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World’s glacier retreat is accelerating dangerously, study finds

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Thanks to the analysis of twenty years of unexploited satellite archives, an international team of researchers has been able to assess the mass loss of mountain glaciers with unprecedented precision. The results were published in the scientific journal Nature on April 28.

The global and continuous observation of our planet by satellites allows unprecedented monitoring of changes affecting our environment, especially in times of global warming. These innumerable data, accumulated over the years, offer, among other things, a valuable view of the evolution of glaciers around the world.

Global and increasing alteration of glaciers

In a new study, researchers report that the melting of these continues to accelerate. In fact, some 220,000 mountain glaciers have lost nearly 300 billion tonnes of ice per year between 2015 and 2019. A rate of melting 71 billion higher than that of the period 2000-2004, able to cover France with one meter of water every year. Overall, over the period 2000-2019, the average loss is estimated at 267 billion tonnes per year, with an acceleration estimated at 48 billion tonnes per year each decade. In short, the mass loss is now 31% higher than it was just 15 years ago.

Details of mass changes region by region (bubbles). The overall loss is shown on the left. The horizontal bar reports the variation in glacier elevation. It is recalled that Greenland and Antarctica are not taken into account in the study. Credits: Hugonnet et al. & Al. 2021.

As the figures show, the retreat of mountain glaciers is a major contributor to sea level rise. The authors show thatit accounts for around 21% of the increase observed since 2000, and between 6% and 19% at its acceleration. However, the various regions of the world do not contribute equally to raising the level of the ocean. As the paper details, half of the losses come from North America. In addition, some glaciers were even able to remain stable. However, these are very specific cases, far from being representative of a world trend characterized by a very rapid decline.

Ever more precise quantification thanks to satellites

These results were obtained following the study of twenty years of images satellite so far unexploited. By cross-checking this dataset with independent measurements in order to validate its relevance, they were able to assess how the altitudes of glacial surfaces have changed, in the three dimensions of space. In other words, to precisely quantify the associated ice loss. Incidentally, mountain glaciers are currently losing more mass than Greenland or Antarctica taken in isolation. This, while they do not cover What 700,000 km² – an area close to that of Turkey.

Credits: Needpix.

We expect our estimates (…) will provide a better understanding of the factors that govern the distribution of glacial changes and expand our ability to predict them at all scales Says the paper in its summary. ” Forecasts rigorously compared to observations are essential to design adaptive policies for the management of water resources and cryospheric risks at local and regional scales, as well as for the mitigation of sea level rise. worldwide “.



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