Scientists from Queen's and Carleton universities head a national multidisciplinary research team that has uncovered startling new evidence of the destructive impact of global climate change on North America's largest Arctic delta.
"One of the most ominous threats of global warming today is from rising sea levels, which can cause marine waters to inundate the land," says the team's co-leader, Queen's graduate student Joshua Thienpont. "The threat is especially acute in polar regions, where shrinking sea ice increases the risk of storm surges."
By studying growth rings from coastal shrubs and lake sediments in the Mackenzie Delta region of the Northwest Territories -- the scene of a widespread and ecologically destructive storm surge in 1999 -- the researchers have discovered that the impact of these salt-water surges is unprecedented in the 1,000-year history of the lake.
"This had been predicted by all the models and now we have empirical evidence," says team co-leader Michael Pisaric, a geography professor at Carleton. The Inuvialuit, who live in the northwest Arctic, identified that a major surge had occurred in 1999, and assisted with field work.
The researchers studied the impact of salt water flooding on alder bushes along the coastline. More than half of the shrubs sampled were dead within a year of the 1999 surge, while an additional 37 per cent died within five years. A decade after the flood, the soils still contained high concentrations of salt. In addition, sediment core profiles from inland lakes revealed dramatic changes in the aquatic life -- with a striking shift from fresh to salt-water species following the storm surge.
"Our findings show this is ecologically unprecedented over the last millennium," says Queen's biology professor and team member John Smol, Canada Research Chair in Environmental Change and winner of the 2004 NSERC Herzberg Gold Medal as Canada's top scientist. "The Arctic is on the front line of climate change. It's a bellwether of things to come: what affects the Arctic eventually will affect us all."
Since nearly all Arctic indigenous communities are coastal, the damage from future surges could also have significant social impacts. The team predicts that sea ice cover, sea levels and the frequency and intensity of storms and marine storm surges will become more variable in the 21st century.
Other members of the team include Trevor Lantz from the University of Victoria, Steven Kokelj from Indian and Northern Affairs Canada, Steven Solomon from the Geological Survey of Canada and Queen's undergraduate student Holly Nesbitt. Their findings are published in the Proceedings of the National Academy of Sciences.
Research funding comes from the Natural Sciences and Engineering Research Council of Canada (NSERC), the Polar Continental Shelf Program, the Cumulative Impact Monitoring Program, and Indian and Northern Affairs Canada.
- Michael F. J. Pisaric, Joshua R. Thienpont, Steven V. Kokelj, Holly Nesbitt, Trevor C. Lantz, Steven Solomon and John P. Smol. Impacts of a recent storm surge on an Arctic delta ecosystem examined in the context of the last millennium. Proceedings of the National Academy of Sciences, 2011; DOI: 10.1073/pnas.1018527108
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