Tropical rainforests have been a cause celebre among environmentalists and climate change activists for decades. But research released in advance of this week's climate conference in Cancun shows that hectare-for-hectare British Columbia's rainforests store twice as much carbon.

Tropical rainforests store an average of between 360 and 460 metric tons of carbon dioxide equivalents per acre, while temperate rainforests in the Pacific Northwest store as much as 800 metric tons per acre, according to a synthesis of research by 30 scientists.

"Rainforests in the Pacific Northwest and Alaska... store the equivalent of more than twice the world's [annual] carbon dioxide pollution released by the burning of fossil fuels," said Dominick A. DellaSala, an Oregon conservation biologist who compiled the research.

Temperate and boreal rainforests are found in only 10 regions of the world, and comprise less than 3 per cent of the earth's forest land. Europe's rainforests were destroyed or degraded centuries ago. More than a third of the remaining temperate rainforest is in the Pacific Northwest.

"Carbon is stored for centuries in massive tree trunks, dense foliage, and rich soils in these rainforests that help stabilize the global climate," DellaSala said. "When these rainforests are cut down, much of that carbon is released to the atmosphere where it contributes to global warming pollution."

DellaSala is president of the North America section of the Society for Conservation Biology and editor of "Temperate and Boreal Rainforests of the World: Ecology and Conservation" (Island Press, 2010).

Monte Paulsen reports on carbon shift for The Tyee.