Sea ice reduction drives genetic differentiation among Barents Sea polar bears

Simo Njabulo MadunaJon AarsIda FløystadCornelya F. C. KlütschEve M. L. Zeyl FiskebeckØystein Wiig… See all authors Published:08 September 2021


Loss of Arctic sea ice owing to climate change is predicted to reduce both genetic diversity and gene flow in ice-dependent species, with potentially negative consequences for their long-term viability. Here, we tested for the population-genetic impacts of reduced sea ice cover on the polar bear (Ursus maritimus) sampled across two decades (1995–2016) from the Svalbard Archipelago, Norway, an area that is affected by rapid sea ice loss in the Arctic Barents Sea. We analysed genetic variation at 22 microsatellite loci for 626 polar bears from four sampling areas within the archipelago. Our results revealed a 3–10% loss of genetic diversity across the study period, accompanied by a near 200% increase in genetic differentiation across regions. These effects may best be explained by a decrease in gene flow caused by habitat fragmentation owing to the loss of sea ice coverage, resulting in increased inbreeding of local polar bears within the focal sampling areas in the Svalbard Archipelago. This study illustrates the importance of genetic monitoring for developing adaptive management strategies for polar bears and other ice-dependent species.

1. Introduction

Climate change is rapidly altering the structure, dynamics and functioning of ecosystems, leading to large-scale changes in the distribution, demography and phenology of species [1]. The current warming trend is fastest in the Arctic, causing a reduction of the extent, thickness, multiyear persistence and seasonal duration of sea ice cover [2]. Species relying on ice-habitats for foraging, reproduction and movement are therefore particularly vulnerable [36]. Population declines as well as contraction and fragmentation of geographical ranges have indeed been documented in ice-dependent species such as the Adélie penguin (Pygoscelis adeliae) and chinstrap penguin (Pygoscelisantarcticus, [7,8]), Baltic ringed seal (Pusa hispida botnica, [9]) and polar bears (Ursus maritimus, [1013]).

Detrimental ecological and demographic effects of reductions in sea ice cover may ultimately reduce the standing genetic variation of species [1417]. Loss of genetic diversity over time (genetic erosion) could introduce an additional level of adversity for affected species, by diminishing the adaptive potential enabling species to respond to anthropogenic pressures, pathogen outbreaks and environmental change [15,18]. Documenting changes in genetic diversity, spatial population structure and exchange in response to long-term climatic trends is therefore crucial for predicting the future fates of species [15,18]. Nevertheless, direct assessments of climate-induced temporal changes of intraspecific genetic diversity and population connectivity of species affected by reductions in sea ice cover remain scarce. This is largely owing to a lack of coordinated long-term ecological sampling and monitoring efforts [18,19]. In addition, it is unknown if spatial climate gradients, which are often used as proxies to predict responses to environmental change, fully capture the underlying population-genetic processes [18].

Our analysis focused on the polar bears inhabiting the Svalbard Archipelago in the northwest Barents Sea, because there is long-term genetic monitoring data available for this subpopulation going back until 1995. Moreover, the reduction of sea ice cover for the area inhabited by the Barents Sea polar bear subpopulation is an ongoing process. This includes both an estimated increase of ice-free days by 41 per decade between 1979 and 2014 [20] and a documented northward shift in the distribution of optimal habitat for polar bears in all seasons [21]. Coinciding with this period of sea ice loss, studies in Svalbard have revealed both reduced numbers of pregnant females reaching traditional denning areas than before [22,23] and that polar bears spent less time at glacier fronts hunting seals and more time on land and near bird colonies, eating birds and bird eggs, than they did in earlier years [2426].

Most polar bears in the Barents Sea subpopulation, which was estimated to be approximately 2650 (95% confidence interval (CI) 1900–3600) individuals in August 2004 [27], hunt on pack ice (marginal ice zone) and have been termed ‘pelagic’ [28]. In summer and autumn, when there is no continuous sea ice cover surrounding Svalbard, roughly 10% of the subpopulation (approx. 250 individuals) occur in the Svalbard Archipelago, and ‘local’ polar bears that stay in this area year-round predominate [27,29]. In winter and in spring, however, pelagic bears also occur in this area. Thus, depending on the presence of sea ice, there is marked seasonal variation in both the density of bears and the proportion of bears with different movement strategies across the Svalbard Archipelago. Consequently, sea ice reduction is predicted to reduce both the magnitude and duration of the seasonal influx of pelagic bears [30,31]. Importantly, the loss of sea ice habitat in Svalbard in spring, during the mating season of the local polar bears [32], has been more profound than in the remaining Barents Sea areas occupied by the subpopulation, and the loss here has continued in recent years [21]. This increase in ice-free days could reduce mating opportunities and long-range breeding dispersal among regions connected by sea ice and lead to a higher proportion of local mating owing to population fragmentation.

The Svalbard Archipelago has undergone over two decades of rapid sea ice loss [20]. To assess whether and how the declining yearly sea ice season in the Svalbard Archipelago impacts population-genetic parameters of polar bears, we applied an extensive temporal and spatial sampling design to estimate the direction and rate of change of genetic diversity and differentiation in Svalbard polar bears over two decades (1995–2016). Given that the generation time of polar bears is approximately 12 years (International Union for Conservation of Nature/Species Survival Commission Polar Bear Specialist Group 2015), the study covers at least two generations, in particular if one takes into account that the individuals sampled in the early years of the interval were born up to 20 years earlier (year of birth ranged from 1975 to 2015). Temporally, as both sea ice habitat and connectivity among areas used by pelagic and local bears are in a decline, our hypothesis was that ‘local’ bears would become increasingly isolated, and that this would be reflected as increasing differentiation among and decreasing genetic diversity within areas. Spatially, because the extent of ice loss is uneven across Svalbard, with the west coast of Spitsbergen (the most western island) showing the highest loss [25], we expected to observe the strongest effects in northwestern Svalbard, where the great majority of bears are ‘local’ [29].

2. Material and methods

(a) Study area, sample collection and genetic methods

Polar bears from the Barents Sea were captured throughout the Svalbard Archipelago from 1995 to 2016 by the Norwegian Polar Institute, Tromsø, Norway, following standard immobilization, sampling and handling procedures [33] (figure 1). We extracted total genomic DNA from collected tissue samples using the DNeasy Blood & Tissue Kit (Qiagen) following the manufacturer’s protocol. For genetic typing, we used 22 published nuclear microsatellite loci with polymerase chain reaction protocols optimized for seven multiplex assays (electronic supplementary material, appendix S1, tables S1–S3). The overall microsatellite data consisted of 626 unique polar bear genotypes, including 206 bears that were previously genotyped following a similar protocol (see the electronic supplementary material, appendix S1). Based on sampling location, we allocated the genotyped bears to four geographical areas: north-western Svalbard (NWS, n = 123), northeastern Svalbard (NES, n = 110), southwestern Svalbard (SWS, n = 241) and southeastern Svalbard (SES, n = 152) (see the electronic supplementary material, appendix S1). For each of the four areas, we divided the 22-year sampling period into five temporal groups: T1: 1995–1999; T2: 2000–2004; T3: 2005–2009; T4: 2010–2014; T5: 2015–2016, but excluded periods with fewer than 10 individuals (electronic supplementary material, appendix S1, table S1-1). Thus, our final dataset comprised 16 spatio-temporal groups and 622 individuals, although to explore our results we also evaluated other plausible temporal divisions (electronic supplementary material, appendix S1, table S1-2).

Figure 1.
Figure 1. (a) Distribution of polar bears sampled in the present study across four geographical areas of the Svalbard Archipelago with sample sizes indicated. (b) Global surface-air temperature trends since 1979 (linear trends in °C decade−1 for December–February). Data source: (c) Sea ice extent trends in the Barents Sea for April (typical month with the highest prevalence of ice in the region) from 1979 to 2018. Data source: The period of the present study is shaded in grey (c). (Online version in colour.)

(b) Spatio-temporal patterns of genetic diversity, inbreeding and differentiation


Then and now: Arctic sea-ice feeling the heat

By Mark Kinver
Environment reporterPublished1 day agoShare

In our monthly feature, Then and Now, we reveal some of the ways that planet Earth has been changing against the backdrop of a warming world. The shrinking sea-ice in the Arctic is not only a sign of climate change, it is causing the planet to warm more quickly. This is because more sunlight is being absorbed by the darker ocean, rather than being reflected back into space.

Arctic sea-ice plays an important role in controlling the planet’s temperature, and any problem with this natural thermostat is a cause for concern.

Figures from the US space agency (Nasa) suggest the loss of the minimum Arctic sea-ice extent is in the region of 13.1% per decade, based on the 1981 to 2010 average.

major report on climate change in 2007 linked the growing concentration of greenhouse gases in the atmosphere, caused by human activity, with declining sea-ice extent in the region.

The disappearance of the sea-ice in a warming world also contributes to rising average surface temperatures. The sea-ice is estimated to reflect 80% of sunlight back into space, meaning it does not warm the surface.

But when the sea-ice has melted, the darker ocean surface is exposed, which absorbs about 90% of the sunlight hitting it. This results in warming of the region.

This phenomenon is known as the Albedo effect, and it occurs because light surfaces reflect more heat than dark surfaces.

Vanishing point

The freezing and thawing of the ocean in the Arctic is a seasonal occurrence, with the freezing peaking in March and the melting reaching its maximum in September.

Arctic sea ice
image captionData suggests that the extent of Arctic sea-ice is shrinking by 13% each decade as the world warms

However, data from on-the-ground observations and from satellites tell us that the extent of sea-ice in the Arctic polar region is declining as the planet warms.

As this occurs, the albedo (or reflectivity) is reduced, because the dark ocean waters absorb more heat than the lighter sea-ice. This in turn causes the land and oceans to warm even more.

Ultimately, scientists fear, the increasing amount of ground being exposed in regions traditionally covered with snow will trigger a “tipping point”. This is where the warming of the atmosphere reaches a point where human interventions will no longer be able to halt it.

Smaller and warmer world

Another impact of the decreasing density of ice in the northern polar region is the opening of the Northwest Passage. This trading route links the North Atlantic Ocean with the North Pacific Ocean.

The Northwest Passage

Since the 19th Century, there has been clamour to find a navigable route through frozen Arctic waters between Greenland and Canada’s Arctic islands.

It has long been a deadly pursuit for mariners who braved the frozen seascape. However, some experts estimate that the route will become commercially viable in the near future as the sea-ice retreats in the summer months.

For some, it is going to revolutionise the global shipping sector. For others, it is a disaster waiting to happen.

Environmental groups fear a growing volume of shipping traffic through the pristine Arctic waters will damage slow-growing, long-lived marine ecosystems.

They particularly fear a ship encountering a mishap in the remote polar waters, resulting in a potentially devastating pollution incident.

Lack of food

Evidence suggests that the thinning sea-ice is affecting wildlife, including top-of-the-food-chain predators such as polar bears. The ice is not strong enough to support the animals’ weight, forcing them to embark on energy-sapping swims and making it more difficult to catch prey.

A polar bear in the Arctic National Wildlife Refuge
image captionStudies show that polar bears are struggling to hunt on the melting sea-ice during summer months

As well as causing starvation, it is also reportedly resulting in bears coming into human settlements looking for food.

Another concern among scientists is that melting sea-ice is affecting a major ocean current in the Arctic – the Beaufort Gyre.

Freshwater is less dense than salty seawater. The researchers said a sudden influx of freshwater from the Arctic Ocean into the northern Atlantic Ocean could alter the strength of the current.

This is because the force pushing water down the eastern coast of continental North America will be reduced, resulting in a smaller volume of warmer tropic waters from equatorial regions being displaced towards western Europe.

Models suggest the reduction in warmer waters heading towards western Europe will result in lower temperatures in the region. This, in turn, would also affect weather patterns in the global climate system.

Our Planet Then and Now will continue each month up to the UN climate summit in Glasgow, which is scheduled to start in November 2021

Arctic sea ice thinning twice as fast as thought, study finds

Less ice means more global heating, a vicious cycle that also leaves the region open to new oil extraction

Snow weighs the ice down, so it is critical to know how deep it is in order to calculate the thickness of the ice
Snow weighs the ice down, so it is critical to know how deep it is in order to calculate the thickness of the ice. Photograph: Natalie Thomas/Reuters

Damian Carrington Environment editor@dpcarringtonFri 4 Jun 2021 01.01 EDT

Sea ice across much of the Arctic is thinning twice as fast as previously thought, researchers have found.

Arctic ice is melting as the climate crisis drives up temperatures, resulting in a vicious circle in which more dark water is exposed to the sun’s heat, leading to even more heating of the planet.

The faster ice loss means the shorter north-eastern shipping passage from China to Europe will become easier to navigate, but it also means new oil and gas extraction is more feasible.

Calculating the thickness of sea ice from satellite radar data is difficult because the amount of snow cover on top varies significantly. Until now, the snow data used came from measurements by Soviet expeditions on ice floes between 1954 and 1991. But the climate crisis has drastically changed the Arctic, meaning this information is out of date.

The new research used novel computer models to produce detailed snow cover estimates from 2002 to 2018. The models tracked temperature, snowfall and ice floe movement to assess the accumulation of snow. Using this data to calculate sea ice thickness showed it is thinning twice as fast as previously estimated in the seas around the central Arctic, which make up the bulk of the polar region.

Robbie Mallett of University College London, who led the study, said: “Sea ice thickness is a sensitive indicator of the health of the Arctic – and, when the Arctic warms, the world warms.

“Thicker ice acts as an insulating blanket, stopping the ocean from warming up the atmosphere in winter and protecting the ocean from the sunshine in summer. Thinner ice is also less likely to survive during the Arctic summer melt.”

Changes in the Arctic are also increasingly believed to influence extreme weather such as heatwaves and floods around the northern hemisphere. The rapid thinning of sea ice has consequences for human activities in the Arctic as well.

The newly exposed waters enabled storms to hit coastal communities and erode coasts, Mallett said. The opening of the shorter north-eastern shipping route around Siberia means less fuel is needed to transport goods between China and Europe, leading to lower carbon emissions.Advertisement

In February, a cargo ship made a round trip for the first time in winter. “However, this also raises the risk of fuel spillages in the Arctic, the consequences of which could be dire,” said Mallett.

“There’s also a lot of interest in oil and gas extraction from the Russian shelf seas,” Mallett said. But the research revealed much greater annual variability in ice thickness than estimated before. “Knowing the thickness of the ice is pretty critical to planning those activities, so the enhanced variability is generally bad news for those planning to work in the Arctic,” he said.

The Soviet-era data was hard won, Mallett said. “They sent these brave guys out and they sat on these drifting stations and floated around the Arctic, sometimes for years at a time, measuring the snow depth.” But the Intergovernmental Panel on Climate Change identified the lack of more recent data as a key knowledge gap in 2019.

Sea ice thickness is calculated from satellite radar data that measures how high the ice sits above the sea surface. Snow on top of the ice is invisible to the radar signals but it weighs the ice down, so it is critical to know the depth of snow.

“Sea ice has begun forming later and later in the year, so the snow on top has less time to accumulate,” said Mallett. “Our calculations account for this declining snow depth for the first time.” The research is published in the journal The Cryosphere.

“We are still learning about the changes to the Arctic environment, and one of the big unknowns – or less well-knowns – is snow cover,” said Walt Meier, at the US National Snow and Ice Data Center, and not involved in the new research. “The approach in the study is a significant improvement over older methods, and the results fit with other changes we’re seeing with Arctic sea ice, including earlier melt onset, lower summer ice cover, and later freeze-up.”

Prof Julienne Stroeve, at UCL, said: “There are [still] a number of uncertainties but we believe our new calculations are a major step forward. We hope this work can be used to improve climate models that forecast the effects of long-term climate change in the Arctic – a region that is warming at three times the global rate and whose ice is essential for keeping the planet cool.”

Harp seals were a conservation success story. Climate change is a new threat.

April 18, 2021, 7:26 PM

Magdalen Islands, Canada — Most winters, it’s possible to see newborn harp seal pups on packs of ice near the Magdalen Islands in the Gulf of Saint Lawrence in late February and March. Tourists come from around the globe.

Kimberly Krussell traveled from Hawaii last year. 

“It’s just an amazing experience,” Krussell said. “From the ride out there, being just inches away from its liquid chocolate eyes, to watching the adults singing to each other out on the ice.”

Most travel by helicopter to the ice where the pups are born.

Their white fur serves a purpose, so they can absorb sunlight and stay warm until they develop blubber. They lose their fur when they’re about 3 or 4 weeks old.

Harp seal, Magdalen Islands, Quebec
A harp seal seen on the Magdalen Islands, Quebec, Canada.  C. DANI & I. JESKE / DE AGOSTINI PICTURE LIBRARY VIA GETTY IMAGES

For centuries, demand for that fur was booming business. But bad publicity over the brutality of the hunt has taken a toll on the commercial sale of seal products, according to Sheryl Fink, director of the International Fund for Animal Welfare, which formed to fight the commercial seal hunt. 

“Over 36 countries around the world have implemented trade bans on seal products, there are no longer any markets for seal products,” Fink said.

And killing the white-furred pups has been banned since 1987. Once devastated, the seal population has rebounded and now numbers more than 7.5 million.

“It’s probably the highest it’s been since about the 1850s, so it’s — overall, it’s a conservation success story,” said Mike Hammill of the Fisheries and Oceans Canada.


But now, there’s a new, more ominous threat.

This year’s tour season was canceled because the ice was too thin for choppers to land.

It’s the fourth cancellation since 2010.

Why is this happening? “We think overall it’s linked to climate change,” Hammill said.  

In the Gulf, pilots say the changes are already obvious.


“Suddenly, yes, a few years ago — ‘Oh we might have a problem there,’ there’s no, not enough ice coverage,” said helicopter pilot David Arsenault. “So yes, it is concerning. and it’s surprising.”

For the seals, melting ice is a matter of life and death. They need it to survive the weeks of life. Without it, they’ll head north — where predators await.

“We don’t have any polar bears in the Gulf of Saint Lawrence,” Hammill said. “If they have to move up the Labrador Coast, then they’re going to run into polar bears much more often so that adds another mortality fact to them.” 

Over a third of Antarctic ice shelf could collapse as climate change warms the Earth

By Chelsea Gohd 8 hours ago

The Larsen C ice shelf.

The Larsen C ice shelf. (Image credit: NASA ICE)

Over a third of the Antarctic ice shelf is at risk of collapsing as Earth continues to warm. 

In a new study, scientists at the University of Reading have found that as climate change continues, if Earth’s global temperature rises to 7.2 degrees Fahrenheit (4 degrees Celsius) above pre-industrial levels, about 193,000 square miles (500,000 square kilometers) of the Antarctic ice shelves could collapse into the sea. Ice shelves are permanent floating slabs of ice attached to coastline, and the collapse of these shelves could significantly raise global sea levels, the researchers suggest. 

“Ice shelves are important buffers preventing glaciers on land from flowing freely into the ocean and contributing to sea level rise. When they collapse, it’s like a giant cork being removed from a bottle, allowing unimaginable amounts of water from glaciers to pour into the sea,” lead study author Ella Gilbert, a research scientist in the University of Reading’s Department of Meteorology, said in a statement

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Every summer in Antarctica, ice on the surface of the ice shelf melts and that water travels into the snow below where it refreezes. But in years with more melting ice than snowfall, that water ends up pooling on the ice shelf’s surface and falls into cracks in the ice, melting and growing those cracks until the ice shelf breaks off into the ocean. This exact thing happened with the Larsen B ice shelf in 2002 and in this study researchers identify ice shelf Larsen C as at particular risk for collapse in warmer temperatures. 

In this study, researchers used high-resolution regional climate modeling technology to predict how melting ice and water runoff will affect ice shelf stability over time and at different global temperatures. They modeled ice shelf vulnerability at global temperatures 2.7 degrees F (1.5 degreesC), 3.6 degrees F (2 degrees C) and 7.2 degrees F (4 degrees C) above pre-industrial levels, three scenarios that are all possible within this century, according to the statement. 

“We know that when melted ice accumulates on the surface of ice shelves, it can make them fracture and collapse spectacularly. Previous research has given us the bigger picture in terms of predicting Antarctic ice shelf decline, but our new study uses the latest modelling techniques to fill in the finer detail and provide more precise projections,” Gilbert said. 

They found that, at 7.2 degrees F (4 degrees C) above pre-industrial global temperatures, 34%of all Antarctic ice shelves (including 67%of the ice shelf area on the Antarctic Peninsula) 

“The findings highlight the importance of limiting global temperature increases as set out in the Paris Agreement if we are to avoid the worst consequences of climate change, including sea level rise,” Gilbert said. 

The Paris Agreement is an international treaty that was signed in 2016, made within the United Nations Framework Convention on Climate Change. Under the agreement, nations have pledged to work to limit global temperature increase to 3.6 degrees F (2 degrees C), or preferably 2.7 degrees F (1.5 degrees C), above pre-industrial levels.

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Scientists have been worried about the continued effects of global warming on floating ice shelves for some time. 

“The floating ice shelves around the coast of Antarctica are of particular concern,” Paul Cutler, a program director for National Science Foundation’s Antarctic Sciences Division, said during a live webinar Thursday (April 8). “They interface with the ocean which is changing, and they hold back the flow of the inland ice as it moves towards the ocean. So if you lose the integrity of those ice shelves, you release more inland ice to the ocean, and you cause even more sea level rise.”

Rising sea levels can have many dangerous effects including extreme coastal flooding, destructive erosion and more. 

Additionally, “with the loss of the glaciers, you actually lose their gravitational pull,” Cutler said. “So when you lose West Antarctica, you lose its gravitational pull on the United States. And actually, part of the sea level rise we see in the U.S. is related to the loss of ices by that indirect gravity effect as well.” 

“Limiting warming will not just be good for Antarctica — preserving ice shelves means less global sea level rise, and that’s good for us all,” Gilbert said.

A third of Antarctic ice shelf risks collapse as our planet warms

By Amy Woodyatt, CNN

Updated 9:07 AM ET, Thu April 8, 2021

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London (CNN)More than a third of the Antarctic ice shelf risks collapsing into the sea if global temperatures reach 4 degrees Celsius (7.2 degrees Fahrenheit) above pre-industrial levels as climate change warms the world, a new study from the UK’s University of Reading has warned.In a forecasting study, scientists found that 34% of the area of all Antarctic ice shelves, measuring some half a million square kilometers, could destabilize if world temperatures were to rise by 4 degrees. Some 67% of the ice shelf area on the Antarctic Peninsula would be at risk of destabilization under this scenario, researchers said.Ice shelves are permanent floating platforms of ice attached to areas of the coastline, formed where glaciers flowing off the land meet the sea. They can help limit the rise in global sea levels by acting like a dam, slowing the flow of melting ice and water into the oceans.

Each summer, ice at the surface of ice shelves melts and runs into smaller gaps in the snow below, where it usually refreezes. But when there is a lot of melting and little snowfall, this water instead pools onto the ice’s surface or flows into crevasses. This deepens and widens the crevasses, causing the shelf to fracture and collapse into the sea.

This huge iceberg calved from the Larsen C ice shelf.This huge iceberg calved from the Larsen C ice shelf.”Ice shelves are important buffers preventing glaciers on land from flowing freely into the ocean and contributing to sea level rise. When they collapse, it’s like a giant cork being removed from a bottle, allowing unimaginable amounts of water from glaciers to pour into the sea,” study lead author Ella Gilbert, a climate scientist in the University of Reading’s Department of Meteorology, said in a statement.

Gilbert told CNN that low-lying coastal areas, particularly small island states such Vanuatu and Tuvalu, in the South Pacific Ocean, are most at risk from global sea level rise.close dialog

Receive Fareed Zakaria’s Global Analysisincluding insights and must-reads of world newsActivate Fareed’s BriefingBy subscribing you agree to ourprivacy policy.“However, coastal areas all over the world would be vulnerable, and countries with fewer resources available to mitigate and adapt to sea level rise will see worse consequences,” she said.

In the new study, which used high-resolution regional climate modeling to predict the impact of increased melting and water runoff on ice shelf stability, researchers say that limiting temperature rise to 2 degrees Celsius rather than 4 degrees Celsius would halve the area at risk and potentially avoid significant sea level rise.The Intergovernmental Panel on Climate Change concluded in a landmark report that we only have until 2030 to drastically reduce our dependence on fossil fuels and prevent the planet from reaching the crucial threshold of 1.5 degrees Celsius (2.7 degrees Fahrenheit) above pre-industrial levels.This image shows a large iceberg which has separated from Pine Island Glacier.This image shows a large iceberg which has separated from Pine Island Glacier.Global net emissions of carbon dioxide would need to fall by 45% from 2010 levels by 2030 and reach “net zero” around 2050 in order to keep the warming around 1.5 degrees Celsius.”The findings highlight the importance of limiting global temperature increases as set out in the Paris Agreement if we are to avoid the worst consequences of climate change, including sea level rise,” Gilbert added.In the Paris accord, 197 countries agreed to the goal of holding global temperatures “well below” 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit it to 1.5 degrees Celsius.

Antarctic sponges discovered under the ice shelf perplex scientistsBut we are on track for a world that is 3.2 degrees Celsius warmer by the end of the century.Gilbert told CNN that increased temperatures means melting occurs more frequently, and more intensely.Researchers identified four ice shelves that would be threatened by a warmer climate: The Larsen C, Shackleton, Pine Island and Wilkins ice shelves, which are vulnerable due to their geography, and the runoff predicted in those areas.Larsen C is the largest remaining ice shelf on the Antarctic Peninsula, and the Pine Island glacier has received a lot of attention in recent years because it has been melting rapidly in response to climate change, Gilbert said.

If these ice shelves all collapsed, which is not guaranteed, the glaciers they currently restrain would flow into the ocean, contributing to sea level rise — potentially by tens of centimeters, she explained.The study was published Thursday in the journal Geophysical Research Letters.

Russian tanker cuts a previously impossible path through the warming Arctic


FEBRUARY 23, 2021 / 10:33 AM / CBS NEWS

Moscow — A Russian natural gas tanker has completed an experimental round trip along the Northern Sea Route — the first time the path across the Arctic has been forged at this time of year. The voyage by the Christophe de Margerie tanker through the ice is the latest visual indicator of climate change in the delicate region.

The tanker, run by the Sovcomflot shipping company, returned to the remote Russian gas terminal at Sabetta on February 19, taking Russia one step closer to its goal of year-round commercial navigation through the warming Arctic.

The LNG (liquefied natural gas) tanker set out from the Chinese port of Jiangsu on January 27 after delivering its cargo. It entered the Northern Sea Route, which traverses Russia’s north coast, a few days later near Cape Dezhnev, where it was met by the Russian nuclear icebreaker 50 Let Pobedy (50 Years of Victory). Together they completed the 2,500-nautical-mile voyage through the ice in 11 days and 10 hours.

The vessel managed to complete the first leg of the trip from Russia to China without an icebreaker. Both of the journeys broke records for winter navigation due to the changing climate in the Arctic allowing passage through thinner ice. Using the Northern Sea Route enables shippers in Russia and other countries to avoid a much lengthier southern journey around Europe, the Middle East and all of southern Asia, saving millions of dollars.

The deepest ice encountered by the ships was about 5 feet thick. The vessels encountered no multi-year buildup of old ice on the route, however, and meteorologist and journalist Eric Holthaus called that a clear indicator of “a climate emergency.”

Last May, the Christophe de Margerie became the first large-capacity cargo vessel to complete an eastbound transit of the Northern Sea Route, two months earlier in the year than the journey traditionally has been made. 

The Russian tanker Christophe de Margerie is seen as it steams across the Northern Sea Route in February 2021. SOVCOMFLOT

“As a result of the early Northern Sea Route (NSR) voyage completed by Christophe de Margerie in May 2020, as well as the current NSR voyage, the navigation in the Eastern part of the Arctic was practically doubled,” Sovcomflot CEO Igor Tonkovidov said earlier this month. He noted that for decades the transit route along that segment of the NSR had typically remained closed by ice from November until July.

Climate Change 

“The Arctic is ours”

Novatek, the company that operates the LNG gas plant in Sabetta, plans to continue experimental voyages eastward along the Northern Sea Route, with the next one scheduled this spring, the daily Russian business newspaper Kommersant quoted the company’s boss as saying.

An illustration by the European University at St. Petersburg shows the Northern Sea shipping route, which a Russian tanker traversed for the first time ever in the winter in February 2021, and the southern Suez Canal route.EUROPEAN UNIVERSITY AT ST. PETERSBURG

Last year, Russia moved almost 33 million tons of cargo along the Northern Sea Route, including over 18 million tons of LNG. Cargo traffic along the NSR has grown almost fivefold in the past five years alone.

“The route can handle a lot more than that,” Russian Deputy Prime Minister Yury Trutnev said during a government meeting last week. He said that according to a decree issued by President Vladimir Putin, cargo traffic along the NSR should rise to 80 million tons per year by 2024. 

“One way that target can be achieved is by expanding the period of Arctic navigation,” Trutnev said.

To help it achieve its lucrative Arctic ambitions, Russia has been renewing its unique civilian fleet of nuclear-powered icebreakers. Last year Russia unveiled the new flagship of that fleet, the Arktika, said to be the world’s biggest and most powerful.

Nuclear-powered icebreaker Arktika returns to Saint Petersburg on December 14, 2019, after tests.OLGA MALTSEVA/AFP/GETTY

“Russia’s Arctic attracts many who are interested in its resources,” St. Petersburg Governor Georgy Poltavchenko said at the launch ceremony. “But the Arctic is ours, and we’ve proved it.”

By the end of 2022 Russia plans to launch two more ships in the same series.

Environmentalists have raised concern over the growing presence of nuclear power in the sensitive Arctic region, which is already plagued by problems linked to climate change.

According to some estimates, the Arctic holds oil and gas reserves equivalent to 412 billion barrels of oil, about 22% of the world’s undiscovered oil and gas. 

“Alarming” and “extraordinary” rate of change as the Arctic warms, NOAA report says


DECEMBER 9, 2020 / 7:42 AM / CBS NEWS

The Arctic is warming and changing rapidly, with record or near-record conditions documented across the region in 2020. That’s according to an international team of 133 researchers from over a dozen countries who contributed to the 15th annual NOAA Arctic Report Card, released on Tuesday.

The report is a comprehensive year-in-review of Arctic conditions — what NOAA calls vital signs — that characterize the health and stability of the Arctic ecosystem. They include variables like air temperature, sea ice and wildland fires. While climate conditions in this frigid part of the world typically change naturally at a glacial pace, in recent years the transformation has been occurring at a breakneck speed.

In the a video accompanying the report, NOAA says there have been “alarming rates of change observed” since the 2006 Arctic Report Card, and adds, “the rate of change has been extraordinary.” Report Card 2020 by NOAAPMEL on YouTube

This is evidenced by the intense heat and wildfires in Siberia this summer. It’s not often that events deep in rural Arctic territory make headlines around the world, but in late June, for the first time on record, the temperature soared past the 100-degree Fahrenheit mark above the Arctic Circle, in a town called Verkhoyansk. That was part of a several months long heat event which climate scientists said was made 600 times more likely by human-caused climate change.

From October 2019 to September 2020, Arctic surface temperatures were the second warmest on record — almost 2 degrees Celsius (3.6 degrees Fahrenheit) above the 1980-2010 normal average — behind only 2016, a year affected by a very strong global El Niño event.


The cause of the rapid warming is straightforward and well understood: It is human-caused climate change. But in the Arctic, the pace of warming is 2 to 3 times the global average — a phenomenon known as Arctic amplification. 

According to the report, the sea-ice extent at the end of the summer in 2020 was the second lowest in the 42-year satellite record, behind only the summer of 2012, a summer characterized by unusual stormy conditions which breaks up ice. But this October, when sea-ice typically rebounds quickly, it did not, dropping to the lowest levels on record

The sea-ice reconstruction shows sea-ice extent has remained relatively constant over the past 1500 years, but in recent decades there has been a dramatic decline.ZACK LABE

October 2020 sea-ice volume also recorded the lowest value on record. The ice was so thin that Russia was not able to find thick enough ice to test its new nuclear-powered ice-breaker ship. This drop is ice volume is part of a long-term trend in which sea-ice volume, due primarily to declines in ice thickness, has dropped by two-thirds since the 1970s. 

Comparison of sea-ice thickness from 1980 to 2020ZACK LABE

This dramatic drop in Arctic ice is the main driver for rapid Arctic changes.

Climate Change 

Large expanses of sea-ice, and to a lesser degree snow, stabilize the Arctic climate by regulating air and ocean temperatures. The white shading reflects sunlight back to space, limiting heating. But as temperatures have continued to climb over the past few decades, ice cover has diminished rapidly, exposing typically more of the darker-colored ocean and land. That darker surface is absorbing more heat, leading to warmer temperatures and more melting.

This does not represent a mere subtle shift in the way the system works — it is a dramatic change. The way in which ice regulates the climate versus exposed land and ocean is drastically different. Not only does the exposed area absorb more heat, it also allows ocean and air currents to penetrate deeper into the Arctic, allowing warmth from southern latitudes to invade.

Rick Thoman is an Alaskan climate specialist from the University of Alaska, Fairbanks, and co-author of the report. He says the systemic changes occurring in the Arctic should raise eyebrows to the south, because they foreshadow what may be in store for the rest of us.

“The Arctic continues to sound the bell as a warning to lower latitudes on how rapidly things can change when thresholds are crossed,” said Thoman. “The thresholds will not be the same, of course, but the Arctic is living proof that major environmental change need not proceed gradually over generations.”

Arctic Report Card
In this July 24, 2017 file photo, an iceberg floats past Bylot Island in the Canadian Arctic Archipelago. NOAA’s annual Arctic Report Card, released on Tuesday, Dec. 8, 2020, shows how warming temperatures in the Arctic are transforming the region’s geography and ecosystems.DAVID GOLDMAN / AP

It may seem counterintuitive, but snow accumulation during the 2019-20 winter was above normal across the entire Arctic. However, this makes sense because a warmer atmosphere holds more moisture, dumping more snow, as long as the air temperatures are still near or below freezing. 

With that said, the exceptional spring warmth across the Eurasian Arctic still resulted in the lowest June snow cover extent in this region since the observational record began in 1967. And this drop in late spring snow cover is not just confined to 2020. Since 1981, June Arctic snow cover extent is decreasing at a rate of 15% per decade. 

Variability in seasonal snow cover is an important control on wildland fire activity in high northern latitudes, and as a consequence of dwindling spring and summer snow cover, wildfires are escalating in the Arctic. In 2020, record-setting Arctic fires — mainly in the boreal forest of Siberia — emitted 35% more carbon dioxide than the year before, which was also a record-breaker. 

These more intense wildfires are due to the drying out of accumulated layers of partially decomposed organic matter by prolonged warm, dry conditions, like the ones observed this year in Siberia. This provides a high-octane fuel source. 

Areas in red indicate parts of the Arctic which are now more flammable.NOAA

The report says, “Increasing trends in air temperature and fuel availability over the 41-year record (1979-2019) suggest that conditions are becoming more favorable for fire growth, with more intense burning, more fire growth episodes, and greater consumption of fuels.”

The changes are not only being experienced on land, but also in the Arctic Ocean. Sea surface temperatures this summer were 1 to 3 degrees Celsius (2 to 5 degrees Fahrenheit) above normal.  

The abnormally warm water is one of the reasons sea-ice took so long to regrow this fall. 

Nearly all of the Arctic experienced warmer than normal seas, illustrated in the red shading.NOAA

But this warmer water also comes with some positive biological impacts. NOAA reports that ocean primary productivity — a technical term for the amount of life, like plankton — in the Laptev Sea near Siberia was 2 to 6 times higher than normal. Benefitting from this increase in biological activity are bowhead whales, a staple resource for coastal Indigenous people from Russia to Greenland. Over the past 30 years the bowhead whale population has increased, partly due to increases in Arctic Ocean life.

While there are those rare examples of positive impacts, most of the changes are happening so fast that they are destabilizing for Indigenous populations, ecosystems and for weather and climate patterns. And Thoman says the Arctic will not be settling into a “new normal,” or back to what used to be considered normal, anytime soon, because the only constant at the moment in the Arctic is change.  

“Because the Arctic changes are intimately tied with ice and snow changes, and these are positive feedback loops, this is not something that can be reversed with one cold winter (multi-year ice takes, well, multiple years to grow),” explains Thoman. “It would take generations for ‘frozen Arctic’ like the, say, 1960s to return, and some things, like permafrost in some areas, would take far longer to regrow.”

First published on December 8, 2020 / 8:37 PM

Uh-Oh. Russia’s Laptev Sea Should Have Started to Freeze by Now

Normally, the ‘birthplace of ice’ freezes by late October. For the first time in recorded history, it hasn’t. That could have knock-on effects across the Arctic.

laptev sea

THIS STORY ORIGINALLY appeared in The Guardian and is part of the Climate Desk collaboration.

For the first time since records began, the main nursery of Arctic sea ice in Siberia has yet to start freezing in late October.

The delayed annual freeze in the Laptev Sea has been caused by freakishly protracted warmth in northern Russia and the intrusion of Atlantic waters, say climate scientists who warn of possible knock-on effects across the polar region.

Ocean temperatures in the area recently climbed to more than 5 C above average, following a record breaking heat wave and the unusually early decline of last winter’s sea ice.

The trapped heat takes a long time to dissipate into the atmosphere, even at this time of the year, when the sun creeps above the horizon for little more than an hour or two each day.

Graphs of sea-ice extent in the Laptev Sea, which usually show a healthy seasonal pulse, appear to have flatlined. As a result, there is a record amount of open sea in the Arctic.

“The lack of freeze-up so far this fall is unprecedented in the Siberian Arctic region,” said Zachary Labe, a postdoctoral researcher at Colorado State University. He says this is in line with the expected impact of human-driven climate change.

“2020 is another year that is consistent with a rapidly changing Arctic. Without a systematic reduction in greenhouse gases, the likelihood of our first ‘ice-free’ summer will continue to increase by the mid-21st century,’ he wrote in an email to The Guardian.

This year’s Siberian heat wave was made at least 600 times more likely by industrial and agricultural emissions, according to an earlier study.

The warmer air temperature is not the only factor slowing the formation of ice. Climate change is also pushing more balmy Atlantic currents into the Arctic and breaking up the usual stratification between warm deep waters and the cool surface. This also makes it difficult for ice to form.

“This continues a streak of very low extents. The last 14 years, 2007 to 2020, are the lowest 14 years in the satellite record starting in 1979,” said Walt Meier, senior research scientist at the US National Snow and Ice Data Center. He said much of the old ice in the Arctic is now disappearing, leaving thinner seasonal ice. Overall the average thickness is half what it was in the 1980s.

The downward trend is likely to continue until the Arctic has its first ice-free summer, said Meier. The data and models suggest this will occur between 2030 and 2050. “It’s a matter of when, not if,” he added.

Scientists are concerned the delayed freeze could amplify feedbacks that accelerate the decline of the ice cap. It is already well known that a smaller ice sheet means less of a white area to reflect the sun’s heat back into space. But this is not the only reason the Arctic is warming more than twice as fast as the global average.

The Laptev Sea is known as the birthplace of ice, which forms along the coast there in early winter, then drifts westward carrying nutrients across the Arctic, before breaking up in the spring in the Fram Strait between Greenland and Svalbard. If ice forms late in the Laptev, it will be thinner and thus more likely to melt before it reaches the Fram Strait. This could mean fewer nutrients for Arctic plankton, which will then have a reduced capacity to draw down carbon dioxide from the atmosphere.

More open sea also means more turbulence in the upper layer of the Arctic ocean, which draws up more warm water from the depths.

Stefan Hendricks, a sea ice physics specialist at the Alfred Wegener Institute, said the sea ice trends are grim but not surprising. “It is more frustrating than shocking. This has been forecast for a long time, but there has been little substantial response by decisionmakers.”

Antarctica: 60% of ice shelves at risk of fracture, research suggests

Collapse of shelves would accelerate loss of Antarctic ice sheet and increase sea-level rise

Fracture at the front of Ross ice shelf, the largest in Antarctica. A platform of ice nearly four times the size of the UK is at risk of collapse.
 Fracture at the front of Ross ice shelf, the largest in Antarctica. A platform of ice nearly four times the size of the UK is at risk of collapse. Photograph: Martin Wearing/PA

Approximately 60% of Antarctica’s ice shelves could be vulnerable to fracture, accelerating the loss of the Antarctic ice sheet and increasing sea-level rise, according to a paper.

Antarctica’s ice shelves, floating extensions of the ice sheet, help slow the flow of ice into the ocean. But if these shelves fracture and then collapse, the flow of melting glaciers into the oceans accelerates.

A study published in the journal Nature has mapped areas where ice shelves hold back upstream ice and are susceptible to “hydrofracture”, where meltwater flows into crevasses and fissures in the ice and enlarges them, potentially triggering the collapse of the ice shelf.

This process could accelerate the loss of Antarctic ice more than some climatic models predict as atmospheric warming increases. The study follows scientists’ recent announcement that Earth has lost 28tn tonnes of ice from its surface since 1994.

Most climatic models do not include the impact of hydrofracturing in their calculations, although one 2016 paper did account for them in a simpler way than the new study.

Hydrofracturing can only occur if the surface of an ice shelf is inundated with meltwater. Large pools of meltwater have existed in many areas of Antarctica for decades without causing the collapse of an ice shelf because the flow of water into surface fissures is slow or refreezes.

A tributary ice stream flowing from the Transantarctic mountains into the Ross ice shelf.
 A tributary ice stream flowing from the Transantarctic mountains into the Ross ice shelf. Photograph: Martin Wearing/PA

While some areas are not susceptible to fracture, Ching-Yao Lai of the Earth Institute at Columbia University and colleagues identified that 60% of the Antarctic ice shelf was both slowing the flow of ice into the ocean and also vulnerable to fracture.

While fractures in the ice are visible in satellite imagery, manual mapping is impractical because of the extent of the ice. So Lai and colleagues used machine learning to identify fracture-like features in satellite pictures of Antarctica, before modelling which fractures were vulnerable to hydrofracturing.

They developed a model to predict where fractures could form and found close agreement with the fractures mapped by their machine learning algorithm.

Lai said: “We predicted that the ice-shelves areas that can collapse due to hydrofracture are mostly the crucial part of ice shelves that hold back the upstream flow of ice sheets. Thus the loss of these ice-shelf areas due to hydrofracture can substantially affect the flow of ice sheets into the ocean.

“But predicting how much and how fast the loss of Antarctic ice and sea-level rise will occur due to the hydrofracturing process will require coupling our new fracture model with an ice-sheet and climate model, which is an important next step.”

The researchers hope their fracture model can help create more accurate models of the fate of the ice sheets, which together with climatic modelling will produce more accurate predictions of sea-level rise, which scientists believe could exceed one metre by the century’s end.

The researchers warned that while many areas of Antarctic meltwater were not currently likely to cause the hydrofracture of the ice beneath, with global heating these areas could become newly at risk in the future.

“Increased meltwater ponding in resilient locations will not lead to widespread hydrofracturing according to our analysis,” the authors wrote. “However, predictions of future melt suggest that melt rates seen in locations that experience meltwater ponding today could become widespread by 2100 under high-emissions scenarios.”