Emissions are putting species in lethal danger

Emissions are putting species in lethal danger

Scientists warn that lizards, coral reefs and forests are all seriously under threat unless agreement is reached to reduce drastically fossil fuel emissions.

LONDON, 27 August, 2015 – Global warming is going to be very bad for the boreal forests of Siberia and Canada, calamitous for the coral reefs of the tropics and the cold deep waters – and lethal for the lizards of North America.

New research warns that the double assault of warmer and increasingly acidic oceans will affect coral reefs everywhere, growing conditions will move north faster than trees can migrate, and increasing extremes of heat will roast vulnerable reptile embryos to death.

As humankind pours more and more carbon dioxide into the planetary atmosphere as a consequence of fossil fuel combustion, these are among the impacts scientists say we should prepare for by 2100 and perhaps even earlier.

About one-third of the planet’s woodlands are strewn across Europe, Scandinavia, Russia, Alaska and Canada. These forests are a “sink” for atmospheric carbon, and at the same time they provide shelter for rich ecosystems and a source of income for tens of millions of people around the world.

Climate zone shifting

But the climate is changing. The region of the northern forests is warming at 0.5°C per decade, and by 2100 it could be on average between 6°C and 11°C higher that it is now. The climate zone is shifting at least 10 times faster than trees can migrate, according to a new study in Science journal.

The likelihood is that the species to the south will be at greater risk of wildfire, drought, infection and insect assault, but the species at the northern fringe will not be able to colonise new ground to keep up. The loss of forest could accelerate global warming even further, although researchers cannot yet be sure.

“These forests evolved under cold conditions, and we do not know enough about the impacts of warming on their resilience and buffering capacity,” says one of the report’s co-authors, Anatoly Shvidenko, a senior researcher in the forestry programme at the International Institute for Applied Systems Analysis in Austria.

The consequences for the coral reefs of the world have been well reported, but geochemists at a global conference in Prague thought it worthwhile spelling out the dangers yet again.

“I find it very unlikely that coral reefs as I knew them in the mid-1960s will still be found
anywhere on this planet by mid-century”

Peter Sale, a marine biologist at the University of Windsor, Canada, used the hazard to the coral ecosystems to underscore the urgency of an international agreement at the UN’s forthcoming Paris conference on climate change to take steps to control emissions and limit average temperature increase to 2°C this century. But that may not be enough.

“Even if Paris is wildly successful, and a treaty is struck, ocean warming and ocean acidification are going to continue beyond the end of this century,” Sale says.

“This is now serious. I find it very unlikely that coral reefs as I knew them in the mid-1960s will still be found anywhere on this planet by mid-century. Instead, we will have algal-dominated, rubble-strewn, slowly eroding limestone benches.

“I see little hope for reefs unless we embark on a more aggressive emissions reduction plan.”

Lizards lay their eggs in the ground in spring and summer and leave them to gestate for up to two months. They are cold-blooded creatures that respond to the heat to become more active, and seek shade when it becomes too hot. − but infant lizards have no such freedom.

A team of scientists from Arizona State University (ASU) report in the Proceedings of the Royal Society B that, in experiments, they found that while adult animals might benefit from a warmer world, their embryos could be seriously at risk.

Pessimistic forecasts

They found that the lizard embryos die when subjected to temperatures greater than 43°C (110°F). Right now, only about 3% of the US gets to this temperature in the shade. By 2100, under the more pessimistic climate forecasts, this could have grown to 48%.

This could be bleak news for whole ecosystems, because lizards consume insects, and are in turn prey for snakes and birds and mammals.

“Lizards put all of their eggs in one basket, so a single heat wave can kill an entire group of eggs,” says Ofir Levy, postdoctoral fellow at the ASU School of Life Sciences, who led the study.

“If mothers don’t dig deeper nests to lay their eggs, we expect this species to decline throughout the United States.” – Climate News Network

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Carbon emissions threaten British butterflies

Carbon emissions threaten British butterflies

By mid-century carbon dioxide emissions in the United Kingdom could be causing recurrent droughts severe enough to force several butterfly species into extinction.

LONDON, 16 August, 2015 – If 25 years from now you can’t see a speckled wood near the English woodland, it wont be because of natural camouflage. And if you suddenly miss the large skipper, it wont be because it has led the team off the field.

Both species of British butterfly could be extinct because of global warming. And other flying insects, and even birds, may face similar jeopardy.

Under a range of climate change scenarios, extreme droughts are expected to become more frequent. Tom Oliver of the UK Centre for Ecology and Hydrology and colleagues report in the journal Nature Climate Change that they looked at long-term butterfly population records from 129 sites monitored under the UK Butterfly Monitoring Scheme to work out how 28 species had fared during an extreme drought event in Britain in 1995, and identified six species more than usually sensitive to brilliant sunshine and extended dry seasons.

Besides large skipper and speckled wood, these include the ringlet, large white, small white and green-veined white.

The authors warn that by 2050 the recurring droughts forecast by climate scientists under a “business as usual” scenario, in which humans go on expanding the use of fossil fuels, thus putting more and more of the greenhouse gas carbon dioxide into the atmosphere to raise global average temperatures, could cause population collapses.

Recovery impossible

“Should this occur repeatedly, populations may be unable to recover, resulting in local extinctions,” they warn.

The research was backed by the charity Butterfly Conservation, by the agency Natural England and by the University of Exeter.

Butterflies, transient and brightly coloured, make good tests of local ecological health, and so are well studied. So has been their response to climate change. Some species have responded by extending their range uphill or northwards in response to the overall shift in average temperatures, while other populations have dwindled.

A shift in climate is naturally expected to help some species flourish, others fade, But butterflies, like birds, are popular symbols of the natural world and there is pressure to conserve. The study is designed to examine the big challenges that will face conservation agencies by 2050.

“We consider the average response across Great Britain. Losses are likely to be more severe in drier areas with more intensive land use, whilst wetter areas with less fragmented habitat will provide refugia.

“The study looked at butterflies but the conclusions are potentially valid for other species”

“We assume that butterflies wont have time to evolve to become more drought-tolerant, because their populations are already small, and evolution would need to be very rapid. The study looked at butterflies but the conclusions are potentially valid for other species such as birds, beetles, moths and dragonflies,” said Dr Oliver.

Worryingly, the researchers found that simply devoting more space and habitat to conservation – and in a world in which rising population means greater pressure on farmland, this would not be easy – and especially by creating corridors along which species could migrate, would not be enough.

Even more worryingly, the scientists found that some species would be at risk of widespread extinction even under relatively favourable greenhouse emissions scenarios.

“The results are worrying. Until I started this research, I hadnt quite realised the magnitude and potential impacts from climate change,” said Dr Oliver. “For drought-sensitive butterflies, and potentially other taxa, widespread population extinctions are expected by 2050.

“To limit these losses, both habitat restoration and reducing CO2 emissions have a role. In fact, a combination of both is necessary.” – Climate News Network

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Climate change imperils an entire UK ecosystem

Climate change imperils an entire UK ecosystem

In the upland peat bogs of Britain, global warming is killing insects and jeopardising the rare birds that depend on them.

LONDON, 3 August, 2015 – The UK may still be fairly well sheltered from the impacts of climate change, but British scientists now say the increasingly warm trend is threatening an entire eco-system.

They have found that several rare upland bird species are at risk, together with other ecosystem functions, because of the effects of climate change on the UK’s blanket bogs −  the peat bogs found mainly in the wetter western and northern uplands of Britain.

Following their study of uplands from mid-Wales to northern England, they report in Nature Communications that “climate change could drive substantial declines in abundances of keystone invertebrates and their predators, acting through soil moisture”.

Risk for people

Several bird species − including the dunlin, golden plover and red grouse − depend on these wetlands for nesting and feeding, and there is a risk for people as well, because most drinking water comes from the upland peats.

Ecologists at the University of York and colleagues found that climate change threatens the bogs, not only through rising temperatures from increasing peat decomposition but also because of altered rainfall patterns, with summer droughts drastically affecting the bogs’ hydrology.

The study showed that an insect called the crane fly − often known as the daddy longlegs − is crucial to determining the impact of climate change on peatland bird species.

The birds depend on the protein-rich crane flies as food for chicks, but the scientists found that summer droughts, which are predicted to increase, could cause significant declines in the flies, by 56%-81%, and therefore in the birds that depend on them.

“Everything works together like a jigsaw puzzle − if you change a piece, you will change
others around it”

Based on a peatland model developed at the University of York, and on the latest climate change predictions, they say the decline of crane flies could by 2051-80 mean a 50% fall in dunlin numbers, 30% in golden plovers and 15% in red grouse.

Another concern is the role of blanket bogs as a carbon store – or source. Globally, peatlands are an important carbon store, representing about 60% of the world’s terrestrial carbon, although they cover less than 3% of the Earth’s surface, and even the UK’s bogs play a significant part.

While they are forming, peatlands can absorb carbon, but in degraded peatlands carbon dioxide and other greenhouse gases can be released. So peatlands have a massive potential influence on climate change.

Bug-to-bird link

The peatland model was developed by Dr Andreas Heinemeyer, a Stockholm Environment Institute ecologist based at the University of York. He says: “This is one of the first studies to follow this bug-to-bird link, down the food chain, between climate change and something happening to an entire eco-system, with relevance to people.

“There is a very strong relationship between the moisture of the peat and the survival of the larvae of the crane fly during summer. July and August are peak times: if it is too dry, the larvae just desiccate and die, and are then not available for the bird chicks the following year.”

And it isn’t only rare birds that were at risk from climate change. Dr Heinemeyer says “We might be in for big change, not just in connection with our birds, but with our drinking water as well.

“If you end up being very dry as a blanket bog, you store less water and your water quality seems to deteriorate . . . everything works together like a jigsaw puzzle. If you change a piece, you will change others around it.” – Climate News Network

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Muslim scholars say climate change poses dire threat

Muslim scholars say climate change poses dire threat

Islamic declaration adds to growing pressure religious leaders are exerting on richer nations to reduce the burden they are putting on the Earth’s climate.

LONDON, 15 July, 2015 − Human beings could cause the ending of life on the planet, says a group of Islamic scholars − and countries round the world, particularly the rich ones, must face up to their responsibilities.

Climate change, they say, is induced by human beings: “As we are woven into the fabric of the natural world, its gifts are for us to savour – but we have abused these gifts to the extent that climate change is upon us.”

The views of the scholars – some of the strongest yet expressed on climate from within the Muslim community – are contained in a draft declaration on climate change to be launched officially at a major Islamic symposium in Istanbul in mid-August.

Allah, says the declaration, created the world in mizan (balance), but through fasad (corruption), human beings have caused climate change, together with a range of negative effects on the environment that include deforestation, the destruction of biodiversity, and pollution of the oceans and of water systems.

Natural resources

The draft declaration has been compiled by the Islamic Foundation for Ecology and Environmental Sciences (IFEES), a UK-based charity focused on environmental protection and the management of natural resources. The declaration mirrors many of the themes contained in a recent encyclical issued by Pope Francis, the head of the Catholic church.

The Islamic declaration makes particularly strong criticism of the world’s richer and more powerful countries, which, it says, have delayed through their selfishness the implementation of a comprehensive climate change agreement.

“Their reluctance to share in the burden they have imposed on the rest of the human community by their own profligacy is noted with great concern,” the declaration says.

Wealthy oil-producing countries must “refocus their concerns from profit to the environment
and to the poor of the world”

Interestingly, the draft declaration – which is still being worked on by various Muslim academics around the world – says that, in particular, wealthy oil-producing countries must “refocus their concerns from profit to the environment and to the poor of the world”. Saudi Arabia, where Mecca is located, is one of the world’s leading oil-producing countries.

Carbon footprint

The declaration says a new economic growth model should be found that recognises that the planet’s resources are finite.

It also calls on big business to face up to its social responsibilities and not exploit scarce resources in poor countries, and says that businesses should also take a more active role in reducing their carbon footprint.

The declaration says Muslims everywhere in their particular spheres of influence should seek to play a role in tackling climate change – and that other faith and religious groups should also join in realising the aims of the Islamic scholars “to compete with us in this endeavour so we can all be winners in this race”.

The declaration quotes extensively from the Qur’an, the Muslim holy book, as the basis of its arguments.

Besides IFEES, Islamic Relief Worldwide, the Climate Action Network International and GreenFaith have also been involved in formulating the declaration. – Climate News Network

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Natural world feels the heat as temperatures soar

Natural world feels the heat as temperatures soar

Birds, insects and trees are all under threat as the rise in gobal average temperatures makes drought and heatwaves much more likely.

LONDON, 12 July, 2015 – Extremes of heat − and an extra helping of drought − have begun to change the planet in small, subtle ways, and will almost certainly continue the process of change, according to new research.

Bird species such as the Elegant Tern have begun to move north from the Gulf of California in Mexico, a species of ant that lives underground has shown it cannot take the heat, and the giant trees of the world’s forests may be at risk.

The link between any single extreme of heat and drought, and global warming as a consequence of the emissions of greenhouse gases from human burning of fossil fuels, is almost impossible to prove, but climate science has begun to show that, in general, heatwaves and drought become more likely as global average temperatures soar.

Atmospheric circulation

But the argument is not conclusive. Daniel Horton, research fellow in Earth system science at Stanford University, California, and colleagues show in the journal Nature that extremes of temperature in Europe and North America could be linked to changes in atmospheric circulation and to the distribution of heat and water vapour in the atmosphere.

That still leaves open the question: is that because of some natural cycle, or a response to global warming?

Kevin Trenberth,  Distinguished Senior Scientist in the climate analysis section at the US National Centre for Atmospheric Research, and colleagues argue in Nature Climate Change that this is hardly an either/or question.

Natural variability and human-induced climate change may both be at work in extreme events. So there could be other ways of putting the question. Given a flood, where did the moisture come from? Could it be linked to high ocean temperatures that in turn could be linked to human-induced climate change?

Put like that, it might be possible to make connections between the steady rise of carbon dioxide in the atmosphere and catastrophic events such as Superstorm Sandy in 2012, or supertyphoon Haiyan  in 2013.

“It is important to know that micro-habitat could be an indicator of heat tolerance”

But while humans argue, the natural world responds. Most of the world’s population of the Elegant Tern (Thalasseus elegans) has, historically, nested on a tiny island in the Gulf of California, in Mexico. Lately, the birds have arrived to nest as usual, but increasingly have departed without nesting.

It happened in 1998, in 2003, and then in 2009, 2010, 2014 and 2015. The population has expanded north to San Diego, Los Angeles Harbour and other places.

Ecology researcher Enriqueta Velarde, of the Universidad Veracruzana, Mexico, and colleagues report in Science Advances that the Gulf of California has been abnormally warm for the last 15 years. And when that happens, the supplies of nutrient – and the small pelagic fish that eat the nutrient – tend to decline.

Inadequate conditions

“Whenever the terns perceive the conditions in the Gulf as inadequate to ensure successful reproduction, they move to alternative nesting grounds,” Dr Velarde says.

Gulls and terns can migrate when things are uncomfortable. And many species of ant – such as army ants, the nomadic, swarming predators of the central American jungles − can cope with temperature changes. But unexpectedly, at least one subset cannot, according to Kaitlin Baudier, a biologist at Drexel University, Philadelphia, and colleagues.

These are the army ants that dwell underground, theoretically insulated from surface temperatures but actually at risk. Turn up the heat, and they suffer.

She and her co-authors report in the Journal of Animal Ecology that micro-habitat seems to be closely linked to a creature’s thermal physiology.

“This shows us the ways that these species respond to a changing climate will be different depending on habitat type, and it is important to know that micro-habitat could be an indicator of heat tolerance,” says Sean O’Donnell, a biology professor at Drexel, and senior author of the report.

Law of fluid flow

But while gulls can fly away, and ants can march or die, trees can only stay put and sicken when the heat is on.

That is because a tree’s survival depends on water that has to be sucked up to a great height through solid tissue − and this process is therefore subject to a law of fluid flow formulated in the 19th century by a French engineer, Henry Darcy.

Nathan McDowell, a climate researcher at Los Alamos National Laboratory, New Mexico, and Craig Allen, a research ecologist at the US Geological Survey, report in Nature Climate Change that, under climate warming, Darcy’s law predicts “widespread forest mortality”.

They put the question: given that trees have the problem of hauling water to a great height through old wood, what will higher average temperatures do to established forests?

The ones most likely to die, they found, were those that were very tall, and that functioned with isohydral stomatal regulation, low hydraulic conductance, and high leaf area. Helpfully, the scientists supplied the translation in the next sentence.

“Thus, tall trees of old-growth forests are at the greatest risk of loss,” they say, “which has ominous implications for terrestrial carbon storage.” – Climate News Network

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Climate change may knock seafood off the menu

Climate change may knock seafood off the menu

Researchers warn of a serious threat to fish, mussels and other marine species as carbon dioxide acidifies the world’s waters and increases temperatures.

LONDON, 7 July, 2015 – Pink salmon – the smallest and most abundant of the Pacific salmon species, and a supper table mainstay in many parts of the world – may be swimming towards trouble.

And they are not the only dish likely to disappear from the menu. Mussels, oysters, clam and scallop could all become scarcer and more expensive as the seas become more acid. And as the world’s waters warm, fish will start to migrate away from their normal grounds at an ever-increasing rate.

New research shows that as the world’s waters acidify because of carbon dioxide levels in the atmosphere, the pink salmon (Oncorhynchus gorbuscha) could become smaller and less likely to survive.

Potentially problematic

Previous studies have repeatedly and consistently explored potentially problematic consequences of change in the pH value of the world’s oceans. The higher the carbon dioxide concentrations in the air as a consequence of the burning of fossil fuels, the greater the change in oceanic acidity levels.

But researchers at the University of British Columbia, Vancouver, and colleagues looked at the special problems of freshwater fish.

Only about 0.8% of the world’s water is fresh – that is, found in lakes and rivers – but freshwater species represent 40% of all fishes. Salmon spawn and the young are reared in fresh water, before taking to the seas to mature, then returning to repeat the cycle.

The Vancouver scientists report in Nature Climate Change that they tested very young embryos in water at acidity levels expected at the end of this century, and observed them for 10 weeks.

They found that these laboratory-reared salmon were smaller, and their ability to smell was reduced, which could mean problems in returning to their spawning grounds or for scenting danger and responding to it.

“It is not too late for society to benefit greatly from immediate reductions in CO2 emissions”

At the age of seaward migration, they were less able to use oxygen in their muscles, which promised problems finding food, evading predators or making long journeys.

“The increase in carbon dioxide in water is actually quite small from a chemistry perspective, so we didn’t expect to see so many effects,” said Michelle Ou, lead author of the study. “The growth, physiology and behaviour of these developing pink salmon are very much influenced by these small changes.”

Salmon aren’t the only freshwater fish at risk from climate change. Research published in the journal Environmental Toxicology and Chemistry reveals that a rise in water temperatures of 5°C could make common pesticides and industrial contaminants ever more toxic.

Ronald Patra, an environmental scientist at the Department of Planning and Environment in New South Wales, Australia, and colleagues tested rainbow trout, silver perch, rainbowfish and western carp gudgeon at temperatures higher than optimum for the species and in the presence of endosulfan, chlorpyrifos and phenol − all of which wash into waterways from the land.

Results varied according to pollutant, species and temperature, but, overall, all three chemicals became increasingly toxic as water temperatures rose.

Future toxicity

On the coast of Mangalore in southwest India, where mussel farming has become a growing industry, researchers decided to test future toxicity conditions for the green mussel.

The Society of Experimental Biology meeting in Prague learned that the bivalves were raised in high temperature and low salt conditions and exposed to toxic algae and bacteria of the kind that might be expected in a changing climate, which in turn affected the timing of the monsoon in ways that could lower seawater salinity.

“This is likely to increase the chance of outbreaks of toxic plankton blooms and make farming bivalves such as mussels increasingly challenging,” the meeting was told.

But changes to water chemistry – once again, the shift in pH values as yet more carbonic acid builds up in the seas – create problems enough for the commercial shellfisheries.

Wiley Evans, research associate at the Ocean Acidification Research Centre of the University of Alaska Fairbanks, and colleagues report in the Public Library of Science journal PLOS One that shellfish farmers off the Alaska coast might, at extra expense, have to start modifying the sea water in their hatcheries because, the researchers reported, they expect “significant effects” from acidification by 2040.

The scientists monitored for 10 months the effects of water chemistry changes on oyster, clam, scallop and other shellfish larvae.

Alaska – with a limited growing season, melting glaciers that affect salinity, and with colder waters that more readily dissolve carbon dioxide – is a special case.

But in general, as researchers have repeatedly found, increasingly corrosive waters would make it more difficult for shellfish to exploit the calcium carbonate minerals needed to make shells.

Shellfish spend their maturity in one spot, whereas fish can and do shift their grounds when the conditions become uncomfortable − with consequences for established commercial catches such as sardines and sea bass.

Likely to migrate

But a 5°C average warming in global atmospheric temperatures – and climate scientists have repeatedly warned that this is possible before 2100 – means that fish are likely to migrate away from their existing habitats considerably faster than they are doing now.

Jean-Pierre Gattuso, of the Oceanological Observatory in Villefranche, France, and colleagues looked at the evidence on a global scale and report in Science journal that, without attempts to mitigate global warming, the oceans and the creatures in them will be seriously affected by temperature changes and acidification.

This is very bad news for the millions of people in the communities that depend on the seas for a living.

“On a positive note, we still have options to substantially reduce these impacts now, but the longer we wait the fewer and fewer options we have,” warns co-author William Cheung, of the fisheries centre at Canada’s University of British Columbia.

Commenting on the research, Jason Hall-Spencer, a professor of marine biology at Plymouth University in the UK, said: “This review screams at me that the evidence is in, and it is not too late for society to benefit greatly from immediate reductions in CO2 emissions.” – Climate News Network

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Global warming is accelerating loss of species

Global warming is accelerating loss of species

Human-induced climate change adds to threats vertebrates face from hunting and habitat loss as researchers warn that modern extinction rates are exceptionally high.

LONDON, 24 June, 2015 – Biologists have once again confirmed their own worst fears – that humans have launched a new phase of mass extinction.

There have been five catastrophic episodes in the 500 million-year history of complex life, and humanity has now precipitated a sixth, according to a new study.

Gerardo Ceballos, a researcher in the Department of Ecology Biodiversity at the National Autonomous University of Mexico, and colleagues report in the journal Science Advances that their calculations are based on the most conservative possible estimates of extinction in recent human history.

They compared those with the calculated “background”, or normal, rate of extinction throughout evolution, and came to the conclusion that vertebrate species are slipping away into the eternal night at least 114 times faster than they would if there were no humans around to hunt them, destroy their habitats or change the climates in which they had evolved.

Potentially calamitous

All such stories fall into the “stop me if youʼve heard this one” category. For more than two decades, zoologists in particular have repeatedly warned of potential calamitous extinction rates.

They have reasoned that the pressures already driving down animal populations are likely to be made worse by global warming due to the burning of fossil fuels – either by moving the climatic zones to which the creatures are adapted faster than they can migrate, or by simply becoming too warm overall, which is something that happened 55 million years ago.

One recent study even linked atmospheric levels of carbon dioxide with the worst event of all, the “Great Dying” of the Permian period 252 million years ago.

“We can confidently conclude that modern extinction rates . . . suggest a mass extinction
is under way”

But there has always been a problem of numbers – in fact, two problems of numbers. Biologists have no sure idea of how many species inhabit the planet today, and they have great difficulty establishing that any particular animal is really extinct, as opposed to just rare and difficult to identify.

So Dr Ceballos and his co-researchers went back and did the sums again, working from a recent estimate of the background rate of extinction of two mammal extinctions per 10,000 species per century.

They looked at all the written evidence for recent extinctions – the dodo of Mauritius, Steller’s sea cow, the Rodrigues giant tortoise, and all the other amphibians, birds, reptiles, fish and mammals that have slipped away to oblivion, first since 1500 and then since 1900. And the researchers then chose conservative and highly conservative calculations of loss.

Creatures vanishing

They found that, even using the most generous estimates of “normal” extinction, and the most highly conservative calculations of present loss, based on data from the 2014 International Union for Conservation of Nature’s Red Listthey had evidence that creatures are now vanishing at more than 100 times the background rate.

Almost all human health and wealth is based on what grows in the ground or grazes upon it. If the loss goes on, then within as little as three human lifetimes, humanity as a species could be deprived, the researchers warn, of “many biodiversity benefits”.

With this research, they say they have placed a “lower bound” on humanity’s impact on all other living things.

They conclude: “Although biologists cannot say precisely how many species there are, or exactly how many have gone extinct in any time interval, we can confidently conclude that modern extinction rates are exceptionally high, that they are increasing, and that they suggest a mass extinction is under way – the sixth of its kind in Earth’s 4.5 billion years of history.” – Climate News Network

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Global warming means double jeopardy for sea life

Global warming means double jeopardy for sea life

Some sea creatures seeking to escape warming oceans as the mercury rises will find that climate change is damaging the areas which could give them refuge.

LONDON, 9 June, 2015 − Global warming is likely to drive marine creatures away from the equator in search of new and cooler habitats − and  is likely to limit the safest options for many migrant fish, crabs and corals.

One problem for marine life is that warmer waters hold less oxygen, so the corals that move to higher latitudes will have to settle in shallower water to take advantage of the diminishing light. This, too, creates hazards.

Curtis Deutsch, an oceanographer at the University of Washington in the US, and colleagues report in the journal Science that the ocean’s denizens could be heading for respiratory stress. Warmer waters speed up the metabolic need for oxygen, but those same warmer waters hold lower levels of dissolved gases.

“If your metabolism goes up, you need more food and you need more oxygen,” Dr Deutsch says. “This means that aquatic animals could become oxygen-starved in the warmer future, even if oxygen doesn’t change. We know that oxygen levels in the ocean are going down now, and will decrease more with climate warming.”

Shifting habitats

His co-author, Hans-Otto Pörtner, head of the Department of Integrative Ecophysiology at the Alfred Wegener Institute in Bremerhaven, Germany, says: “If the oxygen level in a given region of the ocean drops below a species’ minimum requirements, it forces the animals to abandon their native habitat. This combines with the effect of warmer temperatures.

“Since animals evade to cooler regions, their habitat shifts towards the poles or to greater water depths. In Atlantic cod and many other fish species, we can already observe the shift now.”

That change is undoubtedly on the way. One group has just calculated that between 50% and 70% of the world’s oceans could see changes in biodiversity as the sea surface temperatures creep upwards.

The next question is: what kinds of change and what kinds of habitat will be available for submarine climate refugees? The researchers chose four well-studied marine species for their simulations of the impact of climate change on the maritime world.

Combined stress

These are the open ocean-dweller Atlantic cod, the coastal water-dwelling Atlantic rock crab, the sharp snout sea bream of the sub-tropical Atlantic and Mediterranean, and the common eelpout, a bottom-dwelling fish that lives in the shallow waters of the high northern latitudes.

The study suggests that, for many species, the combined stress of higher metabolic rates and lower levels of dissolved oxygen will mean that possible habitats will contract by between 14% and 26% because at the present species’ ranges nearer the equator, peak oxygen demand would become greater than the supply.

Also in Science journal, a team led by Paul Muir, acting curator for corals at the Museum of Tropical Queensland in Australia, reports on the potential future for 104 species of staghorn corals – the tiny creatures whose skeletons make up the reefs that offer the richest habitats in the tropical seas.

Corals are sensitive to extremes of temperature. As the mercury levels climb, they can “bleach” and reject the algae on which they depend for survival. And if conditions are too hot for too long, they can perish.

Little sunlight

But the Australian team found that these animals, too, are caught in a kind of habitat trap. As they migrate away from the equator, they must nest in shallower water to take advantage of the lower levels of winter sunlight that penetrate the waters at higher latitudes.

The corals are likely to have to rise 0.6 metres for every one degree of latitude of migration. But there is a limit to how high in the water they can rise because, at a certain point, temperature, salinity and wave damage will start to take their toll.

“The two studies remind us that climate change will reshape marine species’ habitats, but not necessarily expand them,” warns Joan Kleypas, a marine ecologist/geologist at the US National Centre for Atmospheric Research, in the same journal.

“Both studies highlight little-recognised barriers to future range expansions in the oceans,” he says. “Each is based on physiological limitations of marine organisms that are quantifiable, and thus increase our ability to predict species habitats into the future.” − Climate News Network

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Climate change could treble risks for marine life

Climate change could treble risks for marine life

Scientists warn that even stabilised levels of fossil fuel use could cause changes to ocean ecosystems far greater than any witnessed in the last 50 years.

LONDON, 4 June, 2015 − Severe global warming – a rise in annual average global temperatures driven by ever-increasing burning of fossil fuels – could force change in up to 70% of the ocean ecosystems, according to new research.

Even moderate global warming, in which greenhouse gas emissions stabilise in the next 25 years, could trigger changes three times greater than any seen in oceans over the last 50 years.

Marine biologist Grégory Beaugrand, of the University of Science and Technology at Lille in France, and colleagues report in Nature Climate Change that they used a new approach to calculate the overall pattern of winners and losers in tomorrow’s world, as carbon dioxide levels in the atmosphere soar and climates change.

They found that tropic and warm water regions would become poorer in living things, with biodiversity decreased. Some species would become extinct, some might adapt, and others would migrate.

Higher latitudes, however, would see a greater mix of living creatures – an increase in diversity of up to 300% – as species migrated north or south towards the polar regions in response to sea temperature change.

Ground-breaking model

The scientists started from the basis that − local variations in fishing, hunting, food supply and water chemistry aside − what mattered in the marine world was mostly temperature.

“We developed a ground-breaking new model for how biodiversity is arranged in the oceans and tested its accuracy using real world examples from plankton to whales − in fact the smallest of sea creatures to the largest,” Dr Beaugrand says.

“The main environmental variable in our model influencing where species like to live is temperature. We demonstrated that our model can reconstruct accurately patterns of marine biodiversity, and then we used it to see how biodiversity may reorganise in response to four different levels of global warming.”

The scientists used the past as a guide to the present and to future change. They compared the distribution of species now with what the fossil record showed for the mid-Pliocene epoch about  three million years ago, when the world was 3°C warmer than it is now, and during the last glacial maximum 20,000 years ago, when the world was 4°C to 5°C cooler.

“Any changes in biodiversity will inevitably affect interactions among species, and consequently how the ecosystem functions”

The researchers from France, Britain and Monaco have once again confirmed that the warmer the planet, the greater the potential change. But most previous research has focused on the impact of climate change on the terrestrial world. In fact, Earth is 70% ocean, and 70% of the planet’s people live within 60km of the shoreline.

Humans survive on the sea’s productivity, landing 80 million tonnes of fish each year, and the oceans play a decisive role in the regulation of the planetary climate.

The oceans have already begun to respond to climate change, as familiar species move north or dive deeper in search of the ideal temperatures in which to thrive, and invasive species eat away at long-established ecosystems.

But it is harder to predict quite how nature rebalances itself in oceans that will also be changed by increasing acidity and pollution.

“Any reorganisation of marine biodiversity will affect us in some way,” Dr Beaugrand says. “Some individual changes may be good, and some may be bad. For example, harmful algal blooms may increase in some places and decrease in others.

Function and productivity

“However, together, any changes in biodiversity will inevitably affect interactions among species, and consequently how the ecosystem functions and how productive it is, which are important aspects to understand and predict.”

If the world’s nations keep to the commitment to limit global warming to below 2°C, only about 15% of the ocean would undergo changes greater than happened over the last 20,000 years, and only 25% would see a change greater than since the mid-Pliocene more than  three million years ago.

However,  at 2°C, between 37% and 46% of the oceans would experience changes in biodiversity, and at higher levels these changes could range from 50% to 70%, the scientists say.

If emissions peak in the next five years and begin to decline, any biological changes might not be very different from existing patterns of variability seen in the last 50 years. But change is on the way.

“Our results show that climate change may rapidly reorganise marine biodiversity over large oceanic regions, and that the intensity of this reorganisation will depend, unsurprisingly, on the magnitude of warming,” the authors conclude. – Climate News Network

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Aerosols may offer short-term lifeline to corals in crisis

Aerosols may offer short-term lifeline to corals in crisis

Reducing the bleaching of corals by blocking the sun’s rays might buy time to keep tropical reefs alive if efforts are increased to halt global warming.

LONDON, 29 May, 2015 − A new solution has been proposed for the forthcoming crisis of the coral reefs: blot out some of the sunlight.

Scientists from the US, UK and Australia suggest a form of climate engineering called solar radiation management, which involves pumping aerosols into the stratosphere to reduce global temperatures − and especially the warming of the tropic seas.

If sea temperatures rise just 1°C to 2°C above the normal summer high, something gruesome happens to the coral reefs: they bleach.

This is because they sicken, and expel the colourful algae with which they cohabit. It is a survival technique known to biologists as symbiosis. But if the bleaching goes on for long enough, they die.

Human-induced warming

Lester Kwiatkowski − a researcher with both the University of Exeter in the UK and the Carnegie Institution for Science in the US − and colleagues report in Nature Climate Change that human-induced global warming because of the burning of fossil fuels could raise temperatures enough by 2050 to bleach and degrade 90% of the world’s coral reefs.

So, the authors argue, the world must accept that the loss of the reefs is inevitable − or buy time to save them.

The latter option could be addressed by squirting massive quantities of sulphate aerosols into the stratosphere to reflect radiation and darken the skies, while humans get on with the much-delayed challenge of reducing atmospheric carbon dioxide concentrations by switching to renewable sources of energy.

The irony is that Dr Kwiatkowski has only lately dismissed at least one ocean geoengineering solution – to cool the sea surfaces by pumping up cold water from the ocean depths – because, in the long run, it might make the climate change crisis even worse. Nor is he the only scientist to make that point.

“We need to accept that the loss of a large percentage of the world’s reefs is inevitable,
or start thinking beyond conventional
mitigation of CO2 emissions”

Geoengineering has repeatedly been defined as the wrong answer to problems of soaring human numbers and uncontrolled economic growth.

So the real message of this latest study may be that the choices facing humankind have become increasingly unwelcome.

Coral reefs are the richest ecosystems in the oceans, and 500 million people depend on the living coral and its co-dependants for food, tourist income and coastal protection.

The tropical reefs have bleached before, in extremes of heat, but after a few years have recovered. Whether they could survive both a sustained rise in temperatures and the increasing acidification of the oceans that goes with higher carbon dioxide levels is another matter.

Ecosystem at risk

So the researchers decided to see what it would take to reduce the risk. They took some account of the impact of the debilitating effect of increasing ocean acidity. Then they considered the hypothetical fate of corals in a warming world.

There is no doubt that bleaching is a consequence of hotter seas, or that by 2100 the entire reef ecosystem will be at risk.

At least one other group has proposed that some form of solar protection could be an answer, but another has suggested that at least some corals might adapt.

“Coral reefs face a dire situation, regardless of how intensively society decarbonises the economy,” says Peter Cox, professor of climate system dynamics at the University of Exeter.

“In reality, there is no direct choice between conventional mitigation and climate engineering, but this study shows that we need to accept that the loss of a large percentage of the world’s reefs is inevitable, or start thinking beyond conventional mitigation of CO2 emissions.” – Climate News Network

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