The Register reports on a study by NASA scientist Dr. Drew Shindell suggesting a strong correlation between the fight against acid rain in the 1970s and the abrupt reversal in northern hemisphere temperature trends.
Dr Drew Shindell of NASA's Goddard Institute of Space Studies has led a new study which indicates that much of the general upward trend in temperatures since the 1970s - particularly in the Arctic - may have resulted from changes in levels of solid "aerosol" particles in the atmosphere, rather than elevated CO2. Arctic temperatures are of particular concern to those worried about the effects of global warming, as a melting of the ice cap could lead to disastrous rises in sea level - of a sort which might burst the Thames Barrier and flood London, for instance.So, the reduction in sulfate pollution meant the elimination of a significant counterbalance to increasing soot pollution.
Shindell's research indicates that, ironically, much of the rise in polar temperature seen over the last few decades may have resulted from US and European restrictions on sulphur emissions. According to NASA:Sulfates, which come primarily from the burning of coal and oil, scatter incoming solar radiation and have a net cooling effect on climate. Over the past three decades, the United States and European countries have passed a series of laws that have reduced sulfate emissions by 50 percent. While improving air quality and aiding public health, the result has been less atmospheric cooling from sulfates.
Am I advocating the wholesale repeal of sulfate emission restrictions? Not really -- in fact, I'm not ready to concede any human influence in the climate cycle (hence the blog name). I do note, though, that those who believe in consequential human influence on climate must acknowledge that attempts to "fix" what is allegedly broken can often have unforeseen effects.