Sea rise may still pose a man-sized threat

Sea rise may still pose a man-sized threat

Although new research discounts the likelihood of a two-metre sea rise this century, the predicted impacts of global warming are still bad news for the many millions of people living at or near sea level.

LONDON, 21 October, 2014 − For those who think climate change means deep trouble, some comfort: there is a limit to how deep. Danish-led researchers have looked at all the projections and satisfied themselves that, at the very worst, sea levels this century will rise by a maximum 1.8 metres − roughly the height of an average man.

They report in Environmental Research Letters that they contemplated rates of melting in Greenland and Antarctica, the retreat of mountain glaciers worldwide, and the impact of groundwater extraction for agriculture and industry.

They also looked at all the projections for thermal expansion of the oceans, because warmer water is less dense than colder water and therefore occupies a greater volume. Then they began to calculate the band of possibilities.

“We have created a picture of probable limits for how much global sea levels will rise this century,” said Aslak Grinsted, assistant professor in the Niels Bohr Institute’s Centre for Ice and Climate at the University of Copenhagen. “Our calculations show that seas will likely rise by around 80cm. An increase of more than 180 cm has a likelihood of less than 5%. We find that a rise in sea levels of more than 2 metres is improbable.”

Critical infrastructure

The worst-case scenario, he says, is something that it would be wise to consider for critical infrastructure, such as the Delta Works, a series of construction projects that protect a large area of land in the south-west of the Netherlands, or the Thames Barrier, which aims to prevent London from being inundated by exceptionally high tides and storm surges from the North Sea.

The finding comes with two important provisos: one is that any significant rise remains extremely bad news for people in those regions of the planet that are already more or less at sea level − among them the coral atolls of the tropical oceans, the Netherlands, the Nile Delta, Bangladesh, Venice in Italy, and some of the world’s great maritime cities.

The other is that the man-high limit extends only to 2100, and researchers have repeatedly warned that, once begun, sea level rise will continue for centuries.

The Danish calculations fall into the category of things that could happen: melting in polar waters inevitably means even warmer equatorial waters, and another ominous projection for the near future is that commercially valuable fish could desert the tropics by 2050.

William Cheung, head of the Changing Ocean Research Unit at the University of British Columbia, Canada, and Miranda Jones, an environmental scientist at the same university, considered what would happen if the world warmed by 3°C by 2100.

“The tropics will be the overall losers. This area has
a high dependence on fish for food, diet and nutrition”

They report in ICES Journal of Marine Science that, under such a scenario, tropical fish could move away from their present habitats at a rate of 26 kilometres a decade. Even with a 1°C warming, they would desert their home waters at 15 km a decade.

Altogether, the two scientists considered the possibilities for 802 commercially important species, concluding that such a set of migrations might introduce new potential catches in Arctic waters, but could be very bad news for tropical fishermen, and for the hundreds of millions who depend on fish as a source of protein.

“The tropics will be the overall losers,” Dr Cheung said. “This area has a high dependence on fish for food, diet and nutrition. We’ll see a loss of fish populations that are important to the fisheries and communities in these regions.”

Accelerated rates

Paradoxically, as researchers consistently forecast accelerated rates of melting in polar waters, the Antarctic sea ice in September occupied a greater area than ever before, with the five-day average on September 19 reaching 20 million sq km, according to the US National Snow and Ice Data Centre.

That means that while most of the planet continued to warm, the Antarctic continent and the seas around it were icier, for one season at least.

Such measurements ultimately depend on satellite and aerial surveillance, and according to Claire Parkinson, climate change senior scientist at  the NASA Goddard Space Flight Centre, the anomaly simply reflects the complexity of climate dynamics and the diversity of the Earth’s environments.

“The planet as a whole is doing what was expected in terms of warming,” she says. “Sea ice as a whole is decreasing as expected, but just like with global warming, not every location with sea ice will have a downward trend in ice extent.”

But, overall, the planet is still saying goodbye to ice. The Antarctic’s gain is roughly a third in area of the loss of ice in the Arctic. – Climate News Network

Oceans’ greater heat explains warming ‘pause’

Oceans' greater heat explains warming 'pause'

New technology is helping scientists to re-assess how much heat is being absorbed by the world’s oceans – much more in some regions than realised, they say.

LONDON, 7 October 2014 – One of the most hotly-argued questions in climate research – whether global warming has slowed or even stopped – appears to have been definitively answered. And the scientists’ conclusion is unambiguous: the Earth continues to warm at a dangerous pace.

All that’s happening, they say, is that the extra heat being produced – mainly by the burning of fossil fuels – is concentrating not in the skies but in the seas. They have found new evidence that backs them up.

Instead of driving up the temperature of the atmosphere quite as fast as predicted, the evidence shows that the heat from greenhouse gas emissions is warming the oceans much more rapidly than had been realised.

In some regions the water appears to have been warming, for over 40 years, more than twice as quickly as thought, for instance in the upper 2,300 feet (700 metres) of the southern hemisphere’s oceans.

Paul Durack from the Lawrence Livermore National Laboratory in California and colleagues compared direct and inferred sea temperature measurements with the results of climate models. Together the three sets of measurements suggest estimates of northern hemisphere ocean warming are about right.

Serious under-estimate

But the team report in Nature Climate Change their estimate that warming in the southern seas since 1970 could be far higher than scientists have been able to deduce from the limited direct measurements from this under-researched region. Globally, they conclude the oceans are absorbing between 24 and 58% more energy than thought.

The researchers were able to use data from satellites and from a new source – Argo floats, a fleet of more than 3,000 free-floating monitors which drift through the water and measure the temperature and salinity of the upper 6,500 feet (2,000 m) of the ocean.

A year ago, the Intergovernmental Panel on Climate Change published its Fifth Assessment Report. Professor Chris Rapley, a former director of both the British Antarctic Survey and  the Science Museum in London, told the Climate News Network then of his alarm at what the IPCC said about the oceans.

He said the Earth’s energy imbalance, and evidence that the 93% of the energy build-up absorbed by the oceans continued to accumulate, meant the slow-down in the rise of surface temperatures appeared “a minor and temporary fluctuation”.

Speaking of the latest research, Profesor Rapley told the Network: “The newly reported results of a combination of satellite altimetry measurements of globally mapped sea level rise combined with ocean heat modelling, and a further analysis of the in situ measurements from the Argo buoys, add to the evidence that the so-called ‘pause’ in global warming is confined to surface temperature data, whilst the planet’s energy imbalance continues unabated.

Cold depths

“Once more we need to assess our appetite for risk, and consider seriously what measures we should take to minimise the threats to food and water supplies, the impacts of extreme weather, and the consequences of these to the world economic system and human wellbeing.”

A second study, also published in Nature Climate Change, by scientists at NASA’s Jet Propulsion Laboratory in Pasadena, California, concluded tentatively that all ocean warming from 2005 to 2013 had occurred above depths of 6,500 feet, and that it was not possible to detect any contribution by the deep oceans to sea level rise or energy absorption.

Josh Willis, a co-author of this study (which like that by Dr Durack and his colleagues results from the work of NASA’s newly-formed Sea Level Change Team)  said the findings did not throw suspicion on climate change itself. He said: “The sea level is still rising. We’re just trying to understand the nitty-gritty details.”

This study therefore leaves several questions still unanswered. Will more research find evidence that deep water is in fact warming, for instance? Why are the oceans now apparently absorbing more heat than they once did? And if the southern oceans are heating up faster, then may that help to speed up Antarctic ice melt?

One urgent question that needs answering is how much longer the water near the surface can continue to absorb the extra heat which human activities are producing. Another is what will happen when the oceans no longer absorb heat but start to release it. The answers could be disturbing. – Climate News Network

Surfers fear climate will wipe out big waves

Surfers fear climate will wipe out big waves

Dedicated surfers, deeply involved with monitoring the natural coastal environment around the world, warn that climate change now poses a major threat to this booming leisure industry.

LONDON, 5 October, 2014 − The world’s oceans are alive with surfers enjoying one of the fastest growing leisure activities. It is estimated there are now at least 35 million people around the globe who regularly ride the waves, and many thousands of people are employed in what has grown into a multi-billion dollar industry.

A warming world should be good news for all those artists of the waves. Warming oceans mean more storms, and the theory goes that more storms will lead to ever bigger waves. So why then are surfing websites – the internet is waterlogged with them – full of concern about changes in the climate?

Two studies appearing in the journal Nature Climate Change have made surfers stand up on their boards and reconsider the situation.

A study led by Dr Andrew Dowdy, a researcher at the Centre for Australian Weather and Climate Research (CAWCR) predicts that rising temperatures will in fact reduce the number of storms causing big waves by the end of the century on the central east coast of Australia.

Potentially destructive

The storms that do occur could be more intense and potentially destructive – but the consistency of wave patterns will be reduced.

That’s bad news for surfers of the future in that area – one of the world’s surfing hotspots. They’ll just have to move elsewhere. Dowdy told the Climate News Network that his projections only relate to that particular region, and they are not necessarily applicable to other coastal regions.

But another study, led by Mark Hemer, a senior research scientist at CAWCR, indicates that surfers might be having to ride smaller waves in future in other parts of the world as well.

Using ocean modelling techniques, Hemer and his colleagues predict a decrease in annual wave height over more than 25% of the global ocean area by the end of the century. The North Atlantic is likely to see a decrease in wave heights during all seasons, and waves are likely to be smaller in the winter months in the North Pacific and Indian Ocean.

But all is not lost. The study predicts that some regions − including  the waters off the south coast of Australia and New Zealand − will see bigger waves of between 5% and 10% above present size averages during winter months.

Surfers are worried about other climate change related threats to their activities. There are fears that rising sea levels could threaten key surfing areas.

Surfers regularly monitor water conditions – everything from acidity levels to rubbish content and sewage levels in the seas.

Surf zone

The Save the Waves Coalition − a US-based group that lobbies to protect the coastal environment, with a particular focus on what it calls the surf zone − monitors development activities in surfing areas worldwide.

Its “endangered waves” campaign lists projects that threaten key surfing areas – from plans to construct a nuclear power station on the coast of South Africa to a series of coal-fired power plants proposed for the coast of Chile.

And Climate change is seen as a major challenge facing the surfing industry.

“The unfortunate truth is that the threats to surfing habitat are now growing exponentially due to the impacts of man-made climate change,” says the California-based Sustainable Surf organisation. – Climate News Network

Why Greenland is likely to melt more quickly

Why Greenland is likely to melt more quickly

Scientists who have examined the role of the bedrock on which the Greenland ice sheet rests think it shows the huge island is more vulnerable than realised to global warming.

LONDON, 1 October – Climate scientists have thought a little more deeply about the state of the Greenland ice sheet and their conclusions are ominous.

They think that the northern hemisphere’s largest assembly of ice and compacted snow is more vulnerable to climate change than anybody had previously thought.

Marion Bougamont of the Scott Polar Research Institute in Cambridge, UK, and colleagues report in Nature Communications that they factored in not just a mathematical model of the melting ice from Greenland, but also the role of the soft, yielding and absorbent mud and rock beneath.

The Greenland ice sheet is the planet’s second largest body of terrestrial ice. It covers 1.7 million square kilometres and if it were all to melt, the world’s sea levels would rise by more than seven metres.

Right now, about 200 gigatonnes of Greenland ice a year turn to water and run into the sea. This alone raises sea levels at the rate of 0.6 millimetres a year. In fact the increase in sea levels from all causes – glacier retreat worldwide, ice cap melting and ocean thermal expansion –  is now 3 mm a year.

Researchers have repeatedly found evidence of an acceleration of melting, in some cases by looking at what is happening within the ice or on the surface, or by taking a new look at satellite data.

Less stable

But the latest calculation goes even deeper: into the mud below the ice. According to the new model, and to evidence from surveys, melting will be complicated by the conditions deep under the ice.

The ice sheets are moving, naturally and at different speeds, causing the ice to shear or flow, and the assumption has always been that the ice is flowing over hard and impermeable rock. A closer look suggests a different process.

Lakes of summer meltwater tend to form on the ice sheet surface: if the ice below fractures, these lakes can drain in a matter of hours. The meltwater flows down within the ice, and into the sediment below it.

“The soft sediment gets weaker as it tries to soak up more water, making it less resistant, so that the ice above moves faster. The Greenland ice sheet is not nearly as stable as we think,” said Poul Christofferson, a co-author.

And Dr Bougamont said: “There are two sources of net ice loss: melting on the surface and increased flow of the ice itself, and there is a connection between these mechanisms that isn’t taken into account by standard ice sheet models.”

Rapid change

At present, the annual flow of ice meltwater is more or less stable. In warmer years, the ice sheet becomes more vulnerable because more meltwater gets to the muddy absorbent bedrock. Because there is a limit to how much the sediment below can hold, the ice sheet becomes more vulnerable during extreme events such as heat waves.

And, of course, if under such a scenario it is vulnerable, it continues to become more vulnerable as average temperatures rise and extreme events become more frequent, and more extreme. And a closer look at recent geological history shows just how fast change can happen.

In a separate study in Nature Communications, Katharine Grant of the Australian National University and colleagues report that they examined evidence of the melting process at the close of each of the last five ice ages.

They looked at data from wind-blown dust in sediment cores from the Red Sea, and matched these with records from Chinese stalagmites to confirm a picture of pronounced climate change at the end of each ice age, and calculated that sea levels rose at the rate of 5.5 metres per century.

These however were exceptional events, and there were more than 100 smaller sea level events in between the big five.

“Time periods with less than twice the modern global ice volume show almost no indications of sea level rise faster than about 2 metres per century,” said Dr Grant. “Those with close to the modern amount of ice on Earth show rates of up to one to 1.5 metres per century.” – Climate News Network

Fresh water causes Antarctic seas to rise faster

Fresh water causes Antarctic seas to rise faster

Researchers in the UK have established that billions of tonnes of fresh water from melting glaciers are causing Antarctic sea levels to rise much higher and faster than the global average.

LONDON, 7 September, 2014 − Sea levels around Antarctica are rising faster than anywhere else in the southern ocean. The global average rise in ocean heights in the last 19 years has been 6cms, but the rise in seas around Antarctica is 2cms higher.

This seemingly counter-intuitive finding is certainly a consequence of melting ice in the Southern Ocean, but the connection with global warming is, for the moment, tenuous. The agency that is behind the rising sea levels is simply an excess of fresh water from melting glaciers − about 350 billion tonnes of it.

“Fresh water is less dense than salt water, and so in regions where an excess of fresh water has accumulated we expect a localised rise in sea level,” says Craig Rye, an oceanography researcher at of the University of Southampton in the UK, who, with colleagues, has published the findings in Nature Geoscience.

Partly because the oceans are warmer and are therefore expanding, and partly because the terrestrial glaciers are in retreat, global sea levels on average have crept up by about 3 millimetres a year. Waters off the Antarctic shelf seem to be gaining an additional 2mm a year.

Less saline

The scientists studied satellite scans of a region of more than a million square kilometres to make their finding, and used ship-based studies of the Antarctic sea water to confirm that is has become less saline.

The melting of the Antarctic ice sheet – German scientists recently calculated that around 125 cubic kilometres of meltwater is running off the continent each year − and the thinning of the floating ice shelves is enough to explain the unexpected rise.

Computer model studies confirm the interpretation that the rise is happening because the southern seas have just got fresher. The consequences in the longer term are uncertain.

Rye, a postgraduate researcher, said: “The interaction between air, sea and ice in these seas is central to the stability of the Antarctic ice sheet and global sea levels, as well as other environmental processes, such as the generation of Antarctic bottom water, which cools and ventilates much of the global ocean abyss.” – Climate News Network

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

Doors open at Ban Ki-moon's 'Last Chance Saloon'

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

Plan to make renewables cheaper than coal within 10 years

Plan to make renewables cheaper than coal within 10 years

Three weeks before the UN Secretary-General’s extraordinary meeting of world leaders in New York to tackle climate change, a leading British scientist unveils plans for a global low-carbon fund on a par with the Apollo Moon programme.

LONDON, 2 September 2014 – There are prospects of significant progress in the response of world governments to climate change, according to a former UK Government chief scientist, Sir David King.

“There are signs that a leadership role is beginning to emerge”, he told a conference in London held by the Green Economy Coalition.

Sir David also announced that he and a colleague are working with governments to raise funds to help all countries, including developing countries,  to switch to renewable energy. Their scheme hopes to raise nearly as much as the cost of the Apollo programme, NASA’s moon-landing project.

“President Obama is getting ready to commit the US to action, and last week the Chinese Prime Minister, Li Kichiang, announced that his country’s emissions had fallen by 5% in a year”, he said.

“The US and China are positioning themselves for an agreement. And that’s not all. The first speech by the new leader of India, Narendra Modi, spoke of his determination ‘to solarise’ the economy.

Ice in retreat

“Brazil’s emissions, including from deforestation, have fallen from 16.5 tonnes per person to 6.5 tonnes since 2005. Across the Andes in Peru, where the UN climate convention negotiations will take place in December, they know well enough about climate change.

“From Lima they can see the ice retreating up the mountains. At its lowest point it is now 1,000 metres above where it reached to 30 years ago..”

Sir David praised the UK’s commitment to cut greenhouse emissions by 80% by 2050, compared with their 1990 levels. He said the target – matched by Mexico – was likely to be met. The biggest climate challenge confronting the UK, he said, was from rising sea levels.

Some critics say, despite this, that the UK Government is dragging its feet, especially on supporting renewable energy. With a colleague, the economist Professor Lord Richard Layard, Sir David is working on a scheme to raise money to address this.

“It’s called the Global Apollo Programme”, he explained. “We are urging all governments to form a Commission to spend 0.02% of their GDP, which should raise US$10-20 bn p a over 10 years,  to fund RD&D for low-carbon technology.

“We are encouraging governments to launch the Programme at the UN during Ban Ki-moon’s Climate Summit on 23 September. The objective is that by 2020 renewable power should be cheaper than coal in all sunny parts of the world, and by 2025 in all parts of the world.”

Sir David, who for seven years was the UK Government’s chief scientist, is now its Foreign Secretary’s special representative for climate change. Asked if he were hopeful about progress to tackle climate change, he replied: “I’m in this job because I’m an optimist.”

Global reach

His hopes were echoed by another speaker, Hunter Lovins, president of the Colorado-based Natural Capitalism Solutions.  She told the Climate News Network: “We can do it. But it’s going to be tough. So will we do it?

“I don’t agree with the exponents of the idea of near-term human extinction (NTHE), who say we face total collapse by around 2030 or 2035.

‘”What we need is to find incentives for business, to get big countries behind solar+, the idea David King is working on – combining renewables and efficiency, with back-up where it’s needed.”

Professor Lovins told the conference: “Business-as-usual is going to get really ugly. What’s the narrative we can produce to compete with neo-liberalism?” – Climate News Network

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

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

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

Antarctic warming could accelerate sea level rise

Antarctic warming could accelerate sea level rise

An international study says warming is affecting not only the Arctic but also the Antarctic – and that could significantly raise global sea levels much faster than previously predicted.

LONDON, 20 August, 2014 − The effect of climate change on the world’s two polar regions looks like a stark contrast: the Arctic is warming faster than most of the rest of the Earth, while most of Antarctica appears to remain reassuringly locked in a frigid embrace.

But an international scientific team says the reality is quite different. The Antarctic is warming too, it says, and the southern ice could become the main cause of global sea level rise during this century − far sooner than previously thought.

The study, led by the Potsdam Institute for Climate Impact Research (PIK) in Germany, found that ice discharge from Antarctica could contribute up to 37 centimetres to global sea levels by 2100.

Computer simulations

The study is the first comprehensive estimate of the full range of Antarctica’s potential contribution to global sea level rise based on physical computer simulations. It combines state-of-the-art climate models and observational data with various ice models.

The results of the study − published in the European Geosciences Union’s journal, Earth System Dynamics − reproduce Antarctica’s recent contribution to sea level rise, as observed by satellites over the last two decades.

“If greenhouse gases continue to rise as before, ice discharge from Antarctica could raise the global ocean by an additional 1 to 37 centimetres this century,” says the study’s lead author, Anders Levermann, PIK professor of dynamics of the climate system.

“Science needs to be clear about the uncertainty,
so that decision-makers can consider the potential implications . . .”

“This is a big range – which is exactly why we call it a risk. Science needs to be clear about the uncertainty, so that decision-makers on the coast and in coastal mega-cities like Shanghai or New York can consider the potential implications in their planning processes.”

The scientists analysed how rising global average temperatures resulted in a warming of the ocean around Antarctica, influencing the melting of the Antarctic ice shelves.

Antarctica currently contributes less than 10% to global sea level rise and is a relatively minor player in comparison with the impact of the oceans’ increasing thermal expansion and the melting of glaciers.

But the major contributors to future long-term sea level rise are expected to be the huge volumes of ice locked up in Greenland and the Antarctic ice sheets. The marine ice sheets in West Antarctica alone could raise sea level by several metres over a period of several centuries.

The study’s computed projections for this century’s sea level contribution are significantly higher than the upper end of the latest projections by the Intergovernmental Panel on Climate Change. These suggest a probable rise by 2100 of around 60cm, although other estimates put the figure almost twice as high.

Even if governments can agree and enforce strict climate policies limiting global warming below the international target level of a maximum 2°C increase, Antarctica’s contribution to global sea level rise is expected still to range from 0 to 23cm this century.

Critical input

A co-author of the study, Robert Bindschadler, from the NASA Goddard Space Flight Center, said: “This paper is a critical input to projections of possible future contributions of diminishing ice sheets to sea level by a rigorous consideration of uncertainty of not only the results of ice sheet models themselves but also the climate and ocean forcing driving the ice sheet models.

“Billions of dollars, euros, yuan, etc, are at stake, and wise and cost-effective decision-makers require this type of useful information from the scientific experts.”

But major modeling challenges still remain. Datasets of Antarctic bedrock topography, for instance, are still inadequate, and some physical processes of interaction between ice and ocean cannot yet be sufficiently simulated.

The team also emphasises that the study’s results are limited to this century, while all 19 of the comprehensive climate models used show that the impacts of atmospheric warming on Antarctic ice shelf cavities will hit with a time delay of several decades.

However, Levermann says: “Earlier research indicated that Antarctica would become important in the long term. But pulling together all the evidence, it seems that Antarctica could become the dominant cause of sea level rise much sooner.” − Climate News Network

Canada puts oil exploitation before forests

Canada puts oil exploitation before forests

Having repudiated the Kyoto Protocol on reducing fossil fuel use, Canada is still exploiting tar sands for oil − despite accepting that climate change is destroying its forests.

LONDON, 9 August, 2014 − Detailed evidence that Canada’s vast natural areas are undergoing major changes because of climate change is produced in a new report by Natural Resources Canada.

The government body describes problems with disappearing glaciers, sea level rise, melting permafrost and changing snow and rainfall patterns. One of the country’s most important natural resources, the forests that cover more than 50% of its land area, is under pressure because of pests, fire and drought.

There may, the reports says, be some pluses for Canada in climate change − at least in the short term − because some staple cereal crops will also be able to be grown further north because of warmer weather, assuming that the soil is suitable.

The report, Canada in a Changing Climate, concentrates on impacts and adaptation, but does not mention the causes, or the fact that Canada is now an international pariah in the environmental community because of its exploitation of tar sands for oil.

The country does attempt, for economic reasons, to be more energy efficient, but has repudiated the Kyoto Protocol and international efforts to curb fossil fuel use. The country had accepted a target of cutting emissions on 1990 levels by 5% by 2012, but the government backed out in 2011.

Highest emissions

Average greenhouse gas emissions for oil sands extraction and upgrading are estimated to be 3.2 to 4.5 times as intensive per barrel as for conventional crude oil produced in Canada or the US. If Alberta, where the oil is produced from tar sands, was a country and not a merely a province of Canada, it would have the highest per capita greenhouse gas emissions in the world.

The only mention the report makes of tar sands extraction is the problem caused by its large use of water, and it makes the point that the industry is recycling as much as possible.

A tar sands mine at Mildred Lake, Alberta Image: TastCakes/Janitzky via Wikimedia Commons
A tar sands mine at Mildred Lake, Alberta
Image: TastyCakes/Janitzky via Wikimedia Commons

Mitigation is not on the agenda, as the country’s politicians are intent on exploiting as much of the country’s oil and gas as possible.

A study of forests says that 224,410 people are directly employed in the sector, although it makes up only 1.1% of GDP. About 5% of the forests are damaged annually because of outbreaks of pests and fire. Temperatures in the forest areas have risen far more sharply than on the rest of the planet, with far-reaching consequences for the future, the report says.

In 2009, over three million hectares of forest were destroyed by fire in a single year. The number of fires is expected to increase, with the area being burned being three to five times as much in Western Canada by the end of the century. Large fires are raging again this year, but the quantity of the damage has yet to be assessed.

Severe outbreaks

One of the pests moving north and devastating mature trees is the mountain pine beetle. The beetle is endemic, but is killed by winter temperatures below minus 35˚C, thus limiting its numbers from year to year. However, winter temperatures in many areas now fail to drop below this level, leading to larger and more severe outbreaks of the pest.

A report in 2012 concluded that 18.1 million hectares of forest dominated by mature Lodgepole pine (Pinus contorta) had been affected. Scientists conclude that productivity of the forests will decline rapidly in British Columbia, and thousands of jobs will be lost. Meanwhile, the beetle is continuing to move north and east.

One advantage of the increased temperatures in Canada is that trees can grow further north and higher up mountains than previously, and there is a longer growing season.

Trees that live 100 years cannot migrate fast enough to take advantage, so local governments are going in for assisted migration.

This involves planting the seeds of suitable species 100 to 200 metres above the existing tree line on mountains, and in some cases two degrees of latitude northwards (about 100 miles) of the existing forests into what is currently tundra or scrub. – Climate News Network