Tag: Arctic

Arctic Climate Change Update 2021: Arctic warming three times faster than the planet

by oceanecology, posted in News

Arctic Monitoring and Assessment Programme (AMAP)

The Arctic has warmed three times more quickly than the planet as a whole, and faster than previously thought according to the newly published ‘Arctic Climate Change update 2021’.

Arctic sea ice looks set to be an early victims of rising temperatures, with each fraction of a degree making a big difference: the chance of it disappearing entirely in summer is 10 times greater if Earth warms by 2 degrees Celsius above pre-industrial levels compared to 1.5C, the goal set by the 2015 Paris Accord.

The finding comes from the Arctic Monitoring and Assessment Programme (AMAP) in their new report.

In less than half a century, from 1971 to 2019, the Arctic’s average annual temperature rose by 3.1C, compared to 1C for the planet as a whole.

That’s more than previously suspected. In a 2019 report on Earth’s frozen spaces, the UN’s Intergovernmental Panel on Climate Change (IPCC) concluded that Arctic surface air temperature has likely increased “by more than double the global average”.

According to researchers, a turning point came in 2004 when the temperature in the Arctic surged for largely unexplained reason.

Since then, warming has continued at a rate 30 percent higher than in previous decades.

Warming has immediate consequences for the Arctic ecosystem, including changes in habitat, food habits and interactions between animals and the migration of some species.

The warming and freshening of the Arctic Ocean directly and indirectly affect the lifecycles of marine species, leading to changes in seasonality, range shifts, and broad changes in ocean ecosystems.

The decline in sea ice affects marine ecosystems through changes in the open water areas and increases in the length of the open water period (both of which affect phytoplankton and ice algae, including the timing of phytoplankton blooms), as well as under-ice productivity and diversity. These changes are having cascading effects through ecosystems, with widespread impacts on the distribution, seasonality, and abundance of a variety of species.

Migrating narwhals

Satellite data show an increasing trend in primary production in all regions of the Arctic Ocean over the past two decades, explained by complex changes in light and nutrient conditions. The consequences of warming near the ocean surface on primary producers in the surface and subsurface ocean layers are still poorly understood, and there is new evidence that dominant Arctic phytoplankton species may be able to adapt to higher temperatures.

Phytoplankton bloom in northern Norway. NASA

Changes in the Arctic Ocean gateways

Warmer waters from the Pacific and Atlantic are also pushing farther into the Arctic Ocean, with widespread impacts on ocean ecosystems. The composition of Arctic plankton communities that form the basis of marine food webs is changing, as are the distribution and abundance of a variety of invertebrate, fish, and marine mammal species.

Find the summary report here:

https://www.amap.no/documents/doc/arctic-climate-change-update-2021-key-trends-and-impacts.-summary-for-policy-makers/3508

Potentially toxic plankton algae may play a crucial role in the future Arctic

by oceanecology, posted in News, Research article

As the sea ice shrinks in the Arctic, the plankton community that produces food for the entire marine food chain is changing. New research shows that a potentially toxic species of plankton algae that lives both by doing photosynthesis and absorbing food may become an important player in the Arctic Ocean as the future sea ice becomes thinner and thinner.

Microscopic plankton algae, invisible to the naked eye, are the foundation of the marine food web, feeding all the ocean´s living creatures from small crustaceans to large whales. Plankton algae need light and nutrients to produce food by photosynthesis.

A thick layer of sea ice – sometimes covered with snow – can reduce how much sunlight penetrates into the water and stop the algae getting enough light. However, as the sea ice is becoming thinner and less widespread in the Arctic, more and more light is penetrating into the sea. Does this mean more plankton algae and thus more food for more fish, whales and seabirds in the Arctic? The story is not so simple.

More light in the sea will only lead to a higher production of plankton algae if they also have enough nutrients – and this is often not the case. With the recent increase in freshwater melt from Arctic glaciers and the general freshening of the Arctic Ocean, more and more fresh and nutrient-depleted water is running out into the fjords and further out into the sea. The fresher water lies on top of the more salty ocean and stops nutrients from the deeper layers from mixing up towards the surface where there is light. And it is only here that plankton algae can be active.

Mixotrophic algae play on several strings

However, a new study published in the journal Nature – Scientific Reports shows that so-called mixotrophic plankton algae may play a crucial role in the production of food in the Arctic Sea.

When the spring sets in in the Arctic, the metre-thick sea ice begins to melt. Melt ponds on the surface of the sea ice bring so much sunlight into the underlying seawater that the mixotrophic plankton algae start to grow dramatically. During an approx. 9-day period, the plankton can produce up to half of the total annual pelagic production in the high-Arctic fjord, Young Sound, in northeast Greenland. Several mixotrophic algae species are toxic. Photo credit: Lars Chresten Lund Hansen and Dorte H. Søgaard

Mixotrophic algae are small, single-celled plankton algae that can perform photosynthesis but also obtain energy by eating other algae and bacteria. This allows them to stay alive and grow even when their photosynthesis does not have enough light and nutrients in the water.

In northeast Greenland, a team of researchers measured the production of plankton algae under the sea ice in the high-Arctic fjord Young Sound, located near Daneborg.

“We showed that the plankton algae under the sea ice actually produced up to half of the total annual plankton production in the fjord,” says Dorte H. Søgaard from the Greenland Climate Research Centre, Greenland Institute of Natural Resources and the Arctic Research Centre, Aarhus University, who headed the study.

“Mixotrophic plankton algae have the advantage that they can sustain themselves by eating other algae and bacteria as a supplement to photosynthesis when there isn’t enough light. This means that they are ready to perform photosynthesis even when very little light penetrates into the sea. In addition, many mixotrophic algae can live in relatively fresh water and at very low concentrations of nutrients – conditions that often prevail in the water layers under the sea ice in the spring when the ice melts,” Dorte H. Søgaard explains.

Toxic algae kill fish

For nine days, the researchers measured an algal bloom driven by mixotrophic algae occurring under the thick but melting sea ice in Young Sound during the Arctic spring in July, as the sun gained more power and more melt ponds spread across the sea ice, gradually letting through more light.

The algae belong to a group called haptophytes. Many of these algae are toxic, and in this study they bloomed in quantities similar to those previously observed in the Skagerrak near southern Norway. Here, the toxic plankton algae killed large amounts of salmon in Norwegian fish farms.

“We know that haptophytes often appear in areas with low salinity – as seen in the Baltic Sea, for example. It is therefore very probable that these mixotrophic-driven algae blooms will appear more frequently in a more freshwater-influenced future Arctic Ocean and that this shift in dominant algae to a mixotrophic algae species might have a large ecological and socio-economic impact.” says Dorte H. Søgaard.

The researchers behind the project point out that it is the first time that a bloom of mixotrophic algae has been recorded under the sea ice in the Arctic.

More information: An under-ice bloom of mixotrophic haptophytes in low nutrient and freshwater-influenced Arctic waters.http://www.nature.com/articles/s41598-021-82413-y

Record-high Arctic freshwater will flow to Labrador Sea, affecting local and global oceans

by oceanecology, posted in News, Research article

Freshwater is accumulating in the Arctic Ocean. The Beaufort Sea, which is the largest Arctic Ocean freshwater reservoir, has increased its freshwater content by 40% over the past two decades. How and where this water will flow into the Atlantic Ocean is important for local and global ocean conditions.

A new study shows that this freshwater travels through the Canadian Archipelago to reach the Labrador Sea, rather than through the wider marine passageways that connect to seas in Northern Europe. The open-access study was published in Nature Communications.

“The Canadian Archipelago is a major conduit between the Arctic and the North Atlantic,” said lead author Jiaxu Zhang, a UW postdoctoral researcher at the Cooperative Institute for Climate, Ocean and Ecosystem Studies. “In the future, if the winds get weaker and the freshwater gets released, there is a potential for this high amount of water to have a big influence in the Labrador Sea region.”

The finding has implications for the Labrador Sea marine environment, since Arctic water tends to be fresher but also rich in nutrients. This pathway also affects larger oceanic currents, namely a conveyor-belt circulation in the Atlantic Ocean in which colder, heavier water sinks in the North Atlantic and comes back along the surface as the Gulf Stream. Fresher, lighter water entering the Labrador Sea could slow that overturning circulation.

A simulated red dye tracer released from the Beaufort Gyre in the Artic Ocean (center top) shows freshwater transport through the Canadian Arctic Archipelago, along Baffin Island to the western Labrador Sea, off the coast of Newfoundland and Labrador, where it reduces surface salinity.

“We know that the Arctic Ocean has one of the biggest climate change signals,” said co-author Wei Cheng at the UW-based Cooperative Institute for Climate, Ocean and Atmosphere Studies. “Right now this freshwater is still trapped in the Arctic. But once it gets out, it can have a very large impact.”

Fresher water reaches the Arctic Ocean through rain, snow, rivers, inflows from the relatively fresher Pacific Ocean, as well as the recent melting of Arctic Ocean sea ice. Fresher, lighter water floats at the top, and clockwise winds in the Beaufort Sea push that lighter water together to create a dome.

When those winds relax, the dome will flatten and the freshwater gets released into the North Atlantic.

“People have already spent a lot of time studying why the Beaufort Sea freshwater has gotten so high in the past few decades,” said Zhang, who began the work at Los Alamos National Laboratory. “But they rarely care where the freshwater goes, and we think that’s a much more important problem.”

Using a technique Zhang developed to track ocean salinity, the researchers simulated the ocean circulation and followed the Beaufort Sea freshwater’s spread in a past event that occurred from 1983 to 1995.

Their experiment showed that most of the freshwater reached the Labrador Sea through the Canadian Archipelago, a complex set of narrow passages between Canada and Greenland. This region is poorly studied and was thought to be less important for freshwater flow than the much wider Fram Strait, which connects to the Northern European seas.

In the model, the 1983-1995 freshwater release traveled mostly along the North American route and significantly reduced the salinities in the Labrador Sea — a freshening of 0.2 parts per thousand on its shallower western edge, off the coast of Newfoundland and Labrador, and of 0.4 parts per thousand inside the Labrador Current.

The volume of freshwater now in the Beaufort Sea is about twice the size of the case studied, at more than 23,300 cubic kilometers, or more than 5,500 cubic miles. This volume of freshwater released into the North Atlantic could have significant effects. The exact impact is unknown. The study focused on past events, and current research is looking at where today’s freshwater buildup might end up and what changes it could trigger.

“A freshwater release of this size into the subpolar North Atlantic could impact a critical circulation pattern, called the Atlantic Meridional Overturning Circulation, which has a significant influence on Northern Hemisphere climate,” said co-author Wilbert Weijer at Los Alamos National Lab.

More information: https://www.nature.com/articles/s41467-021-21470-3

Are cold winters in Europe caused by melting sea-ice in the Arctic?

by oceanecology, posted in News, Research note

They are diligently stoking thousands of bonfires on the ground close to their crops, but the French winemakers are fighting a losing battle. An above-average warm spell at the end of March has been followed by days of extreme frost, destroying the vines with losses amounting to 90 percent above average. The image of the struggle may well be the most depressingly beautiful illustration of the complexities and unpredictability of global climate warming. It is also an agricultural disaster from Bordeaux to Champagne.

Nasa

It is the loss of the Arctic sea-ice due to climate warming that has, somewhat paradoxically, been implicated with severe cold and snowy mid-latitude winters.

“Climate change doesn’t always manifest in the most obvious ways. It’s easy to extrapolate models to show that winters are getting warmer and to forecast a virtually snow-free future in Europe, but our most recent study shows that is too simplistic. We should beware of making broad sweeping statements about the impacts of climate change.” Says professor Alun Hubbard from CAGE Center for Arctic Gas Hydrate, Environment and Climate at UiT The Arctic University of Norway.

Melting Arctic sea ice supplied 88% of the fresh snow

Hubbard is the co-author of a study in Nature Geoscience examining this counter-intuitive climatic paradox: A 50% reduction in Arctic sea-ice cover has increased open-water and winter evaporation to fuel more extreme snowfall further south across Europe.

The study, led by Dr. Hanna Bailey at the University of Oulu, Finland, has more specifically found that the long-term decline of Arctic sea-ice since the late 1970s had a direct comparison to one specific weather event: “Beast from the East”—the February snowfall that brought large parts of the European continent to a halt in 2018, causing £1bn a day in losses.

Researchers discovered that atmospheric vapor traveling south from the Arctic carried a unique geochemical fingerprint, revealing that its source was the warm, open-water surface of the Barents Sea, part of the Arctic Ocean between Norway, Russia, and Svalbard. They found that during the “Beast from the East,” open-water conditions in the Barents Sea supplied up to 88% of the corresponding fresh snow that fell over Europe.

Climate warming is lifting the lid off the Arctic Ocean

“What we’re finding is that sea-ice is effectively a lid on the ocean. And with its long-term reduction across the Arctic, we’re seeing increasing amounts of moisture enter the atmosphere during winter, which directly impacts our weather further south, causing extreme heavy snowfalls. It might seem counter-intuitive, but nature is complex and what happens in the Arctic doesn’t stay in the Arctic.” says Bailey.

When analyzing the long-term trends from 1979 onwards, researchers found that for every square meter of winter sea-ice lost from the Barents Sea, there was a corresponding 70 kg increase in the evaporation, moisture, and snow falling over Europe.

“This study illustrates that the abrupt changes being witnessed across the Arctic now, really are affecting the entire planet,” says professor Hubbard.

Their findings indicate that within the next 60 years, a predicted ice-free Barents Sea will likely become a significant source of increased winter precipitation—be it rain or snow—for Europe.

More information: Hannah Bailey et al, Arctic sea-ice loss fuels extreme European snowfall, Nature Geoscience (2021). DOI: 10.1038/s41561-021-00719-y

Provided by UiT The Arctic University of Norway