Dramatic ice loss from U.S. and western Canadian glaciers
It’s not just the heat. It may also be the wildfires.
We’re not at 1.5C yet, but we’re pushing new highs. And Earth systems are responding. I feel like it’s never very long before I come across the next scientific study that documents rapid change.
The latest example: Glaciers in western Canada and the United States lost 12 percent of their mass in only four years from 2021 through 2024, new research has found.
The major losses — in a glacier region that includes Montana’s Glacier National Park, the Rocky Mountains, and the Cascades — amounted to more than 80 billion tons of ice across these four years, the new research finds.
The study, published in the journal Geophysical Research Letters, relied on extensive aircraft surveys and some local measurements to assess the state of glaciers in the region. It observed not only dramatic shrinkage but also that glacier surfaces were getting darker in hue, a change that is likely hastening the losses and could be linked to a surprising source — worsening wildfires.
“It is temperature to some degree, but it really also seems to be the surface darkening,” said Brian Menounos, a scientist with the University of Northern British Columbia and the Geological Survey of Canada Pacific, and the study’s lead author.
Overall, data provided by the researchers shows that glaciers in the region have lost about a third of their total volume since the mid-1960s, and about half of the change has come in the last 20 years.
Famous glaciers in the region above include not only those found in Montana’s Glacier National Park, but also the glaciers of Rocky Mountain National Park, Mount Rainier, North Cascades National Park, Whistler, Banff National Park in Alberta, and many more.
The study also examined glaciers in the Swiss Alps — where central Europe’s largest concentration of ice lies — finding a similarly dramatic rate of change in another mid-latitude zone. The work was conducted by Menounos with geoscientists from the U.S. and Canadian governments as well as scientists at institutions in Switzerland and Austria.
Menounos and two other study authors contributed to a recent global assessment of accelerating glacial ice loss, which I wrote about here.
This pattern of large and quickening retreat is showing up in mountain glaciers globally, though not always as rapidly as in these two regions. In a visualization of that broader study’s findings, I combined together the Western Canada and U.S. region with Alaska, which contains more ice — but the big picture is that glacial ice is rapidly shrinking around the world:
For the Western Canada and U.S. region, the new study suggests that along with extra warm temperatures and low snowfall, the falling out of dark particles from recent extreme wildfires may be driving fast loss rates.
“Reanalysis data shows that black carbon, a proxy for impurities coming in from wildfire, have really shot up in western Canada in the last few years,” said Menounos.
Canada’s worst wildfire year on record, by far, was 2023. This was also the year when black carbon deposition on the ice was the greatest. If glacier surfaces are darker, they absorb more sunlight, increasing local temperatures and melting rates.
To underscore the point, Menounos shared this image, from one of the aircraft surveys done as part of the research with the Hakai Institute in British Columbia. It’s a view of Glacier National Park’s iconic Sperry Glacier, with the highest altitude regions at the bottom of the image. As you can see, these regions are surprisingly dark in color, especially considering these are locations at the top of the glacier in elevation.
“You usually see the exact opposite,” Menounos said.
This is not a sea level rise story. Glaciers in regions farther north — Alaska, the Canadian Arctic — hold more ice volume than those in North America’s middle latitudes. So while the overall ice losses in this region do contribute a smidge to sea level rise (about 1 millimeter in total), they aren’t a big factor here.
However, the region’s glaciers are key tourist attractions and also supply water to myriad rivers throughout the region. But in the long term, most glaciers in the area are now expected to be severely diminished by 2100, if they still exist at all.
“We are looking at glacier extinction in Glacier National Park, the Cascades,” said Menounos. “Most of the ice in western Canada is projected to be gone by the end of the century.”
Speaking of Canada’s wildfires, by the way:
Carbon bursts from Canada’s massive wildfires can swamp the entire country’s emissions.
Last month I posted about the enormous greenhouse gas emissions that have already been released from wildfires in Canada, which as of then were tracking the worst year on record, 2023. The situation has moderated a little since then, but a lot of emissions have nonetheless already occurred this year, with more still to come.
As it happens, Canada also recently reported its greenhouse gas emissions to the United Nations, as part of the annual reporting process under the Framework Convention on Climate Change. Reporting for developed nations like Canada is always two years behind, so the latest report runs through 2023, the worst fire year on record — so large that almost a quarter of all the world’s wildfire emissions came from Canada that year.
In a spreadsheet cell deep in the filing, Canada notes that just shy of 900 million tons of carbon dioxide were emitted due to “natural disturbances” on lands that the country considers to be under its management, a number which takes into account plant regrowth following prior disturbances. That total is more than the country’s entire carbon dioxide emissions of just under 550 million tons reported in that year. (I’m not counting here emissions of other greenhouse gases, either when it comes to the wildfires or for Canada’s economy as a whole.)
I’m working with a talented student at UVA this summer, Elisabeth Doty, who made the following chart to demonstrate this.
Canada does not actually count the emissions from many of the really large and severe fires as part of its formal emissions total (although it transparently reports them). The country has argued that many of these super intense blazes, which can take out entire stands of forest, are beyond its control.
The approach has engendered some controversy. I contributed to a big story about this here in 2022. And here is a U.N. expert panel critiquing Canada’s reporting methods on this front. The panel noted that Canada’s “assumption that human activity has neither a positive nor a negative net impact on the wildfire regime across the country is not supported by long-term data and scientific understanding.”
I reached out to Environment and Climate Change Canada for a response on these criticisms.
Canada’s approach “enables the impacts from human activities on [greenhouse gas] emissions and removals from forests and harvested wood products to be assessed and reported,” said Samuel Lafontaine, a spokesperson for the agency, by email. “Otherwise, the impact of human activities could be masked by the impacts from natural disturbances, largely wildfires, which can be relatively high and vary substantially from year to year, based on variations in the area impacted by wildfire burn.”
Lafontaine said Canada’s approach is consistent with Intergovernmental Panel on Climate Change (IPCC) reporting guidelines, and that recommendations from the review process cited above “address highly technical issues in how the IPCC methodology is implemented, and work is on-going to address these recommendations.”
You can understand the difficult position Canada is in, where it is trying to reduce its emissions, but wildfires can come along and if you count them, the emissions could suddenly double or more! That’s a terrible predicament. Still, with the fire behavior we’re seeing lately, it really does raise the issue — and not just in Canada — of whether the warming Earth, through wildfires, forest dieback, permafrost releases, and more, will claw back any emissions progress that we make.
Also in the realm of not overly faulting Canada: The country tells us clearly which emissions it is including in the accounting, and which ones it is not. In contrast, the U.S. has not formally reported its 2023 greenhouse emissions yet, though the Environmental Defense Fund, through FOIA, has received the report that was drafted prior to the Trump administration’s arrival. The Trump administration has withdrawn from the Paris climate agreement, but the emissions reporting process predates that agreement, and began under the older U.N. Framework Convention, which was ratified by the U.S. Senate. But perhaps the administration will try to withdraw from that too. This is a broader topic, and one I hope to go into more. But whatever you say of its practices, Canada is giving us the data.