The world’s glaciers lose their ice faster and faster. This is shown by a study that the development of the glaciers outside the continental ice shields of Greenland and the Antarctic in the period between 2000 and 2023 worldwide. According to this, these ice currents have lost an average of 273 billion tons of ice per year during the examination period, and the trend is rising. As a result, the sea level has already increased by 18 millimeters. The freshwater supplies of the earth also shrink with the glaciers. The researchers found a particularly strong decline in small glaciers, especially in the Alps and in the Pyrenees.
The approximately 275,000 glaciers worldwide store huge amounts of fresh water. In 2000, these ice streams stretched out to over 705,221 square kilometers outside the large ice armor of Greenland and Antarctica and had a mass of an estimated 121,728 billion tons of ice cream. The drain, especially the large mountain glacier, feeds numerous rivers and plays a crucial role in the water supply in many regions of the world. If the glaciers gain as much ice cream in winter as in the warm months, there is a sustainable balance. But due to man -made climate change, the glaciers lose more and more ice.
Accelerated decline
An international research team around Michael Zemp from the University of Zurich has now created the most extensive overview of the mass losses of the glaciers worldwide. For this purpose, the researching field measurements combined directly on glaciers with radar, laser and gravime data from numerous satellite missions. “We have compiled 233 calculations of regional glacier mass changes from around 450 data sources from 35 research teams,” explains Zemp.
The results show that the decline of the glaciers has accelerated again since the turn of the millennium: the glaciers lost 273 billion tons of ice cream per year on average, with the losses in the second half of the examination period, i.e. 36 percent from 2012 to 2023 than between 2000 and 2011. Since 2019, more than 400 billion tons of ice have been lost every year and in the last year of observation, In 2023, the researchers recorded a record loss of 548 million tons of ice cream. This means that more ice is melted on the glaciers of the world than on the ice shields in Greenland and Antarctic.
Small glaciers particularly affected
Overall, the mass of glaciers worldwide has decreased by 6,542 billion tons in the observation period. “These ice losses contributed 18 millimeters to the increase in sea level,” reports the research team. The glacier melt thus has the second highest proportion of the increase in sea level according to the expansion of water due to increased temperatures.
How strongly the individual glaciers have melted varies regionally. While the polar glaciers of the Antarctic and Subantarctic Islands lost only 1.5 percent of their mass, the mountain glaciers in the Alps and the Pyrenees have shrunk the strongest with around 39 percent. “Due to their low altitude, these glaciers are particularly affected by the increased temperatures,” explains co-author Tobias Bolch from the Technical University of Graz. The comparatively low expansion of most mountain glaciers is also a disadvantage: “Glacier generally has a cooling effect on the microclimate of their surroundings,” says Bolch. “With small glaciers, however, this effect is only weak, which is why they melt faster than large glaciers.”
Shrinking fresh water tank
The glaciers of the Alps feed numerous large European rivers, including the Rhine, the Rhône and the buttocks. In recent decades, the amount of water has increased due to the reinforced glacier melt. However, the further the mountain glaciers shrink, the fewer fresh water reserves are available. “In the European Alps, we have already exceeded the drain tip, so our glaciers will provide less and less water from the rivers,” says Bolch. “This becomes a problem, especially in longer dry periods: then glacier inflows are particularly important as continuous water suppliers. This stabilizing effect is increasingly lost. ” In other regions of the world, the loss of the glaciers will also endanger water supply in the future.
“Our observations and the latest model studies indicate that the mass loss of the glaciers will continue and may accelerate by the end of this century,” says Zemp’s colleague Samuel Nussbaumer. “This underpins the request of the World Clime Council for urgent and concrete measures to reduce greenhouse gas emissions and the associated warming. This is the only way to limit the effects of the glacier loss on local georisics, the regional availability of fresh water and the global sea level rise. “
Source: Michael Zemp (University of Zurich, Switzerland) et al., Nature, DOI: 10.1038/S41586-024-08545-Z