An abnormal season of intense glacial melt in 2002 triggered multiple distinct changes in the physical and biological characteristics of Antarctica’s McMurdo Dry Valleys (MDV) over the ensuing decade, new research led by CWEST's Education Committee Chair Michael Gooseff shows.
The findings suggest that even abrupt, short-lived climate events can cause long-term alterations in polar regions that unfold over the span of several years and subsequently change the overall trajectory of an ecosystem.
The new research appears today in the journal Nature Ecology and Evolution.
The MDV are the largest ice-free region of Antarctica and are considered a polar desert environment due to their low humidity and scarce precipitation. Now in its 25th year, the NSF’s McMurdo Dry Valleys Long-Term Ecological Research (LTER) has provided a continuous multi-decade record of atmospheric and ecological data at the MDV research site.
Between 1987 and 2000, the MDV region experienced a period of cooling, during which mean summer temperatures steadily declined while solar radiation gradually increased. The trend resulted in expected changes to most biological variables, including decreased streamflow and increased thickness of permanent ice covers on lakes.
In 2002, however, the MDV experienced an abnormally warm and sunny summer season, triggering the greatest amount of glacial meltwater since 1969. The abrupt event prompted numerous changes in the lakes, streams and soils of the MDV over the following decade.
“This flood year was the pivot point,” said Gooseff, INSTAAR Fellow and CEAE Professor, and the lead investigator for the MDV LTER project. “Prior to that, all physical and biological indicators had been moving in the same direction.”
Instead of a tightly-correlated change, however, biological responses to the 2002 season varied and, in some cases, lagged behind by years. For example, the researchers found that one previously declining dominant soil species increased slowly following the flood year while a rarer species responded more positively to the moisture Mpulse and saw population increases carry over into subsequent summers.
Read the full, original article by Trent Kross at CU BoulderToday. In addition to Nature's commentary on the paper, Dr. Gooseff provides an insider's perspective on the ecological legacies of Antarctica.