Winter storms are speeding up the loss of Arctic sea ice

A scientist checks cracks in the Arctic sea ice after a storm (April 2015, N-ICE2015 expedition).
Amelie Meyer/NPI, Author provided

Arctic sea ice is already disappearing rapidly but our research shows winter storms are now further accelerating sea ice loss.

The research is based on data we gathered during an expedition on a small Norwegian research vessel, the Lance, that was left to drift in the Arctic sea ice for five months in 2015.

Time series of air temperature anomalies in the Arctic for the period 1981-2010: Temperatures in the Arctic in May and June 2019 period were the warmest in the satellite records.
Zack Labe (@ZLabe)

The expedition was intense and felt more like going to the Moon than going on a typical research cruise. What took us by surprise were the many winter storms that battered the ice (and our ship and ice camp).

It has taken us years to collate these data but now we know the winter storms play a key role in the fate of Arctic sea ice, particularly in the Atlantic sector of the Arctic.

Norwegian research vessel ‘Lance’ frozen in the Arctic sea ice in February 2015 during the N-ICE2015 expedition.
Paul Dodd (NPI)

How winter storms amplify climate change

On average, about 10 extreme storms will reach all the way to the North Pole each winter. While these winter storms are short (they last on average 6-48 hours), they can be incredibly intense.

During a storm in winter 2015 we saw the air temperature rise from -40℃ (-40℉) to 0℃ (32℉) in just a day, and then fall back to -30℃ (-22℉) the next day, when cold Arctic air returned after the storm.

These storms bring heat, moisture and strong winds into the Arctic, and next we look at how they impact sea ice and its surroundings.

Warming and weakening the ice

The heat from the storms warms up the air, snow and ice, slowing down the growth of the ice. Moisture from the storms falls as snow on the ice. After the storm, the blanket of snow insulates the ice from the cold air, further slowing the growth of the ice for the remainder of winter.

The strong winds during the storms push the ice around and break it into pieces, making it more fragile and deforming it, more like a boulder field.

The strong winds also stir the ocean below the ice, mixing up warmer water from deeper waters to the surface where it melts the ice from below. This melting of the ice in the middle of winter can happen for several days after the storms when the air is already back to well below freezing.

Processes related to Arctic winter storms. In the first storm phase, strong southerly winds compress the ice cover and transport warm air, moisture, and bring strong winds. In the second phase, northerly winds transport ice southwards. After the storm has passed, cold and calm conditions return, allowing new ice to grow in leads. When the next winter storm arrives, it further drives the ice cover into a relatively thin-ice, snow-covered mosaic of strongly deformed ice floes. These new conditions impact surrounding ecosystems by shaping habitats and light conditions.
Graham et al., 2019 (Scientific Reports)

Thinner ice, shelter for life and accelerated melting

The breakup of the ice opens big passages of open water between ice floes, called leads. In winter these passages end up refreezing rapidly, generating new super-thin ice.

These thinner refrozen patches of ice let more light through in the following spring, allowing ocean plants (phytoplankton) to bloom earlier.

The rougher sea ice landscape becomes a shelter for many ice-associated Arctic organisms, including ice algae, becoming biological hot spots in the following spring.

The broken up and deformed ice drifts faster, reaching warmer waters where it melts sooner and faster.

So really, winter storms precondition the ice to a faster melt in the following spring with an impact that continues well into the following season.

Why is Arctic sea ice declining?

Winter sea ice cover in the Atlantic sector of the Arctic has been retreating at a record breaking pace, especially in the Barents Sea off Norway and Russia.

Average September Arctic sea ice extent from 1979 to 2018. Black line shows monthly average for each year; blue line shows the trend.
National Snow and Ice Data Center

The Arctic is particularly sensitive to human driven climate change. We know the decrease in sea ice is due to both the warming of the Arctic (air and ocean) and changing wind patterns that break up the ice cover.

But there are also amplifying mechanisms or “feedback” mechanisms, in which one natural process reinforces another. Their role in the decrease of sea ice is hard to predict. We now know winter storms in the Arctic contribute to these feedback mechanisms.

More storms ahead

Arctic winter storms are increasing in frequency and this is likely due to climate change.

With the thinner Arctic sea ice cover and shallower warmer water in the Arctic Ocean, the mechanisms we observed during the winter storms will likely strengthen and the overall impact of winter storms on Arctic ice is likely to increase in the future.

Two weeks ago, the Arctic sea ice reached its minimum extent for 2019, after another winter of intense winter storms. The minimum ice extent was effectively tied for second lowest since modern record-keeping began in the late 1970s, along with 2007 and 2016, reinforcing the long-term downward trend in Arctic ice extent. Arctic sea ice has been declining for at least 40 years, and amplifying mechanisms such as the winter storms are accelerating this retreat.

Arctic sea ice extent just reached its annual minimum extent for 2019 on September 18. This season was a tie for the *2nd lowest* on record, along with 2007 and 2016 and behind 2012, which holds the overall record minimum.
Zack Labe (@ZLabe)

As highlighted in the recent IPCC Ocean and Cryopshere report, these changes in September sea ice are likely unprecedented for at least 1,000 years.

Remember also that changes in the Arctic don’t just affect the immediate region: Arctic warming has been linked to the polar vortex, and weather extremes across central Europe and north America.

As we start taking into account feedback mechanisms like the winter storms, our predictions for the first Arctic sea ice free summer are indicating it will likely happen before 2050.

Amelie Meyer, Research fellow, University of Tasmania

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

Half the world’s ecosystems at risk from habitat loss, and Australia is one of the worst

James Watson, The University of Queensland; Eve McDonald-Madden, The University of Queensland; James Allan, The University of Queensland; Kendall Jones, The University of Queensland; Moreno Di Marco, The University of Queensland, and Richard Fuller, The University of Queensland

Habitat loss is the most insidious of all threats facing land-living wildlife, and protected areas like national parks are one of the best ways to combat the destruction. But in research published recently in Conversation Letters, we show that in some places the pace of protected areas isn’t keeping up with the losses.

We found that since 1992, an area of natural habitat two-thirds the size of Australia has been converted to human use (such as farms, logging or cities). Half of the world’s land area is now dominated by humans.

When we looked at specific habitats (or “ecoregions”), we found that in almost half of them, more habitat has been lost than has been protected. Of developed nations, Australia is performing the worst.

This week, 196 signatory nations of the Convention of Biological Diversity, including Australia, are meeting in Cancun, Mexico, to discuss their progress towards averting the current biodiversity crisis.

While topics will vary widely from dealing with climate change, invasive species and illegal wildlife trade, a chief issue will likely be one that has been central to the convention since its ratification at Rio in 1992: how best to deal with habitat loss.

The view from space

Human activity affects the planet on a scale so vast it can be easily seen from space. Whether it’s deforestation in the Amazon, urban development in Asia, or mining in the Arctic, humans have modified Earth’s land area dramatically.

For almost all wild species on Earth, once the places they live have been dramatically altered, they are unable to survive in the long term. The number of vertebrate species extinctions has been 53 times higher than normal since 1900, and the majority of them are associated with direct habitat loss.

The best tool we have at our disposal to combat habitat loss, alongside strict land regulation, is the creation of large, well-connected protected areas, especially in places that are likely to be at risk of future destruction.

When well managed and strategically placed, protected areas work at protecting biodiversity from destructive actives such as agriculture, mining and urbanisation.

In the two and a half decades since the Rio de Janeiro Earth Summit in 1992, there has been a dramatic increase in protected areas. Now 15% of the land is placed under protection – an area greater than South and Central America combined.

That’s the good news. The bad news is that it may not be enough.

Half Earth

Using the latest update of the global human footprint, we discovered that while 75% of the world has a clear human footprint, more than 50% of the world’s land area has been significantly converted to human dominated land uses.

The degree of degradation varies across the major ecosystems. Some areas such as the tundra have been only slightly modified. Other ecosystems have been decimated: 90% of mangroves and sub-tropical forests have been converted to human uses.

Concerningly, since the convention was ratified in 1992, an extra 4.5 million square kilometres of land has been converted from natural habitat to human land uses. And much of this loss occurred in areas that already faced considerable losses in the past.

As a consequence, almost half of the world’s 800 ecoregions – those places that have distinct animal and plant communities – should be classified at very high risk, where 25 times more land has been converted than protected.

Forty-one of these ecoregions are in crisis, where humans converted more than 10% of the little remaining habitat over the past two decades and there is almost nothing left to protect.

41 of the world’s ecoregions are in crisis.

These crisis ecoregions are concentrated in Southeast Asia (Indonesia and Papua New Guinea), and Africa (Madagascar, Democratic Republic of the Congo and Angola). It’s crucial that we establish protected areas in these places, but conflict and corruption make them some of the hardest places for conservation to work.

Australia: world expert in land clearing

While crisis ecoregions are mostly confined to the developing world, arguably the most concerning outcome of our research is that in many developed countries, like the United States and Canada, the proportion of protected areas to habitat loss is slipping.

And Australia is the worst performing developed nation of them all. Habitat loss greatly outpaced protection in 20 of Australia’s most wildlife-rich ecoregions. The most threatened ecoregions now include savannas in the southeast and southwest of Australia, and southeast temperate forest ecosystems.

Our analysis shows massive habitat loss occurred in Queensland, New South Wales and Western Australia during the past two decades, driven by land clearing for pasture, agriculture and urbanisation.

Australia has extremely high land-clearing rates and is the only developed nation now containing a deforestation front.

Arguably, things will continue to get worse without land-clearing law reform, but this is challenging, as shown by the recent failure of Queensland’s vegetation law changes and the poor vegetation-offset reforms in New South Wales.

Time for global action

As nations meet in Mexico to discuss their progress towards the Convention of Biological Diversity’s 2020 strategic plan, it is now time for them to undertake a full, frank and honest assessment on how things are progressing.

This means recognising that the current situation, where nations only report on protected area expansion, clearly tells half the story – and it is jeopardising the chance for halting the biodiversity crisis.

Australia must take the lead. It is time for this nation – one of the most wildlife-rich in the developed world – to account fully for both conservation gains and losses, and as such formally report on how much habitat is being destroyed. This is the necessary first step to identify ways to mitigate these losses and prioritise conservation actions in those regions that are at risk.

At the same time, all nations must recognise that the integrity of habitat within existing protected areas must be maintained, especially in those areas that contain imperilled species. Allowing activities which cause habitat loss to occur in protected areas is a backwards step for conservation, and governments must enforce their own environmental policies to stop this.

A good example is Springvale Station in Queensland, where mining is being considered within a newly purchased protected area, clearly threatening its biodiversity.

We need to change how we report on, and deal with, habitat loss, otherwise the mission of the convention – to stop the global extinction crisis – will fail.

James Watson, Associate Professor, The University of Queensland; Eve McDonald-Madden, Senior lecturer, The University of Queensland; James Allan, PhD candidate, School of Geography, Planning and Environmental Management, The University of Queensland; Kendall Jones, PhD candidate, Geography, Planning and Environmental Management, The University of Queensland; Moreno Di Marco, Postdoctoral Researcher in Conservation Biology, The University of Queensland, and Richard Fuller, Associate professor, The University of Queensland

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

Extinction means more than a loss of species to Australia’s delicate ecosystems

Matthew McDowell, Flinders University

European settlement of Australia, and the exotic predators and herbivores they brought with them, caused rapid widespread biodiversity loss. As a result, for the past 200 years Australia has had the highest mammal extinction rate in the world.

Humans wiped out the Thylacine, also known as the Tasmanian Tiger.
Wikimedia

Some extinct species were deliberately persecuted, such as the Tasmanian Tiger, Thylacinus cynocephalus, and some were neglected, such as the recently extinct Bramble Cay Mosaic-tailed Rat, Melomys rubicola.

Others, such as Gilbert’s Potoroo, Potorous gilbertii, appear to have simply been in the wrong place at the wrong time. Not yet extinct, but considered the most endangered marsupial in the world, it lost 90% of its natural habitat to a bushfire in late 2015.

When a species is lost from a community, the processes and functions it performed are also lost. All species contribute to the maintenance of their community ecology, but few contribute more than fossorial (digging) species such as bettongs, potoroos and bandicoots.

Part of the cycle

Bettongs are particularly important because most species mainly eat hypogeal fungi (truffles) and spread fungal spores wherever they dig.

As all Eucalyptus plants form a symbiotic relationship with hypogeal fungus during at least part of their life, spreading spores is one of the most important ecosystem services a mammal can perform.

Bettongs also facilitate seedling germination and establishment, soil aeration, incorporate organic matter and improvement moisture infiltration.

Before European settlement, at least five species of bettongs lived on mainland Australia, now (excluding the Rufous Bettong, Aepyprymnus rufescens, a similar beast but not of the genus Bettongia) only Bettongia tropica remains, and it’s listed as endangered.

The almost total loss of these ecosystem engineers from mainland Australia has far-reaching implications that may ultimately lead to vegetation succession, the gradual replacement of one plant community by another. In this case, it will be an impoverished one.

An incomplete skull and jaws are all that remains of the only individual of *Bettongia anhydra* ever to be found alive. The rest of the animal probably went into the cooks pot!
Matthew McDowell, Author provided

Last year, I published a description of the Desert Bettong (Bettongia anhydra) in the Journal of Mammalogy based on the skull and jaws of an animal that was collected alive near the southwestern corner of the Northern Territory in 1933.

Until now, it has been considered synonymous with its morphologically similar cousin the Burrowing Bettong, Bettongia lesueur. Sadly, the newly-identified Desert Bettong has never been encountered alive since. How many other native mammals have been lost without being recognised or have their remains resting in museum cabinets just waiting for the right person to look at them?

Recent breakthroughs in DNA research have shown that what were once considered wide-ranging species are in many cases species complexes. For example, molecular research on the Dusky Antechinus, Antechinus swainsonii, has revealed a complex of five species.

The good and the bad news

The good news is Australia’s biodiversity is richer than we thought. But the bad news is we’re still losing species at an alarming rate. So what can we do to reduce further loss of our unique mammals beyond protecting pristine areas?

Before attempting a restoration project, we really need to know what it is we want to restore. Many native mammals became locally extinct before historical records were compiled. As a result, Holocene (<10,000 year old) fossils provide better evidence of species distribution and habitat preferences than historical records.

Unfortunately, conservation and natural resource managers rarely consult the fossil record. If they did, they’d see that the modern distributions of many species poorly reflect their fossil distributions.

For example the Broad-toothed rat, Mastacomys fuscus, presently lives in alpine regions, but the fossil record shows that less than 1,000 years ago, it lived near sea level on the Fleurieu Peninsula and the Coorong.

Evidence-based restoration

The Mulligans Flat restoration project, in north-eastern ACT, is a great example where Holocene fossils were used to make evidence-based conservation decisions.

The research team used fossil and other evidence to identify species that once lived in their study area. Then, they prioritised the order of species reintroduction based on the range of ecological services each species performed.

Releasing Eastern or Tasmanian Bettongs, Bettongia gaimardi, was their first priority. Their reintroduction appears to be improving soil quality profoundly. I believe the practices used at Mulligans Flat should be applied to all future restoration projects.

The Eastern Bettong is considered secure on Tasmania and the Northern Bettong, Bettongia tropica, still persists naturally on mainland Australia.

All other surviving bettongs live on small islands. This affords protection from predators but limits population size, genetic diversity and reintroduction potential.

If we can’t restore original faunas, I think we have to seriously consider building novel, self-sustaining communities even if they lack present or past analogues. They may even need to include exotic species. Though it sounds extreme, it may be the only way to achieve lasting protection against extinction for what remains of Australia’s unique fauna.

Matthew McDowell, Postdoctoral Researcher, Flinders University

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