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


The Arctic Ocean’s deep past provides clues to its imminent future

AUGUST 16, 2021

by Princeton University

The Arctic Ocean’s deep past provides clues to its imminent future
Global climate change is warming the Arctic Ocean and shrinking sea ice. Here, the blue-white ice cap shows the coverage of sea ice at its smallest extent in summer 2020, and the yellow line shows the typical Arctic sea ice minimum extent between 1981 and 2010. Some have proposed that the newly exposed sea surface will lead to a plankton population boom and a burgeoning ecosystem in the open Arctic Ocean, but a team of Princeton and Max Planck Institute for Chemistry scientists say that’s not likely. They have examined the history and supply rate of nitrogen, a key nutrient. Their recent work finds that stratification of the open Arctic waters, especially in the areas fed by the Pacific Ocean via the Bering Strait, will prevent surface plankton from receiving enough nitrogen to grow abundantly. Credit: Jesse Farmer, Princeton University; modified from Rebecca Lindsey and Michon Scott, “Climate change: Arctic sea ice,” NOAA

As the North Pole, the Arctic Ocean, and the surrounding Arctic land warm rapidly, scientists are racing to understand the warming’s effects on Arctic ecosystems. With shrinking sea ice, more light reaches the surface of the Arctic Ocean. Some have predicted that this will lead to more plankton, which in turn would support fish and other animals.

Not so fast, says a team of scientists led by Princeton University and the Max Planck Institute for Chemistry.

They point to nitrogen, a vital nutrient. The researchers used fossilized plankton to study the history of sources and supply rates of nitrogen to the western and central open Arctic Ocean. Their work, detailed in a paper in the current issue of the journal Nature Geoscience, suggests that under a global warming regime, these open Arctic waters will experience more intense nitrogen limitation, likely preventing a rise in productivity.

“Looking at the Arctic Ocean from space, it’s difficult to see water at all, as much of the Arctic Ocean is covered by a layer of sea ice,” said lead author Jesse Farmer, a postdoctoral research associate in the Department of Geosciences at Princeton University who is also a visiting postdoctoral fellow at the Max Planck Institute for Chemistry in Mainz, Germany. This sea ice naturally expands during winters and contracts during summers. In recent decades, however, global warming has caused a rapid decline in summer sea ice coverage, with summer ice cover now roughly half that of 1979.

As sea ice melts, photosynthesizing plankton that form the base of Arctic food webs should benefit from the greater light availability. “But there’s a catch,” said contributing author Julie Granger, an associate professor of marine sciences at the University of Connecticut. “These plankton also need nutrients to grow, and nutrients are only abundant deeper in the Arctic Ocean, just beyond the reach of the plankton.” Whether plankton can acquire these nutrients depends on how strictly the upper ocean is “stratified,” or separated into layers. The upper 200 meters (660 feet) of the ocean consists of distinct layers of water with different densities, determined by their temperature and saltiness.

The Arctic Ocean’s deep past provides clues to its imminent future
These white lumps are fossilized foraminifera from an Arctic Ocean sediment core, magnified 30 times. The researchers used organic material inside these “forams” — plankton that grew in surface waters, then died and sank to the sea floor — to measure the isotopic composition of nitrogen. Credit: Jesse Farmer, Princeton University

“When the upper ocean is strongly stratified, with very light water floating on top of dense deep water, the supply of nutrients to the sunlit surface is slow,” said Farmer.×280&!1&btvi=1&fsb=1&xpc=B2oMazGoT5&p=https%3A//

New research led by scientists from Princeton University shows how the supply of nitrogen to the Arctic has changed since the last ice age, which reveals the history of Arctic Ocean stratification. Using sediment cores from the western and central Arctic Ocean, the researchers measured the isotopic composition of organic nitrogen trapped in the limestone fossils of foraminifera (plankton that grew in surface waters, then died and sank to the sea floor). Their measurements reveal how the proportions of Atlantic- and Pacific-derived nitrogen changed over time, while also tracking changes in the degree of nitrogen limitation of plankton at the surface. Ona Underwood of the Class of 2021 was a key member of the research team, analyzing western Arctic Ocean sediment cores for her junior project.

Where the oceans meet: Pacific waters float above saltier, denser Atlantic waters

The Arctic Ocean is the meeting place of two great oceans: the Pacific and the Atlantic. In the western Arctic, Pacific Ocean waters flow northward across the shallow Bering Strait that separates Alaska from Siberia. Arriving in the Arctic Ocean, the relatively fresh Pacific water flows over saltier water from the Atlantic. As a result, the upper water column of the western Arctic is dominated by Pacific-sourced nitrogen and is strongly stratified.

However, this was not always the case. “During the last ice age, when the growth of ice sheets lowered global sea level, the Bering Strait didn’t exist,” said Daniel Sigman, Princeton’s Dusenbury Professor of Geological and Geophysical Sciences and one of Farmer’s research mentors. At that time, the Bering Strait was replaced by the Bering Land Bridge, a land connection between Asia and North America that allowed for the migration of humans into the Americas. Without the Bering Strait, the Arctic would only have Atlantic water, and the nitrogen data confirm this.

The Arctic Ocean’s deep past provides clues to its imminent future
Study co-author Julie Granger sampled water from the Arctic Ocean aboard the US Coast Guard icebreaker Healy. Credit: Julie Granger, University of Connecticut

When the ice age ended 11,500 years ago, as ice sheets melted and sea level rose, the data show the sudden appearance of Pacific nitrogen in the open western Arctic basin, dramatic evidence of the opening of the Bering Strait.

“We had expected to see this signal in the data, but not so clearly!” Sigman said.

This was just the first of the surprises. Analyzing the data, Farmer also realized that, prior to the opening of the Bering Strait, the Arctic had not been strongly stratified as it is today. Only with opening the Bering Strait did the western Arctic become strongly stratified, as reflected by the onset of nitrogen limitation of plankton in the surface waters.

Heading eastward away from the Bering Strait, the Pacific-sourced water is diluted away, so that the modern central and eastern Arctic are dominated by Atlantic water and relatively weak stratification. Here, the researchers found that nitrogen limitation and density stratification varied with climate. As in the western Arctic, stratification was weak during the last ice age, when climate was colder. After the ice age, central Arctic stratification strengthened, reaching a peak between about 10,000 and 6,000 years ago, a period of naturally warmer Arctic summer temperatures called the “Holocene Thermal Maximum.” Since that time, central Arctic stratification has weakened, allowing enough deep nitrogen to reach surface waters to exceed the requirements of plankton.

Global warming is quickly returning the Arctic to the climate of the Holocene Thermal Maximum. As this warming continues, some scientists have predicted that reduced ice cover would enhance the productivity of Arctic plankton by increasing the amount of sunlight reaching the ocean. The new historical information acquired by Farmer and his colleagues suggests that such a change is unlikely for the open basin waters of the western and central Arctic. The western Arctic will remain strongly stratified due to persistent inflow of Pacific water through the Bering Strait, while the warming will strengthen stratification in the central Arctic. In both of these open ocean regions, slow nitrogen supply is likely to limit plankton productivity, the researchers concluded.

“A rise in the productivity of the open Arctic basin would likely have been seen as a benefit, for example, increasing fisheries,” said Farmer. “But given our data, a rise in open Arctic productivity seems unlikely. The best hope for a future rise in Arctic productivity is probably in the Arctic’s coastal waters.”

‘Airpocalypse’ smoke reaches North Pole for the first time ever

By Mark Puleo, AccuWeather staff writer

Updated Aug. 11, 2021 4:22 PM PDTCopied 0% This video file cannot be played.(Error Code: 232001)

The frozen ground in Siberia continues to burn, tearing through more than 3.7 million acres of forest.

Santa Claus isn’t supposed to see smoke. For the first time in recorded history, hazy smoke from raging wildfires in the Arctic has reached the North Pole, and NASA satellites have the images to prove it.

On Aug. 6, the space agency’s MODIS, an imaging sensor on the Aqua satellite, captured true-color images of what NASA called a “vast, thick, and acrid blanket of smoke” that clouded the North Pole. The smoke originated from enormous blazes in the Siberian region of northern Russia.

According to China’s Xinhua news agency, the Mongolian capital city of Ulaanbaatar was blanketed in “white smoke,” NPR reported. The republic of Yakutia – home to Oymyakon, the coldest inhabited place on Earth – has also been shrouded in smoke, as captured by MODIS images on Aug. 8.

Satellite imagery from NASA shows smoke from wildfires in the Siberian region of Russia have reached the North Pole in what the agency is calling “a first in recorded history.” (NASA)

The thick smoke in Yakutia sent air quality measurements in recent weeks plummeting to an extreme category dubbed “airpocalypse,” a category described by officials to have “immediate and heavy effects on everybody,” The Guardian reported.

In the images captured on Aug. 6, that “airpocalypse” inducing smoke was shown to have traveled 1,864 miles from Yakutia to the North Pole, according to NASA.

“The smoke, which was so thick that most of the land below was obscured from view, stretches about 2,000 miles (3,200 km) from east to west and 2,500 miles (4,000 km) from south to north,” the agency wrote. “But it captures only a small part of the smoke from the Russian fires.”

To reach Ulaanbaatar on Aug. 4, NASA added that the smoke needed to have traveled more than 1,200 miles. From there, it appeared to waft over nearly the entire Arctic Circle, impacting Nunavut, Canada, and areas of western Greenland.

Wildfires have been burning in Siberia more frequently than ever before. While the total number of burned acreage is difficult to determine in the remote area, Russia’s weather monitoring institute, Rosgidromet, said this week that close to 8.4 million acres were burning and more than 34.5 million total acres have been destroyed this season, the second-worst on record. For comparison, during the 2020 California wildfire season, which was the worst on record, just under 4.4 million acres were burned.

Smoke from the Siberian wildfires can be seen stretching across the Arctic Circle, shrouding the North Pole and impacting areas of Greenland and Canada. (NOAA/CIRA)

In the United States, Americans have seen firsthand this year how wildfire smoke can travel thousands of miles. Fires currently burning in California and Montana have drastically impacted air quality levels in cities such as Denver, located over 1,000 miles away from California’s Dixie Fire.

Americans themselves have also been on the receiving end of Siberian wildfire smoke, including in 2019 when wind currents carried smoke across the Pacific Ocean and into Alaska and northwestern Canada.

High concentrations of ‘forever’ chemicals being released from ice melt into the Arctic Ocean

JULY 27, 2021

by Lancaster University

High concentrations of ‘forever’ chemicals being released from ice melt into the Arctic Ocean
Dr Jack Garnett on the research expedition in the Arctic. Credit: Christian Morel

Known as ‘forever’ chemicals due to the fact they do not break down in the environment, poly- and perfluoroalkyl substances (PFAS) are used in a wide range of products and processes from fire proofing to stain resistant surfaces.

The Lancaster University study has found them in the surface seawater close to melting Arctic ice floes at concentrations of up to two times higher than levels observed in the North Sea, even though the region of the Barents Sea under investigation was thousands of kilometers from populated parts of Europe.

The research has shown these chemicals have traveled not by sea, but through the atmosphere, where they accumulate in Arctic sea ice. Because Arctic ice is melting more quickly than before, these harmful chemicals are efficiently released into surrounding seawater resulting in some very high concentrations.

Lancaster’s Dr. Jack Garnett and Professor Crispin Halsall along with colleagues from HZG, Germany, have been investigating the long range transport and deposition of PFAS to the Arctic as part of EISPAC—a project jointly funded by UK’s NERC and Germany’s BMBF as part of the Changing Arctic Ocean program.

PFAS comprise of a very large number of chemicals that have myriad uses, including processing aids in the manufacture of fluoropolymers like Teflon, stain and water repellents in food packaging, textiles and clothing, as well as use in firefighting foams.

One particular group of these chemicals—the perfluoroalkyl acids (PFAAs) – are extremely stable and do not degrade in the environment but can bioaccumulate and are known to be toxic to humans and wildlife.

PFAAs can enter the food chain due to their mobility in the environment and protein-binding characteristics. The longer carbon chain compounds of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are generally associated with liver damage in mammals, with developmental exposure to PFOA adversely affecting fetal growth in humans and other mammals alike.

Dr. Jack Garnett discovered an unusual phenomenon whereby PFAAs present in the atmosphere are deposited with snowfall onto the surface of ice floes where they can eventually accumulate within the sea ice. Jack made this observation while taking ice and water samples as part of a scientific expedition under the Norwegian Nansen Legacy project (×280&!1&btvi=1&fsb=1&xpc=URI40QTyKI&p=https%3A//

Undertaking both salinity and stable isotope analysis of snow, ice and seawater, he was able to determine what contribution of the water locked in snow and ice came from the atmosphere and what contribution arose from seawater. This way it was possible to assess the role that atmospheric transport from far away regions had on the presence of these chemicals in the ice.

The PFAA present in the atmospheric component was much higher than the seawater component, confirming that long range transport and deposition from the atmosphere is the main source of these chemicals to the remote Arctic rather than ‘recycling’ of older stocks of these pollutants present in ocean waters.

Furthermore, the team’s studies conducted in a sea ice facility at the University of East Anglia, found that the presence of brine (highly saline water) in young ice serves to enrich contaminants like PFAS in different layers within the sea ice. PFAS like other organic pollutants, generally reside in the brine rather than the solid ice matrix itself. As the ice ages the brine becomes more concentrated resulting in an enrichment of these pollutants into focused areas within the ice pack.

Prolonged periods of thaw, particularly when the ice floes are still covered in snow, results in the re-mobilization of the ice brine and also the interaction of snow meltwater with the brine. This can result in marked release of PFAAs into the underlying seawater.

Brine channels on the underside of ice serve as unique habitats for organisms at the base of the marine foodweb, and, as a consequence, they will be exposed to high levels of PFAAs released with brine drainage and meltwater from the thawing ice pack.

Prof Halsall a co-author of the recent Arctic Monitoring Assessment Program (AMAP) report on “POPs and Chemicals of Emerging Arctic Concern: The Influence of Climate Change,” says that we have an unfortunate situation where the Arctic Ocean is now dominated by one-year ice at the expense of multi-year ice due to global warming. Meaning that the majority of the ice in the Arctic has formed the previous winter, rather than over many years.

This one-year ice contains a lot of mobile brine that interacts with the overlying snowpack and can serve to concentrate pollutants like PFAS which are usually found at very low levels.

Unfortunately, with earlier and more erratic thaw events, this can lead to the rapid release of the stored chemicals resulting in high concentrations in the waters surrounding the ice floes.

It is only through this type of investigative science that we can understand the dynamics of pollutant behavior and identify key hazards, particularly those related to climate change.

In turn this can drive international legislation so that chemicals that exhibit this type of behavior are banned.

Explore furtherNewer PFAS compound detected for first time in Arctic seawater

Lightning Rises Sharply in the Arctic

Warmer temperatures and higher humidity may be key factors

Lightning Rises Sharply in the Arctic
Credit: Getty Images

Lightning is relatively uncommon in the Arctic—the air is usually not warm enough for thunderstorms. Now that might be changing, new data suggests.

study recently published in the journal Geophysical Research Letters finds that Arctic lightning has tripled in the last decade alone.

The researchers, led by Bob Holzworth of the University of Washington, analyzed data collected by the World Wide Lightning Location Network between 2010 and 2020. The network, operated by the University of Washington, has lightning sensors all over the world.

The new study focused on summer lightning flashes, or “strokes,” detected above 65 degrees latitude—that includes parts of northern Canada, Alaska and Russia, as well as Greenland and the central Arctic Ocean.

The data suggests that the total number of Arctic lightning strokes has risen sharply since 2010.

Still, the scientists wanted to be sure. The World Wide Lightning Location Network has added a number of sensors over the last 10 years, and the increase in strokes could have been the simple product of better detection. So the team adjusted their data to account for the new equipment.

The increase still held up.

Next, the researchers compared the rate of Arctic lightning strokes with lightning around the rest of the world. They found that the fraction of Arctic lightning compared with global lightning tripled between 2010 and 2020.

The study points out that summer temperatures in the Arctic have risen by about a half-degree Fahrenheit over the last decade.

While scientists know there’s a connection between air temperature and thunderstorms, the study doesn’t actually prove that warming has caused the lightning. It simply suggests there could be a link. More research would be needed to demonstrate the connection.

Still, other studies have suggested that continued climate change may cause an increase in Arctic thunderstorms. One recent paper, published in September in Climate Dynamics, projects that thunderstorms would triple in Alaska by the end of the century under a severe climate change scenario.

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follow-up study published last month in the same journal suggests that increased humidity, driven by warming and melting sea ice, is the driver.

More research may still be needed to determine exactly what’s going on with Arctic storms. Nature recently reported that at least one other global lightning detection network has not recorded the same increase in Arctic lightning, although its records only extend back to 2012.

But if lightning is on the rise at the top of the world, it’s worth paying attention to. Lightning can be a big driver of wildfires in the northern reaches of the world.

2017 study in Nature Climate Change found that lightning ignitions across Canada and Alaska have been steadily increasing since 1975.

Average Arctic Ocean temperatures in February warmer than past two decades

BY ZACK BUDRYK – 03/08/21 10:40 AM EST 426508

Average Arctic Ocean temperatures in February warmer than past two decades

© Cyril Christo and Marie Wilkinson

The Arctic Ocean saw February temperatures that were warmer than the past two decades’ average, according to a report released Monday by Europe’s Copernicus Climate Change Service.

Worldwide, the month’s temperatures were close to the average for the past 30 years but included the coldest anomaly in nearly six years, according to the organization’s report.

“Conditions were much colder than its 1991-2020 average over much of Russia and North America, but much warmer than average over parts of the Arctic and in a band stretching eastward from north-western Africa and southern Europe to China,” the report states. “Temperature for Europe as a whole, for February 2021, was also close to the 1991-2020 average, though parts of Europe saw considerable variation in temperatures during the month.”

Copernicus further found that the extent of sea ice was lower than average in the arctic and Antarctic regions during February, with coverage lowest compared to years past in Canada’s northeastern regions.

Other northern regions of the globe saw colder-than-average temperatures in February, particularly the northwestern regions of Russia, although Norwegian island chain Svalbard was an exception to the trend, according to the report.

Twelve-month average temperatures were the highest above the 1991-2020 average over northern Siberia and over Canada’s far northeastern regions, according to the research. They were above the 12-month average over most of the European continent except for parts of its northwestern and eastern regions.

“The average December-February temperature for Europe was 0.6°C above the 1991-2020 average for the season,” the report states. “This is 2.3°C lower than the corresponding value for 2019/20, the warmest winter average on record. Winter 2020/21 was similar in average European temperature to the winters of 2017/18 and 2018/19, but nine of the earlier winters since 1979/1980 were warmer.”

Scientists have said the warming of the earth’s poles are in part to blame for extreme weather events such as the winter weather that battered the Great Plains and Texas in February.

“It’s no secret that extreme weather events are happening more frequently,” Jennifer Francis, a senior scientist at the Woodwell Climate Research Center in Woods Hole, Mass., told Bloomberg News. “Climate scientists have been predicting this behavior for years, maybe decades, so it comes as no surprise whatsoever that we’re seeing back-to-back extremes of various types around the globe.”

Texas snowstorms are due to rapid heating of the Arctic, say scientists

A warming Arctic Circle could be responsible for bursts of cold weather in the south.

STEPHEN JOHNSON18 February, 2021

Texas snowstorms are due to rapid heating of the Arctic, say scientists

Credit: Philip via Adobe Stock

  • Winter Storm Uri brought snow and freezing temperatures to Texas this week, causing multiple deaths and damage to infrastructure.
  • Climate scientists have spent years exploring the relationship between extreme winter weather and warming temperatures in the Arctic Circle.
  • Some studies suggest that the warming Arctic disrupts a natural phenomenon known as the polar vortex, which normally contains cold air in the north.

Winter Storm Uri battered the southern U.S. this week with frigid temperatures and unusually high snowfall. In Texas, the cold weather brought widespread power outages and damage to infrastructure, contributing to at least several dozen deaths.

But while the consequences of the storm are evidence, its causes are more of a mystery. In the context of climate change, the recent weather raises an obvious question: If the climate is warming, why are some parts of the world experiencing bouts of extreme cold?

It’s a topic climate scientists have been exploring for years.

One idea centers on the pattern of cold air above the Arctic Circle. This pattern, known as the polar vortex, is an area of cold, low-pressure air that swirls in the stratosphere above Earth’s North and South poles. When it’s strong, the polar vortex spins in a regular pattern, with the jet stream serving as a barrier that keeps cold air contained in the north.

But warm weather can disrupt this system. When temperatures rise, the jet stream weakens and becomes wobbly, sometimes allowing cold air to shoot out across the planet. What may be contributing to disruptions in the polar vortex is a phenomenon called Arctic amplification, which describes how the Arctic has warmed by more than twice the global average in recent decades.

Credit: NOAA/

Although some studies suggest relationships between the warming Arctic and increased winter storms, scientists still aren’t exactly sure how Arctic climate change might be reshaping winters around the world. For example, the polar vortex is a natural phenomenon, and so some of its fluctuations could be attributed to natural variability. What’s more, other factors, like changes to Arctic atmosphere and sea ice, might also play a role.

Credit: NOAA

Given the complexity of climate systems, it’s difficult for scientists to determine how changing temperatures in one region may affect weather patterns in another. But that’s not to say they’re all in complete disagreement. A 2020 paper published in Nature, for example, commented on the “divergent consensuses” between various observational and model studies on the topic of Arctic warming and severe winter weather.

“The divide on the influence of Arctic change has contributed to the impression that this research topic is controversial and lacking consensus,” the authors wrote. “An alternative interpretation is that the wide range of results should be expected, owing to the varying approaches to studying the problem and the complexity and intermittency of Arctic/midlatitude connection.”

While scientists continue to study the relationship between the Arctic and weather patterns across the globe, other climate trends are relatively clear.

The average surface temperature of the planet has risen about 2.12 degrees Fahrenheit since the late 19th century, warming at a rate nearly 10 times faster than the planet did after the Ice Age, according to NASA. And despite warmer temperatures, the NOAA reports that the U.S. was hit by nearly twice the amount of extreme winter storms during the later half of the 20th century than the first.

Climate change and record cold: What’s behind the arctic extremes in Texas


FEBRUARY 20, 2021 / 7:20 AM / CBS NEWS

For many, especially folks who live in the South, the arctic outbreak that has gripped the nation’s heartland for the past week is the kind of cold that only happens once in a century. Countless record cold temperatures were set. Conditions overwhelmed the Texas power grid, cutting off electricity to millions and bursting water pipes, creating a humanitarian crisis.

But with climate change making for generally warmer winters and causing heat records to outnumber cold records by 2 to 1 globally over the past decade, this historic cold snap may seem counterintuitive. It’s not. In fact, paradoxically, a warmer climate may have actually contributed to the extreme cold.

The science of meteorology has come a long way in the past few decades, so much so that meteorologists saw this extreme winter weather coming many weeks in advance. That’s because this extreme pattern was initiated by a large and recognizable phenomenon which unfolded in the Arctic at the beginning of the year called Sudden Stratospheric Warming, or SSW.

CBS News previewed the wild winter weather in this January 7th article, explaining how over the course of just a few days in late December and early January, temperatures in the atmosphere high above the North Pole warmed by 100 degrees Fahrenheit — jumping from minus-110 degrees Fahrenheit to minus-10.

SSW’s are a natural occurrence which happen every couple of winters and portend extreme weather in the weeks following them. That’s because when the Arctic warms rapidly it disrupts a spinning mass of cold air — the polar vortex — a semi-permanent weather system which is present each winter. 

Normally the jet stream winds around the vortex and acts as a lasso of sorts, keeping the cold air trapped inside. But when it gets warm in the Arctic, the jet stream weakens and elongates, allowing the cold air to plunge south.

Climate Change 

This enables a broad mountain of warm air to form over the Arctic, temporarily supplanting the cold vortex. The warm mountain acts as an atmospheric block, redirecting the jet stream and bitter cold air southward.

While this bitter cold air mass was certainly memorable for the upper Midwest, it wasn’t all that out of the ordinary for them. The record set back in 1899 was much more widespread and severe in the northern tier of the U.S.

What made this particular situation historic was that the core of the cold air — a piece of the polar vortex — plunged much further south than it really ever does: a full 4,000 miles from its usual home near the North Pole.

As a result, hundreds of daily record lows were set within the past week, focused on the south-central Plains States. Dozens of all-time records were also set as the unprecedented cold gripped cities and towns unaccustomed to and unprepared for the bitter blast. The animated loop below shows monthly records in dark blue dots and all-time record cold in black dots.

This has produced some astonishing visuals. A frozen waterfall in the Ozarks of Arkansas.

And frozen swamps in Louisiana.

This comes despite a long-term trend in which winters have been warming all across the U.S. and cold has been lessening. In Minneapolis-St. Paul, for example, from 1970 to 2020 the coldest temperature of the year has edged upwards by 12.1 degrees Fahrenheit.

The recent extreme weather was not limited to the U.S. When the jet stream is extreme in one region, it is often extreme all across the globe. In Saudi Arabia, snow-covered camels made for a rare, but not unheard of, sight.

Snow also fell in Jerusalem and parts of Jordan and Syria, while at the same time record heat was impacting other parts of the Middle East like Iraq, where the temperature soared to 93 degrees in winter.

How extreme cold and extreme heat are connected

While this extreme cold paired with extreme heat may seem odd, it’s actually what meteorologists would expect of a wavy jet stream. Think of it this way: what goes up must come down. When the atmosphere forces cold air south, there must be an equal and opposite reaction forcing warm air north. When air masses are displaced into places they don’t typically visit, weather extremes and the impacts they bring to society follow.

A number of climate scientists think that climate change may not only be making sudden stratospheric warming more likely, but that climate change itself may have a similar effect in the Arctic, because it is also causing significant warming. Due to human-caused climate change, the Arctic is warming at three times the pace of the global average.

The wavy jet stream theory, as it relates to climate change, was pioneered by Dr. Jennifer Francis at Woodwell Climate Research Center. The theory makes logical sense: Arctic warming reduces the gradient between warm and cold air, and thus weakens the temperature contrast mechanism which powers the strength of the jet stream. That results in a weaker, more wavy jet stream, which is more likely to spill its cold air southward. 

The theory has since been adopted by many other climate scientists, who view the apparent increasing extremes, like this latest bitter blast, as sign the theory has merit. But a sizable group of other scientists have their doubts about the impact of climate change and Arctic amplification on the jet stream. 

That’s partly because the atmosphere is very noisy and climate models are not quite yet capable of reproducing the finer details of a complex system. Thus, finding evidence to definitively prove or disprove the theory has been a challenge. But many long-time meteorologists believe the logic, the research and the qualitative evidence they have observed is enough to make the case.

What all meteorologists and climate scientists can agree on is this extreme event was set in motion by a Sudden Stratospheric Warming. That was the driving force. 

For those tired of cold and snow, good news: it seems the extreme pattern has about run its course. The globe is about to return to a more normal pattern. That does not preclude cold air outbreaks and snowstorms for the U.S. as we head into spring, but it should allow the weather to return to some degree of normalcy.

Polar vortex to unleash frigid Arctic blast


FEBRUARY 10, 2021 / 6:53 AM / CBS NEWS

The polar vortex has become synonymous with winter’s most brutal cold. For days, the weather system has been sitting and spinning right along the U.S.-Canada border, with temperatures as low as 43 degrees below zero in northern Minnesota. 

But now, there are signs it is about to surge south, bringing with it record-shattering cold air from the far reaches of Alaska and Northern Canada. By the weekend, temperatures in Kansas City and St. Louis will be below what’s normal for Fairbanks, Alaska.

Ahead of this Arctic blast, there will be a series of winter storms along the collision zone of cold and warm air, bringing ice from Texas to Tennessee and significant snow to Washington, D.C.

The polar vortex is a sprawling area of cold upper-level low pressure that typically resides in the Arctic. But every so often, the normal winter pattern becomes disrupted, splitting the polar vortex and sending pieces flying in different directions. One of those pieces is sitting just north of the U.S.-Canada border.

This bitter airmass landed there because of a phenomenon called a sudden stratospheric warming, a natural event that occurs 50,000 to 100,000 feet above the Arctic every couple of years, throwing weather patterns off-kilter. This event is often followed by a mountain of unusually warm air near the Arctic circle that acts to reroute pieces of the cold polar vortex southward. 


This type of pattern creates extremes all over the world. For the past couple of weeks, instead of a gradual temperature gradient around the Northern Hemisphere, there have been pockets of extreme cold intermixed with record warmth.

As a result, temperatures on Tuesday dropped to 43 degrees below zero Fahrenheit in Cotton, Minnesota, which was 133 degrees colder than the hottest temperature in the U.S. — 90 degrees — in south Florida.

In a bout of weather whiplash, the bitter cold comes on the heels of one of the top 10 warmest Januarys on record in the U.S., with the highest departures from normal right where the coldest air is now.

And the most frigid air has yet to invade the U.S. Currently, record-setting high pressure, which is associated with the coldest airmasses, is building in Alaska and western Canada. It’s so cold in Saskatchewan, Canada, that residents are pulling out the old bucket of water trick, when water instantly freezes into ice crystals when it hits the air.

This most frigid airmass will begin it’s move southward, down the east slope of the Rockies on Friday. Temperatures this Valentine’s Day weekend will be 40 to 50 degrees Fahrenheit below normal throughout the middle of the country.

From Friday through Monday, more than 100 record low readings will be in jeopardy in the heartland, with temperatures as low as 40 degrees below zero in the northern Plain States and wind chills as low as 60 below on Sunday morning.


Temperatures will drop to near zero as far south as North Texas. On Sunday, temperatures in Kansas City and St. Louis, Missouri, will not climb out of the single digits, colder than the normal high temperature of 7 degrees in Fairbanks, Alaska, this time of year.

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Extreme cold will not be the only hazard. Disturbances will ride along the frontal boundary separating bitter cold to the north and warm, moist air to the south. From Wednesday through Friday snow, ice and rain will straddle the boundary, with some areas from Dallas, Texas, to Little Rock, Arkansas, to Lexington, Kentucky, getting a glaze of treacherous ice.

Washington, D.C., will be just north of the front, and for the nation’s capital, that means mainly snow. From Wednesday afternoon through Friday morning, the area will pick up an extended period of intermittent light to moderate snowfall. In total, from West Virginia to Roanoke and Northern Virginia a general 5 to 10 inches will accumulate.


Further north in New York City, the cold-dry airmass will block the storm system, keeping it to the south. While snow showers will fly on Thursday and Friday, they will not amount to much. That is, until Sunday, when a stronger storm looks to take aim at the rest of the Northeast. If it materializes, another significant snow and ice storm may be in the cards.

Biden takes Day One action to protect Arctic lands and waters

January 22, 2021 By Tim Woody

Animals from the Porcupine Caribou Herd in the Arctic Refuge
The Hulahula River runs from Alaska’s Brooks Range to the cArctic Refuge’s coastal plain, which is the calving ground of the Porcupine Caribou Herd.EDWARD BENNETT/BENNETT IMAGES LLC

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After Trump’s sell off, the Arctic Refuge gets a reprieve

Just hours after being sworn into office, President Biden took a number of monumental actions to protect public lands, address the climate crisis and combat systemic racism, including an executive order that places a moratorium on all oil and gas activity in the Arctic National Wildlife Refuge.

This occurred only one day after the previous administration issued leases for drilling in the refuge’s coastal plain in a rushed, flawed and likely illegal process.

Biden’s action was met with great enthusiasm, particularly by many Gwich’in and Iñupiat peoples who have depended on and protected the refuge for thousands of years and rely on the caribou and other resources in the refuge to sustain their communities and cultures.

“Mashi’ choo, President Biden,” said Bernadette Demientieff, executive director of the Gwich’in Steering Committee. “The Gwich’in Nation is grateful to the president for his commitment to protecting sacred lands and the Gwich’in way of life.”

The executive order also reinstated President Obama’s withdrawal of most of the Arctic Ocean and parts of the Bering Sea from oil and gas drilling—an order that had been reversed by the Trump administration. Protecting offshore areas from the threat of a major oil spill benefits not only marine species such as fish, seals and bowhead whales, but the coastlines of sensitive lands like the Arctic Refuge, too.

We are grateful to President Biden for his commitment to protect the refuge, address the climate crisis and respect the human rights of Indigenous peoples. We are also grateful to the millions of people who made today’s announcement possible by putting the climate and social justice first. This action is a result of years of advocacy from people across the United States, including members and supporters of The Wilderness Society, who refused to stay silent as oil corporations and their friends sought to put drilling rigs in the Arctic Refuge.

This action is a result of years of advocacy from people across the United States, including members and supporters of The Wilderness Society.

This does not mean the fight to protect the Arctic Refuge and the calving grounds of the Porcupine Caribou Herd is over. The moratorium is temporary. But it’s a huge first step in Biden’s plan to review the legality of the Jan. 6 Arctic Refuge lease sale and the issuance of leases to the winning bidders.

We will continue to work with our Gwich’in and Iñupiat partners—as well as the Biden administration and our allies in the Congress and the conservation community—as we explore all options for ensuring that drilling never occurs on the coastal plain of the Arctic Refuge. We’ll also keep putting pressure on corporations like banks and insurers.

But today we rest, raise a glass and celebrate a new day for the Arctic.