Field Notes
Field Notes

Canadian lakes reveal the impacts of climate change on waters around the world

Monday, July 17, 2017
Posted by
Greg Seitz

Lakes and esker
An esker (the sandy remnant of a river that ran under a glacier) and some of the countless lakes in the area. (Photos by Mark Edlund)

The tundra of northern Canada doesn’t have much in common with the forests and prairies of Minnesota. Most importantly, humans have had little impact there, while invasive species, pollution, and other forces affect our state’s lakes.

But, while Manitoba and Minnesota’s landscapes are very different, they share the global climate — which has been steadily warming in recent decades.

“There might be no bigger question about the future of climate change than how it will affect the world’s water,” Research Station scientist Mark Edlund says. To answer that question, Edlund traveled to Manitoba, where climate change impacts could be seen independent of other human forces.

The hunting lodge that served as the scientists' base camp during the study.

Climate affects lakes in many ways, including simply making the water warmer, longer ice-free seasons, increased wind, which helps mix lake water together, and changes in precipitation patterns. It can also make them more susceptible to invasive species, algae blooms, and increased nutrients.

But just what will it mean for Minnesota’s lakes and rivers? For the Mississippi River? How might it interact with other impacts?

At a remote camp in Manitoba, Edlund and the research team of Charles Umbanhowar (St. Olaf), Phil Camill (Bowdoin), Christoph Geiss (Trinity), and students took sediment core samples from the bottom of lakes nestled in barren tundra. The sun barely set each night, and the researchers were surrounded by the ghosts of caribou.

The tubes of mud they retrieved would show how the lakes have changed over millennia. Edlund specializes in using the fossils of algae called diatoms to reconstruct the history of a lake’s conditions — from its acidity to clarity to nutrient loads. The organisms are sensitive to change, so digging down through the mud tells stories about the past to anyone who knows how to read their messages.

The story the diatoms told in Manitoba is that the factors affecting how arctic lakes respond to the climate for thousands of years have been “broken.” Changes connected to global warming have been drastic and unprecedented — far greater in magnitude in the past 200-300 years than during previous periods of natural climate change.

Not even the Little Ice Age, a period of dramatic global cooling that began around 1300 and lasted until about 1850, significantly affected the waters compared to what has happened in the last 200 years.

“Significant twentieth-century changes in the aquatic ecosystem cannot be explained wholly by changes in the terrestrial ecosystem, suggesting that future changes to the lakes of N. Manitoba will be strongly influenced by direct climatic effects to the lakes,” a new paper from Edlund and the team has found.

Poring over maps and picking the lakes that would be studied.

While still more needs to be studied about climate and lakes, the Manitoba study has already demonstrated that the effects of a warming world are dramatic — and they can be seen far from any source of the carbon emissions which are causing the changes.

And pinpointing the impact of climate in remote Canada will help future research into how it fits into the forces at work on Minnesota’s waters. 

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