Bruce Anderson didn’t set out to prove that the rise in global temperatures since the start of the Industrial Revolution is caused by human activity. And the five-year study that he and four colleagues then published in the October 2012 Journal of Climate doesn’t draw that conclusion, but it does suggest that man-made pollutants are to blame.
The study, which tested three hypotheses about causes of the warming trend, debunks alternative theories that have been floated in recent years. At the same time, says Anderson, a College of Arts & Sciences associate professor of earth and environment, the research strengthens the theory that humans are responsible for the phenomenon, in which carbon dioxide, methane, nitrous oxide, and the other gases we emit accumulate in the atmosphere, trapping the heat that radiates from the Earth.
Winter is getting warmer, spring is coming earlier, and plants are enjoying an extended growing season in northern areas. But that is not good news. In this weeklong series, BU researchers explore the science behind Earth’s environmental changes, and what they mean for our future.
“It’s the initial gold rush,” says Ranga Myneni, a College of Arts & Science professor of earth and environment, but what will follow will not be pleasant. As vegetation flourishes, it could draw down the water supply, bringing on drought, insect infestations, and forest fires. What was once green, lush land could become brown and barren.
In an article published in Nature Climate Change on March 10, Myneni and 21 collaborators describe how seasonal temperatures and vegetation north of the U.S.-Canada border have shifted over the past 30 years to what is typically experienced four to seven degrees latitude to the south. Should global warming continue at its current pace, Bruce Anderson, a CAS associate professor of earth and environment, who worked with Myneni on the paper, predicts a further latitudinal shift of as much as 20 degrees south by the end of the century. That means arctic and boreal regions of Canada would look and feel much more like the southern United States.