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The last fully intact ice shelf in Canada in the Arctic has collapsed, having lost about 80 sq km, or 40%, of its area over a two-day period in late July, according to the Canadian Ice Service. The collapse of the 4 000 year-old Milne Ice Shelf was exacerbated by record-setting temperatures in the region, which measured 5 degrees Celsius above the 30-year average this past summer, as well as wildfires.

A research camp was lost in the collapse, as well as the northern hemisphere’s last known epishelf lake, which is a freshwater lake damned by ice that floats on top of salty ocean water. Additionally, two of Canada’s ice caps, located on the Hazen Plateau in St. Patrick Bay, disappeared this summer, two years earlier than predicted. 

Unlike glaciers, ice shelves are part of the ocean. The ice shelf on Ellesmere Island in Canada’s Nunavut territory fell into the Arctic Sea and started to drift before breaking into two large chunks. Images captured by the Copernicus Sentinel satellite captured the event, showing that when the fallen pieces split into two, the large piece formed an iceberg roughly the size of Manhattan

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canada ice shelf
The Milne Ice Shelf in Canada lost nearly 40% of its ice over a two-day period in late July (Source: Sentinel Playground, Sinergise Ltd.). 

Adrienne White, ice analyst at the Canadian Ice Service, says, “This is a huge, huge block of ice. If one of these is moving toward an oil rig, there’s nothing you can really do aside from move your oil rig.”

The service explained that above normal air temperatures, offshore winds and open water in front of the ice shelf contribute to ice shelf break up. 

Now that a large part of the ice shelf is in the ocean, there is potential for additional cracking and movement, the Water and Ice Research Laboratory (WIRL) said in a press release. It warns that the ice shelf is still unstable and further ice breaks are possible in the coming days and weeks.

Ice shelves can help limit rising sea levels because they act like a dam. As average Arctic temperatures warm, more sea ice has been melting during the summer than in previous decades. With more melting, the Arctic Ocean absorbs more of the sun’s rays and gets warmer, delaying ice from growing back again until later in the fall. However, with less sea ice present in the autumn to reflect sunlight, the entire region warms up even more, perpetuating this feedback loop.

Studies estimate that global sea level rise could be between 0.91 meters and 1.5 meters, which will have detrimental effects on coastal cities. 

The Arctic has warmed at twice the global average rate in recent decades, but scientists say that this summer was even more extreme. In July, Arctic sea ice hit its lowest recorded extent, while the Russian Arctic has experienced record heat and wildfires, with temperatures exceeding 37 degrees Celsius in the Siberian town of Verkhoyansk in late June.  

Featured image by: U.S. Geological Survey

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

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

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