The authors said it was difficult to get accurate measurements of glacier melt or glacier mass loss. Glaciers are generally located in incredibly remote or inaccessible locations, which means that only a few hundred of the 200,000+ glaciers are routinely monitored.
However, using NASA space data sets, they were able to show that glaciers lost nearly 5,073 gigatonnes of mass from 2000 to 2019 – or 11,180,000,000,000,000 lbs. Equivalent to about 553,465,346 Eiffel Tower.
The authors write that from 2000 to 2019, glacier melt accelerated from 0.36 meters per year to 0.69 meters per year.
In contrast, the authors believe that melting glaciers have contributed to an estimated 21% rise in sea level – nearly a quarter of an inch – since 2000.
They found that the fastest increase in glacier melt was in Alaska, western Canada and the United States. In New Zealand, glaciers are said to have melted nearly seven times as fast between 2015 and 2019 compared to the turn of the century.
According to scientists, the retreat of global glaciers is one of the most direct consequences of global warming and one of the main indicators of climate change. Although the authors did not investigate why the glaciers melt, they found that areas where glaciers have shrunk experienced prolonged precipitation and temperature changes consistent with climate change.
When calculating the rates of melting of glaciers, the 11 authors write that they hope this contributes to more accurate forecasts of sea level rise and water management.