Using knowledge on glacier velocity, South America’s tropical Andes mountains had been discovered to have as much as 23% much less ice and freshwater availability. Darker colours overlayed right here on Peru’s Cordillera Blanca vary, signify sooner glacial velocity. Credit: IGE-CNRS ©Mapbox ©OpenStreetMap ©Maxar
Findings on glacier velocity and depth revise outlook for freshwater availability and sea stage rise.
The first atlas to measure the motion and thickness of the world’s glaciers provides a clearer, however combined image of the globe’s ice-bound freshwater assets, in response to researchers from the Institute of Environmental Geosciences (IGE) and Dartmouth College.
The worldwide survey, revealed in Nature Geoscience, measures the velocity and depth of more than 250,000 mountain glaciers. The research revises earlier estimates of glacial ice volume, now suggesting that there is 20% less ice available for sea level rise in the world’s glaciers than previously thought.
The results have implications on the availability of water for drinking, power generation, agriculture, and other uses worldwide. The findings also change projections for climate-driven sea level rise expected to affect populations around the globe.
Included in the research was the first mapping of the entire Patagonia icefields. The massive Upsala Glacier, shown here, was found to be moving at a speed of about 1 mile per year. Deep red and violet colors indicating faster moving glaciers. Credit: IGE-CNRS ©Mapbox ©OpenStreetMap ©Maxar
“Finding how much ice is stored in glaciers is a key step to anticipate the effects of climate change on society,” said Romain Millan, a postdoctoral scholar at IGE and lead author of the study. “With this information, we will be closer to knowing the size of the biggest glacial water reservoirs and also to consider how to respond to a world with less glaciers.”
“The finding of less ice is important and will have implications for millions of people around the world,” said Mathieu Morlighem, the Evans Family Professor of Earth Sciences at Dartmouth and co-author of the study. “Even with this research, however, we still don’t have a perfect picture of how much water is really locked away in these glaciers”
The new atlas covers 98% of the world’s glaciers. According to the study, many of these glaciers are shallower than estimated in prior research. Double counting of glaciers along the peripheries of Greenland and Antarctica also clouded previous data sets.
Fly by way of animation of glaciers within the Karakoram Range of the Himalayas. Research utilizing a wide range of sensor knowledge on glaciers was used to find out measurement and velocity of glaciers. Here, the velocity is represented with darkish colours indicating faster-moving glaciers. Credit: IGE-CNRS, Dartmouth College, ©Google Earth
The research discovered much less ice in some areas and extra ice in others, with the general consequence that there’s much less glacial ice worldwide than beforehand thought.
The analysis discovered that there’s practically 1 / 4 much less glacial ice in South America’s tropical Andes mountains. The discovering means that there’s as much as 23% much less freshwater saved in an space from which hundreds of thousands of individuals rely throughout their on a regular basis lives. The discount of this quantity of freshwater is the equal of the whole drying of Mono Lake, California’s third largest lake.
Romain Millan, postdoctoral scholar at IGE and lead writer of the research. Credit: IGE
On the opposite, Asia’s Himalayan mountains had been discovered to have over one-third extra ice than earlier estimates. The consequence means that about 37% extra water assets could possibly be obtainable within the area, though the continent’s glaciers are melting shortly.
“The overall trend of warming and mass loss remains unchanged. This study provides the necessary picture for models to offer more reliable projections of how much time these glaciers have left,” mentioned Morlighem.
The melting of glaciers resulting from local weather change is among the primary causes of rising sea ranges. It is presently estimated that glaciers contribute 25-30% to general sea stage rise, threatening about 10% of the world’s inhabitants residing decrease than 30 toes above sea stage.
The discount by 20% of glacial ice obtainable for sea stage rise lessens the potential for glacial contribution to sea stage by three inches, revising it downward from 13 inches to only over 10 inches. This projection consists of contributions from all of the world’s glaciers besides the 2 massive ice sheets of Greenland and Antarctica, which have a a lot bigger potential contribution to sea stage rise.
“Comparing global differences with previous estimates is just one side of the picture,” mentioned Millan. “If you start looking locally, then the changes are even larger. To correctly project the future evolution of glaciers, capturing fine details is much more important than just the total volume.”
According to the research, depth measurements beforehand existed for less than about 1% of the world’s glaciers, with most of these glaciers solely being partially studied.
The glacial ice estimates that did exist previous to the brand new research had been virtually completely unsure, in response to the analysis staff. The uncertainty is due, partially, to the dearth of ice circulation measurements displaying the situation of thick and skinny ice, all of which is gathered by way of oblique strategies.
Mathieu Morlighem, the Evans Family Professor of Earth Sciences at Dartmouth and co-author of the research. Credit: Eli Burakian/Dartmouth
To create the huge ice circulation database, the analysis staff studied greater than 800,000 pairs of satellite tv for pc photos of glaciers, together with massive ice caps, slender alpine glaciers, sluggish valley glaciers and quick tidewater glaciers. The high-resolution photos had been acquired between 2017-18 by NASA’s Landsat-8 and the European Space Agency’s Sentinel-1 and Sentinel-2 satellites. The data was processed using more than 1 million hours of computation at IGE.
“We generally think about glaciers as solid ice that may melt in the summer, but ice actually flows like thick syrup under its own weight,” said Morlighem. “The ice flows from high altitude to lower elevations where it eventually turns to water. Using satellite imagery, we are able to track the motion of these glaciers from space at the global scale and, from there, deduce the amount of ice all around the world.”
The resulting first global map of flow velocities covers most of the world’s terrestrial glaciers, including regions where no previous mapping existed, such as the southern cordilleras of South America, sub-Antarctic islands, and New Zealand.
Although the new atlas marks a major improvement in glacier ice and water potential estimates, the thickness distribution of the world’s glaciers is still subject to large gaps of information.
“Our estimations are closer, but still uncertain, particularly in regions where many people rely on glaciers,” said Millan. “Collecting and sharing measurements is complicated, because glaciers are spread throughout so many countries with different research priorities.”
According to the team, without direct field measurements, the estimate of glacier freshwater resources will remain uncertain.
The study calls for a re-evaluation of the evolution of the world’s glaciers in numerical models as well as direct observations of ice thicknesses in the tropical Andes and the Himalayas, which are major water towers but that remain poorly documented.
Reference: “Ice velocity and thickness of the world’s glaciers” by Romain Millan, Jérémie Mouginot, Antoine Rabatel and Mathieu Morlighem, 7 February 2022, Nature Geoscience.
DOI: 10.1038/s41561-021-00885-z
Jérémie Mouginot and Antoine Rabatel, of the Institute of Environmental Geosciences (IGE) – Grenoble Alpes University, the French National Center for Scientific Research (CNRS), the French National Research Institute for Sustainable Development (IRD) and Grenoble INP Graduate Schools of Engineering and Management, made significant contributions to the study. Millan and Morlighem conducted part of the research at the University of California Irvine. Millan is also affiliated with CNRS and the Department of Geosciences and Natural Resources Management of the University of Copenhagen. Research was supported by France’s National Center for Space Studies (CNES).
