Like archives, glaciers store microbiological and viral data that can help scientists to predict our future climate thanks to new knowledge about ancient ecosystems
Understanding what is a glacier
A glacier is a large and perennial mass made of dense crystalline ice and snow. It moves at a slow pace under its own weight. Both glacier typologies, the alpine glaciers, and the ice sheets, are located in areas where the snowfall has exceeded the ablation over time; allowing for more snow to accumulate each season than it melts.
«It forms where the accumulation of yearly persistent snow exceeds its ablation, or removal; over many years and eventually it accumulates and transforms into ice. Each year, new layers of snow bury and compress the previous layers. Over time, the snow compacts and increases in density. After about a year the snow compacts and transforms to an intermediate state called firn. After several years as the firn is buried deeper and deeper, the increasing overlying weight transforms it into ice». Explained Lonnie G. Thompson, distinguished University Professor in the School of Earth Sciences at The Ohio State University.
The process of firnification, where the snow mutates into hard and dense ice called firn, allows for the existence of glaciers. All over the world, glaciers are losing a significant portion of their mass. This is due to climate change and the rise in global temperatures.
Glaciers – the world’s freshwater reservoir
The world’ glaciers, including mountain glaciers, ice caps, and the ice sheets of Antarctica and Greenland. They cover ten percent of our planet’s total land surface. As glacier ice comprises over fifteen million square kilometers (five-point-eight million square miles) on Earth (National Snow and Ice Data Center).
The Earth stores 332.5 million mi3 of water (USGS), making up two-point-one percent of the total amount of water located on the globe. Two-point five percent of the planet’s freshwater is unavailable. With ice caps, glaciers, and permanent snow trapping 24,064,000 km3 of freshwater; over 68 percent of the total global freshwater supply. The thickest ice in the world, measures about 4,700 meters (15,400 ft). It is located in Antarctica in the Astrolabe Subglacial Basin, a basin south of the Adélie Coast.
The origin of glaciers
During the Pleistocene Epoch, the geological epoch spanning from around two-point-six million years ago and about 11,000 years ago (NOAA), the most recent glacial period, known as the Ice Age, occurred. During this time, around 1,000,000 years ago, the oldest glacier ice in Antarctica was formed (USGS). At the time, glaciers covered much of the world’s temperate zones, including large parts of North America and Europe. The ice sheets reached their most considerable extension about 18,000 years ago. While today about eighty percent of Greenland is covered in ice; 125,000 years ago during the last interglacial period, there were no glaciers in vast areas of the country.
From the early 14th century through the mid-19th century; the Northern Hemisphere experienced a modest cooling of less than a degree Celsius. This is relative to late twentieth century levels (Intergovernmental Panel on Climate Change Third Assessment Report, 2001). During this time, called the Little Ice Age (LIA), which took place after the Medieval Warm Period (c. 950 to c. 1250). Europe experienced harsher winter temperatures with the British and Dutch canals covering with ice layers thick enough to allow for winter festivals and ice skating; as depicted by several works of the Dutch painter Hendrick Avercamp (1585-1634). Since the end of the Little Ice Age, glaciers have retreated. Many glaciers disappeared during the 20th Century (Hughes, 2014).
The world’s glaciers are melting
Glaciers are indicators of climate change; as their glacial mass is affected by climate change-induced long-term climatic changes. Such as the variation in precipitation patterns and seasonal temperatures. The melting glaciers, which release a great amount of meltwater in the seas, are causing rising sea levels.
From January 1 through October 31, 2020, the total aerial extent of surface melting in Greenland reached 23.10 million square kilometers (8.92 million square miles). With around seventy percent of the ice sheet experiencing melting (National Snow and Ice Data Center). On July 27 2021, in the middle of Greenland’s melting season, which most times lasts from June to August; the nation’s ice caps lost 8.5bn tons of surface mass.
The melted ice released into the sea during that single day was enough to submerge the state of Florida under two inches of water. Later that week, Greenland experienced the record high temperature of nineteen-point-eight degrees Celsius. In August 2021, rain precipitation fell on the highest peak of Greenland’s ice cap. This reaches 3,216-metre (10,551ft) in elevation, for the first time on record. At said location (72.58°N 38.46°W), the air temperature stayed above the freezing point for about nine hours (National Snow and Ice Data Center).
The Scandinavian country’s sole remaining mountaintop glacier
On September 2, 2021, the researchers from the Tarfala research station, owned and managed by Stockholm University, measured the southern peak of the Kebnekaise massif in Sweden. The Scandinavian country’s sole remaining mountaintop glacier location was measured at 2,094.6 meters above sea level. One-point-two meters below the northern peak at 2096.8 meters, reaching its lowest since the measurements started. Due to the warmer climate, the southern peak, which is covered in ice, unlike the rocky northern peak, has decreased by 24 meters (78.74ft) over the past 50 years (Stockholm University).
«Glacier ice is considered one of nature’s best thermometers. Its retreat throughout the world provides evidence of the recent warming. Glaciers serve as both recorders and indicators of changes in our global climate system. As they integrate and respond to most key climatological variables. Such as temperature, precipitation, cloudiness, humidity, and radiation. Global glaciers’ retreat at the beginning of the 21st Century is driven for the most part by the increasing temperatures. Although regional factors such as deforestation, for example, may also play a role. Because ice and snow exist close to the melting point, they are among the first components of the Earth system to respond to climate changes, particularly those involving temperature».
The larger impact of glaciers loss
Thanks to a decontamination method that permitted them to extract clean inner ice; a team of scientists from Ohio State University, Lawrence Berkeley National Laboratory, and the University of Nebraska–Lincoln was able to find and study microbes and phages of about 15,000-years of age from the glacier ice found in the Guliya ice cap on the Qinghai-Tibetan Plateau. Functioning as natural archives, glaciers contain a wealth of microbiological and viral data. These can help scientists to predict future climate change by allowing them to acquire knowledge about ancient ecosystems.
«New areas of ice core research have developed over the past few years. One of them is the isolation and identification of ancient microorganisms such as bacteria and viruses. Recent research has found that glaciers from the polar regions to the tropics preserve microbial communities. That can range in age from hundreds to hundreds of thousands of years. The microbes found in ice cores represent those in the atmosphere at the time of their deposition. Hence may reflect climatic and environmental conditions during that time period».
«This new area of investigation offers the opportunity to study ancient microorganisms that survived and thrived during different climatic regimes. We know very little about viruses and microbes in these extreme environments. The documentation and understanding of microbes are important to answer questions such as how bacteria and viruses react to climate change. How they evolved through time, how they evolve as the world goes through ice ages and warm periods. What is the geographical distribution of viruses in these extreme environments». The paleoclimatologist says.
Glaciers as frozen archives
«The Microbiome study was conducted by an interdisciplinary group of researchers; including paleoclimatologists in the Byrd Polar and Climate Research Center and microbiologists in the Microbiology Department and the Center of Microbiome Science at The Ohio State University. In this study thirty-three viruses, twenty-eight of which had not been previously identified, were discovered in 15,000-year-old ice from the Guliya ice cap on the far western Tibetan Plateau».
«This type of research on such frozen archives has the potential to provide a better understanding of the microorganisms transported through the atmosphere today and in the past. As well as their effects on atmospheric processes and the environments where they are deposited such as pathogens affecting animal or plant health. They also provide the potential to study microbial evolution through time. In addition, microbial studies in ice cores on Earth may help us understand how life may have arisen on cold planets such as Mars». Clarifies Professor Thompson.
«As glaciers warm and melt all over the Earth everything stored in them is being released into the environment. Some reporting of the studies on microbes in glaciers has raised the specter of new pandemics. These may result from release of long dormant bacteria and viruses into populations that lack prior exposure and immunity to them. Over the decades our team has drilled ice cores in 16 countries though; in addition to Antarctica and Greenland. During the field activities we have drunk the melt water from these glaciers without ill effects. Moreover, people living in these areas have been drinking the glacier meltwater for thousands of years. So we think that it is highly unlikely that microbes released from the melting of the Earth’s glaciers will have an effect on the health of plants and animals, including humans».
Lonnie G. Thompson
One of the world’s authorities on paleoclimatology and glaciology, Lonnie G. Thompson has led sixty-four expeditions during the last forty-five years, conducting ice-core drilling programs in the Polar Regions.
