Facts, figures and analysis pour from Robert Watson. He talks like a man in a hurry, as you would expect from someone who believes that time is running out if we want to save the world from global warming. The bottom line, he says, is that the climate has changed and the likelihood is that it will change more in the future, with adverse effects on agriculture, water resources and sea levels – and human health.

What do we have to do? Well, a lot of things. We need to move to a low-carbon economy and produce energy in a way that emits fewer greenhouse gases. We need to capture our C02, produce more energy from renewable sources, build more efficient buildings and slow down deforestation. Fresh economic thinking is required, such as paying communities to manage eco systems better, re-examining subsidies in agriculture and transportation and embracing carbon trading.

Individuals can make choices, whether it is to install the most efficient light bulbs, walk to the shops more, turn the heating down or eat less meat. “I need to do more myself,” Watson admits. There must be behavioural change, but it doesn’t have to lead to a radically different lifestyle. If we all turned our thermostats down two degrees, it would have an impact. “Even small changes can make a big difference.”

The private sector must innovate. Watkins is cheered by developments that are in the pipeline, such as cheaper solar panels for houses and research and development that is taking place on fuel-efficient cars. He applauds restaurants that eschew waste by offering smaller portions.

Science: Big questions, small answers

With leading scientists, we set out to answer some of the fundamental questions of life, the universe and everything

Background

• Jodrell Bank founder condemns closure plan

• Britain’s window on the stars faces closure

• Turning a blind eye to marvellous things

Background

• Clouds of acid make sky bright but eat the ozone

• Encyclopedia of Life to be published online

• Branson calls for hydrogen filling stations

Background

• Biofuels cannot save the planet

• Biofuels rush threatens starvation

• Forget biofuels — we need our daily bread

Co-operation at intergovernmental level is crucial. Europe needs to pledge to reduce emissions to 60 per cent below 1990 levels, or even more, by 2050. The developing world will require financial assistance to move to low-carbon economies. The next two to four years, as a successor to Kyoto is negotiated, are “absolutely critical”.

It’s a gloomy picture, but Watson is an optimist. “We do have the technology and the human capacity to address these issues. The trouble is the clock is ticking. I can’t imagine the human race allowing itself to sink, but the time to act is now. Do we throw up our hands? Or do we say: ‘We have a major challenge. Business as usual will not work.’ If we work together we can leave an Earth for our children and grandchildren as good as the one we inherited.”

Times Recommends

• Anne Darwin's performance of a lifetime
• Renaissance for canals as new boaters come aboard
• Case study: forced to marry a cousin at 17