Mountaintop glacier ice disappearing in tropics around the world

From 1976, when Ohio State teams first collected ice samples from the glacier in Peru, the ice fields at Quelccaya have shrunk by 46 percent. Credit: Byrd Polar and Climate Research CenterA new study shows that mountaintop glacier ice in all four hemispheres has significantly reduced area-in one case, as much as 93%-than it did 50 years ago.A study published in the journal Global and Planetary Change recently found that a glacier in Papua New Guinea near Puncak Jaya lost 93% of its ice in a 38-year span from 1980 to 2018. The area that was covered by the glaciers at Kilimanjaro in Africa declined by almost 71% between 1986 and 2017.This study is the first to combine satellite imagery from NASA with data from ice cores collected during field expeditions on tropical glaciers all over the globe. This combination shows that climate change has caused these glaciers to disappear, which had been water sources for local communities for many years. It also indicates that the glaciers have lost more ice in recent years.These two datasets enabled the researchers to determine how much ice was lost by tropic glaciers. These glaciers are "the canaries of the coal mines," Lonnie Thompson, a distinguished university professor and senior researcher at Ohio State's Byrd Polar and Climate Research Center, said the study's lead author.Thompson stated that these glaciers are located in remote areas of the planet. They're not near big cities so there's no local pollution effect. "These glaciers, which are early warning systems for our planet, are sentinels. They are all saying the exact same thing.The study compared changes to the area of glaciers in four areas: Kilimanjaro, Tanzania; the Andes, Peru and Bolivia; the Tibetan Plateau, Central and South Asia; and ice fields from Papua New Guinea and Indonesia. Thompson led expeditions to all of these glaciers, and retrieved ice cores from each. These cores, which are long columns made of ice, act as a timeline for the climates in these regions over many centuries and millennia. Each year snow falls onto a glacier and is compressed into ice layers. These layers trap and preserve the chemistry and any other biological material, such as pollen and pollutants. Scientists can examine these layers to determine what was in the atmosphere at the time of the formation of ice.One image of Huascarn's top in 2019, the world's highest tropical mountain, was taken in 2019. It shows the ice retreating downslope, exposing the rock below. Researchers at the University of Colorado found that the area of glacier ice that topped that mountain had decreased by almost 19% between 1970 and 2003. The surface area of the Quelccaya Ice Cap in 2020, which is the second-largest glaciated area within the tropics after the summit's first ice core was drilled by Thompson in 1976, has decreased 46%.NASA launched its first Landsat mission around the time Thompson was on his first expedition. Landsat, a group of satellites that take photographs of the Earth's surface, has been in operation since 1972. It provides the longest continuous space-based record on Earth's land and ice, as well as water.Satellite images show how the ice caps on Mount Kilimanjaro in Tanzania have receded from 1975 to 2019. Credit: NASA Goddard Space Flight CenterThompson stated that "We are in a unique position where we can have ice core records of these mountaintops, Landsat has detailed images of glaciers, and we can combine these two data sets to see clearly what's happening."Glaciers in the Tropics are more responsive to climate change than others. They live in the most warm areas of the planet, and can only survive at high altitudes where it is colder. The precipitation that fell in the tropics was snow before the Earth's atmosphere warmed. Most of the precipitation now falls as rain, which causes existing ice to melt faster.Christopher Shuman, co-author and an associate research professor at University of Maryland-Baltimore County, said that the ice is no longer being sustained at higher elevations. He also serves as associate research scientist at NASA Goddard Space Flight Center. It's the interplay between warm air at lower elevations melting away the ice field margins, while those at the highest elevations get enough snowfall to maintain the ice caps to their former dimensions.People who live near these glaciers could be affected by this.This study focuses on the story of one community located near the Quelccaya Ice Cap and the consequences of an ice-water flood that resulted from massive amounts of ice falling into a nearby glacial Lake. One family of farmers had spent many years cultivating fields. The flood devastated the family so much that they moved four hours away to begin a new life in the city.The Papua New Guinea ice is culturally significant to many indigenous people living near it. They consider it the head of their god. Thompson predicts that the ice field will disappear completely within two to three years.Thompson stated that it is too late for the glaciers but it is possible to reduce the amount of greenhouse gases and carbon dioxide emitted into our atmosphere. This is causing the planet's temperature to rise.He stated, "Science doesn't change our trajectory. It doesn't matter how clear the science is. We need to do something to change that trajectory."Continue exploring The last remaining glaciers of the Pacific are about to meltMore information: Lonnie Thompson et. al., The effects of warming on rapidly receding high-altitude and low-latitude glaciers, Global and Planetary Climate (2021). Lonnie G. Thomson et al., The effects of warming on rapidly receding high-altitude and low-latitude glaciers, (2021). DOI: 10.1016/j.gloplacha.2021.103538