Abrupt climate change researched

There was heavy snow in June and frost even in July and August. All across the Northeast, farmers’ crops were repeatedly killed by the cold, raising the specter of widespread famine.” So wrote Patrick Hughes of the U.S. Environmental Data Service in 1976 about the summer of 1816, also known in weather lore as the Year without a Summer. Several times, farmers replanted their corn, beans, squash and other crops, only to see them blacken and die after being hit by the cold. The following year saw an exodus from northern New England to the Ohio River valley and other points south.

These conditions hit New England, indeed much of the world’s northern latitudes, by surprise. While the weather of 1816 has been linked to short-lived volcanic eruptions that spewed dust into the atmosphere, it gave people a taste of what scientists today call rapid or abrupt climate change. The potential for such dramatic shifts raises important questions far beyond the farm. Without a better understanding of the factors that affect climate, modern civilization may be just as vulnerable as New England farmers were almost 200 years ago.

Fortunately, scientists at the University of Maine and other institutions are making significant strides in understanding how the Earth’s climate system operates. Their efforts could receive a major boost from new federal research proposed by Maine Sen. Susan Collins. Her program is being developed with help from UMaine scientists and aims to clarify the critical factors that drive the climate system.

Scientists in the Institute for Quaternary and Climate Studies at UMaine have a strong track record in collecting and analyzing climate records from across the globe. Together with colleagues and students, they have drilled ice cores in glaciers and ice sheets in Antarctica, Greenland, Tibet and the Arctic. They have studied the movement of glacial ice in the Antarctic Dry Valleys and determined when glaciers waxed and waned in the mountains of New Zealand and Chile. Each of these places has a unique story to tell about average air temperatures, the extent of sea ice, the chemistry of the atmosphere and even the direction of prevailing winds.

One of the hallmarks of their recent findings, first seen in the ice cores from Greenland, is the rapidity with which climate can change, even during the so-called stable period of the last 10,000 years. Results have shown conclusively that over a period as short as a decade, average temperatures can change as much as 15 degrees. In contrast, the reduction in the average temperature in 1816 has been estimated at three to six degrees.

A report published by the National Academy of Sciences last year notes that changes of up to 16 degrees occurred during the periods just preceding and following the last Ice Age. That such a dramatic shift in the Earth’s natural rhythms can occur is not seriously disputed today.

However, to help citizens, businesses and governments respond, scientists need to continue to search for clues about the nature of this global light switch. Is it related to other cycles such as the North Atlantic Oscillation or the El Nino Southern Oscillation in the Pacific? Is it linked to ocean currents that carry warm salty water toward Europe and sink to combine eventually with Antarctic waters and form the deep, cold currents that scour the ocean floor? How is it affected by the sun or volcanic activity? Clearly, some combination of these and other factors has produced rapid and massive climate changes in the past that have been significant enough to alter human history.

Unfortunately, as the National Academy of Sciences report correctly points out, “at present, there is no plan for improving our understanding of the issue, no research priorities have been identified, and no-policy making body is addressing the many concerns raised by the potential for abrupt climate change.” While the University of Maine and other institutions have done much to improve our understanding of abrupt climate change, we are still a long way from being able to assess the timing or likelihood of future abrupt changes.

Sen. Collins’ proposal, which was successfully adopted as an amendment to the Senate energy bill, would do much to address this problem. The amendment lays out clear research priorities for addressing abrupt climate change. Furthermore, by authorizing $60 million over six years, the amendment would provide the resources necessary to create a nationwide program to shed light on these problems.

UMaine is well positioned to lead such an effort. Answering these and other questions will help scientists understand the risk of rapid climate change in modern times and know what to monitor for signs of such an impending shift. Anyone who depends on natural resources for a living – farmers, foresters, fishermen, tourist business owners – stands to benefit from an early warning system. After all, the modern climate creates the foundation for the fisheries in the Gulf of Maine and makes potato farming possible. It allows the blueberry industry to flourish and brings tourists to enjoy blue skies and sunsets over Maine’s lakes.

During the last year, we’ve seen what a drop in rainfall can do to water levels in lakes and wells. We should all be concerned about the potential for a rapid change to the landscape we take for granted.

George Denton is Libra Professor of Geological Sciences and Quaternary Studies at the University of Maine and a member of the National Academy of Sciences.