In the northern part of Iceland an unknown force is creating mysterious changes in the mud of its deepest lakes. Every 80-100 years, the chemical fingerprint of the lake mud changes dramatically for a brief time and then returns to what it was before. This bizarre cyclical behavior has been going on for at least 900 years and nothing like it has been reported anywhere else in the world. If Lisa Doner is right, the answer to this mystery lies in a climate feature called the North Atlantic Oscillation.
Doner, a research professor at the Center for the Environment at Plymouth State University, was recently awarded a $600,000 National Science Foundation grant to study the deposits in the bottom of lakes in Iceland and how the North Atlantic Oscillation affects the process of deposition. Doner explains, “The North Atlantic Oscillation, or NAO for short, and a related, larger circulation pattern called the Arctic Oscillation (AO), together control most of the Northern Hemisphere’s year-to-year atmospheric variation. The NAO and AO have been credited with causing many of the recent patterns of drought, flooding and severe weather in North America, Europe and the Middle-East, including last winter’s repeated snowstorms in the southeast and the colder and wetter winters in NH.”
So why is Iceland the only region that seems to show this phenomenon? And how does this relate to our regional climate?
Much of Iceland’s climate and land history is similar to that of other northern regions, with land that has been stripped clear of soils and vegetation by thick glacial ice as recently as 11,000 years ago. Unlike other places, however, Iceland has two characteristics that set it apart from regions of similar latitude in North America, Europe and Asia.
“First, Iceland is an island made up entirely of volcanic material,” said Doner. Volcanic rocks are relatively weak, especially compared to the granite that underlies much of New Hampshire, and in breaking down, they create new soils very quickly. These volcanic soils are fragile and easily eroded if their protective vegetation cover is lost, such as occurs with the cutting and removal of forests, over-grazing by herd animals, and poor agricultural practices.
“This brings us to the second aspect that makes Iceland unusual; humans did not occupy Iceland until Nordic settlers came in AD 874. Much like what happened when European settlers arrived in New England almost eight centuries later, the early settlers on Iceland rapidly cut down most of the forest and converted the land to agricultural field and pasture. Massive episodes of soil erosion followed the period of settlement,” Doner further explains. “Unlike New England however, where soil takes thousands of years to redevelop, the soils of Iceland can regenerate quickly, especially if the period of disturbance are short.”
Doner and her team think that, while the NAO may be responsible for the 80-100 year cycle in the lake mud, human land use has amplified this effect and made it the dominant factor controlling the chemical deposits. Since the NAO impacts many of New Hampshire’s winters, the existence of an 80-100 year cycle in that impact is of critical importance, especially when the NAO effect is combined with intensified land use from increasing population and land clearances.
“The depleted soils and subsequent economic devastation that followed New Hampshire’s sheep boom in the early 1800’s highlights the sensitivity of this region to land use impacts,” said Doner. “Our region here may be made even more susceptible during peak NAO intervals.”
From 2010-2014, Doner will head a team of researchers to investigate this phenomenon, including Mark Green, Assistant Professor of Hydrology at PSU’s Center for the Environment; Ann Dieffenbacher-Krall, an Assistant Research Professor in the Climate Change Institute at the University of Maine; Mark C. Serreze, Director of the National Snow and Ice Data Center at the Cooperative Institute for Research in Environmental Sciences and Professor of Geography at the University of Colorado, Boulder; and Bradford Hubeny, Assistant Professor of Geology, Salem State College. Each year, one PSU graduate student and two undergraduate students will travel to Iceland, Maine and Minnesota to collect and analyze samples. The students will also have the opportunity to report their results at national science meetings.