A new study on climate change finds that aerosol emissions may have reduced the devastating effects of global warming on the Arctic before 1970s. Researchers studying the effects of air pollution on sea ice growth in the mid-20th century have observed that sea ice was unperturbed by human-caused climate change until the Clean Air regulation in the 1970s. In fact, there was an extensive sea ice increase before the regulation was implemented.
Looking into a recently recovered Russian observations, scientists find an increase in sea ice from 1950 to 1975 as large as the subsequent decrease in sea ice observed from 1975 to 2005. The new observations of this past sea ice expansion led researchers to develop a new study focused on the search for the cause. The finding of the study reveal that air pollution is to blame for the observed Arctic sea ice expansion.
Researchers say that in the past, particles from aerosol emissions which come primarily from the burning of fossil fuels may have temporarily masked the effects of global warming in the eastern Arctic. Components of aerosol emission, called sulfate aerosols, can reflect sunlight back into space which cools the surface. This cooling effect may have lowered the influence of global warming on Arctic sea ice, the Phys.org reports.
The cooling effect may have also resulted in sea ice expansion that was recorded by Russian aerial surveys over the arctic from 1950 through 1975. "The cooling impact from increasing aerosols more than masked the warming impact from increasing greenhouse gases," John Fyfe, a senior scientist and a co-author of the new study, says. To test the aerosol emission idea, the study used computer modeling to replicare sulfate aerosols in the Arctic from 1950 through 1975, the ZME Science reports.
Unusually high concentrations of aerosol emissions were recorded during these years before regulations like the Clean Air Act limited the use of sulfur dioxide emissions that produce sulfate aerosols. Interestingly, aerosols aren’t chemically stable and only last up to a few weeks in the atmosphere. As a result, the cooling effect gradually dissipated after the 1980s following clean air regulations, leaving greenhouse gases to spike up the rate of ice loss we see today.