Global climate change experts will this week lay out a detailed plan to save the planet from the catastrophic effects of rising temperatures. Climate change could be stopped in its tracks using existing technology, but only if politicians do more to force businesses and individuals to take action.

The United Nations study will conclude that mankind has the knowhow to reduce global greenhouse gas emissions by as much as 26 billion tonnes by 2030 - more than enough to limit the expected temperature rise across the planet to 2-3 degrees Celsius.

Such a move would cost the world economy billions of dollars over the next two decades, but this could be recouped by savings due to the health benefits of lower levels of air pollution.

Cheaper solutions could bring down emissions to 1990 levels, but that would still see average temperatures rise by as much as 4 degrees this century, with devastating consequences for wildlife, agriculture and the availability of water.

The report, from the Intergovernmental Panel on Climate Change (IPCC), will say a range of measures can be introduced across the energy supply, transport, buildings, agriculture and forestry, industry and waste sectors. The best way to limit future emissions is to focus on clean development in developing countries.

The report, the third this year from the IPCC, looks at ways to tackle global warming and is due to be released in Bangkok on Friday. The previous two reports analysed the science of climate change and its likely impacts. Together, the three reports will underpin international negotiations on a new treaty to regulate greenhouse gas emissions to replace the Kyoto protocol.

The summary of the new report, a draft of which has been obtained by the London-based Guardian newspaper, says: "It is technically and economically feasible to stabilise greenhouse gas concentrations in the atmosphere ... provided that incentives are in place to further develop and implement a range of mitigation technologies."

It says global emissions need to peak "within the next two decades" and that the problem is now more serious and requires "more stringent mitigation" than when the IPCC last reported in 2001.

Rachel Warren, of the Cambridge University's Centre for Climate Change Mitigation Research who helped to write the report, said: "We have to reduce our emissions, and the technology to do that already exists or can be commercialised in the coming decades. We need governments, businesses and individuals to be pulling together in the same direction."

The final wording of Friday's report will be hammered out during the coming week by scientists and government officials, who must approve it before its release. Publication of the second IPCC report in Brussels earlier this month was delayed after all-night discussions that saw several scientists walk out in protest at what they viewed as political interference.

This week's talks could see similar scenes, particularly as it deals with the political hot potato of how world governments should act together to bring down emissions. The United States has lobbied for research into futuristic technology such as giant sunlight-blocking mirrors in space as "insurance", an idea which the draft summary dismisses as "largely speculative, uncosted and with potential for unknown side effects".

The report says that taking "optimal" mitigation measures might by 2030 stabilise greenhouse-gas concentrations in the atmosphere at 445 to 534 parts per million, up from an estimated 430ppm today.

It indicates that stabilising concentrations relatively quickly at 450ppm - an unlikely scenario - could still limit the temperature rise to 2 degrees above pre-industrial temperatures, which scientists say could avert severe damage. Achieving the 445-534ppm range could cost up to 3 per cent of global gross domestic product (GDP) over two decades, the draft says.

Geoffrey Levermore, an expert in housing emissions at Manchester University, UK, and another author on the report, said: "With current technology, new technology and new policies, we can do this, but we might not be as prosperous. If someone has to cycle more rather than using the car, perhaps they might not be so productive."

The report says that different technologies will be better suited to different regions, but that energy efficiency will play a key role for all. Greater use of renewable energy, nuclear power and biofuels will be needed to stabilise emissions, while protecting the world's forests could offer a more "cost-effective" solution.

And it calls for the wider use of technology to capture carbon dioxide spewed from power stations and store it underground, known as carbon capture and storage (CCS). The draft says: "A critical issue is how quickly new coal plants are going to be equipped with CCS, because retrofitting power plants with CCS later is economically unattractive." Energy companies in the developing world are building a handful of "capture ready" power stations, which can be adapted when the CCS technology is ready, but hundreds of plants being built throughout China and India are not so advanced and there will be no way to constrain their pollution.

Jim Watson, an energy policy researcher at Sussex University, UK, said: "A lot of the plants that are being built and discussed in China are not up to the highest standards because they are being built by regional governments and utilities, and there isn't much coordination from the centre."

He added: "Generally it's hard to see a lot of concrete moves in the right direction. The technology menu is going to be broadly similar, and the question is are we any further towards getting it deployed?"

One of the most controversial findings of the report is likely to be its discussion of the various strategies international governments could take - the US has refused to adopt binding targets agreed under Kyoto and is resisting attempts to discuss a replacement, preferring voluntary agreements.

The draft report says such voluntary agreements are not effective, but it also raises questions about the success of Kyoto-style treaties based on targets and carbon trading. It says the best approach is to tie development to investment in clean technology.

Catherine Pearce, international climate campaigner with Friends of the Earth, said: "We hope that this report will push governments to take action, by demonstrating that the policies, measures and sustainable energy technologies are readily available. We have no time to lose, and no excuses for further inaction."

David Adam

The Guardian