The air of the future will likely be cleaner than it is today predicted earth scientist Ross Salawitch of the University of Maryland. But wait, there's a downside to less pollution: more global warming.
Pollutants reflect solar radiation and help keep the earth cool, said Salawitch, during a lecture at University Park's Church of the Brethren in October. The member of the University Park Community Solar LLC remains supportive of efforts to curb air pollution.
The extent of the cooling effect of pollutants and other fine particulate matter is unclear. Differing estimates of the cooling effect contribute to the range of predictions made by climate models, which estimate the average temperature will be less than one degree to more than two degrees Celsius warmer by 2050.
Following the eruption of Mount Pinatubo in the Philippines in 1991, temperatures fell across the world by about half a degree Celsius. It was largest terrestrial volcanic explosion since 1912, and ejected massive amounts of sulfur and fine particulate matter into the stratosphere.
Salawitch's research suggests the cooling effect of volcanic eruptions is weaker than most experts believe. He noticed that the eruption of Pinatubo, as well as three other major volcanic explosions, coincided with the cooling phase of the Atlantic Multidecadal Oscillation, a climate pattern which causes the ocean's surface temperature to vary.
This coincidence has lead scientists to overestimate the cooling effects of volcanic explosions because they attribute all of the cooling that followed to the explosions and ignore the Atlantic Multidecadal Oscillation, said Salawitch.
When the effect of the Atlantic Multidecadal Oscillation is taken into account by mathematical climate models, the cooling effect of the Pinatubo eruption is cut in half. Salawitch is writing a paper explaining his finding that other factors contributed to the half degree Celsius cooling between roughly 1991 and 1993. He expects it to be controversial.
Following the Pinatubo eruption, geo-engineering - or man-made manipulation of the atmosphere in an attempt to control the weather- became a popular idea. Plans to inject aerosols into the atmosphere became vogue. Not only are the benefits of doing so unclear, as demonstrated by the professor's research, the risks are great and the unintended consequences are unknown, said Salawitch.
However, he said launching reflective balloons above the Arctic is an intriguing idea because they would help compensate for the lower overall reflectivity of the North Pole as a result of the melting of the icecaps. The lower reflectivity of the North Pole causes it to absorb more heat, leading the icecaps to melt more; this positive feedback loop is leading the Arctic to warm about twice as fast as the rest of planet.