Category Archives: Wildlife

Climate helps to halve world wildlife in 40 years

 

Species at risk: Numbers of  wandering albatross are in decline Image: By 3HEADEDDOG via Wikimedia Commons

Species at risk: Numbers of wandering albatross are in decline
Image: By 3HEADEDDOG via Wikimedia Commons

By Alex Kirby

Conservation campaigners say the plight of much of the world’s wildlife seems “worse than ever” – and climate change is a growing cause of the damage.

LONDON, 30 September 2014 – Human pressure has halved the numbers of many of the Earth’s wild creatures in just four decades, the Worldwide Fund for Nature says.

While the main recorded threat to biodiversity comes from habitat loss and degradation, driven by unsustainable human consumption, it found, climate change is a growing concern.

It says in its Living Planet Report 2014 that vertebrate wildlife populations have declined by an average of just over half, with freshwater species suffering a 76% decline, almost double the average loss of land and ocean species.

In a foreword the director-general of WWF International, Marco Lambertini, writes: “This latest edition of the Living Planet Report is not for the faint-hearted.

“One key point that jumps out is that the Living Planet Index (LPI), which measures more than 10,000 representative populations of mammals, birds, reptiles, amphibians and fish, has declined by 52% since 1970.

“Put another way, in less than two human generations, population sizes of vertebrate species have dropped by half.”

The Report is based on the Index, a database maintained by the Zoological Society of London (ZSL).

Industrial killing

WWF says the state of the world’s biodiversity “appears worse than ever.” But it is confident in the robustness of its findings: “This is a much bigger decrease than has been reported previously, as a result of a new methodology which aims to be more representative of global biodiversity.”

The authors calculated the decline by analysing 10,000 different populations of 3,000 vertebrates. This data was then, for the first time, used to create a representative Living Planet Index, reflecting the state of all 45,000 known vertebrates. The consequences, it shows, can be drastic.

Last week conservationists said that elephant poaching was now happening on an unprecedented and “industrialised” scale in Mozambique, after 22 of the animals were killed for their tusks in the first two weeks of September. Numbers of some marine turtles are estimated to have dropped by 80%.

Professor Ken Norris, director of science at the ZSL, said: “The scale of biodiversity loss and damage to the very ecosystems that are essential to our existence is alarming. This damage is not inevitable but a consequence of the way we choose to live.”

There is wide disagreement about the number of species on Earth. In 2007, when the total was estimated by many scientists at around 1.5 m (it is now thought to be 8.7 m) the number of vertebrate species was put at about 60,000 in the IUCN Red List.

WWF says too that humans are using more resources than the Earth can continue to provide, felling trees more quickly than they can regrow, for example, catching fish faster than they can reproduce, emptying rivers and aquifers -   and emitting too much carbon for natural systems to absorb.

Boundaries crossed

The Report devotes a section to the idea of the Ecological Footprint, the sum of the ecological services that people demand which compete for space. For more than 40 years, it says, humanity’s demand on nature has exceeded what the planet can replenish, principally through climate change.

“Carbon from burning fossil fuels has been the dominant component of humanity’s Ecological Footprint for more than half a century, and remains on an upward trend. In 1961, carbon was 36% of our total Footprint; by 2010, it comprised 53%”, the Report says.

WWF urges respect for “planetary boundaries” beyond which humanity will “enter a danger zone where abrupt negative changes are likely to occur.”

It says “three planetary boundaries appear to have already been transgressed: biodiversity loss, and changes to the climate and nitrogen cycle, with already visible impacts on the well-being of human health and our demands on food, water and energy.”

The Report argues for the diversion of investment away from the causes of environmental problems and towards solutions, and for “ecologically informed” choices about how we manage resources.

Next year world leaders are due to conclude two critical global agreements: the post-2015 development framework, which will include Sustainable Development Goals intended to be met by all countries by 2030; and a UN treaty leading to effective action to cut greenhouse gas emissions. – 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

Offshore turbines get approval of seals

Fishing grounds: Sheringham Shoal wind farm off the north Norfolk coast, England Image: Haradl Pettersen/Statoil via Wikimedia Commons
Fishing grounds: Sheringham Shoal wind farm off the Norfolk coast, England
Image: Harald Pettersen/Statoil via Wikimedia Commons

By Tim Radford

Researchers tracking the movements of seals in the North Sea reveal that “artificial reefs” created by wind farms and pipelines are becoming attractive as foraging grounds on fishing expeditions.

LONDON, 25 July, 2014 − Environmental campaigners and countryside conservators aren’t the only fans of those great arrays of turbines, generating renewable energy from the winds at sea. Grey and harbour seals in the North Sea are beginning to show a preference for offshore wind farms as well.

Deborah Russell, research fellow at the University of St Andrews, Scotland, and colleagues tracked the movements of both the harbour seal (Phoca vitulina) and the grey seal (Halichoerus grypus).

There are an estimated 56,000 harbour seals in the North Sea and around 65,000 of the greys haul out on the British coast on the North Sea alone. Tagged specimens, with their movements tracked by GPS satellite systems as they surface to breathe, reveal a lot about the ecology of each species and their response to environmental change.

Distinct preference

The researchers report in the journal Current Biology that some of their tagged animals seemed to show a distinct preference for offshore wind farms and associated pipelines. Eleven harbour seals headed for two wind farms: one was Alpha Ventus, off northern Germany, and the other was Sheringham Shoal, off the North Norfolk coast, England.

Some individuals regularly cruised the sites, and some even revealed a pattern of grid-like movements as they appeared to forage at individual turbines. Two seals in the Netherlands were tracked along sections of submarine pipeline, on fishing expeditions that lasted 10 days at a time.

A harbour seal with a GPS phone tag used to track movements Image: Current Biology, Russell et al
A harbour seal with a GPS phone tag
Image: Current Biology, Russell et al

The guess is that the seals regarded the offshore structures as artificial reefs where crustaceans settle and fish congregate.

Turbine blades can swirl at speeds of up to 280 kilometres an hour, and represent a danger to  birds and bats − one estimate is that such structures in the US account for 600,000 bat deaths a year. But marine creatures far below the circling blades seem to value a touch of freshly-planted, three-dimensional shelter in the muddy basin of a shallow sea.

“I was shocked when I first saw the stunning grid pattern of a seal track around Sheringham Shoal,” Dr Russell said. “You could see that the individual appeared to travel in straight lines between turbines, as if he was checking them out for potential prey, and then stopping to forage at certain ones.”

Open questions

Only a small proportion of the tracked animals showed a preference for wind farms, and such structures still cover only a trifling area of the available coast. But the research leaves open a number of questions.

One is whether, as wind farms add to the available habitat in the North Sea, they will increase the available fish and crustacean populations, or whether they simply attract the prey and make life easier for innovative predators.

As offshore investment grows, such studies may help engineers to design farms that help both the consumer and the wild things in the offshore waters.

The researchers say: “In this period of unprecedented development of the marine renewables industry, the number of apex predators encountering such structures is likely to increase. The ecological consequences may be dependent on whether such reefs constitute an increase or just a concentration of prey.” – Climate News Network

Old phones offer lifeline to Africa’s forests

Smartphone tracking device ready for installing high in the forest canopy Image: Rainforest Connection
Smartphone tracking device ready for installing high in the forest canopy
Image: Rainforest Connection (RFCx)

By Alex Kirby

A hi-tech approach that uses recycled smartphones to crack down on illegal logging and poaching could help combat devastation of trees and wildlife in threatened forests.

LONDON, 4 July, 2014 – Some of the world’s most endangered forests may soon benefit from better protection, thanks to discarded treasures from the consumer society − mobile phones.

A Californian technology startup, Rainforest Connection (RFCx), has developed a tool − made from recycled smartphones − that it says will pilot new ways to monitor and stop illegal logging and animal poaching throughout Africa’s equatorial forests.

RFCx has formed a partnership with the Zoological Society of London (ZSL), an international scientific charity that works for the worldwide conservation of animals and their habitats.

The two organisations are planning to install the anti-deforestation, anti-poaching technology in Cameroon this year.

Instant alerts

RFCx says it has developed the first real-time detection system for protecting the forests and deterring illegal logging, using discarded Android smartphones to send instant alerts to forest rangers, enabling them to intervene swiftly. It says current monitoring methods often rely on aerial surveys or satellite surveillance, which usually detect deforestation days or even weeks after the event.

The RFCx system was first tested in 2013 against illegal loggers in Western Sumatra, Indonesia, and proved that the technology would work. Using highly-sensitive microphones, each autonomous, low-cost device can protect one square mile of rainforest, often home to over a thousand species of plants and animals.

The devices, built to operate for years, employ a unique solar panel design that can generate adequate electrical power even under the shadow of the tree canopy.

“We think this could be a critical new tool
for protecting large areas of rainforest”

Chris Ransom, programme manager for ZSL in Africa, said: “We think this could be a critical new tool for protecting large areas of rainforest. We’re excited to deploy it this year in collaboration with our local partners in Africa.”

Randy Hayes, the founder of the Rainforest Action Network, said: “This is the most exciting critical new tool I’ve seen that I think can help us get the job done.”

Topher White, RFCx’s founder, believes the right tools have been developed at just the right moment to make a difference. He said: “It’s clear that real-time awareness and intervention is a major missing piece in protecting the world’s last remaining rainforests.

“By using old smartphones and existing telecommunications infrastructure, we have built a system that we think could scale quickly enough to make a real impact.”

Species extinction

Deforestation is a leading contributor to climate change and to global species extinction rates. The US Environmental Protection Agency says that deforestation, land clearing for agriculture, fires or decay of peat soils accounted for 17% of global greenhouse gas emissions in 2004.

RFCx says each of its devices installed is as effective as taking 3,000 cars off the road, in terms of carbon mitigation through averted logging activities.

Dave Grenell, RFCx co-founder, said: “We are experiencing one of the highest rates of species extinction since the time of the dinosaurs.

“Future generations will look back on this as a kind of holocaust. Protecting endangered forests is one of the most important things we can do today to help.” − Climate News Network

Lapland’s mystery moths puzzle science

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A 2°C rise in average temperatures in 30 years seems not to have bothered Lapland's moths Image: By Ximonic, Simo Räsänen via Wikimedia Commons

A 2°C rise in average temperatures in 30 years seems not to have bothered Lapland’s moths
Image: By Ximonic, Simo Räsänen via Wikimedia Commons

By Tim Radford

Arctic moths which continue to thrive despite rising temperatures are challenging science to explain why they seem impervious to climate change.

LONDON, 22 April – Finnish and US scientists have an unsolved puzzle: good news when they expected bad news. They have invested 32 years studying the forest moths of Finnish Lapland to measure the effect of climate change – and there doesn’t seem on the face of it to have been a change. Yet between 1978 and 2009, average annual temperatures in the region rose by 2°C and precipitation was higher.

“You see it getting warmer, you see it getting wetter and you see that the moth populations are either staying the same or going up,” said Mark Hunter of the University of Michigan. “So you might think ‘Great. The moths like this warmer, wetter climate.’ But that is not what is happening.”

The study looked at population records for 80 species of moth, and found that 90% of them were stable or increasing through the three decades. But warmer temperatures and wetter seasons are more likely to reduce the rate of population growth: species tend to do best under the conditions to which they have adapted over thousands of years.

“So the only possibility is that something else other than climate change – some other factor that we did not measure – is buffering the moths from substantial population reductions and masking the negative effects of climate change,” Professor Hunter said.

He and his colleagues report in Global Change Biology that they used nocturnal light traps to catch 388,779 moths from 456 species at the Värriö Strict Nature Reserve inside the Arctic Circle, 100 kilometres from a road and about 6 km from the Russian frontier. They selected the data for the 80 most common species for statistical analysis.

Winners and losers

At such high latitudes, any change in climate means a change in vegetation and an altered ecosystem, which should affect insect numbers. So the logic suggests that some unknown forces are at work, to protect the moth numbers just when they should be going down.

Ecologists don’t like unexplained outcomes. Because insects are the most numerous animals on earth, because they are pests, pollinators, food sources and disease bearers, and because their numbers ought to be indicators of both annual and long-term climate change, ecologists like to know what happens to them, and when, and why.

Researchers in Europe and the US have repeatedly tested animal population responses to climate change to identify winners and losers and understand what makes one species a loser, another a winner.

A 20-year study by Ben Hatchwell and colleagues at the University of Sheffield in the UK has found that warm dry spring weather makes all the difference to long-tailed tits: these short-lived passerines stand a much better chance of rearing chicks and then surviving to the next year, and the next chance to breed. A cold wet autumn normally increases mortality, but a preceding warm dry spring can offset this effect, they report in the journal Oikos.

Wide implications

So the British ornithologists have an explanation for one bird’s good performance. The Finnish entomologists would like to know what helps keep the larvae alive and the moths aflutter in the warming, changing Arctic Circle. The question is important not just for one group of high-latitude moths: scientists could be misreading the effects of climate change across a whole suite of species because these effects might be masked by other, unidentified factors.

And it becomes increasingly important with a prediction, from the Bjerknes Centre for Climate Research in Norway, that northern Europe could warm by 3°C in the winter by mid-century, with increasing rainfall.

Stefan Sobolowski and Robert Vaulard of the Pierre-Simon Laplace Institute in France report in Environmental Research Letters that even if global average warming is kept to 2°C there will be “substantial and robust changes” across Europe. Against such a backdrop, it becomes important to know why one group of animals is doing better than expected – for the moment.

“The big unknown is how long this buffering will last,” said Professor Hunter. “Will it keep going indefinitely, or will the negative effects of climate change eventually just override these buffers, causing the moth populations to collapse?” – Climate News Network

Early springs surprise many species

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Roe deer numbers have been particularly hard hit by seasonal disruption.  Image: Marek Szczepanek via Wikimedia Commons

Roe deer numbers have been particularly hard hit by seasonal disruption.
Image: Marek Szczepanek via Wikimedia Commons

By Tim Radford

As seasonal change suffers ever more disruption, many species are struggling to adapt quickly enough.

LONDON, 7 April – Spring is arriving earlier. This is not necessarily welcome news for Arctic creatures or the roe deer of France. It could be awkward for flower festival organisers as well.

Julienne Stroeve of the US National Snow and Ice Data Centre and colleagues will report in Geophysical Research Letters that the length of the Arctic melt season is growing by several days each decade. When the melt starts earlier, the Arctic Ocean absorbs more radiation: enough in some places to melt four feet in thickness from the Arctic ice cap.

“The lengthening of the melt season is allowing for more of the sun’s energy to get stored in the oceans and increase ice melt during the summer, overall weakening the sea ice cover,” says Stroeve. The Arctic sea ice has now been in decline for four decades.

The seven lowest September sea ice extents in the satellite record have all occurred in the last seven years. A new examination of satellite imagery and data from 1979 to the present shows that the Beaufort and Chukchi Seas are freezing up between six and 11 days later per decade. But the earlier melt is more ominous than the later freeze: the sun is higher and brighter, and delivers more warmth to the seas.

Festival disruption

The earlier spring presents no problems for many plants but it may not be much fun for the organisers of flower festivals who like to announce their events well in advance. Tim Sparks of Coventry University reports in the journal Climate Research that over its 46-year history, the Thriplow Daffodil Weekend in Cambridgeshire in eastern England has been forced to bring its dates forward by 26 days.

The event can attract up to 10,000 visitors, and has raised £300,000 (US $500,000) for charity, so it clearly helps the organisers to set up some advance publicity. Since 1969, mean temperatures in March and April in the UK have risen by 1.8°C.

“The study represents one of the first solid pieces of evidence of flower tourism having to adapt to climate change,” said Professor Sparks. “The issues faced by Thriplow are a microcosm of the wider picture.”

Flower festivals may be able to adapt. Sadly, the roe deer of Champagne have yet to get the message about climate change. To flourish, both nectar seekers and herbivores have to time their breeding patterns to the surge in plant growth.

Three French scientists looked at records of a population of roe deer in the Champagne region of France, and found that although spring has been arriving increasingly earlier, the fawns are being born at around the same dates as they were 27 years ago, and their survival rate is falling, they report in the Public Library of Science journal PLOS Biology. Overall, the roe deer population in the region is also in decline.

Great tits have kept up with climate change, because reproduction is cued by temperature, so they are around at the same time as the explosion in food sources. What sets the biological pace for roe deer is day length, the authors think, and this is not affected by climate change. - Climate News Network

Climate change ‘raises extinction risk’

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A weather eye for possible risks: Climate change will make extinction likelier for many species Image: By Ren West via Wikimedia Commons

A weather eye for possible risks: Climate change will make extinction likelier for many species
Image: By Ren West via Wikimedia Commons

By Tim Radford

Climate change doesn’t pose a unique threat of extinction to a species, scientists say. It just makes the risk more likely to become a reality.

LONDON, 28 February – Environmental scientists believe they have a blueprint for extinction. They report in Nature Climate Change that they have identified those factors that might make a species more likely to slip away into eternal oblivion as the planet warms and climate conditions change.

It turns out that they knew them all along. There is, the researchers conclude, nothing specifically different about climate change as a threat: it could however make extinction much more likely.

Richard Pearson of University College London (and formerly of the American Museum of Natural History) and colleagues decided to take a small subset of species at risk, and look closely at the factors that determine species extinction.

They chose 36 amphibians and reptiles endemic to the United States. Reptiles and amphibians almost everywhere seem to be vulnerable for a mix of reasons: among them habitat destruction, environmental pollution and the introduction of new predators and new diseases. The more exquisite the ecological niche occupied by the species, the smaller its overall population and the more precarious its chances of survival.

The researchers examined all the information available on salamanders, turtles, tortoises, snakes and lizards and concluded that, overall, there was a 28% chance of extinction by 2100. But without climate change, this risk dwindled to 1%.

“Surprisingly, we found that the most important factors – such as having a small range or low population size – are already used in conservation assessments,” said Dr Pearson. “The new results indicate that current systems may be able to better identify species vulnerability to climate change than previously thought.”

Carry on conserving

And his co-author Resit Akçakaya of Stony Brook University in the US said: “The bad news is that climate change will cause many extinctions unless species-specific conservation actions are taken; but the good news is that the methods conservation organisations have been using to identify which species need the most urgent help also work when climate change is the main threat.”

So to preserve biodiversity conservationists have to do what many are doing already: focus on species that occupy a small or dwindling space, or are few in number.

Other predictions of future extinction under climate change have usually been based on the rate at which habitat with the right climate will shift or contract, and researchers have been more concerned with how easily species can adapt or migrate and why some species do better than others at shifting to new ground.

In the latest research, the scientists selected a class of animals but did not try to make individual predictions for each species: what they were looking for were general principles.

“Our analysis will hopefully be able to help create better guidelines that account for the effects of climate change in assessing extinction risk,” said Dr Pearson. – Climate News Network

Half of plants may move in warmer world

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Vegetation changes on a warmer planet may mean that giant pandas go hungry Image: Jeff Kubina via Wikimedia Commons

Vegetation changes on a warmer planet may mean that giant pandas go hungry
Image: Jeff Kubina via Wikimedia Commons

By Tim Radford

An international team of scientists says that by the end of the century one probable consequence of climate change will be a change in patterns of vegetation over much of the planet’s land surface.

LONDON, 16 February – By 2100, vegetation patterns will be shifting in almost half the land area of the planet, according to new research in the journal Global and Planetary Change.

Song Feng of the University of Arkansas in the US and colleagues in Nebraska, China and South Korea have taken a long cool look at what the projected patterns of warming are likely to do to the planet’s mosaic of climate types. And they predict dramatic changes.

Climate type is a century-old idea useful for making sense of geographical zones: regions are grouped according to the type of vegetation they support. Since a global map of native vegetation types can also deliver useful information about altitude, rainfall, soil type, prevailing weather and latitude, geographers regard the Köppen-Geiger classification – and an updated version known as Köppen-Trewartha – as a helpful way of describing the world.

Feng and his colleagues decided to see what projected changes in temperature would do to climate types. He wasn’t the first to do so; scientists from the US National Oceanic and Atmospheric Administration reported in 2013 in Nature Climate Change on the probable speed of change in such zones.

But science advances by challenge and replication, and the Arkansas team began looking for themselves at the details of simulated change under the notorious “business as usual scenario”  – the one in which global fossil fuel use continues to increase and higher levels of carbon dioxide and other greenhouse gases concentrate in the atmosphere.

The Intergovernmental Panel on Climate Change has made a series of predictions of rising global average temperatures, but plants, of course, don’t care about global average temperatures: they are however distinctly vulnerable to local extremes of frost and heat.

The Feng scenario projected an increase of between 3°C and 10°C; the team analysed observations made between 1900 and 2010, and then ran computer simulations from 1900 to 2100.

Drastic changes ahead

In the last three decades of the 21st century, for instance, northern winter temperatures are likely to rise by between 3° and 12°C; Arctic coastal temperatures are likely to rise by 8°C; warming in mid-latitudes is likely to be between 5°C and 7°C, the tropics and the southern hemisphere around 5°C.

The Arctic will shrink. Sub-polar vegetation is expected to advance by 5° of latitude and the temperate zones will push northwards too. Arid and semi-arid climate zones are expected to expand by somewhere between 3.3 and 6.6 million square kilometers in the last three decades of this century.

What this does to native vegetation types is hard to predict in detail but some projections have been made. In the Qinling mountain region of China, for instance, somewhere between 80% and 100% of the bamboo forests on which the giant pandas depend could disappear, because the rising temperature would be “no longer feasible for bamboo growth.”

In the south-western US higher temperatures and drier conditions could lead to more forest fires, and pest outbreaks could lead to changes in forest structure and composition.

As the plants change, the animal species that evolved with the vegetation types could be increasingly at risk. Altogether, up to 46.3% of the planet’s land area could shift to warmer or drier climate types

“Climates are associated with certain types of vegetation. If the surface continues to get warmer, certain native species may no longer grow well in their climate, especially in higher latitudes. They will give their territory to other species. That is the most likely scenario”, said Feng. – Climate News Network

Cat litter killer in the whales of the North

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Blissful domesticity: But even domestic cats can spread Toxoplasma gondii

Blissful domesticity: But even domestic cats can spread Toxoplasma gondii

By Tim Radford

One consequence of a warming climate is new patterns of disease, and researchers have identified two parasites formerly unknown in the Arctic in marine mammals.

CHICAGO, 14 February – The great Arctic thaw – up to 50% of sea ice by area and 75% by volume in the summer season – could be offering new opportunities for one of the planet’s most successful parasites. Toxoplasma gondii, an infection spread by almost all cat species, has been identified for the first time in the western Arctic Beluga whale.

Toxoplasma is found almost everywhere that cats settle: domestic pets, ocelots, cougar, wild cats all carry and spread oocysts of the parasite (structures it uses to transfer to new hosts) in their faeces, to be spread further with discarded cat litter.

The parasite is notoriously hard to kill. Scientists store their samples in sulphuric acid, and the creature can survive unharmed in bleach. It is, however, routinely killed by freezing conditions, or boiling water.

The suspicion is that with the steady, sustained warming of the Arctic over the past 30 years, chiefly because of a buildup of carbon dioxide in the atmosphere, the retreat of the ice has begun to allow new traffic in parasite infections.

Another parasitic killer, a new strain called Sarcocystis pinnipedi, normally found only in the highest, iciest latitudes, has been linked with mass deaths too: 406 grey seals died in 2012 in the north Atlantic. It has also been observed to kill Steller’s sea lions, Hawaiian monk seals, walruses, grizzly bears and polar bears as far south as British Columbia.

In the case of Toxoplasma, warming polar summers could have created conditions in which the parasite could find new warm-blooded hosts further north. In the case of the second parasite, the loss of ice has meant a greater mixing of species, and allowed Sarcocystis to find new hosts in warmer waters.

Cause of blindness

“Ice is a major barrier for pathogens”, Michael Grigg, of the US National Institutes of Health told the American Association for the Advancement of Science annual meeting here. “What we are seeing with the big thaw is the liberation of pathogens gaining access to vulnerable new hosts and wreaking havoc.”

Toxoplasma can also infect people: it is the leading cause of infectious blindness in humans, and can be dangerous to unborn children and to people with compromised immunity.

It has been found in human communities in northern Quebec, perhaps spread by the consumption of dried seal meat. The discovery of Toxoplasma in Beluga whales has begun to worry health officials. Belugas are part of the traditional diet of the Inuit hunters of the far North.

Seals, walruses and polar bears are all what scientists like to call “ice obligate animals”: the ice sheet provides them with their preferred habitat. With the loss of the ice, new species are colonizing the Arctic, and those creatures that cannot now use the ice sheet have been forced to invade new habitats.

“Marine mammals can act as ecosystem sentinels because they respond to climate change through shifts in distribution, timing of their movements and feeding locations”, said Sue Moore of the US National Oceanic and Atmospheric Administration. “These long-lived mammals also reflect changes to the ecosystem in their shifts in diet, body condition and physical health.” – Climate News Network

Equatorial fish feel the heat

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Weaving through the coral: Small fish like these are important sources of food for larger reef species Image: D. Dixson

Weaving through the coral: Small fish like these are important sources of food for larger reef species
Image: D. Dixson

By Alex Kirby

Many species of fish living near the Equator are sensitive to variations in heat and will not thrive in the warmer oceans of the future, scientists in Australia have found.

LONDON, 12 February – Lying in a hot bath may be a pleasant experience, because you can always get out when you’ve had enough. For some of the fish that swim in equatorial seas, though, that is not an option: climate change threatens to make the water not just uncomfortable, but unendurable.

An international team of researchers based in Australia reports in Global Change Biology that the rapid pace of climate change is threatening the future of some of the fish which live near the Equator.

Over a 14-day period the team tested four species of damsel fish and two of cardinal fish. They say: “Our results indicate that low-latitude reef fish populations are living close to their thermal optima and may be more sensitive to ocean warming than higher-latitude populations.”

“Our studies found that one species of fish could not even survive in water just 3°C warmer than it lives in now”, says the lead author of the study, Dr Jodie Rummer from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at James Cook University in Queensland.

Dr Rummer and her colleagues studied six common species living on coral reefs near the Equator. She says many species in this region experience only a very narrow range of temperatures throughout their lives, and so are probably adapted to perform best at those temperatures.

The world’s oceans are projected to warm by 2-3°C by the end of this century. “Such an increase in warming leads to a loss of performance”, Dr Rummer said. “Already, we found four species of fish are living at or above the temperatures at which they function best.”

Breeding compromised

The team measured the rates at which fish use oxygen across different temperatures – at rest and during maximal performance. The results showed that in warmer water fish lose their ability to perform properly. In the wild this would limit activities crucial to survival, such as evading predators, finding food, and finding the energy to breed.

With many of the Earth’s equatorial wild populations now living close to their thermal limits, there will be serious consequences if some – like the fish the researchers studied – cannot adapt to the speed at which the oceans are warming.

The response of many species to increasing warmth is to migrate to somewhere that suits them better, which could help to drain the equatorial oceans of fish which play a key role there. Dr Rummer suggests there will be declines in fish populations as species move away from the Equator to find refuge in areas with more agreeable temperatures.

“This will have a substantial impact on the human societies that depend on these fish,” she says. Many developing countries are in the equatorial zone, and fish are central to the livelihoods and survival of millions of people, including many in Indonesia and south-east Asia.

With rapid climate change, the scientists say, understanding the link between an organism and its environment is crucial to developing management strategies to conserve biodiversity and to allow the sustainable use of marine fisheries. This is especially urgent for ensuring food security for people. – Climate News Network