Tropical forests might be absorbing far more carbon dioxide than earlier estimated, in response to rising atmospheric levels of the greenhouse gas, a new NASA-led study showed, www.universityherald.com reported.

According to the findings, tropical forests absorbed 1.4 billion metric tons of carbon dioxide out of a total global absorption of 2.5 billion -- more than that absorbed by forests in Canada, Siberia and other northern regions, called boreal forests.

"This is good news, because uptake in boreal forests is already slowing, while tropical forests may continue to take up carbon for many years," David Schimel, lead author of the study and member of NASA's Jet Propulsion Laboratory in California, said in a statement.

Up to 30 per cent of human carbon dioxide emissions are removed from photosynthesis by forests and other land vegetation at present. Slowing down of the absorption rate would likely speed up global warming.

The researchers, had, in the new study devised a way to apples-to-apples comparisons of carbon dioxide estimates from several sources of different scales: computer models of ecosystem processes, atmospheric models run backward in time to deduce the sources of today's concentrations (called inverse models), satellite images, data from experimental forest plots and more.