Two-thirds of the world’s oceans fall outside national jurisdictions – they belong to no one and everyone.
These international waters, known as the high seas, harbour a plethora of natural resources and millions of unique marine species.
But they are being damaged irretrievably. Research shows unsustainable fisheries are one of the greatest threats to marine biodiversity in the high seas.
According to a 2019 global assessment report on biodiversity and ecosystem services, 66% of the world’s oceans are experiencing detrimental and increasing cumulative impacts from human activities.
In the high seas, human activities are regulated by a patchwork of international legal agreements under the 1982 UN Convention on the Law of the Sea (UNCLOS). But this piecemeal approach is failing to safeguard the ecosystems we depend on.
A decade ago, world leaders updated an earlier pledge to establish a network of marine protected areas (MPAs) with a mandate to protect 10% of the world’s oceans by 2020.
But MPAs cover only 7.66% of the ocean across the globe. Most protected sites are in national waters where it’s easy to implement and manage protection under the provision of a single country.
In the more remote areas of the high seas, only 1.18% of marine ecosystems have been gifted sanctuary.
The Southern Ocean accounts for a large portion of this meagre percentage, hosting two MPAs. The South Orkney Islands southern shelf MPA covers 94,000 square kilometres, while the Ross Sea region MPA stretches across more than 2 million square kilometres, making it the largest in the world.
The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is responsible for this achievement. Unlike other international fisheries management bodies, the commission’s legal convention allows for the closing of marine areas for conservation purposes.
A comparable mandate for MPAs in other areas of the high seas has been nowhere in sight — until now.
In 2017, the UN started negotiations towards a new comprehensive international treaty for the high seas. The treaty aims to improve the conservation and sustainable use of marine organisms in areas beyond national jurisdiction. It would also implement a global legal mechanism to establish MPAs in international waters.
This innovative international agreement provides an opportunity to work across institutional boundaries towards comprehensive high seas governance and protection. It is crucial to use lessons drawn from existing high seas marine protection initiatives, such as those in the Southern Ocean, to inform the treaty’s development.
The final round of treaty negotiations is pending, delayed by the COVID-19 pandemic, and significant detail within the treaty’s draft text remains undeveloped and open for further debate.
Lessons from Southern Ocean management
CCAMLR comprises 26 member states (including the European Union) and meets annually to make conservation-based decisions by unanimous consensus. In 2002, the commission committed to establishing a representative network of MPAs in Antarctica in alignment with globally agreed targets for the world’s oceans.
The two established MPAs in the high seas are far from an ecologically representative network of protection. In October 2020, the commission continued negotiations for three additional MPAs, which would meet the 10% target for the Southern Ocean, if agreed.
But not a single proposal was agreed. For one of the proposals, the East Antarctic MPA, this marks the eighth year of failed negotiations.
CCAMLR’s progress towards its commitment for a representative MPA network may have ground to a halt, but the commission has gained invaluable knowledge about the challenges in establishing MPAs in international waters. CCAMLR has demonstrated that with an effective convention and legal framework, MPAs in the high seas are possible.
The commission understands the extent to which robust scientific information must inform MPA proposals and how to navigate inevitable trade-offs between conservation and economic interests. Such knowledge is important for the UN treaty process.
As the high seas treaty moves closer to adoption, it stands to outpace the commission regarding progress towards improved marine conservation. Already, researchers have identified high-priority areas for protection in the high seas, including in Antarctica.
Many species cross the Southern Ocean boundary into other regions. This makes it even more important for CCAMLR to integrate its management across regional fisheries organisations – and the new treaty could facilitate this engagement.
But the window of time is closing with only one round of negotiation left for the UN treaty. Research tells us Antarctic decision-makers need to use the opportunity to ensure the treaty supports marine protection commitments.
Stronger Antarctic leadership is urgently needed to safeguard the Southern Ocean — and beyond.
In 2018, a map named after an oceanographer went viral.
The so-called Spilhaus projection, in which Earth is viewed from above the South Pole, was designed to show the connected nature of the ocean basins.
It is a perspective that comes naturally to those who live in the ocean-dominated southern hemisphere.
The Southern Ocean, also called the Antarctic Ocean (or even the Austral ocean), is like no other and best described in superlatives.
Storing heat and carbon
Let’s first look at the Southern Ocean’s capacity to store excess heat and carbon. The world’s oceans take up more than 90% of the excess heat generated by the burning of fossil fuels and a third of the additional carbon dioxide.
The Southern Ocean, south of 30°S, is estimated to store about 75% of this global oceanic uptake of excess heat and about 35% of the global uptake of excess carbon from the atmosphere. It is the primary storage of heat and carbon for the planet.
The Southern Ocean connects all major ocean basins, except the Arctic. The link is the Antarctic Circumpolar Current (ACC) – the largest ocean current on the planet. It carries more than 100 times the flow of all the rivers on Earth and transports enough water to fill Lake Ontario in just a few hours.
A combination of strong winds and a nearly uninterrupted passage around Antarctica give the ACC its strong flows and speed.
The Roaring Forties, Furious Fifties and Screaming Sixties are all popular names for the strong westerly winds that blow, nearly uninterrupted, across the Southern Ocean, creating equally impressive waves. This results in a massively energetic – and hard to measure – ocean surface.
But the heat and carbon exchanges across this complicated interface are globally important, and oceanographers have designed tools specifically for this challenging environment.
To really comprehend the Southern Ocean, one must think in three dimensions. Waters with different properties mix both horizontally and vertically in eddies.
Relatively warm subtropical water is mixed south, deep cool water from the North Atlantic rises back up toward the surface and colder polar water masses mix northward and sink back down.
This complex interplay is guided by the wind and by the shape of the seafloor.
To the north, there are only three major constrictions: the 850km-wide Drake Passage, and the submarine Kerguelan and Campbell Plateaus. To the south, the ACC butts up against Antarctica.
Here the ocean plays another crucial role in the global climate system by bringing relatively warm — and warming — Circumpolar Deep Water into contact with the ice fringing Antarctica.
Annual thaw and freeze of sea ice
The annual cycle of sea ice growing and melting around Antarctica is one of the defining rhythms of our planet and an important facet of the Southern Ocean. The two polar regions couldn’t be more different in this regard.
The Arctic is a small, deep ocean surrounded by land with only narrow exits. The Antarctic is a large landmass with a continental shelf surrounded by ocean. Each year, 15 million square kilometres of sea ice advance and retreat in these waters.
In contrast to the clear and dramatic changes in the north, the rhythm of Antarctic sea ice has followed less obvious patterns. In the face of a warming ocean, it was actually slowly expanding northward until around 2016, when it suddenly started to contract.
Looking at the annual cycle of Antarctic sea ice, one might think it simply grows and melts in place as things get cold and warmer through the year. But in truth, much of the sea ice production happens in polynya – sea ice factories near the coast where cold and fast Antarctic winds both create and blow away new sea ice as fast as it appears.
This process brings us back to global ocean circulation. When the new ice grows, the salt from the freezing sea water gets squeezed out and mixes with the seawater below, creating colder and saltier seawater that sinks to the seafloor and drains northward.
Polynya are in effect a metro stop on a global transport system that sees water sinking at the poles, flowing north to be mixed upwards in a cycle lasting close to 1,000 years.
Not all ice shelves respond the same
Computer simulations have shown how the ice shelves at Antarctica’s fringe have waxed and waned over past millennia.
Because these floating extensions of the ice sheet interact directly with the ocean, they make the ice sheet sensitive to climate. Ocean warming and changes in the source of the water coming into contact with an ice shelf can cause it – and in turn the whole ice sheet – to change.
But not all ice shelves will respond to warming in the same way. Some ocean cavities are cold and slowly evolving. Others are actually described as hot – in polar terms – because of their interaction with Circumpolar Deep Water. The latter are changing rapidly right now.
We can observe many cryosphere processes from space, but to truly understand how far the ocean reaches beneath the ice we have to go hundreds of metres beneath the ice surface.
Making climate predictions requires an understanding of detailed processes that happen on short timescales, such as tidal cycles, in parts of the planet we are only beginning to explore.
How do we sample something so big and so stormy? With robots.
Satellites have been observing the ocean surface since the 1980s. This technology can measure properties such as temperature and ocean surface height, and even be used to estimate biological productivity. But satellites can’t see beneath the surface.
When the game-changing Argo programme started in the 1990s, it revolutionised earth science by building a network of drifting ocean sentinels measuring temperature and salinity down to a depth of two kilometres.
The research vessel Kaharoa holds the record for the most deployments of Argo probes in the Southern Ocean, including its most recent storm-tossed, COVID-19-impacted voyage south of Australia and into the Indian Ocean.
The Argo program is only the start of a new era of ocean observation. Deep Argo probes dive to depths of 6km to detect how far down ocean warming is penetrating.
The past and future Southern Ocean
Earth hasn’t always looked as it does today. At times in the planet’s past, the Southern Ocean didn’t even exist. Continents and ocean basins were in different positions and the climate system operated very differently.
From the narrow view of human evolution, the Southern Ocean has been a stable component of a climate system and subject to relatively benign glacial oscillations. But glacial cycles play out over tens of thousands of years.
We are imposing a very rapid climate transient. The nearly three centuries since the start of the industrial revolution is shorter than the blink of an eye in geological context.
Future changes in the short (say by 2050) and long (by 2300) term are difficult to project. While the physics are relatively clear about what will happen, predicting when it will happen is more challenging.
Simulation tools that get the ocean, atmosphere and ice processes right are only starting to include ice shelf cavities and ocean eddies. The most recent synthesis of climate models shows progress in the simulated workings of the Southern Ocean. But sea ice remains a challenge to simulate well.
This is the frontier: a global research community working to connect data with rapidly improving computer models to better understand how this unique ocean operates.
Life in a sub-zero ocean
At first glance, Antarctica seems an inhospitable and almost barren environment of ice and snow, speckled with occasional seabirds and seals.
But diving beneath the surface reveals an ocean bursting with life and complex ecosystems, from single-celled algae and tiny spineless creatures to the well-known top predators: penguins, seals and whales.
It’s not easy to study life in the Southern Ocean. Waves can be more than 20 metres high, and icebergs and sea ice lurk among them.
The water temperature is often sub-zero – freshwater freezes at 0℃, but saltwater freezes at closer to -2℃. Although scuba diving is possible, a lot of research on life in the Southern Ocean is done through remote sampling.
Marine scientists use robotic tools such as remotely operated underwater vehicles to look at and collect samples, and grabs and dredges to bring up bottom-dwelling organisms. We take genetic samples from marine mammals by shooting tiny biopsy tubes (like needles), attached to a cord for retrieval, into the animal’s flesh from a distance.
We can glean wider information on diversity from environmental DNA (eDNA). Traces of organisms are filtered from samples of water and analysed using genetic tools that can usually identify what sorts of species are or were present.
Every expedition reveals new species – some of which are potentially commercially valuable, and all of which are important parts of the Southern Ocean ecosystem. Our knowledge of the diversity of the region is growing rapidly.
Nonetheless, the Southern Ocean is vast, and much of it remains either unsampled or undersampled.
Down at the bottom of the food chain
In the Southern Ocean, primary producers (organisms at the start of the food chain) range from single-celled algae – such as diatoms with intricately detailed shells made of silica – through to large macroalgae like kelp.
Kelp and other large seaweeds generally only survive where icebergs don’t often scrape the seafloor. Diatoms are diverse, and some species thrive on the underside of sea ice.
Ice algae form an important food source for krill, small crustaceans that are a critical part of Southern Ocean food webs.
Astonishingly, the cold Southern Ocean is also home to hot hydrothermal vent systems. These communities, which include huge densities of crustaceans and echinoderms, get their energy from chemicals that seep out of Earth’s crust, rather than from the Sun.
Antarctic invertebrates make up more than 90% of the species in the Southern Ocean. More than 50% are unique to this ocean.
These invertebrates are often much larger than their relatives in more northern, warmer waters. This phenomenon is know as “polar gigantism” and is found across many groups, with giant sea spiders, huge sponges and scale worms the size of a forearm.
Nobody is quite sure why Antarctic invertebrates grow so large, but it may be related to high oxygen levels, slow growth rates or the absence of key predatory groups such as sharks and brachyuran crabs.
Higher up in the food chain
In the marine food chain, Antarctic krill swim between the algal primary producers and the iconic top predators we always associate with Antarctica.
Baleen whales get much of their energy from great gulps of swarming krill (10,000–30,000 individual animals per cubic metre), and the pink streaks in penguin and seal poo show they are also keen on these tasty crustaceans.
Fish and cephalopods (squid and octopus) thrive in the Southern Ocean, providing food for deep-diving marine mammals such as elephant seals. Some fish species are so well adapted to the oxygen-rich cold waters they no longer produce red blood cells but instead produce antifreeze proteins in their blood to help them survive in the subzero waters.
Protecting marine environments
Arguably the most voracious predators in the Southern Ocean are humans.
Antarctica might be remote, but in the 200 or so years since its discovery, the seas around Antarctica have been heavily exploited by people.
First came the sealers, then the whalers, driving species to the brink of extinction. Even penguins were harvested for their oil.
More recently, fish and krill (which is fished for food or dietary supplements) have been the main targets, and populations of some species have declined sharply as a consequence.
When more indirect impacts like ocean warming and acidification combine with fishing, this can lead to declining populations of krill, which in turn leads to reduced numbers of top predators such as whales.
Fishing in the Southern Ocean can be hard to regulate because these waters do not belong to any one nation. To help manage the impact of fisheries, quotas that limit catches are now managed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR).
This international body is also working to establish more marine protected areas.
Without these efforts to manage catches, critical parts of the food web (such as krill) could be exploited to such an extent that ecosystems could collapse.
Changing environments mean changing ecosystems
More than 21,000 tourists and scientists visit Antarctica each year, potentially bringing pollution, diseases and invasive species. To manage human impacts on Antarctic ecosystems, and to help with political negotiations, the Antarctic Treaty came into force on June 23, 1961.
The impacts of global climate change and ocean acidification are nonetheless evident in the Southern Ocean, with warming ocean temperatures, reduction in sea ice and collapsing ice shelves.
Increasingly, research is showing that even the distant Southern Ocean is not truly cut off from the rest of the world, with warming, plastic pollution and non-native species making their way to Antarctic waters from beyond the mighty polar front.
Rafts of floating seaweeds from outside the Antarctic, some carrying animal passengers, are able to cross the Southern Ocean and reach Antarctic shores. At the moment, they don’t seem able to survive the extreme climate of Antarctica, but that could change with warming.
New species moving in and setting up shop will put a lot of pressure on Antarctica’s unique plants and animals.
It’s not all doom and gloom, though. Over the several decades since the Antarctic Treaty came into force, we’ve seen that nations can work together to help resolve challenges facing the Antarctic. One example is the establishment of Antarctic Marine Protected Areas (MPAs).
This level of international cooperation should give us hope not just for the future of the Southern Ocean, but also for other key challenges the world faces.
Five profiles open our series on the global ocean, delving into ancient Indian Ocean trade networks, Pacific plastic pollution, Arctic light and life, Atlantic fisheries and the Southern Ocean’s impact on global climate. All brought to you from The Conversation’s international network.
Antarctica Day celebrates the icy continent and its unique governance system. It’s the anniversary of the Antarctic Treaty’s adoption on December 1 1959. Framed in a spirit of global co-operation, the treaty acknowledges Antarctica does not belong to any one country. Article IV states:
No acts or activities taking place while the present Treaty is in force shall constitute a basis for asserting, supporting or denying a claim to territorial sovereignty in Antarctica or create any rights of sovereignty in Antarctica.
These five cities on the Southern Ocean rim — Cape Town, Christchurch, Hobart, Punta Arenas and Ushuaia — share a unique interest in Antarctica and an opportunity to shape its future.
How do their residents feel about Antarctica?
Our survey of 1,659 residents of these cities in July this year found they care deeply about the icy continent. Overall, and for many particular groups, environmental care greatly outweighs economic interests. Many residents express hope that this care might translate into more protective policies and action.
However, emotions were mixed, with pessimism and sadness also common responses. When we asked people how they feel about “the future of Antarctica in the next 20 years”, “hope” took first place, followed closely by “pessimism” and “sadness”.
The survey is part of the Antarctic Cities Project, which finishes this month. For the past four years an international team of researchers, city officials, national Antarctic programs and youth groups have worked together to develop a framework to strengthen Antarctic connections and a sense of guardianship for the continent. The framework encompasses the cities’ own urban sustainability strategies within a wider concern for the planet.
Our work focuses on shifting from the limited idea of “gateway” to this broader sense of becoming Antarctic “custodial cities”.
Our online survey of the cities’ residents over the age of 18 asked:
how informed they felt about the relationship between their city and Antarctica
their opinion on how important Antarctica is to their city’s identity
how responsible they, their families and friends think they are for the future of Antarctica.
We posed the question: “Why is it important for your city to develop an identity in relation to Antarctica?” The response “it drives us to take care of the environment” was most common (57%) across all five cities. Other responses included:
“it creates a unique brand for our cities” (36%)
“it creates more jobs” (32%)
“it attracts more tourists” (31%)
“it reinforces residents’ attachment to place” (29%).
Caring for the environment was the most selected option for all ages. Women felt this particularly strongly. Men favoured the more economically oriented options, “it generates more jobs” and “it attracts more tourists”.
Women and people between the ages of 31 and 40 reported higher levels of “hope” and lower levels of “indifference”. Indifference was higher among people between 18 and 30, reaching 16.42%. In this age group, and with men overall, “pessimism” significantly outweighed “hope”. Punta Arenas and Ushuaia residents expressed more “hope” than in other cities.
Young people’s expressions of pessimism and indifference bear witness to the urgent work of reforming our relationship to the Antarctic region. They will be the beneficiaries, and increasingly the drivers, of this reform.
A decade of co-operative custodianship
The cities first came together with the 2009 signing in Christchurch of a statement of intent to promote peaceful co-operation. Though it expired 18 months later, various city and national government policies have reinforced the five cities’ “Antarctic gateway” status. They have put forward visions for enhancing and capitalising on their Antarctic identities, a key part of their relationship to the world.
In an example of action at a local level, the City of Christchurch is moving towards a custodianship model by basing its 2018 Antarctic strategy on two key principles:
embracing the Maori principle of Kaitiakitanga –
meaning guardianship, protection, preservation or sheltering –
and a customary way of caring for the environment based on traditional Māori world view to guide the city’s involvement in the region
taking a leadership role in sustainable actions for the benefit of the Antarctic region and the city.
In coming together, the five cities are showing they can play an important role in defining how Antarctica is imagined, how discourse is framed and how the continent is vicariously experienced.
The Antarctic Cities Project has created an interlinked network of organisations that can learn from and benefit each other. This network of local government, national Antarctic programs, youth groups and polar organisations has produced Antarctic Futures, an educational online serious game.
During 2020 we began work on a Charter of Principles for Antarctic Cities in collaboration with the Hobart and Christchurch city councils. It draws from Christchurch’s 2018 Antarctic Gateway Strategy and the 2017 Tasmanian Antarctic Gateway Strategy. This charter will guide sustainable urban practice and embrace Antarctica’s significance to the economies of these cities while charting ways forward for sustainable development.
The charter aims to celebrate the unique polar heritage of these cities and emphasises the crucial role of youth organisations for engaging with the future of Antarctica. And it acknowledges that human connections with Antarctica extend well beyond the last two centuries, embracing Indigenous conceptions of caring for Country, both land and water.
In the Anthropocene, global public consciousness of, and responsibility for, the icy continent in a time of climate change is increasing. These cities’ relationship with the region to their south and to each other is a valuable part of their urban identity and Antarctica’s future – something worth celebrating on Antarctica Day.
The Western Antarctic Peninsula, the northernmost part of the continent and one of its most biodiverse regions, is particularly vulnerable. It faces the cumulative threats of commercial krill fishing, tourism, research infrastructure expansion and climate change.
In an article published in Nature today, we join more than 280 women in STEMM (science, technology, engineering, maths and medicine) from the global leadership initiative Homeward Bound to call for the immediate protection of the peninsula’s marine environment, through the designation of a marine protected area.
Our call comes ahead of a meeting, due in the next fortnight, of the international group responsible for establishing marine protected areas in the Southern Ocean. We urge the group to protect the region, because delays could be disastrous.
Threats on the peninsula
The Southern Ocean plays a vital role in global food availability and security, regulates the planet’s climate and drives global ocean currents. Ice covering the continent stores 70% of the earth’s freshwater.
Climate change threatens to unravel the Southern Ocean ecosystem as species superbly adapted to the cold struggle to adapt to warmer temperatures. The impacts of climate change are especially insidious on the Western Antarctic Peninsula, one of the fastest-warming places on Earth. In February, temperatures reached a record high: a balmy 20.75℃.
Tourist numbers have doubled in the past decade, increasing the risk of introducing invasive species that hitch a ride on the toursts’ gear. More than 74,000 cruise ship passengers visited last year, up from 33,000 in the 2009-10 season.
The expansion of infrastructure to accommodate scientists and research, such as buildings, roads, fuel storage and runways, can also pose a threat, as it displaces local Antarctic biodiversity.
Eighteen nations have science facilities on the Antarctic Peninsula, the highest concentration of research stations anywhere on the continent. There are 19 permanent and 30 seasonal research bases there.
An MPA around the peninsula was first proposed in 2018, covering 670,000 square kilometres. But the Commission for the Conservation of Antarctic Marine Living Resources (the organisation responsible for establishing MPAs in the Southern Ocean) has yet to reach agreement on it.
The proposed MPA is an excellent example of balancing environmental protection with commercial interests.
The area would be split into two zones. The first is a general protection zone covering 60% of the MPA, designed to protect different habitats and key wildlife and mitigate specific ecosystem threats from fishing.
The second is a krill fishery zone, allowing for a precautionary management approach to commercial fishing and keeping some fishing areas open for access.
The proposed MPA would stand for 70 years, with a review every decade so zones can be adjusted to preserve ecosystems.
No more disastrous delays
The commission is made up of 25 countries and the European Union. In its upcoming meeting, the proposed MPA will once again be considered. Two other important MPA proposals are also on the table in the East Antarctic and Weddell Sea.
In fact, for eight consecutive years, the proposal for a marine park in Eastern Antarctica has failed. Delays like this are potentially disastrous for the fragile ecosystem.
Protecting the peninsula is the most pressing priority due to rising threats, but the commission should adopt all three to fulfil their 2002 commitment to establishing an MPA network in Antarctica.
If all three were established, then more than 3.2 million square kilometres of the Southern Ocean would be protected, giving biodiversity a fighting chance against the compounding threats of human activity in the region.
While greenhouse gases are warming Earth’s surface, they’re also causing rapid cooling far above us, at the edge of space. In fact, the upper atmosphere about 90km above Antarctica is cooling at a rate ten times faster than the average warming at the planet’s surface.
Our new research has precisely measured this cooling rate, and revealed an important discovery: a new four-year temperature cycle in the polar atmosphere. The results, based on 24 years of continuous measurements by Australian scientists in Antarctica, were published in twopapers this month.
The findings show Earth’s upper atmosphere, in a region called the “mesosphere”, is extremely sensitive to rising greenhouse gas concentrations. This provides a new opportunity to monitor how well government interventions to reduce emissions are working.
Our project also monitors the spectacular natural phenomenon known as “noctilucent” or “night shining” clouds. While beautiful, the more frequent occurrence of these clouds is considered a bad sign for climate change.
Studying the ‘airglow’
Since the 1990s, scientists at Australia’s Davis research station have taken more than 600,000 measurements of the temperatures in the upper atmosphere above Antarctica. We’ve done this using sensitive optical instruments called spectrometers.
These instruments analyse the infrared glow radiating from so-called hydroxyl molecules, which exist in a thin layer about 87km above Earth’s surface. This “airglow” allows us to measure the temperature in this part of the atmosphere.
Our results show that in the high atmosphere above Antarctica, carbon dioxide and other greenhouse gases do not have the warming effect they do in the lower atmosphere (by colliding with other molecules). Instead the excess energy is radiated to space, causing a cooling effect.
Our new research more accurately determines this cooling rate. Over 24 years, the upper atmosphere temperature has cooled by about 3℃, or 1.2℃ per decade. That is about ten times greater than the average warming in the lower atmosphere – about 1.3℃ over the past century.
Untangling natural signals
Rising greenhouse gas emissions are contributing to the temperature changes we recorded, but a number of other influences are also at play. These include the seasonal cycle (warmer in winter, colder in summer) and the Sun’s 11-year activity cycle (which involves quieter and more intense solar periods) in the mesosphere.
One challenge of the research was untangling all these merged “signals” to work out the extent to which each was driving the changes we observed.
Surprisingly in this process, we discovered a new natural cycle not previously identified in the polar upper atmosphere. This four-year cycle which we called the Quasi-Quadrennial Oscillation (QQO), saw temperatures vary by 3-4℃ in the upper atmosphere.
Discovering this cycle was like stumbling across a gold nugget in a well-worked claim. More work is needed to determine its origin and full importance.
But the finding has big implications for climate modelling. The physics that drive this cycle are unlikely to be included in global models currently used to predict climate change. But a variation of 3-4℃ every four years is a large signal to ignore.
We don’t yet know what’s driving the oscillation. But whatever the answer, it also seems to affect the winds, sea surface temperatures, atmospheric pressure and sea ice concentrations around Antarctica.
‘Night shining’ clouds
Our research also monitors how cooling temperatures are affecting the occurrence of noctilucent or “night shining” clouds.
Noctilucent clouds are very rare – from Australian Antarctic stations we’ve recorded about ten observations since 1998. They occur at an altitude of about 80km in the polar regions during summer. You can only see them from the ground when the sun is below the horizon during twilight, but still shining on the high atmosphere.
The clouds appear as thin, pale blue, wavy filaments. They are comprised of ice crystals and require temperatures around minus 130℃ to form. While impressive, noctilucent clouds are considered a “canary in the coalmine” of climate change. Further cooling of the upper atmosphere as a result of greenhouse gas emissions will likely lead to more frequent noctilucent clouds.
There is already some evidence the clouds are becoming brighter and more widespread in the Northern Hemisphere.
Human-induced climate change threatens to alter radically the conditions for life on our planet. Over the next several decades – less than one lifetime – the average global air temperature is expected to increase, bringing with it sea level rise, weather extremes and changes to ecosystems across the world.
Long term monitoring is important to measure change and test and calibrate ever more complex climate models. Our results contribute to a global network of observations coordinated by the Network for Detection of Mesospheric Change for this purpose.
The accuracy of these models is critical to determining whether government and other interventions to curb climate change are indeed effective.
Australia wants to build a 2.7-kilometre concrete runway in Antarctica, the world’s biggest natural reserve. The plan, if approved, would have the largest footprint of any project in the continent’s history.
The runway is part of an aerodrome to be constructed near Davis Station, one of Australia’s three permanent bases in Antarctica. It would be the first concrete runway on the continent.
The plan is subject to federal environmental approval. It coincides with new research published this week showing Antarctica’s wild places need better protection. Human activity across Antarctica has been extensive in the past 200 years – particularly in the coastal, ice-free areas where most biodiversity is found.
Australia has successfully operated Davis Station since 1957 with existing transport arrangements. While the development may win Australia some strategic influence in Antarctica, it’s at odds with our strong history of environmental leadership in the region.
The Australian Antarctic Division (AAD), a federal government agency, argues the runway would allow year-round aviation access between Hobart and Antarctica.
Presently, the only Australian flights to Antarctica take place at the beginning and end of summer. Aircraft land at an aerodrome near the Casey research station, with interconnecting flights to other stations and sites on the continent. The stations are inaccessible by both air and ship in winter.
The AAD says year-round access to Antarctica would provide significant science benefits, including:
better understanding sea level rise and other climate change impacts
opportunities to study wildlife across the annual lifecycle of key species including krill, penguins, seals and seabirds
allowing scientists to research through winter.
Leading international scientists had called for improved, environmentally responsible access to Antarctica to support 21st-century science. However, the aerodrome project is likely to reduce access for scientists to Antarctica for years, due to the need to house construction workers.
Australia: an environmental leader?
Australia has traditionally been considered an environmental leader in Antarctica. For example, in 1989 under the Hawke government, it urged the world to abandon a mining convention in favour of a new deal to ban mining on the continent.
Australia’s 20 Year Action Plan promotes “leadership in environmental stewardship in Antarctica”, pledging to “minimise the environmental impact of Australia’s activities”.
But the aerodrome proposal appears at odds with that goal. It would cover 2.2 square kilometres, increasing the total “disturbance footprint” of all nations on the continent by 40%. It would also mean Australia has the biggest footprint of any nation, overtaking the United States.
Within this footprint, environmental effects will also be intense. Construction will require more than three million cubic metres of earthworks – levelling 60 vertical metres of hills and valleys along the length of the runway. This will inevitably cause dust emissions – on the windiest continent on Earth – and the effect of this on plants and animals in Antarctica is poorly understood.
Wilson’s storm petrels that nest at the site will be displaced. Native lichens, fungi and algae will be destroyed, and irreparable damage is expected at adjacent lakes.
Weddell seals breed within 500 metres of the proposed runway site. Federal environment officials recognise the dust from construction and subsequent noise from low flying aircraft have the potential to disturb these breeding colonies.
The proposed area is also important breeding habitat for Adélie penguins. Eight breeding sites in the region are listed as “important bird areas”. Federal environment officials state the penguins are likely to be impacted by human disturbance, dust, and noise from construction of the runway, with particular concern for oil spills and aircraft operations.
The summer population at Davis Station will need to almost double from 120 to 250 during construction. This will require new, permanent infrastructure and increase the station’s fuel and water consumption, and sewage discharged into the environment.
The AAD has proposed measures to limit environmental damage. These include gathering baseline data (against which to measure the project’s impact), analysing potential effects on birds and marine mammals and limiting disturbance where practicable.
But full details won’t be provided until later in the assessment process. We expect Australia will implement these measures to a high standard, but they will not offset the project’s environmental damage.
So given the environmental concern, why is Australia so determined to build the aerodrome? We believe the answer largely lies in Antarctic politics.
Australian officials have said the project would “contribute to both our presence and influence” on the continent. Influence in Antarctica has traditionally corresponded to the strength of a nation’s scientific program, its infrastructure presence and engagement in international decision-making.
Australia is a well-regarded member of the Antarctic Treaty. It was an original signatory and claims sovereignty over 42% of the continent. It also has a solid physical and scientific presence, maintaining three large year-round research stations.
But other nations are also vying for influence. China is constructing its fifth research station. New Zealand is planning a NZ$250 million upgrade to Scott Base. And on King George Island, six stations have been built within a 5km radius, each run by different nations. This presence is hard to justify on the basis of scientific interest alone.
Getting our priorities straight
We believe there are greater and more urgent opportunities for Australia to assert its leadership in Antarctica.
For example both Casey and Mawson stations – Australia’s two other permanent bases – discharge sewage into the pristine marine environment with little treatment. And outdated fuel technology at Australia’s three stations regularly causes diesel spills.
At Wilkes station, which Australia abandoned in the 1960s, thousands of tonnes of contaminants have been left behind.
Australia should fix such problems before adding more potentially damaging infrastructure. This would meet our environmental treaty obligations and show genuine Antarctic leadership.
Since Western explorers discovered Antarctica 200 years ago, human activity has been increasing. Now, more than 30 countries operate scientific stations in Antarctica, more than 50,000 tourists visit each year, and new infrastructure continues to be developed to meet this rising demand.
Determining if our activities have compromised Antarctica’s wilderness has, however, remained difficult.
Our study, published today in Nature, seeks to change that. Using a new “ecological informatics” approach, we’ve drawn together every available recorded visit by humans to the continent, over its 200 year history.
We found human activity across Antarctica has been extensive, especially in the ice-free and coastal areas, but that’s where most biodiversity is found. This means wilderness areas – parts of the continent largely untouched by human activity – do not capture many of the continent’s important biodiversity sites.
One of the world’s largest intact wildernesses
So just how large is the Antarctic wilderness? For the first time, our study calculated this area and how much biodiversity it captures. And, like all good questions, the answer is “that depends”.
If we think of Antarctica in the same way as every other continent, then the whole of Antarctica is a wilderness. It has no farms, no cities, no suburbs, no malls, no factories. And for a continent so large, it has very few people.
But Antarctica is too different to compare to other continents – it should be held to a higher standard. And so we define “wilderness” as the areas that aren’t highly impacted by people. This would exclude, for example, tourist areas and scientific stations. And under this definition, the wilderness area is still large.
It’s about 13,598,148 square kilometres, or more than 99% of the continent. Only the wilderness in the vast forested areas of the far Northern Hemisphere is larger. Roughly, this area is nearly twice the size of Australia.
On the other hand, the inviolate areas (places free from human interference) that the Antarctic Treaty Parties are obliged to identify and protect are dwindling rapidly.
Our analyses suggest less than 32% of the continent includes large, unvisited areas. And even that’s an overestimate. Not all visits have been recorded, and several new traverses – crossing large tracts of unvisited areas – are being planned.
Wilderness areas have poor biodiversity value
If so much of the continent remains “wild”, how much of Antarctica’s biodiversity lives within these areas?
Surprisingly few sites considered really important for Antarctic biodiversity are represented in the “un-impacted” wilderness area.
For example, only 16% of the continent’s Important Bird Areas (areas identified internationally as critical for bird conservation) are located in wilderness areas. And only 25% of protected areas established for their species or ecosystem value, and less than 7% of sites with recorded species, are in wilderness areas.
This outcome is surprising because wilderness areas elsewhere, like the Amazon rainforest, are typically valued as crucial habitat for biodiversity.
Inviolate areas have seemingly even less biodiversity value. This is because people have mostly had to visit Antarctic sites to collect species data.
In the future, remote sensing technologies might allow us to investigate and monitor pristine areas without setting foot in them. But for now, most of our knowledge of Antarctic species comes from places that have been impacted to some extent by people.
How does human activity threaten Antarctic biodiversity?
Antarctica’s remaining wilderness areas need urgent protection from increasing human activity.
Even passing human disturbance can impact the biodiversity and wilderness value of sites. For example, sensitive vegetation and soil communities can take years to recover from trampling.
Increasing movement around the continent also increases the risk people will transfer species between isolated regions, or introduce new alien species to Antarctica.
So how can we protect it?
Protecting the Antarctic wilderness could be achieved by expanding the existing Antarctic Specially Protected Areas network to include more wilderness and inviolate areas where policymakers would limit human activity.
When planning how we’ll use Antarctica in the future, we could also consider the trade off between the benefits of science and tourism activities, and the value of retaining pristine wilderness and inviolate areas.
Evidence of minute amounts of marine life in an ancient Antarctic ice sheet helps explain a longstanding puzzle of why rising carbon dioxide (CO₂) levels stalled for hundreds of years as Earth warmed from the last ice age.
shows there was an explosion in productivity of marine life at the surface of the Southern Ocean thousands of years ago.
And surprisingly, this marine life once played a part regulating the climate. Hence, this finding has big implications for future climate change projections.
Walking into the past
Our research took us on a four-hour flight from Chile to the Weddell Sea, at the extreme southern end of the Atlantic Ocean, to land on an ice runway at a frigid latitude of 79° south.
The Weddell Sea is frequently choked with sea ice and has been hazardous to ships since the earliest explorers ventured south.
In 1914, the Anglo-Irish explorer Ernest Shackleton and his men became stuck here for two years, 1,000 kilometres from civilisation. They faced isolation, starvation, freezing temperatures, gangrene, wandering icebergs and the threat of cannibalism.
Surviving here is tough, as is undertaking science.
We spent three weeks in the nearby Patriot Hills, drilling through ice to collect samples.
Normally when scientists collect ice samples, they drill a deep core vertically down through the annual layers of snow and ice. We did something quite different: we went horizontal by drilling a series of shorter cores across the icescape.
That’s because the Patriot Hills is a fiercely wild place strafed by Weddell Sea cyclones that dump large snowfalls, followed by strong frigid winds (called katabatic winds) pouring off the polar plateau.
As the winds blow throughout the year, they remove the surface ice in a process called sublimation. Older, deeper ice is drawn up to the surface. This means walking across the blue ice towards Patriot Hills is effectively like travelling back through time.
The exposed ice reveals what was happening during the transition from the last ice age around 20,000 years ago into our present warmer world, known as the Holocene.
The Antarctic Cold Reversal
As Earth was warming, carbon dioxide levels in the atmosphere were rising rapidly from around 190 to 280 parts per million.
But the warming trend wasn’t all one way.
Starting around 14,600 years ago, there was a 2,000 year-long period of cooling in the Southern Hemisphere. This period is called the Antarctic Cold Reversal, and is where CO₂ levels stalled at around 240 parts per million.
Why that happened was the puzzle, but understanding it could be crucial for improving today’s climate change projections.
Finding life in the ice
Over three weeks we battled the winds and snow to make a detailed collection of ice samples spanning the end of the last ice age.
To our surprise, hidden in our ice samples were organic molecules – remnants of marine life thousands of years ago. They came from the cyclones off the Weddell Sea, which swept up organic molecules from the ocean surface and dumped them onshore to be preserved in the ice.
Antarctic ice, which forms from snowfall, usually only tells scientists about the climate. What’s exciting about finding evidence of lifẻ in ancient Antarctic ice is that, for the first time, we can reconstruct what was happening offshore in the Southern Ocean at the same time, thousands of years ago.
We found an unusual period, displaying high concentrations and a diverse range of marine microplankton. This increased ocean productivity coincided with the Antarctic Cold Reversal.
Melting sea ice in summer sustains marine life
Our climate modelling reveals the Antarctic Cold Reversal was a time of massive change in the amount of sea ice across the Southern Ocean.
As the world lurched out of the last ice age, the summer warmth destroyed large amounts of sea ice that had formed through winter. When the sea ice melts, it releases valuable nutrients into the Southern Ocean, and fuelled the explosion in marine productivity we found in the ice on the continent.
This marine life caused more carbon dioxide to be drawn from the atmosphere as it photosynthesised, similar to the way plants use carbon dioxide. When the marine life die they sink to the floor, locking away the carbon. The amount of carbon dioxide absorbed in the ocean was sufficiently large to register around the world.
Marine life in the Southern Ocean still plays an important role in regulating the amount of atmospheric carbon dioxide.
But as the world warms with climate change, less sea ice will be formed in polar regions. This natural carbon sink of marine life will only weaken, increasing global temperatures further.
It’s a timely reminder that while the Antarctic may seem remote, it’s impact on our future climate is closer and more connected than we might think.
Chris Turney, Professor of Earth Science and Climate Change, Director of the Changing Earth Research Centre and the Chronos 14Carbon-Cycle Facility at UNSW, and Node Director of the ARC Centre of Excellence for Australian Biodiversity and Heritage, UNSW and Chris Fogwill, Professor of Glaciology and Palaeoclimatology, Head of School Geography, Geology and the Environment and Director of the Institute for Sustainable Futures, Keele University
Jules Verne sent his fictional submarine, the Nautilus, to the South Pole through a hidden ocean beneath a thick ice cap. Written 40 years before any explorer had reached the pole, his story was nevertheless only half fiction.
There are indeed hidden ocean cavities around Antarctica, and our latest research explores how the ocean circulates underneath the continent’s ice shelves – large floating extensions of the ice on land that rise and fall with the tides.
These ice shelves buttress the continent’s massive land-based ice cap and play an important role in the assessment of future sea level rise. Our work sheds new light on how ocean currents contribute to melting in Antarctica, which is one of the largest uncertainties in climate model predictions.
The Ross Ice Shelf is the largest floating slab of ice on Earth, at 480,000 square kilometres. The ocean cavity it conceals extends 700km south from Antarctica’s coast and remains largely unexplored.
We know ice shelves mainly melt from below, washed by a warming ocean. But we have very little data available about how the water mixes underneath the ice. This is often overlooked in climate models, but our new measurements will help redress this.
The only other expedition to the ocean cavity underneath the central Ross Ice Shelf goes back to the 1970s and came back with intriguing results. Despite the limited technology of the time, it showed the ocean cavity was not a static bathtub. Instead, it found fine layering of water masses, with subtly different temperatures and salinities between the layers.
Other ocean studies have been conducted from the edges or from high above. They have provided insight into how the system works but to really understand it, we needed to take measurements directly from the ocean under hundreds of metres of ice.
In 2017, we used a hot-water jet, modelled on a British Antarctic Surveydesign, to drill through 350 metres of ice to the ocean below. We were able to keep the hole liquid long enough to make detailed ocean measurements as well as leave instruments behind to continue monitoring ocean currents and temperature. These data are still coming in via satellite.
We found the hidden ocean acts like a massive estuary with comparatively warm (2℃) seawater coming in at the seabed to cycle close to the surface in a combination of meltwater and sub-glacial freshwater squeezed out from the ice sheet and Antarctica’s hidden rocky foundation.
The hundreds of metres of ice isolate the ocean cavity from the furious winds and freezing air temperatures of Antarctica. But nothing stops the tides. Our data suggest tides push the stratified ocean back and forth past undulations on the underside of the ice and mix parts of the ocean cavity.
This sort of discovery is the ultimate challenge for climate science. How do we represent processes that work at daily scales in models that make projections over centuries? Our data show the daily changes can add up, so finding a solution matters.
For example, data collected outside the ocean cavity and computer models suggest that any given parcel of water spends one to six years making its way through the cavity. Our new data indicate the lower end of the range is more likely and that we should not be thinking in terms of one grand circuit anyway.
The Ross is not the ice shelf in most danger from warming oceans. But its sheer size and its relationship with the neighbouring Ross Sea means it is a vital cog in the planetary ocean system.
The importance of these ice shelves for sea level rise over the next few centuries is very apparent. Research shows that if atmospheric warming exceeds 2℃, major Antarctic ice shelves would collapse and release ice flowing from the continent’s ice cap – lifting the sea level by up to 3 metres by 2300.
What is less well understood, but also potentially a massive agent for change, is the impact of meltwater on the global thermohaline circulation, an oceanic transport loop that sees the ocean cycle from the abyss off the coast of Antarctica to tropical surface waters every 1,000 years or so.
Antarctic ice shelves are like a pit stop in this loop and so what happens in Antarctica resonates globally. Faster melting ice shelves will change the ocean stratification, with repercussions for global ocean circulation – and one result of this appears to be greater climate variability.
Climate scientists long thought Antarctica’s interior may not be very sensitive to warming, but our research, published today, shows a dramatic change.
Over the past 30 years, the South Pole has been one of the fastest changing places on Earth, warming more than three times more rapidly than the rest of the world.
My colleagues and I argue these warming trends are unlikely the result of natural climate variability alone. The effects of human-made climate change appear to have worked in tandem with the significant influence natural variability in the tropics has on Antarctica’s climate. Together they make the South Pole warming one of the strongest warming trends on Earth.
The South Pole lies within the coldest region on Earth: the Antarctic plateau. Average temperatures here range from -60℃ during winter to just -20℃ during summer.
Antarctica’s climate generally has a huge range in temperature over the course of a year, with strong regional contrasts. Most of West Antarctica and the Antarctic Peninsula were warming during the late 20th century. But the South Pole — in the remote and high-altitude continental interior — cooled until the 1980s.
Scientists have been tracking temperature at the Amundsen-Scott South Pole Station, Earth’s southernmost weather observatory, since 1957. It is one of the longest-running complete temperature records on the Antarctic continent.
Our analysis of weather station data from the South Pole shows it has warmed by 1.8℃ between 1989 and 2018, changing more rapidly since the start of the 2000s. Over the same period, the warming in West Antarctica suddenly stopped and the Antarctic Peninsula began cooling.
One of the reasons for the South Pole warming was stronger low-pressure systems and stormier weather east of the Antarctic Peninsula in the Weddell Sea. With clockwise flow around the low-pressure systems, this has been transporting warm, moist air onto the Antarctic plateau.
South Pole warming linked to the tropics
Our study also shows the ocean in the western tropical Pacific started warming rapidly at the same time as the South Pole. We found nearly 20% of the year-to-year temperature variations at the South Pole were linked to ocean temperatures in the tropical Pacific, and several of the warmest years at the South Pole in the past two decades happened when the western tropical Pacific ocean was also unusually warm.
To investigate this possible mechanism, we performed a climate model experiment and found this ocean warming produces an atmospheric wave pattern that extends across the South Pacific to Antarctica. This results in a stronger low-pressure system in the Weddell Sea.
We know from earlier studies that strong regional variations in temperature trends are partly due to Antarctica’s shape.
The East Antarctic Ice Sheet, bordered by the South Atlantic and Indian oceans, extends further north than the West Antarctic Ice Sheet, in the South Pacific. This causes two distinctly different weather patterns with different climate impacts.
More steady, westerly winds around East Antarctica keep the local climate relatively stable, while frequent intense storms in the high-latitude South Pacific transport warm, moist air to parts of West Antarctica.
Scientists have suggested these two different weather patterns, and the mechanisms driving their variability, are the likely reason for strong regional variability in Antarctica’s temperature trends.
Our analysis reveals extreme variations in South Pole temperatures can be explained in part by natural tropical variability.
To estimate the influence of human-induced climate change, we analysed more than 200 climate model simulations with observed greenhouse gas concentrations over the period between 1989 and 2018. These climate models show recent increases in greenhouse gases have possibly contributed around 1℃ of the total 1.8℃ of warming at the South Pole.
We also used the models to compare the recent warming rate to all possible 30-year South Pole temperature trends that would occur naturally without human influence. The observed warming exceeds 99.9% of all possible trends without human influence – and this means the recent warming is extremely unlikely under natural conditions, albeit not impossible. It appears the effects from tropical variability have worked together with increasing greenhouse gases, and the end result is one of the strongest warming trends on the planet.
These climate model simulations reveal the remarkable nature of South Pole temperature variations. The observed South Pole temperature, with measurements dating back to 1957, shows 30-year temperature swings ranging from more than 1℃ of cooling during the 20th century to more than 1.8℃ of warming in the past 30 years.
This means multi-decadal temperature swings are three times stronger than the estimated warming from human-caused climate change of around 1℃.
The temperature variability at the South Pole is so extreme it currently masks human-caused effects. The Antarctic interior is one of the few places left on Earth where human-caused warming cannot be precisely determined, which means it is a challenge to say whether, or for how long, the warming will continue.
But our study reveals extreme and abrupt climate shifts are part of the climate of Antarctica’s interior. These will likely continue into the future, working to either hide human-induced warming or intensify it when natural warming processes and the human greenhouse effect work in tandem.