Previously, climate change scientists had calculated that warmer winters were contributing to fluctuations in the polar ice caps, but a recent discovery may change this perception.
Lance Lesack, professor at Simon Fraser University, discovered an unexpected relationship between the ice breakup on the Mackenzie River, and spring and winter temperature variations. In recent years, attributed to climate change, the Mackenzie River’s ice cover has been breaking up earlier and earlier. Previously, it was suspected that warmer winters responsible for the earlier ice breakup, but an in-depth consideration of all the data led to an interesting discovery, that warmer spring temperatures had a bigger impact.
Going back to all the records available on the Mackenzie River, including water levels, snow depths, air temperatures, and the time of ice-breakup, since 1958, Lesack discovered that climate change hasn’t been leading to warmer winters so much as it has been leading to warmer spring and summer temperatures.
Lesack explained, “Our surprising finding was that spring temperatures, the period when river-ice melt occurs, had warmed by only 3.2 °C, yet this small change was responsible for more than 80 % of the variation in the earlier ice breakups, whereas winter temperatures, warmed by 5.3 °C, explained little of this variation.”
The Mackenzie River, the biggest system in Canada, is showing, at least on a small scale, how climate change is impacting arctic ice cover. Lesack’s research seems to indicate that the same ice-melt experienced on the river, just north of the Arctic Circle, might explain the ice-melt patterns that are being noted on the polar ice caps.