Thank you for making acid rain

Sulphur dioxide has a bad name. As the leading cause of acid rain, it was targeted two decades ago as a killer of forests and a polluter of lakes. More recently, Prime Minister Stephen Harper made it the prime target of the Conservative’s climate change initiative. Yet, according to recent Université du Québec à Montréal (UQAM) research, the lowly chemical compound might have a far more noble distinction: as a fighter of global warming.

As part of International Polar Year, UQAM professor Jean-Pierre Blanchet studied the effects of sulphur dioxide on Arctic climates and found the gas actually helped to counteract the effects of global warming. When water combines with SO2 in the atmosphere, the mixture is more likely to fall as precipitation—which helps to rid the air of the most abundant climate changer of all: water vapour. A recent Texas A&M University study suggests that water vapour can double the climate warming caused by increased carbon dioxide levels in the atmosphere.

“Sulphur dioxide can actually counterbalance global warming,” Blanchet says. “If we take it out of the atmosphere we may actually speed up climate change.” In effect, the research indicates that humankind’s predilection for pumping out climate changing gases like carbon dioxide is at least in part counteracted by its tendency to produce large volumes of sulphur dioxide, which is a by-product of coal and petroleum combustion.

Along with its climate-balancing properties, Blanchet says increased sulphur dioxide in the atmosphere has been a factor in the high number of winter storms as of late. But wary of the political implications of his research, Blanchet says this isn’t an excuse for inaction on climate change. Rather, he says, “governments must do things in the right order. First, they must reduce the amount of greenhouse gases pumped into the atmosphere. Only then should they go after SO2.”