Have you ever seen dark cavities on glaciers, which are also referred to as “cryoconites”? These holes, which can be meters deep,are created from debris on top of glaciers. Dark-colored debris, including soot, dust, and pollen, speed up the melting process of glacial ice as a consequence of their low reflectivity to incoming sunlight. In some cases, glacial surface debris can also form pits in the ice through chemical melting. Hence, most of the glacial thaw holes are filled with melt-water, which become home to cyanobacteria, fungi, and other microbes. However, some large solid debris, in particular boulders, will prevent the ice beneath from melting as surrounding ice, forming glacier tables. Here are some photographs of cryoconites and glacier tables.
“One week-old snow was turning black and brown before my eyes,” American geologist Ulyana Horodyskyj told the Guardian in earlier this year as she stood at her mini weather station, 5,800 meters above sea level on Mount Himlung, on the Nepal-Tibet border. Horodyskyj studies glaciers in Nepal’s Himalaya mountain range and is one of the many scientists, bloggers, and photographers who are documenting the pernicious effects of a phenomenon called “dark snow.”
This so-called dark snow is being discovered everywhere from the Himalayas to Greenland. Snow can be darkened by naturally made particles, such as soot from wildfires and volcanos or dust from bare soil. But industrial pollution is also a culprit: ultra-fine particles of “black carbon” from industrial plants and diesel engines are often carried in on fierce winds from thousands of miles away. The dust, soot and carbon darken the color of the snow, causing it to absorb more light from the sun, which speeds up glacial melting and lengthens the melt season.
“Governments must act, and people must become more aware of what is happening. It needs to be looked at properly,” said Horodyskyj.
In India, about 30 percent of glacial melt is attributed to black carbon, according to the International Centre for Integrated Mountain Development (ICIMOD). In addition, most of the black snow in the Himalayas or the Tibetan Plateau comes from Indian and Chinese soot (e.g. diesel fumes, coal burning, funeral pyres, and etc.). It’s even a problem in the Arctic, according to a paper recently published in Nature Geoscience by a team of meteorologists from the French government. They found that the Arctic ice cap, which is thought to have lost an average of 12.9 billion tonnes of ice a year between 1992 and 2010 due to general warming, may be losing an additional 27 billion tonnes a year due to dust.
This isn’t the first time in the earth’s long history that dust was blamed for glacial melt. Last year, a NASA-led team of scientists published a study in the Proceedings of Natural Academy of Science that found industrial soot led to the retreat of glaciers in the 19th century. The European Alps experienced the abrupt retreat of valley glaciers by about 0.6 miles from 1860 to 1930, during which time the temperature actually dropped continuously. Scientists suspected that the glacier retreats were caused by human activity. After years of research, it turns out that the lower-elevation pollution is a major cause of the mysterious loss of glacier mass.
To better understand and document the dark snow problem, Danish glaciologist Jason Box started the Dark Snow Project around 2 years ago, which measures the impact of changing wildfire soot, industrial black carbons, and snow microbes on snow and ice reflectivity. The Dark Snow Project is currently trying to raise $15,000 for the purchase of three drones to photograph the surface of glaciers in Greenland from a low altitude to examine surface melting.
California droughts and glacier melts lead to massive Mt. Shasta mudslide
“Experts believe glacial melting, accelerated by the drought, may have released “pockets of water” that destabilized massive ice blocks and causing the debris flow Saturday afternoon in Shasta-Trinity National Forest, officials said.”
“When Kaser’s team looked at ice cores previously drilled at two sites high in the western Alps – the Colle Gnifetti glacier saddle 4,455 m up on Monte Rosa near the Swiss–Italian border, and the Fiescherhorn glacier at 3,900 m in the Bernese Alps – they found that in around 1860 layers of glacial ice started to contain large amounts of soot.”
“Every year, billions of tons of rock and soil vanish from Earth’s surface, scoured from mountains and plains and swept away by wind, rain, and other elements. The chief driver of this dramatic resurfacing is climate, according to a new study. And when the global temperature falls, erosion kicks into overdrive.”