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The State of the Polar 2018 Making Sense of Our Changing State of the Polar Oceans

Polar oceans are part of a global feedback loop, infl uenced by our actions and in turn exerting infl uence over us.

Formationrmation

The oceans have absorbed more than 90% of the Surface Current extra heat due to global warming, with the polar oceans playing the key role Deep in this uptake. Formation

Antarctica

Deep Current

2 SouthernSSouthern OceOceanan State of the Polar Oceans

Contents

Foreword 4 How the polar oceans shape the world 6 The polar oceans today, and tomorrow 8 How technology supports polar ocean research 12 Contributors 14

36°C - the amount that the atmosphere would have warmed by if none of the heat trapped by greenhouse gases had been absorbed by the world’s oceans.

3 State of the Polar Oceans

Foreword

The vast frozen of the Polar are a major component of the ’s global system.

The polar oceans are amongst the least understood Over decades studies have shed new light on the environments on our planet. They respond to global consequences of the shrinking ice for ocean temperature change; absorb heat and carbon circulation, climate and the . Surveys from the atmosphere, including that produced by of the deep ocean have yielded vital discoveries humans; they sustain millions of seabirds, about marine and informed an and fi sh; and provide food for a hungry world. international census of . Long-term studies These oceans keep our planet cool and supply have helped understand the marine food chain, other oceans with nutrients. But, because of and have provided critical scientifi c information to their remoteness and inhospitable , data underpin the sustainableRRS management of fi sheries. west of the Peninsula coverage is extremely sparse. The report demonstrates(Pete Bucktrout,that we areBritish advancing Antarctic Survey) our Understanding the polar oceans is absolutely key understanding. There remains, however, an urgent to understanding the big questions about our need for further investigations if we are to be, as we global environment. By working together scientists absolutely must, able to provide the understanding create observing systems to collect and interpret needed to help people live with, and adapt to, crucial scientifi c data that shapes policy, protects environmental change. the environment and ultimately improves people’s lives. Recent technological advances mean that Professor Dame Jane Francis scientists can now combine high-quality land and Director, ship-based observations with high-quality satellite Associate Professor Dr Ole Arve Misund data from previously-inaccessible areas. Director, Norwegian Polar Institute

4 State of the Polar Oceans

Scientists conduct a wide range of multi-disciplinary polar science on board state-of-the-art ice-strengthened research ships (Image: British Antarctic Survey). 5 State of the Polar Oceans

How the polar oceans shape our world

Many species depend on the polar oceans for food The polar oceans are and reproduction. Millions of seabirds, whales and inextricably linked to the rest fi sh all rely on the unique biodiversity of the polar oceans for their survival. Humans, too, benefi t from of our planet in many diverse the polar-ocean : more than seven and multilayered ways. million tonnes of fi sh is caught from Arctic annually, equivalent to ten per cent of the global fi n fi sh catch. The ecosystem is The role they play in the global ecosystem is founded upon Antarctic which, with up to 400 indispensable. They serve as the heart and lungs of trillion individuals, represents one of the largest our planet’s complex circulatory system, provide biomasses of any individual species. food for millions of people and support a huge variety of marine life, both native and migratory. The polar oceans are already economically signifi cant, and likely to become more so in the The polar oceans control global temperatures. future. Reduced Arctic is opening up access Despite accounting for around 20 per cent of the to oil, gas and reserves; the Arctic is thought world’s ocean surface these cold absorb to contain more than 20 per cent of the world’s more than 75 per cent of the total amount of heat undiscovered, recoverable oil and gas. The Protocol absorbed by all of our oceans. The polar oceans on Environmental Protection to the Antarctic are the biggest contributors to a global marine Treaty prohibits commercial mining activities in the heatsink that has taken up more than 90 per cent of southern , but fi shing and tourism activities all the extra heat trapped in the Earth system since there are of growing economic signifi cance. the industrial revolution began. The provides food and economic The polar oceans absorb much of the human- opportunities for indigenous communities who made carbon dioxide that our seas remove from have been living in the Arctic’s coastal regions our atmosphere: the Southern Ocean alone soaks for centuries. These communities possess intimate up around 40 per cent of all the carbon our oceans knowledge of the Arctic environment, and are extract from the air. profoundly aware of its changes. Temperature changes, both within the polar oceans With so many connections to global systems, the and in the air above them, have a pronounced polar oceans cannot be considered in isolation. effect on global sea levels: modest warming can They are part of a multidisciplinary global system, increase the amount of glacial ice that melts into infl uenced by our actions and in turn exerting our seas. The effect is compounded by thermal infl uence over us. expansion, as warmer water takes up more space. It is this multifaceted integration that gives us the The polar oceans drive global ocean circulation, ability to use our observations from these regions to moving gases, dissolved and organic improve our predictions of changes elsewhere. As matter around our planet and injecting new polar science continues to evolve its technologies waters into our seas. Nutrients exported from the and techniques, our understanding of the polar biologically rich Southern Ocean sustain as much as oceans’ relationship with the rest of the planet three-quarters of global ocean – and accordingly the global consequences of outside the Southern Ocean, underpinning marine change in these remote parts of the world – will food chains worldwide. continue to grow.

6 State of the Polar Oceans

South Orkney Islands Southern Shelf MPA is the world’s fi rst MPA in international Antarctic waters, covering 94 000 km2 in the south Atlantic.

Many species depend on the polar oceans for food and reproduction – Millions of seabirds, whales and fi sh rely on the unique biodiversity of the polar oceans.

72% of the MPA – which is the world’s largest marine reserve – is closed to commercial fi shing. Other sections provide for some highly regulated harvesting and krill research fi shing.

ROSS SEA

The Ross Sea is home to large percentages of the world’s Adélie , , , and killer populations. 7 State of the Polar Oceans

The polar oceans today, and tomorrow

International research has , circulation and stratifi cation In the Arctic, there is evidence that properties of shown beyond doubt that the the ocean related to heat, freshwater and energy polar oceans are changing – are changing quite rapidly and with increasing regional variability, and this has an impact on and in many areas the rate of global circulation and distribution of nutrients and that change is accelerating. carbon dioxide. The amount of freshwater and reduction in sea Observations collected over decades in the ice affect the marine life. Freshwater has been Arctic and Antarctic have helped reveal the accumulating in the Canadian Basin and around causes of these changes, and informed detailed , increasing stratifi cation there. At the scientifi c models enabling the prediction of future same time, warm and nutrient-rich Atlantic water trends. Working in collaboration with international entering the less sea-ice-covered Eurasian Basin colleagues, UK and Norwegian scientists are appears to be in closer contact with the productive studying every aspect of polar ocean change. surface layer and the sea ice above it, than before. Microscopic plant-like organisms known as , which underpin the ocean food chain and help oxygenate the sea, require both sunlight and nutrients, so they cannot grow without resupply of nutrients either from deeper waters or from elsewhere in the ocean via currents. While this mixing is inhibited in the stratifi ed ocean, it is still provoked to some extent by storms and currents, and reduced surface ice is also creating more opportunities for upper-layer phytoplankton growth. In the Southern Ocean, the Antarctic Circumpolar Current, driven by strong westerly , has not changed its fl ow signifi cantly despite those winds becoming stronger and moving further south. This is attributed to an increase in the intensity of ocean eddies, which are expected to continue to grow in strength in future years. These strong winds also bring nutrient-rich deep waters up to the sunlit surface, providing phytoplankton with the food for growth. These organisms in turn not only support marine life, but also absorb carbon dioxide, increasing the ocean’s ability to act as a for greenhouse-gas Data from shipborne research programmes reveal that the polar oceans are changing. emissions. (Image: UiT The Arctic University of )

8 State of the Polar Oceans

Temperature changes and sea ice The polar oceans are warming up: summer surface In the Southern Ocean, which has accounted for temperatures in large parts of the Arctic Ocean the largest proportion of the total ocean uptake of are now 2–3°C warmer than the 1982–2010 mean. extra heat since the start of the industrial era, the Unsurprisingly, the warming of the Arctic Ocean is picture is more variable. The greatest increase in having a dramatic effect on Arctic sea ice. Satellite temperature has been recorded in the shallowest records have revealed a signifi cant decrease in 2,000m of the sea, but this does not apply to the sea ice extent in all months, especially in summer. southernmost part of the ocean, where ongoing There has been a reduction in summer sea ice upwelling of colder, deeper waters is helping to extent from about 7 million square kilometres in maintain a more constant surface temperature. the late 1970s to around 4 million square kilometres Despite increasing temperatures, Southern Ocean in 2017; a reduction of nearly 50%. Furthermore, sea-ice extent has actually increased overall during time-series analysis of UK submarine records, and the last few decades – though there is signifi cant measurements covering the sea-ice export from regional variation. This is due to a complex interplay the Arctic Ocean through Strait, concluded of factors including reduced ozone over , that the mean thickness has declined by more than strengthening winds creating areas of open water in 40%. Taken together these changes have led to a which sea ice is more likely to form, and less ocean fundamental shift in the sea ice regime in the Arctic; mixing due to increased freshwater input from the the is no longer dominated by a thick multi- Antarctic . year ice. Instead it is controlled by thinner, more dynamic, fi rst year ice. This counterintuitive development is a perfect illustration of the complexity of the polar ocean systems, where environmental changes are the result of interactions between a myriad of elements including solar , the atmosphere, the ocean and ice. Such complexity makes predicting future change a formidable challenge, but by gathering more evidence, improving technology and evolving numerical models, polar scientists are increasing their ability to draw meaningful conclusions that provide a basis for policy and business decisions.

Summer sea ice in the Arctic has reduced in both area and thickness since the late 1970s. + 2–3°C

The Arctic Ocean is now 2-3 degrees warmer than the 1982-2010 mean.

2018 1979

9 State of the Polar Oceans

Krill fi sheries and Oxygen levels in the world’s oceans have areas that have warmed over recent decades. Krill decreased by an average of two per cent in are sensitive to environmental conditions: they the last 50 years, but nowhere is this trend more benefi t from sea ice to protect their young and prevalent than in the Arctic Ocean. The change adults grow best in cool waters. Increased carbon is a further consequence of stratifi cation, which dioxide levels also make their eggs less likely to prevents deep, oxygen-depleted waters from hatch. These conditions will become less favourable reaching and absorbing oxygen from the surface. for krill and other animals in some areas if climate Because warm water is able to hold less oxygen change continues unabated into the future. than cold, rising temperatures are also restricting the The current annual catch equates to ocean’s ability to absorb oxygen. less than 0.1 per cent of their estimated . Reduced oxygen in Arctic seawater will ultimately Management of this fi shery is part of a wider system of impact on fi sh stocks, causing fi sh to grow more conservation of Southern Ocean marine living resources slowly, to reach smaller sizes, and to produce fewer which includes a developing network of Marine offspring. This will have ramifi cations all the way up Protected Areas (MPAs). Understanding how the krill the food chain, affecting both fi sheries and the stock and the fi sh, seals, seabirds and whales that indigenous and local communities who source their depend on it will respond to climate change is critical food from the seas. for ensuring that the fi shery is well managed into the future. Scientists monitor the krill stock and its predators Increased acidity is changing the workings of the using a variety of research methods. These include , promoting growth of some modelling and comparisons between areas that are while hampering the ability of other open to human activities, including krill fi shing, and species to form protective shells. those where very little human activity takes place. A in the Southern Ocean, Antarctic MPAs enable these studies to contribute to krill is found in its highest abundance in the international policy decisions aimed at protecting Sea and the seas around the , and preserving marine species, biodiversity, and food security. International collaboration, including UK and Norwegian science projects, has advanced our understanding of polar marine ecosystems and the challenges they face. By addressing these major issues in polar and conservation, scientists continue to deepen their understanding of the effects of climate change, fi shing and , and advise on policy measures to protect vulnerable species, preserve biodiversity, improve fi shery management and maintain food security.

Penguins, seals, whales and fi sh feed on krill (Image: British Antarctic Survey).

10 State of the Polar Oceans

Plastics Some three-quarters of all of the litter in our oceans Microplastics are plastic particles smaller than 5mm is believed to be plastic, and every year the global in diameter. They enter the oceans from items such population adds another fi ve million tonnes to our as toothpaste, shower gels and clothing, or form as seas. In the polar oceans, the British Antarctic Survey larger plastic items break down. Tests have shown has been monitoring the presence of large plastic that a single polyester fl eece jacket can release items for more than 30 years, but more recently more than 1,900 microplastic fi bres per wash. scientists have become aware of the accumulation A Norwegian study recently found up to 234 of much smaller plastic debris: microplastics. microplastic particles in a single litre of melted Arctic sea ice. Once these particles enter the seas they The Southern Ocean absorbs billions are ingested by sea creatures who mistake them of tonnes of carbon dioxide from the for food. The long-term effects of this are uncertain, atmosphere every year. Processes within but scientists are initiating monitoring programmes the Arctic Ocean bury and store carbon of plastic levels in both polar oceans, and working for thousands of years. to understand the effect this proliferation of plastic waste is having on polar ecosystems.

Plastic debris is found in both polar oceans (Image: Shutterstock).

11 State of the Polar Oceans

How technology supports polar ocean research

Technological progress is bringingringing ggreaterreater The polar oceans are automation and huge improvementsrovements the least understood bodies in connectivity now enable data to be collected remotely, in realeal ttime,ime, of water on our planet. from across a network of ocean-goingcean-going sensors. This exponential growthowth iinn data Their remoteness, vastness and inhospitable in turn feeds into more advancedanced aandnd environment all present signifi cant challenges when accurate numerical models,s, whwhichich gathering data and conducting science. However, estimate change more preciselycisely and advances in technology are creating opportunities reduce uncertainty in climateate ppredictions.redictions. for data collection that go far beyond what was More immediately, the extraa data also possible even a couple of decades ago. enables improved weatherrf forecasting.orecasting. The international polar science community now has The drive for improved technologieshnologies access to polar observing systems that are more creates opportunities for high-techgh-tech stable, durable and capable than ever before. industry. Development of thesehese Robotic profi ling fl oats alone have allowed scientists systems requires highly-skilleded workers, to gather almost ten times as much temperature and climate scientists and softwaresoftware data from the seas in the 2000s as they were able experts are needed to makeke bbestest to in the 1980s, while UK and Norway researchers use of them. Systems capableble ooff collaborating on numerous Arctic projects have operating in the hostile polarar oceans exploited systems including time-series moorings, are also likely to have applicationscations inin ice-tethered platforms and satellite tagging of seals. other extreme environments.ts. Scientists are beginning to overcome the strong seasonal bias that has traditionally been present in polar research. In the Arctic Ocean, data is now collected consistently throughout the year through a combination of shipborne, autonomous and moored sensors. In the more remote and turbulent Southern Ocean, data collection still takes place predominantly during the austral summer, but this seasonality is becoming less pronounced.

12 Towed bongo nets on the back deck of RRS James Clark Ross in the Southern Ocean (Peter Enderlein, British Antarctic Survey)

13 State of the Polar Oceans

Contributors

Michael Meredith1, Arild Sundfjord2, Stephanie Henson3, Andrew Meijers1, Eugene Murphy1, Richard Bellerby4, Malin Daase5, Finlo Cottier5/6, Mark Belchier1, Melissa Chierici7/10, Ingrid Ellingsen8, Stig Falk-Petersen9, Simeon Hill1, Paul Holland1, Geraint Tarling1, Phil Trathan1, John Turner1, Jeremy Wilkinson1, Layla Batchellier1, Linda Capper1, Jamie Oliver1

1 6 7

2 8

3 9

4 5 10

Edited by James Burton (JB Editorial) Graphics and layout by Ralph Design Ltd Published by British Antarctic Survey, 2018

14 State of the Polar Oceans

Polar bear on sea ice north of Nordaustlandet, Svalbard (Image: Angelika Renner, British Antarctic Survey). 15 Produced with fi nancial support from the Foreign and Commonwealth Offi ce as part of the UK-Norway Memorandum of Understanding on Polar Research and Cultural Heritage www.gov.uk/government/publications/uk-norway-memorandum-of-understanding-on-polar-research-and-cultural-heritage