Humans threaten the Antarctic Peninsula’s fragile ecosystem. A marine protected area is long overdue



Shutterstock

Marissa Parrott, University of Melbourne; Carolyn Hogg, University of Sydney; Cassandra Brooks, University of Colorado Boulder; Justine Shaw, The University of Queensland, and Melissa Cristina Márquez, Curtin University

Antarctica, the world’s last true wilderness, has been protected by an international treaty for the last 60 years. But the same isn’t true for most of the ocean surrounding it.

Just 5% of the Southern Ocean is protected, leaving biodiversity hotspots exposed to threats from human activity.




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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.

Why we must establish a marine protected area around the peninsula, right now. Video: LUMA.

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℃.




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Anatomy of a heatwave: how Antarctica recorded a 20.75°C day last month


The peninsula is also the most-visited part of Antarctica, thanks to its easy access, dramatic beauty, awe-inspiring wildlife and rich marine ecosystems.

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.

Six tourists standing on ice with their backs to the camera
The peninsula is the most visited region in Antarctica.
Shutterstock

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.




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Another big threat to biodiversity in the peninsula is the commercial fishing of Antarctic krill, a small, shrimp-like crustacean which is the cornerstone of life in this region.

A cornerstone of life

Krill is a foundation of the food chain in Antarctica, with whales, fish, squid, seals and Adélie and gentoo penguins all feeding on it.

But as sea ice cover diminishes, more industrial fishing vessels can encroach on penguin, seal and whale foraging grounds, effectively acting as a competing super-predator for krill.




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Climate change threatens Antarctic krill and the sea life that depends on it


In the past 30 years, colonies of Adélie and Chinstrap penguins on the Antarctic Peninsula have declined by more than 50% due to reduced sea ice and krill harvesting.

Commercial Antarctic krill fishing is largely for omega-3 dietary supplements and fish-meal. The fishery in the waters of the Western Antarctic Peninsula is the largest in the Southern Ocean.

Close-up of krill
Krill is a vital part of the food web in Antarctica.
Shutterstock

The krill catch here has more than tripled from 88,800 tonnes in 2000 to almost 400,000 tonnes in 2019 — the third-largest krill catch in history and a volume not seen since the 1980s.

How do we save it?

To save the Antarctic Peninsula, one of critical steps is to protect its waters and its source of life: those tiny, but crucially important, Antarctic krill.

This can be done by establishing a marine protected area (MPA) in the region, which would limit or prohibit human activities such as commercial fishing.




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Why marine protected areas are often not where they should be


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.


Nature 586: 496-499 22 October 2020, Author provided

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.

A map of the current and proposed Marine Protected Areas under consideration.
A map of the current and proposed marine protected areas under consideration.
Cassandra Brooks, Author provided

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.




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Protecting ocean habitats isn’t easy when industries are booming – but can they be part of the solution?


The Conversation


Marissa Parrott, Reproductive Biologist, Wildlife Conservation & Science, Zoos Victoria, and Honorary Research Associate, BioSciences, University of Melbourne; Carolyn Hogg, Senior Research Manager, University of Sydney; Cassandra Brooks, Assistant Professor Environmental Studies, University of Colorado Boulder; Justine Shaw, Conservation Biologist, The University of Queensland, and Melissa Cristina Márquez, PhD Candidate, Curtin University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Carbon emissions are chilling the atmosphere 90km above Antarctica, at the edge of space



Ashleigh Wilson

John French, University of Tasmania; Andrew Klekociuk, University of Tasmania, and Frank Mulligan, National University of Ireland Maynooth

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 two papers 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.

Scientific equipment
Spectrometer in the optical laboratory at Davis station, Antarctica.
John French

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.




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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.

Sea ice in Antarctica
The new temperature cycle is reflected in the concentration of sea ice in Antacrtica.
John French

Measuring change

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.




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The Conversation


John French, Atmospheric physicist, University of Tasmania; Andrew Klekociuk, Principal Research Scientist, Australian Antarctic Division and Adjunct Senior Lecturer, University of Tasmania, and Frank Mulligan, , National University of Ireland Maynooth

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Australia wants to build a huge concrete runway in Antarctica. Here’s why that’s a bad idea



AAD

Shaun Brooks, University of Tasmania and Julia Jabour, University of Tasmania

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.

The area around Davis Station is possibly Antarctica’s most significant coastal, ice-free area. It features unique lakes, fjords, fossil sites and wildlife.

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 Vestfold Hills, the proposed site of the aerodrome.
Nick Roden

Year-round access

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.




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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 says the runway would have significant science benefits.
Australian Antarctic Division

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.

The contribution of disturbance footprint from countries in Antarctica measured from Brooks et al. 2019, with Australia’s share increasing to 35% including the aerodrome proposal.
Shaun Brooks

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.




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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.

An Adélie penguin colony near Davis Station.
Nick Roden

Playing politics

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.




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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.

A Weddell seal and her pup near Davis Station.
Nick Roden

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.The Conversation

Shaun Brooks, University Associate, University of Tasmania and Julia Jabour, Adjunct Senior Lecturer, University of Tasmania

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Humans are encroaching on Antarctica’s last wild places, threatening its fragile biodiversity



SL Chown, CC BY-NC

Rachel Leihy, Monash University and Steven Chown, Monash University

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.

Historical and contemporary human activity on Deception Island.
SL Chown

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.

Antarctica’s wilderness should be held to a higher standard.
SL Chown

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.




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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.

Human activity has been extensive across Antarctica, but large areas with no visitation record might still exist across central parts of the continent.
Leihy et al. 2020 Nature

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.

Ice-free areas are critical habitat for Antarctic biodiversity, like Adélie penguins, and frequently visited by people as well.
SL Chown

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.

Expanding the existing network of Antarctic protected areas can secure remaining wilderness areas into the future.
SL Chown

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.




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This could be done explicitly through the environmental impact assessments required for activities in the region. Currently, impacts on the wilderness value of sites are rarely considered.

We have an opportunity in Antarctica to protect some of the world’s most intact and undisturbed environments, and prevent further erosion of Antarctica’s remarkable wilderness value.The Conversation

Ross Sea Region, Antarctica. Few sites considered really important for Antarctic biodiversity are represented in the wilderness area.
SL Chown

Rachel Leihy, PhD candidate, Monash University and Steven Chown, Professor of Biological Sciences, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Marine life found in ancient Antarctica ice helps solve a carbon dioxide puzzle from the ice age



Chris Fogwill, Author provided

Chris Turney, UNSW and Chris Fogwill, Keele University

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.

Our study
shows there was an explosion in productivity of marine life at the surface of the Southern Ocean thousands of years ago.




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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.

Our Ilyshion aircraft landed on the Union Glacier (Antarctic Logistics and Expeditions).
Chris Turney, Author provided

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.




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What an ocean hidden under Antarctic ice reveals about our planet’s future climate


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.

Those katabatic winds blowing hard.

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.

A walk across the blue ice is a walk back in time.
Matthew Harris, Keele University, Author provided

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.

We collected sample of ice to study later in the lab.
Chris Turney, Author provided

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.

Sea ice formed in winter melts in summer, and dumps nutrients into the ocean.
Shutterstock

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.

What this mean for climate change today

Today, the Southern Ocean absorbs some 40% of all carbon put in the atmosphere by human activity, so we urgently need a better understand the drivers of this important part of the carbon cycle.




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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.The Conversation

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

This article is republished from The Conversation under a Creative Commons license. Read the original article.

What an ocean hidden under Antarctic ice reveals about our planet’s future climate



Craig Stevens, Author provided

Craig Stevens, National Institute of Water and Atmospheric Research and Christina Hulbe, University of Otago

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 field camp on top of the Ross Ice Shelf.
Craig Stevens, Author provided



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Climate scientists explore hidden ocean beneath Antarctica’s largest ice shelf


An unexplored ocean

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.

The team used a hot-water jet to drill through the ice to the ocean below.
Craig Stevens, Author provided

In 2017, we used a hot-water jet, modelled on a British Antarctic Survey design, 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.




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Antarctica’s ice isolates the ocean cavity from furious winds and freezing air temperatures.
Craig Stevens, Author provided

Future projections

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.




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Ice melt in Greenland and Antarctica predicted to bring more frequent extreme weather


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.The Conversation

Craig Stevens, Associate Professor in Ocean Physics, National Institute of Water and Atmospheric Research and Christina Hulbe, Professor and Dean of the School of Surveying (glaciology specialisation), University of Otago

This article is republished from The Conversation under a Creative Commons license. Read the original article.

New research shows the South Pole is warming faster than the rest of the world



Elaine Hood/NSF

Kyle Clem, Te Herenga Waka — Victoria University of Wellington

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.




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The Amundsen-Scott South Pole station is the Earth’s southern-most weather observatory.
Craig Knott/NSF

The South Pole is not immune to warming

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.

Map of the Antarctic continent.
National Science Foundation

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.




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How solar heat drives rapid melting of parts of Antarctica’s largest ice shelf


What this means for the South Pole

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.

The temperature variability at the South Pole is so extreme it masks anthropogenic effects.
Keith Vanderlinde/NSF

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.The Conversation

Kyle Clem, Research Fellow in Climate Science, Te Herenga Waka — Victoria University of Wellington

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Climate change threatens Antarctic krill and the sea life that depends on it



Brett Wilks

Devi Veytia, University of Tasmania and Stuart Corney, University of Tasmania

The Southern Ocean circling Antarctica is one of Earth’s richest marine ecosystems. Its food webs support an abundance of life, from tiny micro-organisms to seals, penguins and several species of whales. But climate change is set to disrupt this delicate balance.

Antarctic krill – finger-sized, swarming crustaceans – might be small but they underpin the Southern Ocean’s food web. Our research published today suggests climate change will cause the ocean habitat supporting krill growth to move south. The habitat will also deteriorate in summer and autumn.

The ramifications will reverberate up the food chain, with implications for other Antarctic animals. This includes humpback whales that feed on krill at the end of their annual migration to the Southern Ocean.

Changes in krill habitat could affect species up the food chain including the humpback whale.
Mike Hutchings/AAP

What we found

Antarctic krill are one of the most abundant animal species in the world. About 500 million tonnes of Antarctic krill are estimated to exist in the Southern Ocean.

Antarctic krill play a critical role in the ocean’s food webs. But their survival depends on a delicate balance of food and temperature. Scientists are concerned at how climate change may affect their population and the broader marine ecosystem.

We wanted to project how climate change will affect the Southern Ocean’s krill “growth habitat” – essentially, ocean areas where krill can thrive in high numbers.

Krill growth depends largely on ocean temperature and the abundance of its main food source, phytoplankton (microscopic single-celled plants).




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Under a “business as usual” climate change scenario, future changes in ocean temperature and phytoplankton varied depending on the region and season.

In the mid-low latitudes, our projections showed temperatures warmed towards the limits krill can tolerate. For example, by 2100 the waters during summer around South Georgia island warmed by 1.8℃.

Warming water was often accompanied by decreases in phytoplankton; in the Bellingshausen Sea during summer a 1.7℃ rise halved the available phytoplankton.

However, phytoplankton increased closer to the continent in spring and summer – most dramatically by 175% in the Weddell Sea in spring.

Antarctic krill habitat will shift south under climate change.
Simon Payne, Australian Antarctic Division

Shifting habitat

Across all seasons, krill growth habitat remained relatively stable for 85% of the Southern Ocean. But important regional changes still occurred.

Krill growth habitat shifted south as suitable ocean temperatures contracted towards the poles. Combined with changes in phytoplankton distribution, growth habitat improved in spring but deteriorated in summer and autumn.




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This early end to the growth season could have profound consequences for krill populations. The krill life cycle is synchronised with the Southern Ocean’s dramatic seasonal cycles. Typically this allows krill to both maximise growth and reproduction and store reserves to survive the winter.

A shift in habitat timing could create a mismatch between these two cycles.

For example, female krill need access to plentiful food during the summer in order to spawn. Since larger females produce exponentially more eggs, a decline in summer growth habitat could result in smaller females and far less spawning success.

Antarctic predators including penguins rely on krill for survival.
Royal Navy

Why this matters

Krill’s significant role in the food chain means the impacts of these changes may play out through the entire ecosystem.

If krill shift south to follow their retreating habitat, less food would be available for predators on sub-Antarctic islands such as Antarctic fur seals, penguins and albatrosses for whom krill forms a significant portion of the diet.

In the past, years of low krill densities has coincided with declines in reproductive success for these species.

Shifts in krill habitat timing may also affect migratory predators. For example, each year humpback whales migrate from the tropics to the poles to feed on the huge amount of summer krill. If the krill peak occurs earlier in the season, the whales must adapt by arriving earlier, or be left hungry.

Krill predators. a. crabeater seal (Lobodon carcinophaga), b. Adelie penguins (Pygoscelis adeliae), c. Antarctic fur seal (Arctocephalus gazella), d. humpback whale (Megaptera novaeangliae).
Photo credits (in order a-d): Kevin Neff, Australian Antarctic Division; Mark Hindell, Institute for Marine and Antarctic Studies; Colin Lee Hong, Australian Antarctic Division; Anthony Hull, Australian Antarctic Division.

Looking ahead

Changes to krill growth habitat may damage more than the ocean food web. Demand for krill oil in health supplements and aquaculture feed is on the rise, and krill are the target of the Southern Ocean’s largest fishery. Anticipating changes in krill availability is crucial to informing the fishery’s sustainable management.

Many environmental drivers interact to create good krill habitat. More research is required, including better models, and an improved understanding of what drives krill to reproduce and survive.

But by examining changes in phytoplankton, we’ve taken significant strides towards predicting climate change impacts on krill and the wider Antarctic marine ecosystem.




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The Conversation


Devi Veytia, PhD student , University of Tasmania and Stuart Corney, Senior lecturer, University of Tasmania

This article is republished from The Conversation under a Creative Commons license. Read the original article.

5 big environment stories you probably missed while you’ve been watching coronavirus



Shutterstock

Rod Lamberts, Australian National University and Will J Grant, Australian National University

Good news: COVID-19 is not the only thing going on right now!

Bad news: while we’ve all been deep in the corona-hole, the climate crisis has been ticking along in the background, and there are many things you may have missed.

Fair enough – it’s what people do. When we are faced with immediate, unambiguous threats, we all focus on what’s confronting us right now. The loss of winter snow in five or ten years looks trivial against images of hospitals pushed to breaking point now.




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As humans, we also tend to prefer smaller, short-term rewards over larger long-term ones. It’s why some people would risk illness and possible prosecution (or worse, public shaming) to go to the beach with their friends even weeks after social distancing messages have become ubiquitous.

But while we might need to ignore climate change right now if only to save our sanity, it certainly hasn’t been ignoring us.

So here’s what you may have missed while coronavirus dominates the news cycle.

Heatwave in Antarctica

Antarctica is experiencing alarmingly balmy weather.
Shutterstock

On February 6 this year, the northernmost part of Antarctica set a new maximum temperature record of 18.4℃. That’s a pleasant temperature for an early autumn day in Canberra, but a record for Antarctica, beating the old record by nearly 1℃.

That’s alarming, but not as alarming as the 20.75℃ reported just three days later to the east of the Antarctic Peninsula at Marambio station on Seymour Island.




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Anatomy of a heatwave: how Antarctica recorded a 20.75°C day last month


Bleaching the reef

The Intergovernmental Panel on Climate Change has warned a global average temperature rise of 1.5℃ could wipe out 90% of the world’s coral.

As the world looks less likely to keep temperature rises to 1.5℃, in 2019 the five-year outlook for Australia’s Great Barrier Reef was downgraded from “poor” to “very poor”. The downgrading came in the wake of two mass bleaching events, one in 2016 and another in 2017, damaging two-thirds of the reef.

And now, in 2020, it has just experienced its third in five years.

Of course, extreme Antarctic temperatures and reef bleaching are the products of human-induced climate change writ large.

But in the short time since the COVID-19 crisis began, several examples of environmental vandalism have been deliberately and specifically set in motion as well.




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We just spent two weeks surveying the Great Barrier Reef. What we saw was an utter tragedy


Coal mining under a Sydney water reservoir

The Berejiklian government in New South Wales has just approved the extension of coal mining by Peabody Energy – a significant funder of climate change denial – under one of Greater Sydney’s reservoirs. This is the first time such an approval has been granted in two decades.

While environmental groups have pointed to significant local environmental impacts – arguing mining like this can cause subsidence in the reservoir up to 25 years after the mining is finished – the mine also means more fossil carbon will be spewed into our atmosphere.

Peabody Energy argues this coal will be used in steel-making rather than energy production. But it’s still more coal that should be left in the ground. And despite what many argue, you don’t need to use coal to make steel.




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Victoria green-lights onshore gas exploration

In Victoria, the Andrews government has announced it will introduce new laws into Parliament for what it calls the “orderly restart” of onshore gas exploration. In this legislation, conventional gas exploration will be permitted, but an existing temporary ban on fracking and coal seam gas drilling will be made permanent.

The announcement followed a three-year investigation led by Victoria’s lead scientist, Amanda Caples. It found gas reserves in Victoria “could be extracted without harming the environment”.

Sure, you could probably do that (though the word “could” is working pretty hard there, what with local environmental impacts and the problem of fugitive emissions). But extraction is only a fraction of the problem of natural gas. It’s the subsequent burning that matters.




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Trump rolls back environmental rules

Meanwhile, in the United States, the Trump administration is taking the axe to some key pieces of environmental legislation.

One is an Obama-era car pollution standard, which required an average 5% reduction in greenhouse emissions annually from cars and light truck fleets. Instead, the Trump administration’s “Safer Affordable Fuel Efficient Vehicles” requires just 1.5%.

The health impact of this will be stark. According to the Environmental Defense Fund, the shift will mean 18,500 premature deaths, 250,000 more asthma attacks, 350,000 more other respiratory problems, and US$190 billion in additional health costs between now and 2050.

And then there are the climate costs: if manufacturers followed the Trump administration’s new looser guidelines it would add 1.5 billion tonnes of carbon dioxide to the atmosphere, the equivalent of 17 additional coal-fired power plants.




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When it comes to climate change, Australia’s mining giants are an accessory to the crime


And so…

The challenges COVID-19 presents right now are huge. But they will pass.

The challenges of climate change are not being met with anything like COVID-19 intensity. For now, that makes perfect sense. COVID-19 is unambiguously today. Against this imperative, climate change is still tomorrow.

But like hangovers after a large celebration, tomorrows come sooner than we expect, and they never forgive us for yesterday’s behaviour.The Conversation

Rod Lamberts, Deputy Director, Australian National Centre for Public Awareness of Science, Australian National University and Will J Grant, Senior Lecturer, Australian National Centre for the Public Awareness of Science, Australian National University

This article is republished from The Conversation under a Creative Commons license. Read the original article.