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Scientists in the Qilian mountains in China have warned that the region’s glaciers are melting at a ‘shocking’ rate, raising the possibility of crippling, long-term water shortages. 

The largest glacier in the 800-km mountain chain on the northeastern edge of the Tibetan plateau has retreated about 450 metres since the 1950s, according to monitoring stations. 

Why Does This Matter?

Qin Xiang, the director at the monitoring station, says that the glacier is also losing thickness, with about 13 metres of ice disappearing as temperatures have risen. 

Xiang says, “The speed that this glacier has been shrinking is really shocking.” 

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The Tibetan plateau is called the world’s Third Pole because of the amount of ice that is locked in it. However, since the 1950s, average temperatures in the region have risen about 1.5 degrees Celsius, with temperatures set to rise further in the coming years. Across the mountains, glacier retreat was 50% faster in 1990-2010 than it was from 1956 to 1990, according to data from the China Academy of Sciences. 

Xiang says that the flow of water in a stream near the boundaries of the Laohugou No. 12 runoff is about double what it was 60 years ago.

Further downstream, near Dunhuang, water flowing from the mountains has formed a lake in the desert for the first time in 300 years, according to state media.  

Climate Change Causing Dangerous Changes

Snowfall and rain has been at times erratic and far less than normal, so while melting glaciers have brought more water runoff, farmers downstream can still face water shortages for their crops and livestock. 

These new fluctuating conditions also bring danger, according to Greenpeace East Asia climate and energy campaigner Liu Junyan. 

Junyan says, “Across the region, glacial melt water is pooling into lakes and causing devastating floods. In spring, we’re seeing increased flooding, and then when water is needed most for irrigation later in the summer, we’re seeing shortages.”

The melting in the mountains could peak before 2030, after which snow melt would decrease sharply due to the smaller, fewer glaciers, according to China Academy of Sciences expert Shen Yongping. He warns that this could bring water crises to the region. 

Featured image by: Flickr

A new report has identified 47 Himalaya lakes that are at risk of breaching, which could cause floods in downstream areas in China, Nepal and India, threatening human lives, livestock and property in the countries.

The report, jointly produced by the International Centre of Integrated Mountain Development (ICIMOD) and the United Nations Development Programme in Nepal, found that overall, 3 624 glacial lakes were mapped in the Koshi, Gandaki and Karnali river basins of Nepal, China and India. Of these, 1 410 lakes are large enough to cause damage downstream if they burst, while 47 need “immediate mitigation action.” 25 of these are in the Tibet Autonomous Region of China, 21 are in Nepal and one is in India. 42 are within the Koshi basin while the Gandaki and Karnali basins have three and two such lakes respectively.

Between 2000 and 2015, the total area of glacial lakes in the Koshi basin increased by 12%, 8% in the Gandaki basin, and 1.27% in the Karnali basin.

Breaching glacial Himalaya lakes could result in glacial lake outburst floods (GLOFs), which occur when melting glaciers create reservoirs of water that can suddenly burst, leading to downstream flooding. They are massive threats in Nepal and other mountainous countries in the Hindu Kush Himalaya. A 2011 study by ICIMOD reported 26 GLOFs that have affected Nepal since 1977. Records show that, on average, Nepal loses 333 lives and property worth over USD$17.24 billion every year to extreme climate events. 

According to a recent study, glacial lakes have grown rapidly around the world in the last three decades, showing the impact of increased meltwater draining off melting glaciers. Between 1990 and 2018, the number of glacial lakes had grown by 53%, expanding the amount of the planet covered by the lakes by about 51%. If global temperatures rise above 1.5C by 2100, two-thirds of glacial ice in the Himalayas will be lost. 

The authors say that outburst floods can occur without any precedent, adding further concerns about the threats posed by glacial lakes in the region. 

Based on remote sensing and past studies, the 47 lakes were classified into three ranks of risk. The authors also considered whether there are communities or infrastructure downstream. Rank I lakes have a greater possibility of expanding and could experience snow and/or ice avalanches and landslides. A slight rise in water levels or a reduction in the strength of their dams could cause a breach. Those lakes under Ranks II and III have the potential to grow, and need to be monitored closely. 

31 lakes are classified as Rank II, 12 as Rank II and four as Rank III. 

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Experts Call for Transboundary Cooperation

Mitigation measures are already being planned at some high-risk glacier lakes, which will reduce the risks of flooding for countries downstream.

Wang Shijin, an associate researcher at the Chinese Academy of Sciences and one of the authors of the study, urges researchers in upstream and downstream countries to work together to address the problem.

ICIMOD has made efforts to encourage more cooperation, however geopolitical tensions in the region have impeded such efforts. The report also calls for more information exchange about mitigation efforts. Already, the water levels of Tsho Rolpa in Nepal was lowered by more than 3 metres in 2000, Imja Tsho, also in Nepal, by 3.4 metres in 2016 and two lakes in Tibet, but the details are unknown. 

However, some local cooperation has been seen. In July, local authorities along the Bhotekoshi river in Tibet warned authorities in Nepal’s Sindhupalchowk district of a possible outburst flood from Keyrung Tshyo glacial lake in Tibet, allowing the Nepali communities to be alerted. 

While there is still little research in high mountain areas, the agencies involved in the report hope that such data will help governments enhance transboundary cooperation to better mitigate and prepare for the effects of the climate crisis.

Featured image by: Flickr  

Scientists have issued new warnings over the Thwaites Glacier, an unusually large and vast ice sheet in Antarctica, that is melting swiftly and whose collapse could lead to rapid sea level rise. Already, ice draining from the glacier into the Amundsen Sea accounts for about 4% of global sea level rise, prompting concerns over the cascading effects the collapse of this glacier would have on the rest of the world.

Termed the ‘Doomsday Glacier’, Thwaites provides important insight into Earth’s future. It is now the focal point of a major research project led by British and American scientists which aims to understand how the glacier is changing, and what these changes mean for rising sea levels. Teams of scientists are drilling into the Thwaites Glacier to determine whether it is about to collapse.

An Inherently Unstable Glacier

Thwaites’ ice shelf destabilises the whole glacier, and research has shown that there is very little ice shelf left in the western part of the glacier. Instead, much of the ice that is there is a slushy mix of icebergs and other bits of floating ice. 

If the whole of the floating ice shelf breaks into icebergs, what will be left is a cliff of ice whose shape makes it especially vulnerable to runaway collapse. The seafloor underneath the glacier slopes downward as it goes inland- called a “retrograde slope”- and the ice sitting on top of it gets thicker. If the Thwaites glacier retreats far enough inland and reaches a certain thickness, it will start to collapse under its own weight. Once this starts, ice cliff modelling suggests, there may not be anything to stop it. 

Thwaites Glacier is losing ice faster and faster, and the process seems to be accelerating; over the past three decades, the amount of ice flowing out of Thwaites and its neighbouring glaciers has nearly doubled.  

The glacier is more than 191 000 sq km and is particularly susceptible to the climate crisis. Rob Larter, marine geophysicist and UK principal investigator for the Thwaites Glacier Project at the British Antarctic Survey, said “it is the most vulnerable place in Antarctica,” with large portions deteriorating and breaking off.

David Vaughan, director of science at the British Antarctic Survey, stressed that if the Thwaites glacier continues to deteriorate at its current rate, it could collapse and be responsible for tens of centimetres of sea level rise by the end of the century. “That doesn’t sound like much, but it is,” Vaughan noted, “it is not about the sea coming up the beach slowly over 100 years – it is about one morning you wake up, and an area that has never been flooded in history is flooded.”

As Thwaites melts, it could propagate a 65 centimetre rise in sea levels, however if Thwaites fully deteriorates, the cascading effect across the Western half of Antarctica would lead to a 2- to 3-meter rise in sea levels, which would be ‘catastrophic’ for most coastal cities. 

Paul Cutler, programme director for Antarctic glaciology at the National Science Foundation in the US, explains how Thwaites glacier “is a keystone for the other glaciers around it in West Antarctica … If you remove it, other ice will potentially start draining into the ocean too.” 

Current models estimate a 61- to 110-centimetre sea level rise by the end of the century, assuming the world continues to emit the same amount of carbon dioxide into the atmosphere. 

The Cascading Effects of Melting Ice

Antarctica holds around 90% of the ice on the planet- the ‘equivalent to a continent the size of Europe covered in a blanket of ice 2 kilometres thick’. As temperatures rise, the Earth does not heat up evenly everywhere: the polar regions warm much faster. Antarctica and Greenland are at the frontline of receiving much of global warming’s negative effects, more so than the rest of the world. Unfortunately, these high temperatures are being fuelled not just by a rise in greenhouse gases, but also by natural weather shifts in the tropics.

A recent study found that the South Pole, the most remote place on Earth, has warmed at three times the global rate since 1989, with temperatures rising 0.6 degrees per decade- a worrying figure that reveals the stark and rapid progression of global warming. 

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Warming Oceans 

Currently, the Antarctic continent contributes about 1 millimetre per year to sea level rise, which is a third of the annual global increase. 

There is a lot yet to understand about the physical properties of ice sheets and how they deteriorate with time- researching the Thwaites glacier is therefore pivotal. Anders Levermann, a professor at the Potsdam Institute for Climate Impact, says, “it is very difficult to say how fast sea level is rising, but it is not very difficult to say how much ice can survive on a planet that is 1C or 2C or 3C warmer, and how much the ocean will expand.” 

Despite reports demonstrating a decrease in carbon dioxide emissions amidst COVID-19 due to worldwide lockdowns, the long-term projection remains unsettling as carbon dioxide can remain in the atmosphere for long periods of time, and its levels are still increasing.

Additionally, the Earth’s core temperature is continuing to rise: last month was the hottest June on record, and in July a heatwave swept the Russian Arctic near Siberia resulting in temperatures of 38 degrees Celsius, which triggered the escalation of the Arctic wildfires.  

Many of the observable effects of the climate crisis are irreversible, and continuous research is needed to understand what the future of rising sea levels holds and what it would mean for Earth’s inhabitants. Reversing these effects entirely is out of the question, scientists protest, but stopping them in their tracks by slowing the rate of global warming would help prevent further damage.

Tackling the Problem 

The challenge lies in tackling the rapid rate of rising sea levels. If infrastructure planners prepare for a 60 or 70 centimeter rise in sea level, then an unprecedented rate of, say, twice as much, would diminish their efforts- making such plans ineffective in accommodating for a potential higher, unpredicted sea level rise. In light of this, research that aims to develop a greater understanding of Thwaites will help experts better plan and prepare for the future of Earth’s climate. 

With higher sea levels comes coastal flooding, damaged infrastructure, heightened storms during typhoons, and destruction to agricultural land due to salty seawater invasion. Coastal cities have already begun preparing for the worst. San Francisco is building defences around its airport, which sits three metres above sea level, and London is considering increasing the height of the Thames barrier. 

According to a study published in the journal Environmental Research Communications, the economic cost of such infrastructure aimed at accommodating rising seas will be as much as 4% of global GDP by the end of the century. 

Thomas Schinko, author of a study published in Nature Climate Change and a researcher at the International Institute for Applied Systems Analysis, says that if we don’t adapt we will experience ‘huge losses’, stressing that it would be more cost-effective to prepare for the worst than to deal with the aftermath of rising sea levels. 

Featured image by: NASA’s Marshall Space Flight Center

Earth.Org analysed satellite data to assess the concentration of methane emissions in the Greenland ice sheet (GiS) in July 2019. The GiS covers an area of roughly 1,7million square km; together with Antarctica’s ice sheet, it contains more than 99% of the world’s fresh water. Most of this water is frozen in masses of snow and ice and as greenhouse gases build, the oceans absorb 93% of the excess heat those gases trap. The warming air and water are causing ice sheets to melt at unprecedented rates. 

Besides sea-level rising, the melting of this ice sheet in Greenland has another side-effect- methane emissions, which has rapidly increased in the past decades and more than doubled from pre-industrial times.

Methane, or CH4, has a 20-year Global Warming Potential (GWP) of 84, which means that over a 20-year time period, it’s 84 times more powerful than CO2 at trapping heat in the atmosphere. Methane emissions are temperature-sensitive and could provide significant feedback mechanisms in a changing climate. 

Arctic Methane

The Arctic region is one of the most abundant natural sources of methane. It is estimated that the Arctic permafrost (carbon-rich soils that remain completely frozen for at least two years straight) stores 1 650 gigatonnes of organic carbon, twice the amount of greenhouse gases in the atmosphere. 

As the temperature rises above 0°C, microbes in the permafrost decompose frozen organic matter into methane, an anaerobic biotic process known as methanogenesis. Thawing of the permafrost produces both methane and CO2. A warming climate can induce environmental changes that accelerate this decomposition and release of greenhouse gases. This feedback can accelerate climate change, but the magnitude and timing of greenhouse gas emissions from these regions and their impact on climate change remain unclear. This makes it all the more concerning that ice sheets are currently ignored in global methane budgets and that there is no existing data on the current methane footprint of ice sheets. 

A study conducted by the University of Bristol found that much of the methane produced beneath the ice likely escapes the GiS in large, fast flowing rivers before it can be oxidised to CO2

A study estimated that 6.3 tonnes of methane was transported by meltwater underneath the ice in the summer of 2015. Every summer, the ice sheets melt in Greenland, peaking in June to August and although this is a natural process, global warming is accelerating the rate of melting. Subglacially produced methane is rapidly driven to the ice margin by the efficient drainage system of a subglacial catchment of the GiS. Another study reported a concentration of methane emissions 15 times the background atmospheric concentration in the air expelled with meltwater in West Greenland in 2016. The total amount of methane released with meltwater remains unestimated.

From 1992 to 2018, about half of the ice loss from Greenland was from melting driven by air surface temperatures, which have risen much faster in the Arctic than the global average (more than double), and the rest was from the speeding up of the flow of ice into the sea from glaciers, driven by the warming ocean. 

The Sentinel- 5P satellite captures methane hot spots where methane-saturated fluxes reach the ice margin. 

While many studies place their focus on the West GiS, the satellite images produced from Sentinel- 5P have revealed another bright hot spot on the north, near the North Pole. 

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Satellite Image of Methane Emissions in Greenland

The image above shows the concentration of methane in Greenland in July 2019 according to images taken by Earth.Org from the Sentinel- 5P satellite. The mean methane concentration over Greenland during the month was 1 809.6 ppb (parts per billion), with a local maximum of 1 968.2 ppb. 

The information for the images above is taken from research by the National Snow and Ice Data Center, which Earth.Org has tabulated. The top graph shows the mean daily melting area during melting seasons from 1981 to 2019, and the bottom graph shows the maximum daily melting area during melting seasons from 1981 to 2019. 

Researchers suggest that the microbes in the frozen soil contain methane-oxidising communities, essentially making the tundra a methane sink. The effect of methane digestion increases with temperature, so it is particularly potent in the growing seasons (July- September).

Studies suggest that a longer growing season results in ‘potentially high emissions’ by permafrost systems. This creates a cycle, called a ‘climate change feedback’, whereby global warming causes ice sheets to melt, which releases more methane, which in turn exacerbates global warming. 

Greenland Ice Melt

According to a study conducted in December, Greenland’s ice is melting seven times faster than it did in 1992. From July 30 to August 3, melting occurred across 90% of the continent’s surface, dumping 55 billion tonnes of water over 5 days. On August 1, the GiS lost 12.5 billion tonnes of ice, more than any day since researchers started recording ice loss in 1950. 

Melting seen at this rate was not expected for another 50 years; by the last week of July, melting had reached levels that scientists with the IPCC had projected for the year 2070 in the most pessimistic scenario. 

The region has lost more than 4.2 trillion tonnes of ice in the last 25 years, which has raised global sea levels over 1cm. The rate of ice loss has risen from 33 billion tonnes a year in the 1990s to 254 billion tonnes a year in the last decade. The IPCC has estimated that global sea levels could rise by 60cm by 2100, putting 360 million people at risk of annual coastal flooding. However, this new study shows that if the current melt rate continues, Greenland will raise sea levels nearly 7cm more than the IPCC’s prediction by 2100, putting an additional 40 million people at risk. 

One of the keys to reducing methane emissions in Greenland, and certainly the rest of the world, is cutting the use of fossil fuels. Additionally, there is too much uncertainty surrounding the impacts of these environments on the planet and they should be considered in the Earth’s methane budget so as to allow researchers and policy makers to collaborate to mitigate and manage the effects of these emissions. 

This is the second of two parts in an Earth.Org investigation of methane emissions in the polar regions. See December 20th’s article, ‘Methane Emissions in the Arctic Could Amplify Global Warming’. 

Featured image by: Christine Zenino

Glaciers and ice sheets currently cover around 10% of the Earth’s surface and are vital for shaping its physical landscape, reflecting intense solar radiation and supplying many people around the world with freshwater. Until recently, however, one characteristic of this environment has remained largely overlooked. What are algae blooms and how are they affecting the landscape?

Algae blooms living on the surface of the south-west coast of the Greenland Ice Sheet (GrIS) are causing darkening of the sheet, leading to increased rates of melting not currently being incorporated into melt rate models.

Glaciers and ice sheets are extremely dynamic ecosystems, capable of hosting abundant and diverse microbial life. Areas of the Earth in which water is found in a solid, frozen form are now termed the Cryosphere, which is considered one of the Earth’s five biospheres. Due to extreme and harsh conditions, particularly in the Arctic and Antarctic, microbial abundance, diversity and activity in these environments have been given little global prominence.  

Microbial life has now been documented in most areas of glaciers and ice sheets, including at the bedrock-ice interface, on the ice surface and inside the ice itself. Most initial research focused on microbial communities living at the bedrock-ice interface due to their influence on nutrient export to fjord and ocean environments. Surface ice environments, comprised of snow packs, bare ice, lakes and streams, have recently begun to take centre stage as microbial communities thriving in these habitats have drastically changed the physical appearance of glaciers and ice sheets worldwide. Areas of high microbial abundance and activity, known as cryoconite holes, have quickly become the primary focus of attention in surface ice environments. Cryoconite is a dark substance now found on most glacier and ice sheet surfaces worldwide, with areas of high abundance described as having the appearance of swiss cheese. 

It wasn’t until 2012 that scientists discovered a habitat other than cryoconite holes: the ice surface itself. A study of the GrIS found that the top two centimetres of the ice surface hosts abundant microbial life, dominated mainly by Streptophyta algae, now termed glacier algae.  

Prior to this finding, satellite imagery revealed a significant annual darkening occurring since 2000 on the surface of the GrIS, on an area about 20-30 km inland and 50 km wide, now known as the ‘Dark Zone’. Many scientists initially attributed this darkening to common light-absorbing particles such as atmospheric dust, black carbon from the burning of fossil fuels, dust melting out of ancient ice and even cryoconite. Cryoconite holes typically cover only 3-6% of the whole GrIS, whereas glacier algae appear to bloom wherever bare ice is present, therefore covering far greater areas.  In fact, a study reported an abundance of up to 85 thousand glacier algae cells per milliliter of melted surface ice collected in the Dark Zone.

Glacier algae have adopted many unique strategies for surviving in this extreme environment, yet one has elevated their global importance. Ice surfaces are subject to intense solar radiation, due to 24 hours of sunlight during the polar summer. As such, glacier algae have developed a dark pigmentation within their cells to help shield them from radiation. Because of this pigmentation and their high abundance in the Dark Zone, several studies have now concluded that pigmented algae have the greatest impact on ice surface darkening compared to any other nonalgal impurity, including black carbon or dust melting out of ancient ice. Yet, at present, algal influence on surface darkening, known as bioalbedo, is not being factored into melt rate models for the GrIS. 

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Pigmented glacier algae, as seen under a microscope. (Source: Yallop et. al, 2012/Nature.com)

The GrIS has experienced a significant increase in net mass loss in the past two decades, increasing from 34 gigatonnes of ice per year during 1992 – 2001 to 215 gigatonnes of ice per year during 2002 – 2011, with surface ice accounting for nearly 68% of that increase since 2009.  As temperatures continue to rise in the Arctic, seasonal snow packs, which form during the winter and melt away in the spring, will retreat earlier, leading to an extended season of bare ice exposure. This will result in more surface ice melt and nutrient and liquid water availability, perfect growing conditions for glacier algae blooms. Furthermore, the burning of fossil fuels releases nutrients necessary for cell growth, such as nitrogen, into the atmosphere, which are transported to surface ice environments that are otherwise nutrient-limited.  This extra abundance of nutrients allows for microbial communities to spend less energy on producing nutrients and more energy on growth.  

It can therefore be expected that these blooms seen on the GrIS, and on glaciers and ice sheets throughout the cryosphere, will continue to escalate leading to further darkening of the sheet and increased melt rates, resulting in increased sea-level rising. 

Featured image by: Christine Zenino

The climate report warns of increasing sea-level rise as the polar ice caps continue to melt and says that as a result, intense storms, coastal flooding, and loss of marine life due to global warming are already inevitable. But the world still has time to avert even more severe consequences.

A new report from the Intergovernmental Panel on Climate Change (IPCC)  warns that extreme events caused by sea-level rise from melting ice caps – high tides, intense storms, and massive floods that used to occur once a century- will strike every year worldwide by 2050, no matter whether global emissions are curbed or not. 

The report, written by more than 100 climate and marine scientists from more than 36 countries, explores the links between oceans, glaciers, ice caps and the climate. It states that sea level rose globally by about 15 cm during the whole of the 20th century, and it is currently raising more than twice as fast, and accelerating over time. 

How does greenhouse gas emission affect sea level rise?

If greenhouse gas emissions are reduced significantly, preventing a 2C temperature increase, global average sea levels could still rise by 30 to 60 cm above current levels by 2100. If emissions keep climbing instead of falling, and it causes 2C or more temperature increase, sea levels could rise by one metre by the end of this century — ten times the rate in the 20th century. At this rate, the rise could exceed five metres by 2300.

The report warns that the world could lose many of its glaciers by the end of this century because of global heating. Small glaciers in Europe, eastern Africa, the tropical Andes, and Indonesia are expected to lose more than 80% of their current ice mass by 2100. “Many glaciers are projected to disappear regardless of future emissions,” the report says. “About 20 cm of sea-level rise from melting glaciers alone is likely in a 2C scenario. If emissions are drastically cut and warming is stabilised at 1.5C, glacier melt from the warming already locked in would contribute about 8.9 cm of sea-level rise.”

As glaciers continue to melt in Greenland and Antarctica, the sea-level rise is further accelerating. “In recent decades the rate of sea-level rise has accelerated, due to growing water inputs from ice sheets in Greenland and Antarctica, in addition to the contribution of meltwater from glaciers and the expansion of warmer sea waters,” says Valérie Masson-Delmotte, co-chair of a UN Intergovernmental Panel on Climate Change group that produced the report. “This new assessment has also revised upwards the projected contribution of the Antarctic ice sheet to sea-level rise by 2100 in the case of high emissions of greenhouse gases.”

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Climate change is devastating the oceans and polar regions as never before, the report warns.

In the Himalayas, glaciers feeding ten rivers, including two prominent trans-boundary rivers in Asia — the Ganges and Yangtze, could shrink dramatically if emissions do not fall, hitting water supplies across the continent. Thawing permafrost in places like Alaska and Siberia could release vast quantities of greenhouse gases, potentially unleashing feedback loops driving faster warming.

The report projects that 20-90% of the world’s current coastal wetlands would disappear by 2100, depending on different sea-level scenarios. Since 1950, more than 50% of the world’s wetlands have already vanished.

Meanwhile, marine heatwaves are becoming more intense, devastating coral reefs — including much of Australia’s Great Barrier Reef. The heatwaves have grown more intense and doubled in frequency since 1982 making oceans hotter, more acidic, and less oxygenated. They would be 20 times more frequent in a 2C world, and if emissions push temperatures past that point, they would happen 50 times more often. 

The world still has time to avert the severe consequences of climate change by curbing global warming below 2C. “We will only be able to keep global warming to well below 2C above pre-industrial levels if we effect unprecedented transitions in all aspects of society, including energy, land and ecosystems, urban and infrastructure as well as industry,” says Debra Roberts, a co-chair of IPCC working group. “The ambitious climate policies and emissions reductions required to deliver the Paris Agreement will also protect the ocean, and ultimately sustain all life on Earth.”

Greenland is the world’s largest island with a vast body of ice sheet covering 1,710,000 sq km, roughly 80% of the surface. The climate here has been exceptionally stable in the past 10,000 years. But the Greenland ice sheet is now changing drastically.

Greenland ice sheet is a relic from the ice age, when gigantic glaciers covered vast stretches of the Northern Hemisphere. The ice in most places–Canada, the northeastern regions of the US, and Scandinavia–had melted away about 10,000 years ago. Although the Greenland ice sheet has persisted so far, it may not, anymore.

Authors of a new study published in the journal Proceedings of the National Academy of Sciences estimates that the Greenland ice sheet is now sloughing off an average of 286 billion tons of ice per year. Two decades ago, the annual average was just 50 billion. An analysis of satellite data reveals that the mass loss has increased sixfold since the 1980s.

Another study published last year reconstructed the changes in Greenland’s ice sheet over the past 350 years using ice cores and satellite data, and cataloged the history of variations in the ice sheet.

The research team found that melting in Greenland ice sheet started to pick up shortly after the dawn of the Industrial Revolution in the mid-1800s, when humans started burning coal, oil, and natural gas in huge quantities, sending tons of heat-trapping greenhouse gases into the atmosphere.

However, it’s only over the last 20 years that the melt rate has definitively increased beyond natural variability. One section of the ice sheet saw its melt intensity surge 575 percent over the last 20 years compared to pre-industrial times.

Sled dogs pull researchers from the Danish Meteorological Institute through meltwater in Greenland. Source: Steffen M Olsen/Twitter

Greenland gains some ice in the winter and loses some in the summer, but as the planet has warmed, the latter has outpaced the former. The ice sheet itself is also changing. The firn layer in the ice sheet, the boundary between snow and ice, is heating up and becoming denser. So water that would ordinarily trickle down through the snow and refreeze runs off the ice sheet instead.

The ice is also getting darker, as soot carried through the air and microorganisms like algae settle on the ice. Dark ice absorbs more solar energy and melts faster.

Besides global warming, a negative phase of the North Atlantic Oscillation (NAO)— a natural, irregular change in atmospheric pressure over the North Atlantic Ocean– also causes the rapid ice melt.   

What does it mean to you?

Although Greenland is located faraway at the northern end of the Atlantic Ocean, the sheer volume of ice melting into the ocean will have global repercussions affecting all of our lives.

Nasa reveals that if the Greenland ice sheet were to completely melt into the ocean, sea levels would rise by about 7 meters (23 feet) globally. The Earth’s rotation would slowdown lengthening the days. 

Greenland’s ice caps are currently the biggest single source of meltwater adding to the volume of the world’s oceans. They contribute about 20% of global sea-level rise, which is running at 4mm per year. All the melted ice has already contributed to more than 1.5 cm of global sea-level rise since 1972. Half of that increase came about in the last eight years alone. This pace is primed to double by the end of the century, according to the recent models used by the UN Intergovernmental Panel on Climate Change.

Rising water has already swallowed up at least eight low-lying islands in the Pacific Ocean. It also has increased coastal erosion. In Bangladesh and Thailand, coastal mangrove forests–important buffers against storms and tidal waves–are giving way to ocean water. Low-lying island nations, especially in equatorial regions, have been hardest hit. 

Vietnam is among the most vulnerable nations to global sea-level rise

A World Bank study found that if sea level were to rise by 1 metre, an area of 74,000 sq km in twelve countries–Brunei, Cambodia, China, Indonesia, North and South Korea, Malaysia, Myanmar, Papua New Guinea, Philippines, Thailand, and Vietnam–would be submerged permanently. Coastal communities in these countries will continue to face billion-dollar disaster recovery bills as flooding becomes more frequent and storms become more intense.  

Besides rising sea level, the relentless stream of meltwater threatens to disrupt oceanic currents stemming from the Gulf of Mexico that warm Europe’s coasts, contributing in no small measure to upkeeping the temperate climate north of the Mediterranean. Altering these currents, collectively known as the Atlantic Conveyor could lead to considerable changes in climate and rainfall patterns throughout the Northern Hemisphere. 

Ice sheets act as a protective cover over the land and ocean. They reflect the majority of the solar radiation back into space, keeping the planet cooler. Once they melt away, the excess heat would remain in the atmosphere causing a so-called feedback loop, which will warm the planet further. This temperature increase in air and ocean will create more frequent and intense coastal storms like hurricanes and typhoons in the Northern Hemisphere.  

Letting global temperatures get any higher could lead to irreversible mass loss of ice in Greenland. Cutting greenhouse gas emissions as aggressively as possible to limit the warming is the only solution. As the Intergovernmental Panel on Climate Change pointed out, limiting the temperature to 1.5C by 2050 would require an unprecedented global coordinated effort. 

 

 

Cold War-era US reconnaissance satellites have gone out of orbit. But they have left images that reveal the horrifying realities of climate change. A new study based on declassified satellite imagery revealed that the melting of Himalayan glaciers has doubled since the turn of the 21st century, compared to the previous 25 years.

A team of researchers led by doctoral student Joshua Maurer, from Columbia University’s Lamont-Doherty Earth Observatory, analysed Cold War-era spy imagery combining it with modern satellite data and found that 8bn tonnes of ice are being lost every year. Over 650 of the largest glaciers across India, China, Nepal, and Bhutan, which together represent 55% of the region’s total ice volume, have lost the equivalent of a vertical foot and a half of ice each year this century due to global heating caused by human activities.

Earlier, scientists had documented the rate at which the Himalayas had lost ice mass in the course of this century using more sophisticated satellite imagery. But this is the first comprehensive look at the melting rates of the Himalayan glaciers over a 40-year time span.

The Once-Secret Source

During the 1970s and 1980s, at the height of the Cold War, a US spy programme–Hexagon–had launched 20 satellites into orbit to secretly photograph the Earth.  The satellite missions, run by the National Reconnaissance Office, sought to capture wide-ranging views of what transpired around the globe. Each satellite was the size of a truck and weighed over 15,000 kilograms. In all, they photographed some 877 million square miles of Earth.

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One of the satellites KH-9 Hexagon, commonly known as Big Bird, before the launch

The covert images were taken on rolls of film that were then dropped by the satellites into the atmosphere to be collected by military planes. The films were contained in metal canisters, which deployed their parachutes before being captured by high-flying spy planes. The materials were declassified in 2011, and have been digitised by the US Geological Survey for scientists to use.

Among the spy photographs are the Himalayas–an area for which historical data is scarce.

The photos had lain unused in archives for several years. The Columbia University team developed a computer software to turn these old photos into 3D maps allowing them to digitally explore the Himalayan surfaces as they appeared in 1975. They looked at 650 glaciers and compared them with modern satellite data from Nasa and the Japanese space agency (Jaxa) to create the first detailed, four-decade record of ice along the 2,000km mountain chain.

How fast are glaciers melting?

Researchers found that between 1975 and 2000, the average loss of glacial ice was about 25 cm per year, but this doubled to 50 cm in the 21st century. These are average figures, spread out across the region, and in the worst-hit areas, that ice loss is as much as 5 metres a year.

Warming air temperatures have accelerated ice loss. Inferring data from local weather stations, the team found temperatures in the Himalayas have risen one degree Celsius higher than those from 1975 to 2000.  The rising temperatures are consistent with the observed melting. Further calculations also confirmed that one degree was indeed enough to produce such a massive loss of glacier ice.

The Himalayas contain many different types of glaciers — such as those covered in debris or located near bodies of liquid water lakes — in many different environments.

The study concluded that the rate of melt was consistent across all the glaciers they studied.  “All of the glaciers have lost similar amounts of ice. It indicates there is one overarching factor causing this,” said lead researcher Josh Maurer. “Global temperature rise is the only one that makes sense.”

Map of glacier locations and geodetic mass balances for the 650 glaciers.
Circle sizes are proportional to glacier areas, and colors delineate clean-ice, debris-covered, and lake-terminating categories. Insets indicate ice loss, quantified as geodetic mass balances plotted for individual glaciers along a longitudinal transect during 1975–2000 and 2000–2016. Both inset plots are horizontally aligned with the map view. Gray error bars are 1σ uncertainty, and the yellow trend is the (area-weighted) moving-window mean, using a window size of 30 glaciers.

Why are glaciers important?

Glacier loss at this rate points to an impending threat that might devastate an entire region of South Asia in the near future. Glaciers are a key source of fresh water for both natural ecosystems and nearby human communities, helping to feed mountain streams as they melt during the summer months. More than 800 million people from China, India, Pakistan, and Bangladesh rely on seasonal Himalayan runoff for irrigation, hydropower, and drinking water. The ice and snow in the region are the source for Asia’s mighty rivers including the Indus, the Yangtze, and the Ganga-Brahmaputra. As these glaciers shrink, they could alter the local hydrology and disrupt the water supplies. As a result, densely populated areas in South Asia would face more severe water crisis than ever before.

Melting glaciers pose another unpredictable danger: disastrous floods. Glacial water gets blocked by piles of rubble and forms glacial lakes that can burst and flood villages and cities downstream. These lake outburst floods have killed thousands of people in the Andes, Himalayas, and Alps in the past. In May 2012, one such flood killed over 60 people in villages near Pokhara, Nepal; it also destroyed houses and infrastructure.

Another study published last February projected that, even in the best-case scenario, if the world rapidly decarbonised and was carbon neutral by 2050, limiting global warming to 1.5 degrees Celsius, the Himalayan glaciers are still melting rapidly and stand to lose a third of their total ice, because the peaks are warming at a faster rate than the global average.

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