A new study led by Lance Lesack, a Simon Fraser University geographer and Faculty of Environment professor, has discovered unexpected climate-driven changes in the mighty Mackenzie River’s ice breakup. This discovery may help resolve the complex puzzle underlying why Arctic ice is disappearing more rapidly than expected.
Lesack is the lead author on Local spring warming drives earlier river-ice breakup in a large Arctic delta. Published recently in Geophysical Research Letters, the study has co-authors at Wilfrid Laurier University, the University of Alberta and Memorial University.
Its goal was to understand how warming global temperatures and the intensifying Arctic hydrological cycle associated with them may be driving increasing water discharges and more rapid ice breakup in the Arctic’s great rivers.
But the researchers stumbled upon an unexpected phenomenon while trying to figure out why the Mackenzie River’s annual ice breakup has been shortening even though its water discharge isn’t increasing, as in Russian rivers.
Just slightly warmer springs with unexpected snowfall declines — rather than warmer winters or increasing river discharge, as previously suspected — can drive earlier-than-expected ice breakup in great Arctic rivers.
The Mackenzie exemplifies this unexpected phenomenon. The researchers discovered this by accessing records dating back to 1958 of the river’s water levels, snow depths, air temperatures and times of ice breakup.
This finding is significant, as Arctic snow and ice systems are important climate-system components that affect the Earth’s ability to reflect solar radiation.
“Our surprising finding was that spring temperatures, the period when river-ice melt occurs, had warmed by only 3.2 degrees Celsius. Yet this small change was responsible for more than 80 per cent of the variation in the earlier ice breakups, whereas winter temperatures had warmed by 5.3 degrees but explained little of this variation,” says Lesack.
“This is a strong response in ice breakup for a relatively modest degree of warming, but further investigation showed that by winter’s end snow depths had also declined by one third over this period. The lesser snow depths mean less solar energy is needed to drive ice breakup.”
Lesack says this is the first field-based study to uncover an important effect of reduced winter snowfall and warmer springs in the Arctic — earlier-than-expected, climate-change-related ice breakup.
“The polar regions have a disproportionate effect on planetary reflectivity because so much of these regions consist of ice and snow,” says Lesack. “Most of the planetary sea ice is in the Arctic and the Arctic landmass is also seasonally covered by extensive snow. If such ice and snow change significantly, this will affect the global climate system and would be something to worry about.”
Lesack hopes this study’s findings motivate Canadian government agencies to reconsider their moves towards reducing or eliminating ground-based monitoring programs that measure important environmental variables.
There are few long-term, ground-based snow depth records from the Arctic. This study’s findings were based on such records at Inuvik dating back to 1958. They significantly pre-dated remote sensing records that extend back only to 1980. Without this longer view into the past, this study’s co-authors would still be in the dark about the more rapid than expected Arctic melt and planetary heat-up happening.
Quotes by Lance Lesack
Simon Fraser University is consistently ranked among Canada's top comprehensive universities and is one of the top 50 universities in the world under 50 years old. With campuses in Vancouver, Burnaby and Surrey, B.C., SFU engages actively with the community in its research and teaching, delivers almost 150 programs to more than 30,000 students, and has more than 125,000 alumni in 130 countries.
Carol Thorbes | EurekAlert!
Biomass turnover time in ecosystems is halved by land use
23.08.2016 | Alpen-Adria-Universität Klagenfurt
Diversity of habitats at natural oil seeps
22.08.2016 | MARUM - Zentrum für Marine Umweltwissenschaften an der Universität Bremen
Scientists and engineers striving to create the next machine-age marvel--whether it be a more aerodynamic rocket, a faster race car, or a higher-efficiency jet...
Waveguides are widely used for filtering, confining, guiding, coupling or splitting beams of visible light. However, creating waveguides that could do the same for X-rays has posed tremendous challenges in fabrication, so they are still only in an early stage of development.
In the latest issue of Acta Crystallographica Section A: Foundations and Advances , Sarah Hoffmann-Urlaub and Tim Salditt report the fabrication and testing of...
Electrochemists at TU Graz have managed to use monocrystalline semiconductor silicon as an active storage electrode in lithium batteries. This enables an integrated power supply to be made for microchips with a rechargeable battery.
Small electrical gadgets, such as mobile phones, tablets or notebooks, are indispensable accompaniments of everyday life. Integrated circuits in the interiors...
Recent findings indicating the possible discovery of a previously unknown subatomic particle may be evidence of a fifth fundamental force of nature, according...
A nanocrystalline material that rapidly makes white light out of blue light has been developed by KAUST researchers.
25.08.2016 | Event News
24.08.2016 | Event News
12.08.2016 | Event News
26.08.2016 | Life Sciences
26.08.2016 | Life Sciences
25.08.2016 | Power and Electrical Engineering