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2021 was a bad year for glaciers in western North America — and it’s about to get much worse

2021 was a bad year for glaciers in western North America — and it’s about to get much worse

2021 is likely to be a terrible year for glaciers in the southern British Columbia, Alberta and Washington states.

It started out OK. A weak La Niña arrived in the fall of 2020 and continued through the winter. La Niñas tend to favour cool conditions and ample snowfall, so the winter of 2020-21 wasn’t bad for glaciers. But, what came next was.

The so-called “End of June” was the time when the “So-Called” heat domeThe west was covered by snow, which created extraordinary warming. This melting of the glaciers and exposed the ice occurred in just a few days. The timing of the event was unfortunate, as it coincided on days when solar energy is at its highest.

Hot weather also sparked wildfires in British Columbia and Oregon that spread throughout the mountains. When snow and ice become darker due to the accumulation of soot, dirt, and debris from wildfires, they absorb more solar energy and melt faster.

The warm summer temperatures continued all through the year. preliminary workThese summer events are believed to have caused extraordinary levels of mass loss by glaciers. As a glaciologist who has been studying glaciers for over two decades, it is clear that that glaciers are unwell — thanks to us. To avoid widespread loss of glaciers in the Earth’s mountainous regions, policy-makers need the courage to commit to meaningful reductions of greenhouse gas emissions.

A vital natural resource

Mountain glaciers provide vital water reservoirs. There are more than 15,000 individual ice masses in western North America — an area that lies outside of Alaska and the Alaska-British Columbia and the Alaska-Yukon borders.

An overhead view of a mountain glacier.

Helm Glacier is located in British Columbia’s Southern Coast Mountains.
(Hakai UNBC Airborne Coastal Observatory)

Glaciers are primarily fed by snowfall in winter, and then depleted by melting snow and ice in summer. This results in large quantities of snow. cool water into headwater streams. Glacier runoff buffers aquatic ecosystems from heat and water stress, especially during the summer. late summer or years of drought.

To measure the year-to-year health of a glacier, scientists convert winter accumulation and summer melt to a measurement called “water equivalent depth,” which can also be converted to “mass.” The sum of these two terms define the glacier’s health over the year, or its “net mass balance.”

Glaciers are like mother nature’s bank account. If the glacier has a positive mass balance for a year, it means that more water is deposited than taken out. A glacier with a negative mass balance means that it lost more water.

Climate change sensitive indicators

Two events occurred in 1965 that at first glance seemed unrelated. The first was Frank Sinatra’s recording of the song. It Was a Very Good Year. The second was when the began. International Hydrologic DecadeThe period was dedicated to hydrology recognition and standardization of the methods scientists use to study water resources.

Canada was one of the outcomes of the Hydrological Decade. glacier monitoring programto determine and report the amount of water lost or gained from its benchmark glaciers each year, including three in Western Canada: Peyto Place, Helm, and Place.

Back then, Canada’s glaciers were probably valued more as a water resource than as sensitive indicators of climate change, but make no mistake, even in 1965, scientistsThey raised alarm about the dangers posed by excess carbon dioxide in our atmosphere. Since then, carbon dioxide levelsThey have risen 120 percent, and the surface air temperatures of the Northern Hemisphere now hover around 1 C above the 1951-80 average.

Majorly, the reason for the rise in surface air temperatures from 1965 to today is because of this. the trend of mass loss from our monitored glaciers. A different way of looking at it is that each year when the global temperature rises about 1 C, the average depth of the monitored glaciers is about 0.8 m.

graphic showing mass loss with rising temperatures.
Global temperature anomaly (1951-1980) compared to global averaged net balance records. Data: World Glacier Monitoring Service.
(Brian Menounos)

Particularly, glacier mass loss over the past two decades in western North America has acceleratedThe losses suffered in the last decade were four times higher than those of the previous decade. This acceleration coincides with warm, dry conditions over some of the region’s largest icefields, namely those in the Southern Coast Mountains of British Columbia.

Back to Frank’s song. This song always made my heart sad. Is it because the character in this song was in the fall of his life, or its melancholy composition? It also reminds me of the current state western North American glaciers. I’ve taken the liberty to tweak the lyrics somewhat: When I was 51, it was a very bad year …


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Wildfires are likely to accelerate mass loss for glaciers

Despite the fact that glacier mass losses are increasing due to continued warming, they may also be driven by other factors like changes in how reflective ice and snow surfaces to incoming solar energy.

Glacier ice streaked with soot
Dust and soot from burning fossil fuels or wildfires can darken glaciers’ surfaces and absorb more solar energy. This leads to more melting.
(Drew Brayshaw/flickr? CC BY-SA

Debris, dust, carbon and black carbon can darken snow or ice surfaces due to fossil fuel use or wildfires. This allows them to absorb more sun energy, which in turn enhances melt. Warm, dry summers are often favorable to wildfire activity and can lead to pronounced darkening of snow and ice surfacesMore melt. Warm temperatures allow snow grains to become more reflective, which lowers snow reflectivity and enhances melt.

How will glaciers fare over the next decade?

Glacier mass balance is a direct result of meteorological conditions. However, glaciers need to adjust their dimensions over time. Even if temperatures were stable for several decades, glaciers will continue to lose mass and shrink because they haven’t had enough time to adjust to the current climate.

A modelling study in 2011For example, the study showed that Alberta glaciers would lose between 31-40% of their volume even though temperatures stopped rising immediately. A more recent studyEven with moderate future emission scenarios, it shows almost complete deglaciation in the mid- to south areas of British Columbia and Alberta.

Neither of these earlier projection studies take into account the most recent collection of global climate model experiments from the Intergovernmental Panel on Climate Change’s Sixth Assessment Report. These scenarios are currently being used by scientists to update projections of glacier loss for many areas, including western North America. This will help clarify the rate and pattern glacier loss over the next decade. We should expect continued glacier loss as glaciers are still out of balance with the current climate.

We are only beginning to understand the impact of losing these frozen reservoirs. They will die if there is not enough progress at COP26.


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