Tag Archives: Impacts

Bluefin tuna follow prey to warming high Arctic

Large bluefin tuna that were caught among mackerel near Greenland Image: Greenland Fisheries License Control Authority
Large bluefin tuna that were caught among mackerel near Greenland
Image: Greenland Fisheries License Control Authority

By Alex Kirby

A research ship’s surprise catch of bluefin tuna further north than ever recorded indicates that climate change is restructuring the food web as the waters of east Greenland get warmer.

LONDON, 8 September, 2014 − Biologists and fishermen aboard a scientific cruise in the Arctic while they investigated mackerel stocks caught more than they bargained for − three large bluefin tuna, each weighing about 100 kilograms.

The research ship was sailing through the Denmark Strait, which separates Greenland from Iceland. Bluefin tuna are very seldom found near Greenland, and there are no other scientific reports of them venturing that far north. The most recent report of a tuna anywhere near was a stranding in 1900, a long way south at Qaqortoq, on the south-western tip of Greenland.

Details of the find, during a cruise in August 2012 organised by the Center for Macroecology, Evolution and Climate at the University of Copenhagen, have now been published in the journal Global Change Biology.

Expanded range

The lead author, Professor Brian MacKenzie, said bluefin tuna usually search for prey in areas where surface temperatures are warmer than 11°C.

At the time of the catch, the Denmark Strait was unusually warm, and one of tuna’s preferred prey species, mackerel, had already expanded their range into the region.

Professor MacKenzie and his colleagues write: “Regional temperatures in August 2012 were historically high and contributed to a warming trend since 1985, when temperatures began to rise.

“The presence of bluefin tuna in this region is likely due to a combination of warm temperatures . . . and immigration of an important prey species to the region. We conclude that a cascade of climate change impacts is restructuring the food web in east Greenland waters.”

They say their data was too limited to estimate how many tuna came so far north, but because bluefins are a schooling species − with schools having from 10 to 100 individuals − and because the three tuna were caught in the same haul, it is likely there were many more present.

The report says: “Satellite imagery showing the spread of warm water from the south-east towards east Greenland suggests that recent warming and climate change may have opened a migration pathway from the European shelf towards Greenland for migratory species.”

It acknowledges that the fish may have swum to the Denmark Strait from the north-west Atlantic, and concludes: “Our results show that rising temperatures have been progressively leading a . . . trophic [high in the food chain] cascade into east Greenland waters via improved thermal conditions for migratory prey and predator species.”

New fishing quotas

Nobody knows why bluefin tuna disappeared from the waters near Denmark and in the Norwegian Sea during the 1960s, nor when they might return. But Iceland and Norway have been allocated new fishing quotas of 30 tonnes each for the species in 2014.

An adult bluefin tuna is typically 1.5m-2m long, but some have been as big as 4.5m and weighed 650 kg. The fish are highly prized for sushi, especially in Japan.

Further climate-related changes in distributions of commercial fish such as mackerel and herring will mean new fishery and ecosystem management plans are going to be needed, says the report’s co-author, Helle Siegstad, head of the Department for Fish and Shellfish at the Greenland Institute of Natural Resources.

The Denmark Strait tuna will be discussed at the annual science conference of the International Council for the Exploration of the Sea (ICES), which starts on 15 September in the Spanish coastal city of A Coruña. – Climate News Network

Doors open at Ban Ki-moon’s ‘Last Chance Saloon’

Waves wash against the runway at Nauru airport, where sea level rise is a daily reality Image: Dept of Foreign Affairs and Trade via Wikimedia Commons
The runway at Nauru island’s airport in the South Pacific, where sea level rise is a daily reality
Image: Matt Robertson/Australian DFAT via Wikimedia Commons

By Paul Brown

The UN secretary-general is attempting to prevent world leaders sleepwalking into disaster by asking them to make new pledges at a climate summit this month on cutting greenhouse gases.

LONDON, 3 September, 2014  It is widely acknowledged that the planet’s political leaders and its people are currently failing to take enough action to prevent catastrophic climate change.

Next year, at the United Nations climate change conference in Paris, representatives of all the world’s countries will be hoping to reach a new deal to cut greenhouse gases and prevent the planet overheating dangerously. So far, there are no signs that their leaders have the political will to do so.

To try to speed up the process, the UN secretary-general, Ban Ki-moon, has invited world leaders to UN headquarters in New York on 23 September for a grandly-named Climate Summit 2014.

He said at the last climate conference, in Warsaw last year, that he is deeply concerned about the lack of progress in signing up to new legally-binding targets to cut emissions.

If the summit is a success, then it means a new international deal to replace the Kyoto Protocol will be probable in late 2015 in Paris. But if world leaders will not accept new targets for cutting emissions, and timetables to achieve them, then many believe that political progress is impossible.

Danger threshold

Ban Ki-moon’s frustration about lack of progress is because politicians know the danger we are in, yet do nothing. World leaders have already agreed that there is no longer any serious scientific argument about the fact that the Earth is heating up and  if no action is taken  will exceed the 2°C danger threshold.

It is also clear, Ban Ki-moon says, that the technologies already exist for the world to turn its back on fossil fuels and cut emissions of greenhouse gases to a safe level.

What the major countries cannot agree on is how the burden of taking action should be shared among the world’s 196 nations.

Ban Ki-moon already has the backing of more than half the countries in the world for his plan. These are the most vulnerable to climate change, and most are already being seriously affected.

More than 100 countries are currently meeting in Apia, Samoa, at the third UN Conference on Small Island Developing States, which ends tomorrow. In their draft final statement, they note with “grave concern” that world leaders’ pledges on the mitigation of greenhouse gases will not save them from catastrophic sea level rise, droughts, and forced migration.

“We express profound alarm that emissions
of greenhouse gases continue to rise globally”

Many of them have long advocated a maximum temperature rise of 1.5°C to prevent disaster for the most vulnerable nations, such as the Marshall Islands and the Maldives.

The draft ministerial statement says: “Climate change is one of the greatest challenges of our time, and we express profound alarm that emissions of greenhouse gases continue to rise globally.

“We are deeply concerned that all countries, particularly developing countries, are vulnerable to the adverse impacts of climate change and are already experiencing an increase in such impacts, including persistent drought and extreme weather events, sea level rise, coastal erosion and ocean acidification, further threatening food security and efforts to eradicate poverty and achieve sustainable development.”

Devastating consequences

Speaking from Apia, Shirley Laban, the convenor of the Pacific Islands Climate Action Network, an NGO, said: “Unless we cut emissions now, and limit global warming to less than 1.5°C, Pacific communities will reap devastating consequences for generations to come. Because of pollution we are not responsible for, we are facing catastrophic threats to our way of life.”

She called on all leaders attending the UN Climate Summit in New York to “use this historic opportunity to inject momentum into the global climate negotiations, and work to secure an ambitious global agreement in 2015”.

This is a tall order for a one-day summit, but Ban Ki-moon is expecting a whole series of announcements by major nations of new targets to cut greenhouse gases, and timetables to reach them.

There are encouraging signs in that the two largest emitters – China and the US – have been in talks, and both agree that action is a must. Even the previously reluctant Republicans in America now accept that climate change is a danger.

It is not yet known how many heads of state will attend the summit in person, or how many will be prepared to make real pledges.

At the end of the summit, the secretary-general has said, he will sum up the proceedings. It will be a moment when many small island states and millions of people around the world will be hoping for better news.  Climate News Network

Food security faces growing pest advance

Root knot nematode (Meloidogyne incognita) on a tomato plant Image: Courtesy of CABI

Root knot nematode (Meloidogyne incognita) on a tomato plant
Image: Courtesy of CABI

By Tim Radford

A world with more people will see more competition for food. Many of our competitors may not be human, because natural pests are spreading far and wide.

LONDON, 29 August 2014 - Coming soon to a farm near you: just about every possible type of pest that could take advantage of the ripening harvest in the nearby fields.

By 2050, according to new research in the journal Global Ecology and Biogeography, those opportunistic viruses, bacteria, fungi, blights, mildews, rusts, beetles, nematodes, flies, mites, spiders and caterpillars that farmers call pests will have saturated the world.

Wherever they can make a living, they will. None of this bodes well for food security in a world of nine billion people and increasingly rapid climate change.

Dan Bebber of the University of Exeter, UK,  and colleagues decided to look at the state of pest populations worldwide. They combed the literature to check the present status of 1,901 pests and pathogens and examined historical records of another 424 species. This research included the records made since 1822 by the agricultural development organization CABI.

Crop pests often emerge in one location, evolve and spread. That notorious potato pest the Colorado beetle, for instance, was first identified in the Rocky Mountains of the US in 1824.

Rising trend

The scientists reasoned that climate change and international traffic made transmission of pests across oceans and other natural barriers increasingly probable, and tried to arrive at a rate of spread.

They found that more than one in 10 of all pest types can already be found in half of the countries that grow the host plants on which these pests depend. Most countries reported around one fifth of the pests that could theoretically make their home there.

Australia, China, France, India, Italy, the UK and the USA already had more than half of all the pests that could flourish in those countries. The pests that attack those tropical staples yams and cassava can be found in one third of the countries that grow those crops.

This trend towards saturation has increased steadily since the 1950s. So if the trend continues at the rate it has done during the late 20th century, then by 2050 farmers in western Europe and the US, and Japan, India and China will face saturation point.

They will be confronted with potential attack from just about all the pests that, depending on the local climate and conditions, their maize, rice, bananas, potatoes, soybeans and other crops could support.

Early warning

“If crop pests continue to spread at current rates, many of the world’s biggest crop-producing nations will be inundated by the middle of the century, posing a grave threat to global food security,” Dr Bebber said.

Three kinds of tropical root knot nematode produce larvae that infect the roots of thousands of different plant species. A fungus called Blumeria graminis causes powdery mildew on wheat and other grains; and a virus called Citrus tristeza, first identified by growers in Spain and Portugal in the 1930s, had by 2000 reached 105 out of the 145 countries that grow oranges, lemons, limes and grapefruit.

Predictions such as these are intended to be self-defeating: they present a warning of what might happen if no steps are taken.

“By unlocking the potential to understand the distribution of crop pests and diseases, we’re moving one step closer to protecting our ability to feed a growing global population,” said Timothy Holmes, of CABI’s Plantwise knowledge bank, one of the authors. “The hope is to turn data into positive action.” - Climate News Network

Pre-history proof of climate’s see-saw sensitivity

The woolly rhinoceros once roamed wild on the plains of Europe Image: Public Library of Science via Wikimedia Commons
The woolly rhinoceros once roamed wild on the plains of Europe
Image: Public Library of Science via Wikimedia Commons

By Tim Radford

Computer simulations reaching back deep into the last Ice Age have enabled scientists to put a historic perspective on how even small variations in the climate system can lead to dramatic temperature change.

LONDON, 24 August, 2014 − It doesn’t take much to change a planet’s climate – just a little shift in the Northern hemisphere glacial ice sheet and a bit more carbon dioxide in the atmosphere. After that, the response is rapid. The tropical rain belt moves north and the southern hemisphere cools a bit, in some sort of bipolar see-saw response.

Sound familiar? It does, and it doesn’t. It all happened long before the internal combustion engine, or even the new Stone Age.

Researchers from the Alfred Wegener Institute’s Helmholtz Centre for Polar and Marine Research, Bremerhaven, the University of Bremen, Germany, and the University of Cardiff in the UK, report in Nature journal that they have made climate simulations that agree with observations of historical climate change that date back 800,000 years.

Long before the present alarms about global warming through the emission of carbon dioxide from fossil fuels, climate researchers were puzzled by the phenomenon of the Ice Ages and the “interglacials” that punctuated those long periods when the Arctic ice extended from the North Pole to the Atlantic coast of France, and over huge tracts of North America.

Vanished species

Mysteriously, and at great speed, the temperatures would rise by up to 10°C and the vast walls of ice would retreat. Lion, hyena and rhinoceros would invade the wild plains of what is now southern England, and now-vanished species of humans would hunt big game and gather fruit and seeds in the valleys and forests of Europe and America.

Since the end 10,000 years ago of the last ice age – itself a very rapid event – was the springboard for agriculture and civilisation, and eventually an Industrial Revolution based on fossil fuels, the story of climate change plays a powerful role in human history.

So any analysis of the tiny shifts in ice cover that seemed to trigger these dramatic, bygone events can be helpful in understanding the long story of the making of the modern world.

The researchers found a tentative scenario involving weak ocean currents, and prevailing winds that shifted the sea ice and allowed the oceans and atmosphere to exchange heat, pushing warmer water into the north-east Atlantic.

These changes precipitated a dramatic warming of the northern hemisphere in just a few decades, and the retreat of the glaciers for an extended period before the ice returned to claim much of the landmass again. But, overall, such changes tended to occur when sea levels reached a certain height.

“The rapid climate changes known in the scientific world as Dansgaard-Oeschger events were limited to a period of time from 110,000 to 23,000 years before the present,” said Xu Zhang, the report’s lead author.

“The abrupt climate changes did not take place at the extreme low sea levels, corresponding to the time of maximum glaciations 20,000 years ago, or at high sea levels such as those prevailing today. They occurred during periods of intermediate ice volume and intermediate sea levels”

Climate swings

Co-author Gerrit Lohmann, who leads the Wegener Institute’s palaeoclimate dynamics group, said: “Using the simulations performed with our climate model, we were able to demonstrate that the climate system can respond to small changes with abrupt climate swings.

“At medium sea levels, powerful forces − such as the dramatic acceleration of polar ice cap melting − are not necessary to result in abrupt climate shifts and associated drastic temperature changes.”

How much this tells anybody about modern climate change is open to debate. Right now, according to this line of evidence, the planet’s climate could be in one of its more stable phases of the Earth’s history.

But while the conditions for the kind of rapid change recorded in pre-history do not exist today, Prof Lohmann warns that “sudden climate changes cannot be excluded in the future”. – Climate News Network

‘Free riders’ undermine climate treaty hopes

Pollution haze over Beijing's Forbidden City Image: Yinan Chen via Wikimedia Commons
Sins of emission: pollution haze over Beijing’s Forbidden City
Image: Yinan Chen via Wikimedia Commons

By Alex Kirby

Norwegian researchers warn that hopes of getting an effective agreement on climate control will slip further away unless key polluting countries get serious about emissions reductions – and face sanctions if they don’t comply.

LONDON, 23 August, 2014 − An effective treaty to reduce greenhouse gas emissions will probably remain elusive, according to a new research study, because the steps likely to win political agreement would be ineffective, while those that could produce results would be politically unfeasible..

In fact, the Norwegian researchers conclude, the world is actually further away from an effective climate agreement today than it was 15 years ago, when the Kyoto Protocol was adopted.

The research is the work of a team from the Centre for International Climate and Environmental Research – Oslo (Cicero) and Statistics Norway, the country’s Central Bureau of Statistics.

Slow progress

The key question the researchers asked was what conditions could achieve an international agreement that would substantially reduce global climate emissions, in view of the extremely slow progress in the UN negotiations. They concluded that there is little basis for optimism.

Professor Jon Hovi, of the University of Oslo and Cicero, headed the project. He says there are three essentials for a robust agreement:

  • It must include all key countries − in other words, all the major emitters.
  • It must require each member country to make substantial emissions cuts.
  • Member countries must actually comply with their commitments.

While emissions cuts benefit all countries, he says, each country must bear the full costs of cutting its own emissions. So each is sorely tempted to act as a “free rider” − to enjoy the gains from other countries’ cuts while ignoring its own obligations.

“Cutting emissions is expensive, and powerful interests in every country proffer arguments as to why that particular country should be exempted,” Professor Hovi explains. “This inclines the authorities of all countries to take decisions that make them free riders.”

The researchers identified five types of free rider. Some countries − the US, for example − never ratified the Kyoto Protocol. Others, such as Canada, ratified it but later withdrew.

Developing countries ratified the Protocol, but it did not require them to make any cuts. The countries of Eastern Europe also ratified Kyoto, but it cost them nothing as their transition from a centrally-planned economy to a market economy meant their economies could not afford to cause significant emissions anyway.

Finally, the team says, some of the countries that accepted relatively deep commitments under Kyoto may have failed to live up to it. The final compliance figures are not yet available.

“Each and every country must be certain
that the other countries are also doing their part.”

“We must eliminate free riding,” Professor Hovi says. “Each and every country must be certain that the other countries are also doing their part. It’s the only viable option.”

He thinks any country avoiding its treaty commitments must face consequences: “Free riding must be met with concrete sanctions. The question is what type of enforcement could conceivably work and, if such a system exists, would it be politically possible to implement it.”

He and his colleagues recommend financial deposits, administered by an international secretariat. At ratification, each country would deposit a significant amount of money, and continue to do so annually until the agreed emissions reductions start. The total amount deposited by each country should match the cost of its commitments.

At the end of the reduction period, those countries that had met their cuts targets would receive a full refund of their deposit, plus interest. Those that had failed to do so would forfeit part or all of it.

Practical problems

But Professor Hovi concedes that not only would there be several practical problems with such a scheme, but there is little chance that it would be adopted anyway, because strict enforcement of an agreement is not politically feasible.

The researchers say that some countries – such as the US – support international systems of enforcement that can safeguard compliance with an agreement. “At the same time, other key countries have stated a clear opposition to potent enforcement measures – either as a matter of principle or because they know that they will risk punishment,” Professor Hovi says.

“For example, China opposes mechanisms that entail international intervention in domestic affairs as a matter of principle. China is not even prepared to accept international monitoring of its own emissions.

“The UN principle of full consensus allows countries opposed to enforcement measures to prevail by using their veto right during negotiations.”

Governments will try to revive hopes that agreement can be reached on an effective climate treaty when the UN Framework Convention on Climate Change (UNFCCC) meets in Paris late in 2015. − Climate News Network

Climate change heralds end of civilisations

Arid land in the former Fertile Crescent area of south-west Syria Image; Simone Riehl/Tübingen University
Arid landscape in the former ‘Fertile Crescent’ area of south-west Syria
Image; Simone Riehl/Tübingen University

By Paul Brown

New research supports the growing body of evidence that many past civilisations have collapsed because of climate change. So is history repeating itself?

LONDON, 13 August, 2014 –  Scientists looking at what is known as the “Fertile Crescent” of ancient Mesopotamia have found new evidence that drought caused by climate change brings an end to civilisations.

It is the latest study that confirms the threat posed to present civilisations in Africa, Asia and parts of the United States by changes in rainfall pattern that could lead to the abandonment of once-fertile areas − and the cities that once were fed by them.

The focus of research by a team from Tübingen University, Germany, is the area currently part of Iraq and the Persian Gulf where the development of ancient agriculture led to the rise of large cities.

Evidence from grain samples up to 12,000 years old shows that while the weather was good, the soil fertile and the irrigation system well managed, civilisation grew and prospered. When the climate changed and rainfall became intermittent, agriculture collapsed and the cities were abandoned.

Analysed grains

Dr Simone Riehl, of the Institute for Archaeological Sciences and the Senckenberg Center for Human Evolution and Palaeoenvironment at Tübingen University, analysed grains of barley up to 12,000 years old from 33 locations across the Fertile Crescent to find out if they had had enough water while growing and ripening.

The 1,037 ancient samples were between 12,000 and 2,500 years old. They were compared with modern samples from 13 locations in the former Fertile Crescent.

Dr. Riehl and her team measured the grains’ content of two stable carbon isotopes.

When barley grass gets insufficient water while growing, the proportion of heavier carbon isotopes deposited in its cells will be higher than normal. The two isotopes 12C and 13C remain stable for thousands of years and can be measured precisely – giving Riehl and her colleagues reliable information on the availability of water while the plants were growing.

They found that many settlements were affected by drought linked to major climate fluctuations. “Geographic factors and technologies introduced by humans played a big role and influenced societies’ options for development, as well as their particular ways of dealing with drought,” Riehl says.

Her findings indicate that harvests in coastal regions of the northern Levant, at the eastern end of the Mediterranean Sea, were little affected by drought. But further inland, drought led to the need for irrigation or, in extreme cases, abandonment of the settlement.

The findings give archaeologists clues as to how early agricultural societies dealt with climate fluctuations and differing local environments. “They can also help evaluate current conditions in regions with a high risk of crop failures,” Riehl adds.

The study is part of a project, backed by the German Research Foundation, looking into the conditions under which Ancient Near Eastern societies rose and fell.

Scientists carrying out similar research in the Indus Valley, in present Pakistan and north-west India, home to the Harappan Civilisation, also believe that drought was the cause of the civilisation’s demise.

It was characterised by large, well-planned cities with advanced municipal sanitation systems and a script that has never been deciphered. But the Harappans seemed to slowly lose their urban cohesion, and their cities were gradually abandoned.

Cities abandoned

According to an article in Nature in March, a 200-year drought, caused by the failure of the monsoon, led to the abandonment of the cities and the end of the civilisation.

Across the Atlantic, another puzzle was the loss of the Mayan cities and culture in Central America. This was a people that had the time, money and manpower to build massive temples and cities for a population estimated at 13 million.

Many theories have been put forward as to why, over a period of about 200 years from 750 to 950AD, the Mayans abandoned their way of life. Research on the subject by Sigma Xi, The Scientific Research Society, says that a series of droughts caused by local climate change was the cause.

With the latest report of the Intergovernmental Panel on Climate Change predicting a faltering of the monsoon that is vital for the Indian sub-continent’s ability to feed itself, it seems as though history could repeat itself. Certainly, some people in India believe it could happen unless action to curb climate change is taken.

Environmental refugees in Africa are also seen as victims of changing weather patterns, and California is suffering a three-year drought that is badly affecting water supplies in this most prosperous of American states. – Climate News Network

Marine economy sinks as ocean acidity rises

Crab pots and fishing nets at Dutch Harbour, Alaska Image: Michael Theberge/NOAA Photo Library via Wikimedia Commons
Crab pots and fishing nets at Dutch Harbour, Alaska
Image: Michael Theberge/NOAA Photo Library via Wikimedia Commons

By Kieran Cooke

Research has highlighted the negative effect acidification of oceans can have on marine life, but now fishing communities are waking up to the big threat it poses to their livelihoods.

LONDON, 6 August, 2014 − The waters off the US state of Alaska are some of the best fishing grounds anywhere, teeming with salmon and with shellfish such as crab.

But a new study, funded by the US National Oceanic and Atmospheric Administration (NOAA), says growing acidification of Alaska’s waters, particularly those off the southern coast, threatens the state’s whole economy − largely dependent on the fishing industry.

The study, which appears in the journal Progress in Oceanography, says that not only will the state’s commercial fishing sector be badly hit by a growth in acidification, but it will also affect subsistence fisherpeople whose diet mainly consists of the catch from local waters.

Forming acid

The oceans act as a “carbon sink”, absorbing vast amounts of carbon dioxide. Acidification occurs when amounts of carbon dioxide are dissolved into seawater, where it forms carbonic acid.

Scientists say the oceans are now 30% more acidic than they were at the beginning of the industrial revolution about 250 years ago.

Among the sea species most vulnerable to acidification are shellfish, because a build-up of acid in waters prevents species developing their calcium shells. Alaska’s salmon stocks are also at risk as one of the main ingredients of a salmon diet are pteropods, small shell creatures.

Jeremy Mathis, an NOAA oceanographer and a lead author of the study, told the Alaska Dispatch News that whereas past reports had focused on the consequences of increased acidification on ocean species, the aim of this one was designed to examine the wider economic impact.

“This is an economic-social study,” Mathis said. “It focuses on food security, employment opportunity, and the size of the economy.”

Mathis said acidification is more likely in Alaskan waters than in many other parts of the world. He explained: “It’s all about geography. The world’s ocean currents end their cycles here, depositing carbon dioxide from elsewhere. The coastal waters of Alaska sit right at the end of the ocean conveyor belt.”

Elsewhere, acidification is already having a serious impact on fishing and shellfish industries.

Oysters dying

The New York Times reports that billions of baby oysters – known as spat – are dying off the coast of Washington state in the north-western US.

In May this year, the US government’s major report on climate change, the National Climate Assessment, said that waters off the north-west of the country are among the world’s most acidic.

Jay Inslee, Governor of Washington, says an industry worth US$270 million is at risk. “You can’t overstate what this means to Washington,” he says.

Inslee and many others in Washington state are fighting plans by the coal industry to build large coal ports in the region in order to export to China and elsewhere in Asia.

Climate scientists say greenhouse gas emissions resulting from coal burning are a main cause of global warming. − Climate News Network

Climate changes ensnare Antarctic predator

Antarctic fur seals at Stromness on South Georgia island Image: Liam Quinn via Wikimedia Commons
Antarctic fur seals at Stromness on South Georgia island
Image: Liam Quinn via Wikimedia Commons

By Tim Radford

British scientists have recorded lower birth weights in female Antarctic fur seals as warming seas deplete their prime food source − but they have also observed genetic variations that could be crucial for survival.

LONDON, 29 July, 2014 − Climate change has begun to take its toll of one of Antarctica’s top predators. The Antarctic fur seal is being born with a lower weight and tends to breed later than earlier generations − almost certainly in response to the reduced availability of its prime food, krill.

But the fur seal (Arctocephalus gazelle) is also changing in other ways. British Antarctic Survey (BAS) scientists report in Nature that those females that survive to motherhood are more likely to have a higher level of genetic variation − a characteristic known as “heterozygous”, associated with higher fitness in many species.

In a world of environmental change – of warming seas and changing ocean chemistry – this confers a survival advantage, in that the individual is more likely to cope with the stresses of change.

Research such as this is based on long periods of observation, and the scientists gathered data from as far back as 1981 to assess the changes in a population of fur seals in South Georgia, in the southern Atlantic.

Genetic samples

They measured age, body length, weight, counted the numbers of sea pups, noted the diet, and recorded climate data. They also took genetic samples from 1,728 seals.

“Compared with 20 years ago, we can see that female fur seals are now born with a lower weight, those that survive and return to breed tend to be the bigger ones, and they have their first pup later in life than they used to,” said the report’s lead author, Jaume Forcada, BAS marine mammal leader.

“Such changes are typically associated with food stress. An important food source for the seals is Antarctic krill, and decades of data collected at South Georgia show how changes in the seal population have occurred over time with krill availability.

“Even if krill is very abundant, environmental variation determines its availability in the seals’ feeding grounds. This variation is driven by climate, which impacts local atmospheric, sea ice and oceanographic conditions.”

If the climatic conditions are adverse, then krill is harder to find, which makes it tough on fur seals and, directly or indirectly, all other Antarctic predators. But the picture for the moment remains uncertain.

Recently, other researchers pronounced that the population in Antarctica of the Adélie penguin – another greedy consumer of krill – is higher than all previous estimates, which suggests that some species at least are, for the moment, finding enough for supper.

But the krill population is sensitive to a south polar phenomenon called the southern annular mode (SAM), a seasonal pattern of winds and pressures that changes from time to time.

Survival fitness

The BAS team found that the seal population responded to the notorious El Niño cycle in the Pacific, and to the SAM, and that the data from this population clearly showed a response to climate change. Overall, the number of heterozygous seals has increased by 17%, but other indicators of survival fitness are not so encouraging.

“Over the last two decades, the proportion of breeding females that are highly heterozygous has increased, as these individuals are more likely to survive the changing conditions,” said the report’s co-author, Joe Hoffman, reader in population genetics at Bielefeld University, Germany.

“Strong selection by the environment can drive rapid evolution. However, in this case the seals do not appear to be evolving because surviving females do not pass their heterozygosity on to their offspring.

“Therefore, with each new generation the process of selection has to start all over again, with only those individuals that happen to be born heterozygous having a good chance of survival. As the climate continues to change, many fur seal pups are not surviving to adulthood, and the population is declining.” – Climate News Network

Svalbard’s reindeer thrive as climate warms

Warm welcome: Svalbard's distinctive reindeer are increasing in numbers. Image: courtesy of Dr Jonathan Codd, University of Manchester
Warm welcome: Svalbard’s distinctive reindeer are increasing in numbers
Image: courtesy of Dr Jonathan Codd, University of Manchester

By Alex Kirby

The rising temperatures that have many negative impacts in the Arctic region are not a problem for a Norwegian subspecies of reindeer whose population increased by a remarkable 30% last year.

LONDON, 21 July, 2014 − There will be winners as well as losers as climate change intensifies, and scientists say they have just found one species that is prospering already.

Far from threatening the reindeer on the Norwegian high Arctic archipelago of Svalbard, rising temperatures appear to be driving a remarkable increase in the animals’ numbers.

Scientists from the University of Manchester, UK, and the Arctic University of Norway in Tromsø have found that the numbers of Svalbard reindeer, continuing a trend that has been observed over the last 36 years, increased by 30% in the last year.

Physically counted

The scientists established the population spurt by counting the reindeer in the valley of Adventdalen, in central Spitsbergen. They say their research is one of only very few studies on animal populations and climate change that involves animals being physically counted annually, rather than estimated.

The total number of animals − including all births and all deaths − in Adventdalen has been recorded annually since 1979 by a team led by Dr Nicholas Tyler, of the Arctic University of Norway.

Svalbard’s reindeer population had increased in close parallel with winter warming in the last 35 years, growing from an average of around 600 animals in the early 1980s to around 1,000 today.

Dr Tyler said: “Winter warming is widely held to be a major threat to reindeer across the Arctic, but, in Svalbard, global warming has had the opposite effect. Our data provides remarkable confirmation of this counter-intuitive observation.”

This summer, a team from Manchester, led by Jonathan Codd and Nathan Thavarajah, helped with the annual census of reindeer in Adventdalen.

Dr Codd, the programme director for zoology at the university, said: “The results revealed a remarkably successful year for Svalbard reindeer. Despite very high numbers in 2013, the population increased by almost 30% and reached a new record of just over 1,300 animals − more than three times the population size in 1979, when the present series of counts began.”

The team found very little winter mortality and very high calving. There were over 300 calves in the valley, the second highest number recorded.

Streets awash

“The substantial increase in the numbers of reindeer is linked with frequent and pronounced periods of warm weather last winter,” said Dr Codd. “In February, the temperature rose above freezing for six days, reaching a maximum of +4.2°C, and the streets of the Norwegian settlement at Longyearbyen were reported awash with melt water.”

Dr Codd told the Climate News Network: “We count the reindeer by walking the same set routes every day, and there is no possibility of any double counting.

“There are signs that Svalbard’s predators are in good shape. I think most of the polar bear populations are at least stable, and the Arctic foxes are doing pretty well too.

“But neither seems to be bothering the reindeer. The foxes will eat dead deer, but don’t attack live ones. And the main prey of the bears is seals.

“And the reindeer can move fast if they need to. I’ve heard reports that they have been known to reach a speed of 50 miles an hour (80 kph).” − Climate News Network

New clue to Antarctic food-web puzzle

Strength in numbers: thousands of Adélie penguins at a rookery Image: Michael Van Woert/NOAA NESDIS, ORA via Wikimedia Commons
Strength in numbers: thousands of Adélie penguins in an Antarctic rookery
Image: Michael Van Woert/NOAA NESDIS, ORA via Wikimedia Commons

By Tim Radford

A landmark research study that shows one species of penguin is thriving while other populations are in rapid decline offers new insight into how climate change is affecting Antarctica.

LONDON, 16 July, 2014 − Good news from Antarctica: the continent may be warming, the ice shelf may be at risk, and the food chain may ultimately become precarious, but the Adélie penguin population – at least for the moment − is higher than ever before.

The news does not suggest that global warming and climate change are actually good for this important indicator species, which has certainly been in decline on the Antarctic Peninsula. But it does represent an advance: for the first time, a comprehensive study has concluded with a full census of the species.

Heather Lynch, assistant professor of ecology and evelotion at Stony Brook University in New York, and Michelle La Rue, research fellow at the University of Minnesota’s Polar Geopspatial Center, used high resolution satellite imagery to measure levels of penguin guano – the fertiliser industry’s preferred term for seabird excrement – on the continent.

They then used that as the basis for calculating the numbers of birds in a colony necessary to account for all that digested and evacuated seafood.

They report in a journal called The Auk: Ornithological Advances that they identified at least 17 populations of Adélie penguins not previously known to exist, but failed to pinpoint 13 already-recorded colonies, and declared eight of them eradicated.

Their estimate for the total Adélie population in and around the Southern Ocean stands at 3.79 million, which is 53% higher than all previous estimates.

Useful evidence

The researchers call their work a “landmark” study, and see it not as evidence that climate change is going to work for the benefit of one particular species, but more as a useful piece of the great food-web puzzle in a changing climate.

Penguins have been in rapid decline in the West Antarctic Peninsula, which has become one of the fastest-warming regions on the planet. Warmer weather and increased rain have already started to take toll of Magellanic penguins in Argentina, and researchers recently predicted long-term decline for the iconic Emperor penguin on Antarctica itself.

But this is only long-term decline. As long as Antarctica stays cold and the ice shelf stays stable, the researchers say, the population could, in the short term, actually rise.

That is because what matters most to the species that nest in Antarctica is the supply of fish and krill around the continent’s edge. The health and resilience of the Adélie population – and the Emperor penguin, the leopard seal, the cetaceans, and so on – ultimately depend on how the krill and fish populations respond to climate change.

Humans, too, fish for commercial supplies of Antarctic krill, which provides a source of food for fish farms.

“Our finding of a 53% increase in Adélie penguin breeding abundance, compared to 20 years ago, suggests that estimates of krill consumption by this species may be seriously underestimated,” Dr Lynch said. “Leaving enough prey for natural krill predators is an important element in ensuring fisheries proceed sustainably.”

But a second team confirms in Nature Communications that there are strong links between climate and marine life, and that changes in factors such as wind speed and sea ice can have knock-on effects right around the Antarctic food web.

Since 1990, scientists aboard US research vessels have been conducting annual surveys along the western side of the Antarctic Peninsula, measuring populations of photosynthetic algae.

These peak every four to six years, according to changes in atmospheric pressure between the mid-latitudes and Antarctica itself.

Glacial meltwater

In winter, when cold southerly winds blow across the Peninsula, the winter ice extends. Winds drop from spring to summer, reducing the retreat of the ice. So the water column in summer then is stable, and the phytoplankton multiply, fed by iron-rich glacial meltwater.

The blooms of phytoplankton are what the krill need to multiply, and when the krill are around in huge volumes, the Adélie and other penguins, fur seals, baleen whales and albatross don’t have to go so far to find food.

But marine scientist Grace Saba, who did her research while with the Virginia Institute of Marine Science, before moving to Rutgers University, New Jersey, reports that these ideal conditions – negative phases of the Southern Annular Mode (SAM), to give it the technical terminology – are not guaranteed in future. If the world goes on burning fossil fuels, conditions will probably change.

“Projections from global climate models under business-as-usual emission scenarios up to the year 2100 suggest a further increase in temperature and in the occurrence of positive-SAM conditions,” Dr Saba said.

“If even one positive SAM episode lasted longer than the krill lifespan – four to six years with decreased phytoplankton abundance and krill recruitment – it could be catastrophic to the krill population.”  − Climate News Network