The researchers say cutting down on the burning of coal and oil, one of the main goals of international environmental agreements, will drastically heat rather than cool climate.

"When the cooling affect goes away -- and it must do because particles like sulphur dioxide are damaging to humans -- global warming will be much stronger," climate change scientist Dr Peter Cox told Reuters on Wednesday.

Temperatures could increase in the worst case by up to 10 degrees by the end of the century, the researchers said -- much more than current estimates.

Scientists differ as to whether global warming is caused by man-made emissions of carbon dioxide and other "greenhouse" gases, by natural climate cycles or if it exists at all.

Take away fossil fuel by-products like sulphur dioxide without tackling greenhouse gas emissions, and the extra heat will speed warming, irreversibly melting ice sheets and rendering rain forests unsustainable within decades, Dr Cox said.