Glaciers from a research expedition. Credit: Carnegie Mellon College of Engineering
Key Points:
- A new study featuring an unprecedented amount of data says 80 percent of glaciers could be lost by 2100.
- Even in a best-case scenario with low emissions scenarios, over 50 percent will be lost.
- A complete halt to emissions would still take between 30 and 100 years to be reflected in glacier mass loss rates.
Carnegie Mellon’s David Rounce recently led an international effort to produce new projections of glacier mass loss through the century under different emissions scenarios. His work showed that the world could lose as much as 41 percent of its total glacier mass this century—or as little as 26 percent—depending on today’s climate change mitigation efforts.
Findings by the team indicate that continued investment in fossil fuels will result in over 40 percent of the glacial mass disappearing within this century, and over 80 percent by number could disappear.
Even in a low-emissions scenarios, where the global mean temperature is limited to the goal +1.5°C relative to pre-industrial levels, more than 25 percent of glacial mass will be gone and 50 percent will disappear. Rounce did indicated that the majority of the lost glaciers are small by standards, but their loss would still have negative effects.
“Cutting emissions today will not remove previously emitted greenhouse gasses, nor can it instantly halt the inertia they contribute to climate change, meaning even a complete halt to emissions would still take between 30 and 100 years to be reflected in glacier mass loss rates,” said Rounce.
Many processes govern how glaciers lose mass and Rounce’s study advances how models account for different types of glaciers, including tidewater and debris-covered glaciers. Prior work by the environment engineering professor has shown that the thickness and distribution of debris cover can have a positive or negative effect on glacial melt rates across an entire region, depending on the debris thickness.
In this latest work, Rounce found that accounting for these processes had relatively little impact on the global glacier projections, but substantial differences in mass loss were found when analyzing individual glaciers.
The new model is also calibrated with an unprecedented amount of data, including individual mass change observations for every glacier, which provide a more complete and detailed picture of glacier mass change.