Tag Archives: Greenhouse gases

Eat a plant and spare a tree

A Paraguay cattle ranch: More meat will mean fewer forests Image: Peer V via Wikimedia Commons

A Paraguay cattle ranch: More meat will mean fewer forests
Image: Peer V via Wikimedia Commons

By Alex Kirby

A less meat-intensive diet is essential for the sake of wildlife and forests and to slow climate change, says a report by UK-based researchers.

LONDON, 31 August 2014 – Say goodbye to the steaks. Forget the foie gras. Put that pork chop away (assuming you can afford any of them). UK-based scientists say eating less meat is a vital part of tackling climate change.

A study published in Nature Climate Change says that on present trends food production on its own will reach – and perhaps exceed – the global targets for total greenhouse gas emissions in 2050.

Healthier diets – defined as meaning lower meat and dairy consumption – and reduced food waste are among the solutions needed to ensure food security and avoid dangerous climate change, the study says.

More people, with more of us wanting meat-heavy Western diets, mean increasing farm yields will not meet the demands of an expected 9.6 billion humans. So we shall have to cultivate more land.

This, the authors say, will mean more deforestation, more carbon emissions and further biodiversity loss, while extra livestock will raise methane levels.

Inefficient converters

Without radical changes, they expect cropland to expand by 42% by 2050 and fertiliser use by 45% (over 2009 levels). A further tenth of the world’s pristine tropical forests would disappear by mid-century.

All this would cause GHG emissions from food production to increase by almost 80% by 2050 – roughly equal to the target GHG emissions by then for the entire global economy.

They think halving food waste and managing demand for particularly environmentally-damaging food products – mainly from animals -  “might mitigate some” GHG emissions.

“It is imperative to find ways to achieve global food security without expanding crop or pastureland,” said the lead researcher, Bojana Bajzelj, from the University of Cambridge’s department of engineering, who wrote the study with colleagues from Cambridge’s departments of geography and plant sciences and the University of Aberdeen’s Institute of Biological and Environmental Sciences.

“The average efficiency of livestock converting plant feed to meat is less than 3%, and as we eat more meat, more arable cultivation is turned over to producing feedstock for animals… Agricultural practices are not necessarily at fault here – but our choice of food is.”

Squandered resources

This measure of efficiency is based on the units used in the study, which are grams of carbon in the biomass material, plant or meat.

The team created a model that compares different scenarios for 2050, including some based on maintaining current trends.

Another examines the closing of “yield gaps”. These gaps, between crop yields from best practice farming and actual average yields, exist everywhere but are widest in developing countries – particularly in sub-Saharan Africa. The researchers advocate closing the gaps through sustainable intensification of farming.

But even then projected food demand will still demand additional land and more water and fertilisers – so the impact on emissions and biodiversity remains.

Food waste occurs at all stages in the food chain, caused in developing countries by poor storage and transport and in the north by wasteful consumption. This squanders resources, especially energy, the authors say.

“As well as encouraging sustainable agriculture, we need to re-think what we eat”

Yield gap closure alone still shows a GHG increase of just over 40% by 2050. Closing yield gaps and halving food waste shows emissions increasing by 2%. But with healthy diets added too, the model suggests that agricultural GHG levels could fall by 48% from their 2009 level.

The team says replacing diets containing too much food, especially emission-intensive meat and dairy products, with an average balanced diet avoiding excessive consumption of sugars, fats, and meat products, significantly reduces pressures on the environment even further.

It says this “average” balanced diet is “a relatively achievable goal for most. For example, the figures included two 85g portions of red meat and five eggs per week, as well as a portion of poultry a day.”

Co-author Professor Pete Smith from the University of Aberdeen said: “Unless we make some serious changes in food consumption trends, we would have to completely decarbonise the energy and industry sectors to stay within emissions budgets that avoid dangerous climate change.

“That is practically impossible – so, as well as encouraging sustainable agriculture, we need to re-think what we eat.” – Climate News Network

Committed carbon emissions are rising fast

The Pątnów power plant in Konin, Poland Image: Flyz1 via Wikimedia Commons

The Pątnów power plant in Konin, Poland
Image: Flyz1 via Wikimedia Commons

 

 

 

 

 

 

 

 

 

By Tim Radford

As countries build ever more fossil fuel power plants, they commit the atmosphere to rapidly increasing levels of carbon dioxide – the opposite of what governments say they intend.

LONDON, 28 August 2014 – Challenging news for those climate campaigners who believe that renewable sources of energy are on the increase: they may be, but so are carbon dioxide emissions.

Steven Davis of the University of California, Irvine and Robert Socolow of Princeton University in the US report in the journal Environmental Research Letters that existing power plants will emit 300 billion tons of additional carbon dioxide into the atmosphere during their lifetimes. In this century alone, emissions have grown by 4% per year.

The two scientists have already reported on the increasing costs of delay in phasing out fossil fuel sources of energy. This time they have looked at the steady future accumulation of carbon dioxide in the atmosphere from power stations.

“We show that, despite international efforts to reduce CO2 emissions, total remaining commitments in the global power sector have not declined in a single year since 1950 and are in fact growing rapidly,” their paper says.

Massive commitment

“We are flying a plane that is missing a crucial dial on the instrument panel,” said Professor Socolow. “The needed dial would report committed emissions.

“Right now, as far as emissions are concerned, the only dial on our panel tells us about current emissions, not the emissions that capital investment will bring about in future years.”

Governments worldwide have in principle accepted that greenhouse gas emissions should be reduced and average global warming limited to a rise of 2°C.

The scientists asked: once a power station is built, how much carbon dioxide will it emit, and for how long? They assumed a functioning lifetime of 40 years for a fossil fuel plant and then did the sums.

The fossil fuel-burning stations built worldwide in 2012 alone will produce 19 bn tons of carbon dioxide over their lifetimes. The entire world production of the greenhouse gas from all the world’s working fossil fuel power stations in 2012 was 14 billion tons.

“Far from solving the problem of climate change, we’re investing heavily in technologies that make the problem worse”

The US and Europe between them account for 20% of committed emissions, but these commitments have been declining in recent years. Facilities in China and India account for 42% and 8% respectively of all committed future emissions, and these are rapidly growing in number. Two-thirds of emissions are from coal-burning stations. The share from gas-fired stations had risen to 27% by 2012.

“Bringing down carbon emissions means retiring more fossil fuel-burning facilities than we build,” Dr Davis said. “But worldwide we’ve built more coal-burning power plants in the past decade than in any previous decade, and closures of old plants aren’t keeping pace with this expansion.

“Far from solving the problem of climate change, we’re investing heavily in technologies that make the problem worse.” And Professor Socolow said: “We’ve been hiding what’s going on from ourselves. A high-carbon future is being locked in by the world’s capital investments.

“Current conventions for reporting data and presenting scenarios for future action need to give greater prominence to these investments.” – Climate News Network

Europe’s warming raises tropical disease risk

Spreading fear: the Aedes aegypti mosquito biting a human Image: US Department of Agriculture via Wikimedia Commons
Spreading fear: the Aedes aegypti mosquito biting a human
Image: US Department of Agriculture via Wikimedia Commons

By Tim Radford

As greenhouse gases raise temperatures in Europe, British researchers warn that the risk is increasing of the arrival of mosquito-borne diseases that kill many thousands of people every year in tropical regions.

LONDON, 27 August, 2014 − Add one more horror to the list of awful threats that climate change poses: it could introduce dengue fever in Europe.

Dengue fever is already a hazard for 2.5 billion people in humid tropical regions, and 50-100 million people a year are infected by the mosquito-borne disease. It puts 500,000 of them in hospital each year, and kills around 12,000 − many of them children. And there is still no widely effective vaccine.

Since Europe will get warmer as greenhouse gas levels in the atmosphere rise, conditions for the carrier mosquito will become more inviting.

Paul Hunter, clinical professor at the Norwich Medical School at the University of East Anglia in the UK, reports with colleagues, in the journal BMC Public Health, that in their mathematical model of disease spread, the Mediterranean and Adriatic coasts and the Po Valley and surrounding areas in north-east Italy emerged as likely breeding grounds for the carrier mosquito Aedes aegypti and the virus it can transmit.

Isolated cases

Their computer simulation already has support from medical records: the mosquito exists in urban Europe, and in 2010 there were isolated cases of dengue fever reported in Croatia and in France.

Such warnings are not new. Prof Hunter and his co-authors list reported fears of the spread of West Nile fever, leishmaniasis, Rift Valley fever, malaria, tick-borne encephalitis and other fearful infections as possible threats to Europe.

There were even warnings 25 years ago that climate change could make malaria − another mosquito-borne disease − once again a European scourge.

Malaria takes its name from the Italian, mal aria (bad air), and it was once endemic in Italy. A form of the infection also existed in Victorian England. But public health programmes, climate change and changes in land management eliminated the disease from those regions.

Now the risks to public health have begun to grow as international travel continues to increase, and as temperatures rise and the malaria mosquito expands its range in both altitude and latitude.

Dengue claims most of its victims in South-east Asia and the Pacific. But in the latest research, the East Anglia team looked at clinical data from Mexico, and climatic factors such as temperature, humidity and rainfall, and socio-economic data, to try to map the possible spread of the disease in the European Union’s 27 member states.

Rate of infection

Their findings were that the rate of infection by the virus, in the long term, could go from two per 100,000 inhabitants to 10 per 100,000 in some places, with the biggest risks being in the coastal areas of the Mediterranean and Adriatic, and in Italy’s north-east.

The authors acknowledge that their study is incomplete, and at a disadvantage. The temperature variation between winter and summer in Mexico is less dramatic than it is in Europe, and the mosquito is less likely to make it through a north European winter.

This kind of research is precautionary − a preliminary look at what could happen. But it does provide an early warning of potential hazards ahead.

“The exact incidence of dengue fever is dependent on several other factors, some of which we were unable to model at this stage,” Prof Hunter said.

“Nevertheless, public health agencies in high-risk areas need to plan, implement and evaluate effective reporting of mosquito populations and clinical surveillance by local doctors. Work should be carried out to improve awareness among health practitioners and the general public of the increased risk.” – Climate News Network

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

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

By Tim Radford

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

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

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

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

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

Vanished species

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

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

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

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

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

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

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

Climate swings

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

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

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

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

‘Free riders’ undermine climate treaty hopes

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

By Alex Kirby

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

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

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

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

Slow progress

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

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

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

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

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

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

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

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

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

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

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

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

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

Practical problems

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

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

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

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

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

Atlantic depths may hold key to heat hiatus

A jellyfish floats just above the seafloor of the deep Atlantic Image: NOAA/OAR/OER via Wikimedia Commons
A jellyfish floats just above the seafloor of the deep Atlantic Ocean
Image: NOAA/OAR/OER via Wikimedia Commons

By Tim Radford

Researchers analysing millions of oceanographic measurements believe they may finally have got to the bottom of the conundrum about why there is a slowdown in global warming despite greenhouse gas emissions rising.

LONDON, 22 August, 2014 − For years, researchers have puzzled over the temperature rises that haven’t happened – but scientists in China and the US believe they have cracked the mystery of the missing heat.

While calculations indicate that global average temperatures should be rising predictably, the planetary thermometers tell a different story.

But now Xianyao Chen, an oceanographer at the Ocean University of China in Qingdao, and Ka-Kit Tung, an atmospheric scientist at the University of Washington in Seattle, report in Science journal that they think they know where the notional extra heat has gone. It is at the bottom of the Atlantic Ocean.

And this time their conclusion isn’t based only on mathematical models and computer simulations. In their research − funded by the US National Science Foundation and the National Natural Science Foundation of China – they analysed millions of measurements of temperature and salinity taken by oceanographic instruments since 1970, and tracked the pathways that the heat must have taken since the beginning of the 21st century.

High temperatures

But first, a restatement of the conundrum. For more than a century, climate scientists have known that higher levels of carbon dioxide in the atmosphere mean higher atmospheric temperatures. For more than 30 years, every investigation has confirmed this link. And for the last 30 years of the 20th century, as greenhouse gas emissions increased, so did average temperatures.

This rise has continued, with 13 of the 14 warmest years ever recorded all falling in the 21st century, but the rate of increase unexpectedly slowed.

Researchers had expected that there would be some sort of heat hiatus, but not during the first years of the century, and they have been scratching their heads and examining the data again.

Some think that the measurements may be incomplete, or that natural cycles, such as the Pacific cooling event called La Niña, may be at play. Some have suggested that the pattern of trade winds may have a role in taking the warmth into the deep ocean, and some have suspected all along that the heat could be found far below the oceanic surface.

In the same week as the publication in Science, Reto  Knutti, a climate physicist at the federal technology institute ETH Zurich, and his colleague, Markus Huber, reported in Nature Geoscience that the apparent slowdown could be attributed to a cocktail of causes: a longer period of weaker solar irradiance – the sun has its own cycles of intensity − and to the cycle of El Niño and La Niña weather phenomena in the Pacific, and also to incompletely measured data.

“Many of the earlier papers had focused on
symptoms at the surface of the Earth”

But the Science report authors think they have an in-depth solution. “Every week, there’s a new explanation of the hiatus,” said Ka-Kit Tung. “Many of the earlier papers had focused on symptoms at the surface of the Earth, where we see many different and related phenomena. We looked at observations in the ocean to try to find an underlying cause.”

The oceans cover 70% of the planet, and are capable of storing 90% of the planet’s heat content. So the two Science report authors argue that a sudden shift in ocean salinity that corresponded with the slowdown of global warming could have triggered the movement of the heat to much deeper waters.

Saltier water is denser, sinks faster, and takes surface heat with it. As the two scientists see it, the depths of the North and South Atlantic have absorbed more heat in the last 14 years than the rest of the global ocean system put together.

This does not mean that global warming is not a problem: heat in the deep oceans is likely to come back to the surface, and to the atmosphere, sooner or later.

Natural cycle

The changes in the Atlantic ocean circulation system are part of a natural cycle that seems to date back many centuries. The surprise discovery by Chen and Tung is that the heat is tucked away in the Atlantic and Southern Oceans, rather than the Pacific − the suspected hiding place until now.

The argument is a complex one, and the latest research probably hasn’t settled the matter.

“All these analyses of ocean heat content are interpreting small changes in ocean temperature, and it will need to be picked over and repeated by others before being fully accepted,” said Professor Andrew Watson, head of the Marine and Atmospheric Science group at the University of Exeter, UK.

And Piers Forster, professor of climate change at the University of Leeds in the UK, said: “Most importantly, this paper is another nail in the coffin of the idea that the hiatus is evidence that our projections of long-term climate change need revising down.

“Variability in the ocean will not affect long-term climate trends, but may mean we have a period of accelerated warming to look forward to.” – Climate News Network

Antarctic warming could accelerate sea level rise

Warming would cause more Antarctic ice to break off and melt Image: PIK/R.Winkelmann
Rising concern: warming would cause more Antarctic ice to break off and melt
Image: PIK (R.Winkelmann)

By Alex Kirby

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

Human factor speeds up glacial melting

Glaciers such as Artesonraju in the Peruvian Andes are melting at record rates Image: Edubucher via Wikimedia Commons
Glaciers such as Artesonraju in the Peruvian Andes are melting at record rates
Image: Edubucher via Wikimedia Commons

By Tim Radford

Scientists simulating changes in mountain glaciers over the last century and a half have established that rates of melting have increased greatly in recent years – and that humans are the main culprits.

LONDON, 17 August, 2014 – The impact of human activity is melting the glaciers in the world’s mountain regions, and is doing so at an accelerating rate.

Ben Marzeion, a climate scientist at the University of Innsbruck’s Institute of Meteorology and Geophysics, Austria, reports with colleagues in the journal Science that they used computer models to simulate changes in the world’s slow-flowing frozen rivers between the years 1851 and 2010. The study embraced all the world’s glaciers except those in Antarctica.

This kind of manipulation allows researchers to play with the possibilities and see, for instance, how much changes in the sunlight patterns, high-level atmospheric changes because of volcanic eruptions, or simply slow cycles of natural weather patterns might be at work in the ice record.

The answers were unequivocal about human impact on the environment. “In our data, we find unambiguous evidence of anthropogenic contribution to glacier mass loss,” Dr Marzeion says.

In retreat

That glaciers are losing mass − retreating uphill, and melting at a faster rate − is not in doubt. A year ago, one group established without any doubt that worldwide, and overall, glaciers are in retreat.

In South America, some glaciers in the Andes are melting at a record rate, while satellite measurements show that the Jakobshavn glacier in Greenland doubled its flow speed between 1997 and 2003, and has doubled it again since 2003.

In Europe, 19th-century landscape painters, pioneer photographers and mountain guides unwittingly made permanent, easily-accessible records of Alpine glacier geography. These now set a baseline for all modern measurements, and researchers have established that the melt is getting faster.

The challenge is to determine how much of this is due to natural causes, and how much to changes in human land use, and the emission of greenhouse gases.

Higher proportion

The Innsbruck team has calculated that around a quarter of all the melting between 1851 and 2010 can be put down to human activity. But that is the overall picture: the proportion gets higher with time. Between 1991 and 2010, the fraction of melting due to human activity rose to two-thirds.

“In the 19th century and first half of the 20th century we observed that glacier mass loss attributable to human activity is barely noticeable, but since then has steadily increased,” Dr Marzeion says. – Climate News Network

Arctic warming blamed for dangerous heat waves

Feeling the heat: a wildfire rages in New Mexico during the 2012 heat wave in the US Image: Kari Greer/USFS Gila National Forest via Wikimedia Commons
Feeling the heat: a wildfire rages in New Mexico during the 2012 heat wave
Image: Kari Greer/USFS Gila National Forest via Wikimedia Commons

By Paul Brown

Giant waves in the jet stream that often governs our weather are changing as the Arctic warms more rapidly − leading to long periods of soaring temperatures that pose major threats to economies and human health.

LONDON, 16 August, 2014 − Few people have heard of Rossby waves and even less understand them, but if you are sweltering in an uncomfortably long heat wave, then they could be to blame.

New discoveries about what is going on in the atmosphere are helping to explain why heat waves are lasting longer and causing serious damage to humans and the natural world. These events have doubled in frequency this century, and the cause is believed to be the warming of the Arctic.

The weather at the Earth’s surface is often governed by high winds in the atmosphere, known as jet streams. In 1939, Carl-Gustaf Arvid Rossby, a Swedish-born America meteorologist, discovered waves in the northern jet stream that were associated with the high and low pressure systems at ground level that form daily weather patterns.

Jet streams travel at up to 200 kilometres an hour, frequently wandering north and south − with cold Arctic air to the north, and warmer air to the south.

Rapid variations

When the jet stream develops Rossby waves and they swing north, they suck warm air from the tropics to Europe, Russia or the US. And when they swing south, they do the same thing with cold air from the Arctic. The waves constantly change shape, and so cause rapid variations in the weather.

But new research, published in the Proceedings of the National Academy of Sciences of the USA, has discovered a tendency for these waves in the jet stream to get much bigger and to get stuck – particularly in July and August. This causes heat waves that last not just for a few days but for weeks.

This is a serious health and economic threat. A recent example is the record heat wave in the US that hit corn farmers and worsened wildfires in 2012.

Close study of records shows that, from 1980 to 2003, there were two such heat wave events every four years on average. From 2004-07, there were three events, and between 2008-11 there were five.

Ice shrinking

Theory and the new data both suggest a link to processes in the Arctic. Since 2000, the Arctic has been warming about twice as fast as the rest of the globe. One reason for this is that ice is rapidly shrinking in the White Sea − a southern inlet of the Barents Sea on the north-west coast of Russia – and so less sunlight gets reflected back into space, while the open ocean is dark and hence warms more.

“This melting of ice and snow is actually due to our lifestyle of churning out unprecedented amounts of greenhouse gases from fossil fuels,” says Hans Joachim Schellnhuber, co-author of the study and founding director of the Potsdam Institute for Climate Impact Research.

As the Arctic warms more rapidly, the temperature difference to other regions decreases. Yet temperature differences are a major driver of the atmospheric circulation patterns that in turn rule our weather.

“The planetary waves topic illustrates how delicately interlinked components in the Earth system are,” Schellnhuber concludes: “And it shows how disproportionately the system might react to our perturbations.” – Climate News Network

Rise in flights will outweigh carbon cuts

Low-cost airlines have led to more travel for leisure Image: Kurush Pawar via Wikimedia Commons
The proliferation of low-cost airlines has driven up demand in leisure travel
Image: Kurush Pawar via Wikimedia Commons

By Alex Kirby

Researchers warn that the cost of airline tickets will need to rise steadily to decrease demand and counteract the effects of aviation’s growing carbon emissions.

LONDON, 8 August, 2014 − The aviation industry insists that it is making only a tiny contribution to global warming, with just 2% of global carbon dioxide emissions coming from its aircraft.

The problem is the speed at which aviation itself is growing. One aircraft builder believes the number of planes in service in 2011 will have doubled by 2031.

Whatever the industry’s efforts to reduce its carbon emissions, they will be outweighed by the growth in air traffic, even if the most contentious mitigation measures come into force, according to researchers in the UK.

Cut substantially

More aircraft, more flights and more passengers mean more fuel will be burnt and more CO2 emitted − so much more that air traffic growth is likely to prevail over emissions cuts, unless demand for flights is cut substantially.

The researchers, from the University of Southampton, have published their report in the journal Atmospheric Environment.

“There is little doubt that increasing demand for air travel will continue for the foreseeable future,” says co-author and travel expert Professor John Preston. “As a result, civil aviation is going to become an increasingly significant contributor to greenhouse gas emissions.”

The authors have calculated that the ticket price increase needed to drive down demand would value CO2 emissions at up to 100 times the amount of current valuations.

“This would translate to a yearly 1.4% increase on ticket prices, breaking the trend of increasing lower airfares,” says co-author Matt Grote. “The price of domestic tickets has dropped by 1.3% a year between 1979 and 2012, and international fares have fallen by 0.5% per annum between 1990 and 2012.”

However, because any move to suppress demand is likely to be resisted by the airline industry and by governments, the researchers say that a global regulator “with teeth” is urgently needed to enforce CO2 emission cuts.

“Some mitigation measures can be left to the aviation sector to resolve,” says Professor Ian Williams, the head of the Centre for Environmental Science at the university, “For example, the industry will continue to seek improvements to fuel efficiency as this will reduce costs.

“However, other essential measures, such as securing international agreements, setting action plans, regulations and carbon standards, will require political leadership at a global level.”

The literature review conducted by the researchers suggests that the International Civil Aviation Organisation (ICAO) “lacks the legal authority to force compliance, and therefore is heavily reliant on voluntary co-operation and piecemeal agreements”.

Fuel efficiency

Current targets, set at the most recent ICAO Assembly session in October 2013, include a global average fuel-efficiency improvement of 2% a year (up to 2050), and keeping global net CO2 emissions for international aviation at the same level from 2020.

Global market-based measures have yet to be agreed, while the US plane maker Boeing predicts that the number of aircraft in service in 2011 will have doubled by 2031.

And the aircraft are only one part of aviation’s contribution to warming the planet. Airports themselves are huge emitters of greenhouse gases.

Making flying more expensive will have immense economic and social consequences − if it can be achieved.

In May 2013, the website Air Traffic Management reported that the number of seats offered by low-cost carriers in Europe has increased by an average of 14% per year over the last decade, according to OAG, a leading provider of aviation information and analytical services

This compares with an average annual rise of only 1% in capacity among “legacy carriers” – a term derived from the major airlines that existed before the 1978 Airline Deregulation Act in the US.

Thanks largely to the low-cost airlines, flying for leisure is now seen as an unquestioned right, and the national economies of many travellers’ destinations depend, at least in part, on traffic growing, not slackening. − Climate News Network