As the three-day climate-change meeting in Copenhagen wrapped up, British economist Nicholas Stern talked about the relationship between the climate change and the economic recession, pointing out the opportunity to build a more energy-efficient economy.

Lord Stern, the author of a major British government report detailing the cost of climate change, told climate scientists on the final day of the Copenhagen conference that falling prices in the construction sector make it cheaper to insulate homes and preserve energy.

Explaining his reasons why he feels more optimistic about the likelihood of a new, effective global climate agreement today than he was two years ago, Nicholas Stern said that due to the economic crisis, the rapid advancement of low-carbon technology, the deepening of public awareness and the Obama administration's commitment to cutting greenhouse-gas emissions to 80 percent of 1990 levels by 2050 should provide an opening for completely remaking the global energy economy. Investment in low-carbon technologies, the insulation of buildings and public transport, it is reasoned, can make a key contribution to getting the economy moving again.

"Coming out of this (crisis) we have got to lay the foundations for a low-carbon growth, which is going to be like the railways, like the electricity, like the motorcars, this is going to be over the next two-three decades, the big driver in investment," he said.

Lord Stern also said his 2006 landmark review of the economics of climate change underestimated the scale of the risks, and the speed at which the planet is warming. He urged scientists to speak out and tell the politicians what the world would be like if effective measures against global warming were not taken.

The Copenhagen meeting drew about 2,500 scientists, economists, campaigners, dignitaries, industry representatives and journalists. Conclusions of the congress will be presented to politicians when they meet in Copenhagen in December to discuss a new global agreement on greenhouse gas emissions to replace the Kyoto Protocol, which expires in 2012.

Echoing what many climate scientists have been saying with rising vigor for two decades, scientists pressed that there is an urgent need to curb emissions of greenhouse gases, and "inaction is inexcusable."