A leading scientist in understanding glacier and climate change in western Canada collaborated with colleagues around the world to produce a clear picture of the health of Earth's glaciers.
The findings of this international team known as the Glacier Mass Balance Intercomparison Exercise (GlaMBIE) were published in Nature. Brian Menounos, a professor in UNBC's Department of Geography, Earth and Environmental Sciences was a part of the team.
Using a combination of different tools to measure glacier health, the team highlighted the role of climate change in the accelerating rate of glacier loss worldwide, as well as the implications for local geohazards, marine and terrestrial ecosystems, and sea-level rise. Geohazards range from tsunamis, landslides and flooding.
The research found that between 2000 and 2023, glaciers lost between two and 39 per cent of their ice regionally and about five per cent globally. Put another way, the total mass lost from Earth's glaciers over this 23-year period would cover all of Haida Gwaii by about 60 centimetres of water. Vancouver Island would be covered by about 20 centimetres.
Menounos noted that glacier loss in Canada is not uniform. Over the last 23 years, glaciers in western Canada lost 23 per cent of their total volume.
"Considering already committed mass loss owing to the delay in glacier response to climate change, we can expect glacier mass loss to continue in the coming decades, regardless of emission pathways," wrote the team in their paper.
Use for the research
Canada is home to nearly one-quarter of Earth鈥檚 glaciers. The importance of these findings is that this new data can be used to better project glacier loss in the coming decades, which will help inform climate policies.
"Observational data about where and how quickly glaciers are melting provides us with how much these important freshwater sources are changing,鈥� said Menounos. 鈥淭his data also helps us build better physical models used to project changes in glaciers in the decades ahead鈥�.
Policymakers make decisions based on both observed and projected changes, and this data will help in those efforts.
A limitation of the study is that detecting regional mass changes remains a challenge, which the team noted can be addressed through adding glacial observations at multiple local sites.
Methodology
鈥淕laMBIE is an example of collaboration among international scientists, all of whom use different tools to measure glacier health,鈥� said Menounos.
Four distinct observation methods were used: glaciological observations, DEM differencing, altimetry and gravimetry.
Glaciological observations involve studying and measuring glaciers through their mass balance, surface changes, and other related processes.
DEMs are digital representations of a land surface's elevation, typically created using remote sensing techniques like LiDAR or satellite imagery. DEM differencing involves subtracting an older DEM from a newer one, revealing the volume difference between the two.
Altimetry is a technique for measuring height and its change from space- and airborne sensors.
Gravimetry is the method that most directly measures the mass loss of glaciers, by measuring gravitational change measured by satellites.
"No one tool or method is superior, but by combining them, we get the most consistent and reliable picture of how Earth鈥檚 glaciers are doing 鈥� and the news is not good," said Menounos.
Their results underpin the Intergovernmental Panel on Climate Change's call for urgent and concrete actions to reduce greenhouse gas emissions, as well as limit the impact of glacier melting, which will affect regional freshwater availability and global sea-level rise.
