Hudson Bay Lowlands buckle under global warming
The biology of lakes of the Hudson Bay Lowlands has undergone threshold-type responses to pronounced warming starting in the mid-1990s, say researchers at Queen's University, Laurentian University and the Ontario Ministry of the Environment.
In stark contrast to the rest of the Arctic, the Hudson Bay Lowlands has not experienced a rise in air temperature, remaining one of the planet's last Arctic refugia from global warming - that is until very recently. In only a few decades, regional temperatures have increased at a pace and magnitude that are exceptional even by Arctic standards. The team reports that, within this short warming period, pronounced responses in freshwater biota have already become apparent.
The rapid transition of this remote subarctic region from an area that has long maintained relatively cool and stable temperatures to one of intense warming provided the team with a rare, natural observatory for identifying the effects of rapid climate change in the absence of additional human influences.
"Our findings indicate that ecological tipping points have been crossed and, sadly, we are witnessing the loss of Arctic ecosystems as we know them", says Queen's Biology research scientist, Dr. Kathleen Ruhland, from the university's Paleoecological Environmental Assessment and Research Lab (PEARL) and lead author of the study.
In an email exchange, Dr. Kathleen Ruhland answered our questions.
Water Today - Your report states, "We have entered
a new ecological state". what does that mean to someone who isn't a researcher?
Ruhland - What happens in the Arctic will eventually happen in non-Arctic regions. Continued warming at the rate and magnitude currently underway will undoubtedly lead to more pronounced ecosystem responses, the effects of which can cascade throughout the entire ecosystem.
The Hudson Bay Lowlands are home to one of the world’s largest peatlands and so is a significant global carbon reservoir. With warming this sink can switch to a source of carbon and accelerate the warming trend even further. So it is not just of importance for the region but also has global implications.
Water Today - You say "striking biological changes have occurred in the region’s freshwater ecosystems.” This is quite a thing to say, what changes?
Ruhland - Our study shows that for the first time in over ~200 years (and likely longer) the lakes are being affected by climate change. The biological communities of lakes in this region of the Arctic have shown little change for hundreds of years – until the mid-1990s. The rapidity and magnitude of warming here is extraordinary and the fact that we are already seeing a response in the freshwater systems for the first time is noteworthy. In the last few years climate researchers on Hudson Bay have been reporting changes in sea ice due to rapid increases in air temperature but we wanted to see whether these high magnitude and rapid changes in temperature can already be evidenced in the lake sediment records (diatoms which are microscopic unicellular algae that come in numerous different species). Changes to these lake ecosystems are important not just from an environmental stand-point but also for northern communities that depend on freshwater fish for sustenance etc.
One of the key findings is that aside from timing, the changes in diatoms that we observed here is consistent with what we would expect with warming and a longer open water season. It compares very well with our previous findings in other regions of the Arctic. With a longer open water season, new habitats develop on the shorelines of lakes which means more opportunities for diatoms to find a habitat and we have an increase in the kinds of species that are found in these diatoms.
Water Today - You mention dropping water levels caused by heat stress, do the water levels keep dropping? what's worst case?
Ruhland - With continued warming, longer open water seasons and increases in evaporation, lakes in the region can start to dry up. We have already seen these dramatic changes in ponds in the High Arctic from our previous work. There is already some evidence that ponds around the Churchill area are starting to show signs of desiccation over the past few years. There are many shallow lakes and ponds throughout the Hudson Bay Lowlands so this is something that is troubling. Similarly for the rivers in the region that drain into Hudson Bay. This past week for example, the water levels on the Sutton River were quite low and it delayed the moose hunt. With warming and less snow we could see this occur more often in the rivers – but this is variable from year to year and from region to region. More extreme weather conditions are now being observed with this new warming trend.
Water Today - The Report also says "we are not really prepared.” What in your view does
society have to do, to be prepared for something like this? You mentioned
global issues, what does that mean?
Ruhland -Warming in the Hudson Bay Lowlands is particularly worrisome as it is home to the one of the world’s largest peatland ecosystems and a significant global carbon sink. With warming there is the potential that these peatlands will release these vast amounts of carbon to the atmosphere accelerating warming further.
This is obviously not a good news story. And there are no simple solutions. These are issues that require real political change and these changes should be based on sound science. What our study shows is that this is not an issue that is dropping in importance – it is and should remain on our radar screens. It basically comes down to reducing carbon emissions.
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