Polski
For decades, mountaineers and researchers have used every tool available, from wooden stakes to radar, to determine the exact depth of the snow cover on Earth’s highest peak. In May 2022. Wei Yang and his colleagues at the Tibetan Plateau Research Institute in Beijing used a system that sends radar pulses deep into the ground and measures the energy reflected from rocks below the surface. Their published results show that the snow cover at the tip of Mount Everest is nearly 9.5 meters thick – nearly three times as thick as the 2005 estimate disputed by many experts. Since there is more snow than expected, aren’t the alarming reports about the disappearance of glaciers exaggerated?
The authors of the 2022 study. say that regular data will be needed to track seasonal and annual changes and to assess the effects of global warming [1]. However, there is no need to wait for the results of their research, because we already know from other sources that the Earth’s snow cover – in the form of not only snow, but also ice sheets, glaciers and ice floes – has been decreasing in volume for several decades. And this is very bad information for us.
Vanishing landscapes
More than 18,000. – so many glaciers of “outstanding universal value” to humanity have been identified in 50 areas listed as cultural and natural heritage sites (UNESCO) [2]. Their area is estimated at approx. 66 thousand. km², accounting for nearly 10 percent. Earth’s glaciated area. Unfortunately, as studies based on satellite data indicate, the “UNESCO glaciers” have been retreating at an accelerating rate for more than two decades, and each year we are losing resources equal to the combined water consumption of France and Spain.
This disturbing trend is also confirmed by the observations of experts at the World Meteorological Organization. The State of the Global Climate 2022 report, published in April this year [3], reported that the thickness of reference glaciers decreased by an average of more than 1.3 meters between 2021 and 2022 alone. This is more than the average for the last decade. As of 2015. we had six of the ten years with the most negative glacier mass balance in history (1950-2022), and the cumulative volume loss since 1970. is almost 30 m. Snow cover is disappearing in many parts of the world.
Glacier melt records have been recorded in the European Alps. These were caused by adverse weather conditions – minor snowfall and a heat wave between May and early September – as well as the incursion of Saharan dust into Europe in March 2022. (I will return to this topic later). On July 25, 2022, a Swiss weather balloon recorded a temperature of 0°C at an altitude of 5183 meters – a record in nearly 70 years of observation and only the second time in history that 0°C was recorded above 5 km.
Many research centers around the world are developing models of glacier evolution due to the importance of glaciers in climate research. Unfortunately, no matter which results we reach for, the conclusions for future generations are pessimistic. Under all greenhouse gas emission scenarios, glaciers and snow cover in general will continue to melt, which will remain an important driver of sea level rise in the 21st century.
Glaciers and ice caps, with the exception of the large polar ice caps, are expected to lose about 30 percent this century. of its mass in the low gas emission scenario (corresponding to 1.5°C warming) and about 60 percent of its mass in the low gas emission scenario. in the “business as usual” high emissions scenario (4°C temperature increase). As for the UNESCO-listed glaciers, the smaller ones, with an area of less than 10 km², could almost completely disappear by 2050!
In less than 30 years, the last glaciers in Africa (on Kilimanjaro, Mount Kenya and Rwenzori-Virunga) and in other iconic places in Europe and North America, such as the Dolomites (Italy), the Pyrenees – Mont Perdu (France, Spain), Yellowstone and Yosemite National Parks (United States of America), will simply cease to exist. If we continue to emit as much greenhouse gases as we do now, by the end of the 21st century. We will also lose some of the large glaciers (up to 100 km²) with a mass of 8,000 Gt – an amount equal to the volume of water that would cover the entire surface of Brazil with a layer 1 m deep.
That cursed dust
McKenzie Skiles, a University of Utah hydrologist since 2009. Examines changes in snowpack thickness in Utah and Colorado. Initially, he was looking for an answer to the question of how the global increase in air temperature affects the rate of snow melt, but as he skied miles of mountain trails, something quite different caught his attention. As far as the eye could see, the lingering snow cover was covered with a layer of reddish dust. Fourteen years later, it has become clear that 2009 was an exceptional year, with the largest ever recorded dusting of snow by natural pollutants blown in from the deserts of Utah and Colorado and the exposed bed of the Great Salt Lake.
I have been to the mountains every year since then. From March to May, I change my ski boots to collect samples and measure the level of the dust layer. The results of our study, which we published in July 2023. in the journal Environmental Research Letter [4], are alarming. In areas with high deposition of dust from the bottom of the Great Salt Lake, such as the southern Rocky Mountains, snow melt accelerates by one or two months, Skiles explained.
The Great Salt Lake, which is one of the largest reservoirs in the United States and the fourth-largest outletless lake in the world, has been drying up dramatically for several years. The area of its water table is now 60 percent. smaller than the original, and the volume of water has shrunk by 73 percent. The results of the Skils team’s work suggest that even a small increase in the eroding surface area of the lake bottom results in record high dust concentrations.
Continued drying of the Great Salt Lake and more frequent heat waves and droughts will only exacerbate the erosion problem and increase dust levels in the future, contributing to a shorter season for snow cover, especially in high-altitude areas. Fewer days with snow and rapid melting will affect water management in the region and disrupt the development of local tourism based on winter sports. We are also currently exploring other mountain areas – including. Himalayas and Andes – to assess how the snowpack there is affected by soot deposition after forest fires. We hope that our results will allow the development of reliable models of snow melt. We are entering a future that is likely to be very dusty,” Skiles concludes.
The scientist’s concerns are confirmed by, among others. research conducted by a team of scientists from the University of Saskatchewan. Between 2015 and 2020, they conducted observations on the Athabasca Glacier, located in Canada’s Rocky Mountains. Results published in the journal Earth’s Future [5] confirm that during periods of increased fire activity, glacier melt was recorded at a much faster rate, as a direct consequence of dust and soot deposition. The report shows that the snow cover remained dark even after the fire season ended, and the reduced albedo of the snow cover increased the rate of ice melt by up to 10 percent.
The less “white,” the warmer
The definition of albedo is quite simple – it is the ratio of the amount of radiation reflected from a surface to that incident on it. The “0” value of this parameter corresponds to a black body that absorbs all the radiation (and gets very hot), while the “1” value corresponds to a white body that reflects the radiation completely (and its temperature does not increase). Due to the fact that the Earth’s surface varies in color and due to the presence of clouds in the atmosphere, our planet receives different amounts of radiation/heat. This means that cloud cover and snow cover of all kinds are (through varying albedo) an important element in the Earth’s greenhouse system.
In the past, the formation and melting of ice caps, resulting in the discovery of more and more dark areas, had a huge impact on changing climatic conditions and the natural warming and cooling cycles of the Earth’s atmosphere. This system has been disrupted by man by introducing excess heat in the form of greenhouse gases. As a result of rising air temperatures, snow and ice caps are melting, and the surface of the earth and oceans are taking in more heat. And the warmer it gets, the faster the glaciers, ice floes and snow disappear and the weaker the planet’s albedo becomes.
This is one of the best-documented feedback effects in the Earth’s climate system. And we amplify it further when dust from the bottom of a drying water body, soot carried by smoke from fires and anthropogenic aerosols travel thousands of kilometers to finally settle on the earth’s surface, obscuring the last “white” spots of our planet. And even if some time from now another study shows that there is not 9 m but 15 m of snow on the summit of Mont Everest, it will not make much difference. Just another statistic.
In the article, I used, among other things. From the works:
[1] https://doi.org/10.1038/d41586-023-02257-6
[2] https://unesdoc.unesco.org/ark:/48223/pf0000383551
[3] https://public.wmo.int/en/our-mandate/climate/wmo-statement-state-of-global-climate
[4] https://iopscience.iop.org/article/10.1088/1748-9326/acd409
