. Only three technologies can produce large amounts of baseload power: fossil fuels, hydroelectric plants and nuclear power. Given that we want to reduce fossil fuels and that potential hydroelectric sites are becoming scarce, nuclear power is the main option. But Greenpeace and its allies remain in denial despite the fact that many independent environmentalists and now the IPCC see the situation clearly.

Over the past 10 years, Germany and Denmark have poured billions of taxpayers' euros into wind and solar energy in the vain hope that this would allow them to shut down fossil fuel and nuclear plants. They have not succeeded because every solar panel and every wind turbine must be backed up by reliable power when the sun isn't shining and the wind isn't blowing. Wind does have a role to play when peak power is needed and the wind is blowing because then it is possible to turn off some fossil generation. Solar power is so expensive that only the richest countries can afford the luxury. The real crime is that precious dollars spent on solar panels rob money that could be spent on much more cost-effective technologies such hydroelectric, nuclear, geothermal and biomass sources.

I have long realised that in retrospect we made a big mistake in the early years of Greenpeace when we lumped nuclear energy with nuclear weapons as if they were all part of the same holocaust. We were totally fixated, and rightly so, on the threat of all-out nuclear war between the Soviet Union and the United States and we thought everything nuclear was evil.

We failed to distinguish the beneficial and peaceful uses of nuclear technology from its destructive and even evil uses. It would be like including nuclear medicine with nuclear weapons just because nuclear medicine uses radioactive materials, most of which are produced in nuclear reactors.

Greenpeace and company are stuck in the 1970s when it comes to the policy on energy as it relates to climate change. They have invested a great deal of time and money convincing their supporters that nuclear energy is evil. It is time they came clean on the reality facing us all in the 21st century. They should accept the wisdom of the scientists at the IPCC and recognise that nuclear energy is a big part of the climate change solution. And they should stop misleading the public into thinking that wind and solar power can do the job on their own. I will be the first to commend them for their courage.

An adviser to government and industry, Dr Patrick Moore is a co-founder and former leader of Greenpeace, and chairman and chief scientist of Greenspirit Strategies.