Will reflective tarps save glaciers?

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It has now been proven that covering certain portions of glaciers with reflective sheeting helps contain summer melt and thus reduce the deleterious effects of climate change. If the use is currently limited to the local scale, some argue that this process could ultimately offer protection to glaciers around the world …

Over the past ten years or so, the resources deployed to preserve mountain glaciers have multiplied rapidly. Also, in the Swiss Alps, a growing number of winter sports resorts are using reflective covers to slow down the melting of the ice. These geotextile tarpaulins are placed on small portions of the glacial surface in the hot season. They thus make it possible to preserve as much as possible a landscape dear to the ski slopes as to so many other tourist areas.

A technique “neither feasible nor affordable” on a large scale

Since the method is proving effective at the local level, some have proposed to use it on a much larger scale. The idea? Cover the glaciers, no longer on a few segments, but in their entirety and on a global scale. By thus increasing theAlbedo from the surface, the retreat of mountain ice would be very noticeably slowed down. But, while it may seem promising in some ways, is the project viable? This was recently assessed by a team of researchers from the University of Friborg (Switzerland). The findings are set out in a study published this month in the journal Science and technology of cold regions.

Using data from 9 Swiss sites using geotextile layers, the authors showed that the latter were able to reduce summer melt by more than half. However, the prospect of widespread use would inevitably fail. Indeed, the financial cost associated with the sole covering of Swiss glaciers is valued at $ 4.5 billion per year. If we consider the global scale, the amount rises to the astronomical figure of 1000 billion dollars a year. Therefore and even if they remain approximate, these values ​​concretize a real wall to any practical application.

Graphic representation of the cost (vertical axis, in millions of Swiss francs) linked to the safeguard of Swiss glaciers. The red, purple and blue curves correspond to the covering of the 10, 100 and 1000 largest glaciers in the country. The volume of ice saved (horizontal axis, in%) is calculated according to the volume of ice for the recent past (solid lines) and the near future (dotted lines). Credits: Matthias Huss et al. 2021.

Covering glaciers, a question of size

“You can put a blanket in one place in a glacier, say a few hundred square meters, and you can very effectively protect the ice locally. It absolutely works, but it costs a lot of money ”, notes Matthias Huss, lead author of the study. “If you get the corresponding economic income from the glacier, then it works. Saving an entire glacier is a completely different story. You would need to cover all the ice on a much larger scale, with no clear income benefit ”.

In addition, the global deployment of geotextiles would have environmental consequences that are certain but which remain difficult to anticipate. In any case, if it can temporarily and locally be useful, the use of tarpaulins does not replace the reduction of greenhouse gas emissions. In particular, that of CO2 related to the combustion of coal, oil and natural gas. Finally, reducing our dependence on these fossil fuels is the only effective way to act on the heart of the problem and limit future global warming.

“We therefore advocate a clear separation between local scale reduction of glacial melt, which is reasonable and cost-effective, and large-scale theoretical applications. We believe that such a distinction is particularly important for communication with the general public, as false hopes and counterproductive perceptions could arise in the current and urgent debate on climate change ”, concludes the study.

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