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 domeOver the west, the snow melted and exposed the ice quickly. It was particularly bad timing, since it occurred on days when sunlight is at its peak.
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 summer was warm and sunny. 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.
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 ecologies that can be subject to heat or water stress, especially during 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 If glaciers have a positive mass balance, that is when more water is deposited in them than is withdrawn. A negative mass balance indicates that the glacier has lost more water.
Climate Change Sensitive Indices
Two things happened in 1965 that at first glance seem to be unrelated. The first was Frank Sinatra’s recording of the song. It Was a Very Good Year. The second was the beginning of the International Hydrologic DecadeThis was a period that sought to recognize hydrology, and standardize the way scientists study water resources.
Canada was one of many 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, scientistsThe alarm was raised about the dangers of excessive carbon dioxide in the atmosphere. Since then, carbon dioxide levelsThe surface air temperatures in Northern Hemisphere have now reached about 122 degrees, an increase of 120 percent. 1 C above the 1951-80 average.
The major reason for the increase in surface air temperatures since 1965 is the warming of these temperatures. the trend of mass loss from our monitored glaciers. If you look at it another way, when the global temperature is approximately 1 C higher than the 1951-80 average, the monitored glaciers experience an average loss of about 0.8 metres in water equivalent depth.
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 …
Glaciers are likely to experience mass loss from wildfires that is likely to accelerate.
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.
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 can also make snow grains less reflective, lowering snow reflectivity and enhancing melt.
How will Glaciers Do in the Next Decades?
Glacier mass balance is a direct result of meteorological conditions. However, glaciers need to adjust their dimensions over time. Even if temperatures were stable over the next several centuries, glaciers will continue to lose mass or 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 stop increasing 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. However, we should expect glacier shrinkage as glaciers remain out of balance with current-day climate.
These frozen reservoirs could have a devastating impact on our lives that we are only just beginning to understand. They will die if there is not enough progress at COP26.