Satellite—based projections of aerosols’ effect on earth’s climate significantly underestimate their impact which may lie at the heart of the biggest uncertainty in climate change.

“The satellite estimates are way too small,” said Joyce Penner, professor of atmospheric science at the University of Michigan who led the study.

Aerosols are at the core of “cloud drops” - water particles suspended in air that coalesce to form precipitation, the journal Proceedings of the National Academy of Sciences reports.

Increasing aerosol particles, including soot and sulphur dioxide from burning fossil fuels, cause an increase in cloud drops, resulting in brighter clouds that reflect more light and have a greater cooling effect on the planet, according to a university statement.

As to the extent of their cooling effect, scientists offer different scenarios that would raise the global average surface temperature during the next century between under two to over three degrees Celsius.