Trees, plants seen as cheap solution to curb emissions

"The message is stop digging for energy and start growing it," said New Zealand economist Peter Read.

Read's low-cost bioenergy approach contrasted with the pricey, high-tech schemes for curbing carbon dioxide emissions from fossil fuels put forward by other climate experts on the closing day of a meeting called by British Prime Minister Tony Blair.

Blair asked scientists and policy advisers from 30 countries to identify the danger level of atmospheric carbon dioxide, the chief greenhouse gas, and advise leaders at the G-8 summit in Scotland this July how to avoid surpassing it.

Many experts here agreed that carbon dioxide should not be allowed to go above 550 parts per million in the air, double the level before industrialization began in the mid-19th century. But they were less united on the best avoidance strategy, with a few backing a major expansion of nuclear power, others plumping for wind and solar energy and some wanting to pump carbon dioxide into old oil wells or salt caverns.

Read argued a much simpler, more economical solution is taking advantage of the natural biosphere.

Making better use of existing agricultural land would boost global plant production enough to provide wood to burn for electricity and crops like corn or wheat that could be converted into biofuels. Only about 10 per cent of arable land would be needed for this strategy, according to computer projections.

Read said the green approach would also ready the world for a crash program to actually reduce atmospheric levels of carbon dioxide rather than just rein in their increase at the first sign of abrupt climate change. This would be accomplished by capturing and storing the carbon dioxide produced from burning the wood or making ethanol.

"If we are going to need an ark, we need to build it before the rains begin," he said.

A conference wrap-up report said a maximum 2 degrees Celsius increase in average global temperature, a target urged by many experts, means carbon dioxide emissions would have to peak in 2020, so the atmospheric level did not exceed 500 parts per million. The report said a delay of even five years could be significant and require more severe emission reductions to hold the temperature increase to 2 degrees.