Two of Britain's leading scientists have urged the setting up of a world Sunpower Programme to deliver solar electricity that is cheaper than fossil fuel power by 2025. All countries should be invited to participate, says Sir David King, a former government chief scientific adviser, and the economist Lord Richard Layard in an article in the Observer.

The programme's target would be the development of techniques that see solar electricity generate at least 10% of the world's total energy supply by 2025, and 25% by 2030. King and Layard's proposal has been put forward in the wake of the Intergovernmental Panel on Climate Change report on the likely impact of climate change, triggered by rising carbon emissions.

The world desperately needs to wean itself off its fossil fuel habits and find fresh, renewable methods for generating electricity. Nuclear power and wind energy have potential but face political problems. By contrast, solar energy holds vast promise, they say. "The sun sends energy to the earth equal to about 5,000 times our total energy needs. It is inconceivable that we cannot collect enough of this energy for our needs, at a reasonable cost."

They acknowledge that a number of scientific breakthroughs will be needed to make cheap solar energy a global prospect. In particular, scientists will have to find ways to reduce the cost of transmitting electricity from areas of high luminosity and low land value to the major population centres of the world. This will require new materials that are much better at conducting electricity, without loss of power, than present methods. This would be a major aim of the new solar energy programme.

The proposal to set up the Sunpower Programme comes as campaigners, politicians and business leaders have called for "immediate action" on climate change after the starkest warning yet that manmade global warming is leading to catastrophic and irreversible consequences. Leading scientists at the IPCC meeting in Stockholm last week said they were "95% certain" that climate change was occurring and caused by human actions. IPCC chair Rajendra Pachauri said: "Warming of the climate system is unequivocal, and since the 1950s many of the observed changes are unprecedented. The atmosphere and ocean have warmed, snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased."

Connie Hedegaard, the EU's commissioner for climate action, said: "What would you do if your doctor was 95% sure you had a serious illness? Whose side are you on? Those who want to act on 95% certainty or those who gamble on the remaining 5%?" The UN secretary general, Ban Ki-moon, invited world leaders to a summit next year to formulate a plan. "We must act now," he urged.

The IPCC reported that the world was on course for a rise in temperatures of more than 2C by the end of the century, causing heatwaves, droughts, sea level rises and extreme rainfall. Nations have set their own targets for curbing greenhouse gases but experts say these are inadequate to meet the reductions required. Samantha Smith of the World Wildlife Fund said: "We must act or face frightening new impacts. We know that most of the pollution that causes climate change comes from burning fossil fuels. WWF calls on governments and investors to stop investing in dirty energy and start an immediate and just transition by investing in renewables."

Mindy Lubber, who heads a US coalition of financial investors committed to tackling climate change, said: "The IPCC's conclusion is unequivocal – climate change is happening"

Nick Robins, head of HSBC's climate change centre of excellence, warned: "We are putting the weather on steroids. We know that temperatures continue to warm and that impacts are fully in line with what we would expect from a warming world, including rising sea levels and melting glaciers. And this is affecting economies today. Our research shows that India, China, Indonesia, South Africa and Brazil are the G20 nations that are most vulnerable to climate risks."