What if Antarctica’s dormant, ice-covered volcanoes wake up?



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Harvepino / shutterstock

John Smellie, University of Leicester

Antarctica is a vast icy wasteland covered by the world’s largest ice sheet. This ice sheet contains about 90% of fresh water on the planet. It acts as a massive heat sink and its meltwater drives the world’s oceanic circulation. Its existence is therefore a fundamental part of Earth’s climate.

Less well known is that Antarctica is also host to several active volcanoes, part of a huge “volcanic province” which extends for thousands of kilometres along the western edge of the continent. Although the volcanic province has been known and studied for decades, about 100 “new” volcanoes were recently discovered beneath the ice by scientists who used satellite data and ice-penetrating radar to search for hidden peaks.

Some of the volcanoes known about before the latest discovery.
antarcticglaciers.org, Author provided

These sub-ice volcanoes may be dormant. But what would happen if Antarctica’s volcanoes awoke?

We can get some idea by looking to the past. One of Antarctica’s volcanoes, Mount Takahe, is found close to the remote centre of the West Antarctic Ice Sheet. In a new study, scientists implicate Takahe in a series of eruptions rich in ozone-consuming halogens that occurred about 18,000 years ago. These eruptions, they claim, triggered an ancient ozone hole, warmed the southern hemisphere which caused glaciers to melt, and helped bring the last ice age to a close.

Mt Takahe grew over hundreds of thousands of years and its 8km-wide caldera now towers above the ice sheet.
NASA / Jim Yungel, CC BY-SA

This sort of environmental impact is unusual. For it to happen again would require a series of eruptions, similarly enriched in halogens, from one or more volcanoes that are currently exposed above the ice. Such a scenario is unlikely although, as the Takahe study shows, not impossible. More likely is that one or more of the many subglacial volcanoes, some of which are known to be active, will erupt at some unknown time in the future.

Eruptions below the ice

Because of the enormous thickness of overlying ice, it is unlikely that volcanic gases would make it into the atmosphere. So an eruption wouldn’t have an impact like that postulated for Takahe. However, the volcanoes would melt huge caverns in the base of the ice and create enormous quantities of meltwater. Because the West Antarctic Ice Sheet is wet rather than frozen to its bed – imagine an ice cube on a kitchen work top – the meltwater would act as a lubricant and could cause the overlying ice to slip and move more rapidly. These volcanoes can also stabilise the ice, however, as they give it something to grip onto – imagine that same ice cube snagging onto a lump-shaped object.

In any case, the volume of water that would be generated by even a large volcano is a pinprick compared with the volume of overlying ice. So a single eruption won’t have much effect on the ice flow. What would make a big difference, is if several volcanoes erupt close to or beneath any of West Antarctica’s prominent “ice streams”.

A velocity map of Antarctic ice streams as they move toward the ocean.
NASA/JPL, CC BY-SA

Ice streams are rivers of ice that flow much faster than their surroundings. They are the zones along which most of the ice in Antarctica is delivered to the ocean, and therefore fluctuations in their speed can affect the sea level. If the additional “lubricant” provided by multiple volcanic eruptions was channelled beneath ice streams, the subsequent rapid flow may dump unusual amounts of West Antarctica’s thick interior ice into the ocean, causing sea levels to rise.

Under-ice volcanoes are probably what triggered rapid flow of ancient ice streams into the vast Ross Ice Shelf, Antarctica’s largest ice shelf. Something similar might have occurred about 2,000 years ago with a small volcano in the Hudson Mountains that lie underneath the West Antarctica Ice Sheet – if it erupted again today it could cause the nearby Pine Island Glacier to speed up.

The volcano–ice melt feedback loop

Most dramatically of all, a large series of eruptions could destabilise many more subglacial volcanoes. As volcanoes cool and crystallise, their magma chambers become pressurised and all that prevents the volcanic gases from escaping violently in an eruption is the weight of overlying rock or, in this case, several kilometres of ice. As that ice becomes much thinner, the pressure reduction may trigger eruptions. More eruptions and ice melting would mean even more meltwater being channelled under the ice streams.

Mt Erebus is one of Antarctica’s most active volcanoes. The rocks in the foreground are the remnants of several younger subglacial volcanoes.
antarcticglaciers.org, Author provided

Potentially a runaway effect may take place, with the thinning ice triggering more and more eruptions. Something similar occurred in Iceland, which saw an increase in volcanic eruptions when glaciers began to recede at the end of the last ice age.

So it seems the greatest threat from Antarctica’s many volcanoes will be if several erupt within a few decades of each other. If those volcanoes have already grown above the ice and their gases were rich in halogens then enhanced warming and rapid deglaciation may result. But eruptions probably need to take place repeatedly over many tens to hundreds of years to have a climatic impact.

The ConversationMore likely is the generation of large quantities of meltwater during subglacial eruptions that might lubricate West Antarctica’s ice streams. The eruption of even a single volcano situated strategically close to any of Antarctica’s ice streams can cause significant amounts of ice to be swept into the sea. However, the resulting thinning of the inland ice is also likely to trigger further subglacial eruptions generating meltwater over a wider area and potentially causing a runaway effect on ice flow.

John Smellie, Professor of Volcanology, University of Leicester

This article was originally published on The Conversation. Read the original article.

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Antarctic Ocean and Climate Change


The link below is to an article that takes a look at the effects of a 1-degree rise in temperature of the Antarctic Ocean.

For more visit:
http://e360.yale.edu/digest/what-happens-to-the-antarctic-ocean-with-1-degrees-celsius-of-warming

How Antarctic ice melt can be a tipping point for the whole planet’s climate


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Melting Antarctic ice can trigger effects on the other side of the globe.
NASA/Jane Peterson

Chris Turney, UNSW; Jonathan Palmer, UNSW; Peter Kershaw, Monash University; Steven Phipps, University of Tasmania, and Zoë Thomas, UNSW

Melting of Antarctica’s ice can trigger rapid warming on the other side of the planet, according to our new research which details how just such an abrupt climate event happened 30,000 years ago, in which the North Atlantic region warmed dramatically.

This idea of “tipping points” in Earth’s system has had something of a bad rap ever since the 2004 blockbuster The Day After Tomorrow purportedly showed how melting polar ice can trigger all manner of global changes.

But while the movie certainly exaggerated the speed and severity of abrupt climate change, we do know that many natural systems are vulnerable to being pushed into different modes of operation. The melting of Greenland’s ice sheet, the retreat of Arctic summer sea ice, and the collapse of the global ocean circulation are all examples of potential vulnerability in a future, warmer world.


Read more: Chasing ice: how ice cores shape our understanding of ancient climate.


Of course it is notoriously hard to predict when and where elements of Earth’s system will abruptly tip into a different state. A key limitation is that historical climate records are often too short to test the skill of our computer models used to predict future environmental change, hampering our ability to plan for potential abrupt changes.

Fortunately, however, nature preserves a wealth of evidence in the landscape that allows us to understand how longer time-scale shifts can happen.

Core values

One of the most important sources of information on past climate tipping points are the kilometre-long cores of ice drilled from the Greenland and Antarctic ice sheets, which preserve exquisitely detailed information stretching back up to 800,000 years.

The Greenland ice cores record massive, millennial-scale swings in temperature that have occurred across the North Atlantic region over the past 90,000 years. The scale of these swings is staggering: in some cases temperatures rose by 16℃ in just a few decades or even years.

Twenty-five of these major so-called Dansgaard–Oeschger (D-O) warming events have been identified. These abrupt swings in temperature happened too quickly to have been caused by Earth’s slowly changing orbit around the Sun. Fascinatingly, when ice cores from Antarctica are compared with those from Greenland, we see a “seesaw” relationship: when it warms in the north, the south cools, and vice versa.

Attempts to explain the cause of this bipolar seesaw have traditionally focused on the North Atlantic region, and include melting ice sheets, changes in ocean circulation or wind patterns.

But as our new research shows, these might not be the only cause of D-O events.

Our new paper, published today in Nature Communications, suggests that another mechanism, with its origins in Antarctica, has also contributed to these rapid seesaws in global temperature.

Tree of knowledge

The 30,000-year-old key to climate secrets.
Chris Turney, Author provided

We know that there have been major collapses of the Antarctic ice sheet in the past, raising the possibility that these may have tipped one or more parts of the Earth system into a different state. To investigate this idea, we analysed an ancient New Zealand kauri tree that was extracted from a peat swamp near Dargaville, Northland, and which lived between 29,000 and 31,000 years ago.

Through accurate dating, we know that this tree lived through a short D-O event, during which (as explained above) temperatures in the Northern Hemisphere would have risen. Importantly, the unique pattern of atmospheric radioactive carbon (or carbon-14) found in the tree rings allowed us to identify similar changes preserved in climate records from ocean and ice cores (the latter using beryllium-10, an isotope formed by similar processes to carbon-14). This tree thus allows us to compare directly what the climate was doing during a D-O event beyond the polar regions, providing a global picture.

The extraordinary thing we discovered is that the warm D-O event coincided with a 400-year period of surface cooling in the south and a major retreat of Antarctic ice.

When we searched through other climate records for more information about what was happening at the time, we found no evidence of a change in ocean circulation. Instead we found a collapse in the rain-bearing Pacific trade winds over tropical northeast Australia that was coincident with the 400-year southern cooling.


Read more: Two centuries of continuous volcanic eruption may have triggered the end of the ice age.


To explore how melting Antarctic ice might cause such dramatic change in the global climate, we used a climate model to simulate the release of large volumes of freshwater into the Southern Ocean. The model simulations all showed the same response, in agreement with our climate reconstructions: regardless of the amount of freshwater released into the Southern Ocean, the surface waters of the tropical Pacific nevertheless warmed, causing changes to wind patterns that in turn triggered the North Atlantic to warm too.

The ConversationFuture work is now focusing on what caused the Antarctic ice sheets to retreat so dramatically. Regardless of how it happened, it looks like melting ice in the south can drive abrupt global change, something of which we should be aware in a future warmer world.

Chris Turney, Professor of Earth Sciences and Climate Change, UNSW; Jonathan Palmer, Research Fellow, School of Biological, Earth and Environmental Sciences., UNSW; Peter Kershaw, Emeritus Professor, Earth, Atmosphere and Environment, Monash University; Steven Phipps, Palaeo Ice Sheet Modeller, University of Tasmania, and Zoë Thomas, Research Associate, UNSW

This article was originally published on The Conversation. Read the original article.

Drones help scientists check the health of Antarctic mosses, revealing climate change clues



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Mosses are sensitive to even minor changes in their living conditions.
Sharon Robinson, Author provided

Zbyněk Malenovský, University of Tasmania and Arko Lucieer, University of Tasmania

Drones are helping scientists check the health of Antarctic mosses, revealing clues on the pace of climate change.

The scientists say their method could be used for similar research in other harsh environments like desert or alpine regions.

Mosses are sensitive to even minor changes in their living conditions, and scientists traditionally tramped through difficult terrain to collect data on them.

Using the specially-designed drones is faster, kinder to the environment and delivers detailed images that satellite imagery cannot match.

Drones also allow to map much larger areas than previously possible, showing how the moss health responds to meltwater in real time.

The ConversationThese methods could be used for similar research in other harsh environments like desert or alpine regions.

Zbyněk Malenovský, Researcher in Remote Sensing of Vegetation, University of Tasmania and Arko Lucieer, Associate Professor in Remote Sensing, University of Tasmania

This article was originally published on The Conversation. Read the original article.

Antarctic ice reveals that fossil fuel extraction leaks more methane than thought



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The analysis of large amounts of ice from Antarctica’s Taylor Valley has helped scientists to tease apart the natural and human-made sources of the potent greenhouse gas methane.
Hinrich Schaefer, CC BY-ND

Hinrich Schaefer, National Institute of Water and Atmospheric

The fossil fuel industry is a larger contributor to atmospheric methane levels than previously thought, according to our research which shows that natural seepage of this potent greenhouse gas from oil and gas reservoirs is more modest than had been assumed.

In our research, published in Nature today, our international team studied Antarctic ice dating back to the last time the planet warmed rapidly, roughly 11,000 years ago.

Katja Riedel and Hinrich Schaefer discuss NIWA’s ice coring work at Taylor Glacier in Antarctica.

We found that natural seepage of methane from oil and gas fields is much lower than anticipated, implying that leakage caused by fossil fuel extraction has a larger role in today’s emissions of this greenhouse gas.

However, we also found that vast stores of methane in permafrost and undersea gas hydrates did not release large amounts of their contents during the rapid warming at the end of the most recent ice age, relieving fears of a catastrophic methane release in response to the current warming.

The ice is processed in a large melter before samples are shipped back to New Zealand.
Hinrich Schaefer, CC BY-ND

A greenhouse gas history

Methane levels started to increase with the industrial revolution and are now 2.5 times higher than they ever were naturally. They have caused one-third of the observed increase in global average temperatures relative to pre-industrial times.

If we are to reduce methane emissions, we need to understand where it comes from. Quantifying different sources is notoriously tricky, but it is especially hard when natural and human-driven emissions happen at the same time, through similar processes.


Read more: Detecting methane leaks with infrared cameras: they’re fast, but are they effective


The most important of these cases is natural methane seepage from oil and gas fields, also known as geologic emissions, which often occurs alongside leakage from production wells and pipelines.

The total is reasonably well known, but where is the split between natural and industrial?

To make matters worse, human-caused climate change could destabilise permafrost or ice-like sediments called gas hydrates (or clathrates), both of which have the potential to release more methane than any human activity and reinforce climate change. This scenario has been hypothesised for past warming events (the “clathrate gun”) and for future runaway climate change (the so-called “Arctic methane bomb”). But how likely are these events?

Antarctic ice traps tiny bubbles of air, which represents a sample of ancient atmospheres.
Hinrich Schaefer, CC BY-ND

The time capsule

To find answers, we needed a time capsule. This is provided by tiny air bubbles enclosed in polar ice, which preserve ancient atmospheres. By using radiocarbon (14C) dating to determine the age of methane from the end of the last ice age, we can work out how much methane comes from contemporary processes, like wetland production, and how much is from previously stored methane. During the time the methane is stored in permafrost, sediments or gas fields, the 14C decays away so that these sources emit methane that is radiocarbon-free.

In the absence of strong environmental change and industrial fossil fuel production, all radiocarbon-free methane in samples from, say, 12,000 years ago will be from geologic emissions. From that baseline, we can then see if additional radiocarbon-free methane is released from permafrost or hydrates during rapid warming, which occurred around 11,500 years ago while methane levels shot up.

Tracking methane in ice

The problem is that there is not much air in an ice sample, very little methane in that air, and a tiny fraction of that methane contains a radiocarbon (14C) atom. There is no hope of doing the measurements on traditional ice cores.

Our team therefore went to Taylor Glacier, in the Dry Valleys of Antarctica. Here, topography, glacier flow and wind force ancient ice layers to the surface. This provides virtually unlimited sample material that spans the end of the last ice age.

A tonne of ice yielded only a drop of methane.
Hinrich Schaefer, CC BY-ND

For a single measurement, we drilled a tonne of ice (equivalent to a cube with one-metre sides) and melted it in the field to liberate the enclosed air. From the gas-tight melter, the air was transferred to vacuum flasks and shipped to New Zealand. In the laboratory, we extracted the pure methane out of these 100-litre air samples, to obtain a volume the size of a water drop.

Only every trillionth of the methane molecules contains a 14C atom. Our collaborators in Australia were able to measure exactly how big that minute fraction is in each sample and if it changed during the studied period.

Low seepage, no gun, no bomb

Because radiocarbon decays at a known rate, the amount of 14C gives a radiocarbon age. In all our samples the radiocarbon date was consistent with the sample age.

Radiocarbon-free methane emissions did not increase the radiocarbon age. They must have been very low in pre-industrial times, even during a rapid warming event. The latter indicates that there was no clathrate gun or Arctic methane bomb going off.

So, while today’s conditions differ from the ice-covered world 12,000 years ago, our findings implicate that permafrost and gas hydrates are not too likely to release large amounts of methane in future warming. That is good news.

Wetlands must have been responsible for the increase in methane at the end of the ice age. They have a lesser capacity for emissions than the immense permafrost and clathrate stores.

Geologic emissions are likely to be lower today than in the ice age, partly because we have since drained shallow gas fields that are most prone to natural seepage. Yet, our highest estimates are only about half of the lower margin estimated for today. The total assessment (natural plus industrial) for fossil-fuel methane emissions has recently been increased.

In addition, we now find that a larger part of that must come from industrial activities, raising the latter to one third of all methane sources globally. For comparison, the last IPCC report put them at 17%.

The ConversationMeasurements in modern air suggest that the rise in methane levels over the last years is dominated by agricultural emissions, which must therefore be mitigated. Our new research shows that the impact of fossil fuel use on the historic methane rise is larger than assumed. In order to mitigate climate change, methane emissions from oil, gas and coal production must be cut sharply.

Hinrich Schaefer, Research Scientist Trace Gases, National Institute of Water and Atmospheric

This article was originally published on The Conversation. Read the original article.

Don’t worry about the huge Antarctic iceberg – worry about the glaciers behind it


Chen Zhao, University of Tasmania; Christopher Watson, University of Tasmania, and Matt King, University of Tasmania

Icebergs breaking off Antarctica, even massive ones, do not typically concern glaciologists. But the impending birth of a new massive iceberg could be more than business as usual for the frozen continent.

The Larsen C ice shelf, the fourth-largest in Antarctica, has attracted worldwide attention in the lead-up to calving an iceberg one-tenth of its area – or about half the area of greater Melbourne. It is still difficult to predict exactly when it will break free.

But it’s not the size of the iceberg that should be getting attention. Icebergs calve all the time, including the occasional very large one, with nothing to worry about. Icebergs have only a tiny direct effect on sea level.

The calving itself will simply be the birth of another big iceberg. But there is valid concern among scientists that the entire Larsen C ice shelf could become unstable, and eventually break up entirely, with knock-on effects that could take decades to play out.

Ice shelves essentially act as corks in a bottle. Glaciers flow from land towards the sea, and their ice is eventually absorbed into the ice shelf. Removal of the ice shelf causes glaciers to flow faster, increasing the rate at which ice moves from the land into the sea. This has a much larger effect on sea level than iceberg calving does.

While the prediction that Larsen C could become unstable is based partly on physics, it is also based on observations. Using aerial and satellite images, scientists have been able to track very similar ice shelves in the past, some of which have been seen to retreat and collapse.

The death of an ice shelf

The most dramatic ice shelf collapse observed so far is that of Larsen C’s neighbour to the north – the imaginatively named Larsen B. Over the course of just six weeks in 2002 the entire ice shelf splintered into dozens of icebergs. Almost immediately afterwards, the glaciers feeding into it sped up by two to six times. Those glaciers continue to flow faster to this day.

Satellite photo series of Larsen B Ice Shelf collapse from January 2002 to April 2002.
NASA

In our new study, published in Earth and Planetary Science Letters, we turn the clock back even further to look at the Wordie ice shelf, on the west coast of the southern Antarctic Peninsula, which began to retreat in the 1960s and eventually disappeared in January 2017.

Over the past 20 years, observations have shown that the main glacier feeding into the Wordie ice shelf, the Fleming Glacier, has sped up and thinned. Compared with the glaciers feeding Larsen B and C, Fleming Glacier is massive: 80km long, 12km wide, and 600m thick at its front.

Locations of the Larsen C Ice Shelf and the Wordie Ice Shelf-Fleming Glacier system with ice front positions from 1947 to 2016.
Author provided

We used historic aerial photographs from 1966 to create an elevation map of the Fleming Glacier, and compared it to elevation measurements from 2002 to 2015. Between 1966 and 2015 the Fleming Glacier thinned by at least 100m near the front. The thinning rate, which is the elevation change rate, rapidly increased: the thinning rate after 2008 is more than twice that during 2002 to 2008, and four times the average rates from 1966 to 2008.

Ice thinning rate of the Fleming Glacier region during (a) 2002-2008 and (b) 2008-2015.
Author provided

Ice flow speeds have also increased by more than 400m per year at the front since 2008. This is the largest speed change in recent years of any glacier in Antarctica. These changes all point to ice shelf collapse as the cause.

We estimate the total glacier ice volume lost from all glaciers that feed the Wordie is 179 cubic kilometres since 1966, or 319 times the volume of Sydney Harbour. The weight of this ice moving off the land and into the ocean has caused the bedrock beneath the glaciers to lift by more than 50mm.

Other research has suggested this lift could have acted to slow the glacier’s retreat, but it’s clear that the bedrock deformation has not stopped the ice movement speeding up. It seems the Fleming Glacier has a long way to go before it will return to a new stable state (in which snowfall feeding the glacier equals the ice flowing into the oceans).

Fifty years after the Wordie Ice Shelf began to collapse, the major feeding glaciers continue to thin and flow faster than before.

The ConversationWe can’t yet predict the full consequences of the new iceberg calving from Larsen C. But if the ice shelf does begin to retreat or collapse, history tells us it is very possible that its glaciers will flow faster – making yet more sea level rise inevitable.

Chen Zhao, PhD candidate of Antarctic Science, University of Tasmania; Christopher Watson, Senior Lecturer, Surveying and Spatial Sciences, School of Land and Food, University of Tasmania, and Matt King, Professor, Surveying & Spatial Sciences, School of Land and Food, University of Tasmania

This article was originally published on The Conversation. Read the original article.

The winners and losers of Antarctica’s great thaw



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Adélie penguin at the Mt Siple breeding colony, West Antarctica.
Jasmine Lee, Author provided

Jasmine Lee, The University of Queensland; Justine Shaw, The University of Queensland, and Richard Fuller, The University of Queensland

When you think of Antarctica, you probably picture vast, continuous ice sheets and glaciers, with maybe a penguin or two thrown in. Yet most Antarctic plants and animals live in the permanently ice-free areas that cover about 1% of the continent. Our new research predicts that these areas could grow by a quarter during this century, with mixed prospects for the species that currently live there.

Besides everyone’s favourite Emperor and Adélie penguins, terrestrial Antarctic species also include beautiful mosses, lichens, two types of flowering plants, and a suite of hardy invertebrates such as nematodes, springtails, rotifers and tardigrades, many of which are found nowhere else on Earth. Tardigrades – tiny creatures sometimes nicknamed “waterbears” – are so tough they can survive in space.

Antarctica’s ice-free areas are currently limited to a scattering of rocky outcrops along the coastline, or cliff faces, or the tops of mountain ranges. They form small patches of suitable habitat in a huge sea of ice, much like islands.

As a result, the plants and animals that live there are often isolated from each other. But as Antarctica’s climate warms, we expect ice-free areas to get bigger and eventually start joining up. This would create more habitat for native species, but also new opportunities for non-native species to spread.

Our study, published today in Nature, forecasts that climate change will expand Antarctica’s ice-free areas over the course of this century. Under the most severe scenario that we modelled (which is also the one on which the globe is currently tracking), more than 17,000 square km of new ice-free area could emerge across the continent by 2100.

This would increase the current total ice-free area by nearly a quarter. The majority of this new ice-free land will be on the Antarctic Peninsula, which could have three times as much ice-free area as it does today.

Projected Antarctic ice melt this century.
Lee et al. (2017) Nature

Brave new world

As the ice-free areas expand, the distances between them will decrease, giving plants and animals more opportunity to spread through the landscape. On the Antarctic Peninsula, which has already warmed more than anywhere else in Antarctica, many of the ice-free patches will expand so much that they will start joining together.

Will this increase in habitat availability benefit the plants and animals that live there? It will definitely provide new opportunities for some native plants and animals to expand their range and colonise new areas. The warming climate may also give a boost to species that are currently hampered by the lack of warmth, nutrients and water. Some Antarctic mosses, for example, are expected to grow faster as temperatures rise, and Antarctica’s two flowering plant species are already expanding southward.

However, the potential benefits seem likely to be outweighed by the negatives. The joining-up of habitat patches could allow species that have been isolated for much of their evolutionary past to meet suddenly. If the newcomers to a particular area outcompete the native species, then it may lead to localised extinctions. Over the coming centuries this could lead to the loss of many plants and animals, and the homogenisation of Antarctica’s ecosystems.

Antarctic aliens

An even bigger concern is that Antarctica’s great thaw could provide new opportunities for species to invade. Antarctica’s best bulwark against non-native species is its harsh climate and extreme weather, to which native Antarctic species have spent many thousands of years adapting.

A native Frisea springtail.
Melissa Houghton

We already know that many plants and invertebrates are reaching Antarctica, most often in food or cargo shipments. As the climate warms, some of these non-native species may be able to establish themselves on the Antarctic Peninsula, and the increasing connectivity will allow them to easily move through the landscape. Many of these animals and plants may become invasive, competing with the native species for space and resources.

We don’t know how Antarctica’s species will cope with the increasing competition. But if the sub-Antarctic islands provide any indication, the outlook is depressing. Australia’s World Heritage-listed Macquarie Island, for example, was severely impacted by invasive cats, rats, rabbits and mice (although it has since been declared free of these pests after an intensive eradication effort).

Several non-native species have already come to Antarctica, including the invasive annual meadowgrass Poa annua (a common weed around the world), which has colonised newly ice-free areas left behind by retreating glaciers. It is thought to outcompete Antarctica’s native plants, although we don’t yet know what the impact will be on animals.

Invasive meadowgrass on Macquarie Island.
Laura Williams

Humans – both scientists and tourists – are key transporters of non-native species to the continent, and tourist numbers continue to grow (almost 37,000 visited in the 2016-17 summer).

Biosecurity is paramount for the ongoing protection of Antarctica. If bags, shoes, clothes and field equipment are not properly cleaned and inspected before arriving on the continent, then non-native seeds, microbes and insects could be transported to Antarctica and begin to spread.

The ConversationWe call for protection of ice-free areas that will remain intact in a changing climate, and for the Antarctic scientific and tourism communities to pinpoint key areas where greater biosecurity and monitoring for invasive species may be needed.

Jasmine Lee, PhD candidate, biodiversity conservation and climate change, The University of Queensland; Justine Shaw, Conservation Biologist, The University of Queensland, and Richard Fuller, Associate Professor in Biodiversity and Conservation, The University of Queensland

This article was originally published on The Conversation. Read the original article.