McElroy says it’s time to stop seeing global warming as political issue

Michael B. McElroy, Gilbert Butler Professor of Environmental Studies and director of Harvard’s Center for the Environment, is among the scientists who since the 1970s have been using paleoclimatic data to chart changes in the earth’s atmosphere. To obtain these data, researchers drill several kilometers down into polar ice sheets and extract gases from the tiny air bubbles trapped inside. Through these, says McElroy, “you can not only infer a surrogate for temperature, but you can also measure the composition of the atmosphere at that point in the earth’s history. There is a close association between climate and the level of gases like CO2 and methane.” “We have raised the level of carbon dioxide in the atmosphere to a point that is higher than at any time over the past 450,000 years,” McElroy says. “Arguably, it’s higher than it’s been for several million years. Concentrations of CO2 will climb to twice what they currently are by the end of the century. That’s a complete change in the atmosphere.”