Science Cafe - "Ice Out": The Contribution of Citizen Scientists to our Understanding of Climate Change

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Dr. Tim Patterson 
Department of Earth Sciences

Wednesday, December 9th 
6:30 - 7:30 p.m.

Ottawa Public Library 
Sunnyside Branch
1049 Bank Street  


Long-term trends in spring 'ice out' dates for lakes in Maine, New Brunswick and New Hampshire reveal a remarkable coherency across the region. These data have been compiled since the early 19th century, primarily by amateur citizen scientists, for a variety of purposes, including determining fishing seasons, estimating the spring opening of ferry boat routes, community contests, and general curiosity. Ice out dates correlate closely with late-winter/early-spring instrumental temperature records from across the region. This correlation permits use of ice out dates as a proxy to extend the shorter instrumental record. Mean ice out dates trended progressively earlier during the recovery from the Little Ice Age through to the 1940s, and gradually became later again through to the late 1970s, when ice out dates had returned to values more typical of the late nineteenth century. Post-1970’s ice out dates resumed trending toward earlier dates, with the twenty-first century being characterized by the earliest ice out dates on record. Ice out is influenced by several major climate drivers including the Quasi-biennial Oscillation, El Niño, North Atlantic Oscillation, Atlantic Multidecadal Oscillation and Arctic Oscillation. It is important to understand trends in ice out as the duration of the ice free season has a major influence on the ecology of lakes. Are early ice dates in recent years simply the result of natural climate variability, a symptom of human caused climate change, or some combination?


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