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Science finds new routes to energy

April 17, 2014 in Agriculture, Biofuels, Carbon Dioxide, Energy, Technology

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The research opens the way to more nutritious soya beans grown with less water Image: H. Zell via Wikimedia Commons

The research opens the way to more nutritious soya beans grown with less water
Image: H. Zell via Wikimedia Commons

By Tim Radford

Scientists in the US have found new ways to make biofuel, increase crop yields and exploit carbon dioxide through novel applications of familiar materials.

LONDON, 17 April – While politicians posture, and climate scientists sigh sadly, researchers in laboratories continue to devise ingenious new ways to save energy, increase efficiency, and make the most of solar power.

Darren Drewry of the Jet Propulsion Laboratory in California and two colleagues from the University of Illinois have a computer model that could design soybean crops able to produce 8.5% more nourishment, use 13% less water and reflect 34% more sunlight back into space.

They report in the journal Global Change Biology that they can achieve all three goals by breeding for slightly different leaf distribution on the stalk, and for the angle at which the leaf grows, using a technique called numerical optimisation to try a very large number of structural traits to get the best results. “And surprisingly, there are combinations of these traits that can improve each of these goals at the same time,” says Dr Drewry.

In the great evolutionary challenge match, plants fight for the light and try to put each other in the shade. “Our crop plants reflect many millions of years in the wild under these competitive conditions,” said Stephen Long, a plant biologist. “In a crop field we want plants to share resources and conserve water and nutrients, so we have been looking at what leaf arrangements would best do this.”

Once future agricultural scientists have worked out what they most want from a crop – and in arid zones, water economy must rate highly – the programme can decide the best configuration of leaf. From that, future breeders could select traits from the enormous library of existing soybean variations.

Lomg-lasting benefit

They could reduce the canopy to let light through to lower levels to increase yield, or they could heighten the canopy to reflect light back into space and offset climate change.

“We can also model what these plant canopies can do in a future climate, so that it will be valid 40 or 50 years down the line,” says Praveen Kumar, an environmental engineer.

At Stanford University in California, other scientists have thought of a way to make biofuel without benefit of fields, plants or sunlight. They report in Nature that they have devised an oxide-derived copper catalyst that can turn carbon monoxide – the lethal gas in car exhausts and coal-burning power stations – directly into liquid ethanol of the sort now made from corn and other crops.

What’s more, they say, they can do this at room temperature and normal atmospheric pressures. The technique rests on the ability to turn copper oxide into a network of nanocrystals of metallic copper that would serve as a cathode in an electrolysis reaction and reduce carbon monoxide to ethanol.

Biofuel is expensive: it takes time, fields, fertiliser and water. It takes 800 gallons of water to grow a bushel of corn, which in turn yields three gallons of ethanol. The new technique could eliminate the crop, the time, and a lot of the water.

Ten-fold efficiency gain

And it opens another way to exploit captured CO2 as a power source. Carbon dioxide can be turned efficiently and easily into carbon monoxide. The new oxide-derived copper catalyst could then turn carbon monoxide into ethanol with ten times the efficiency of any normal copper catalysts.

The team would like to scale up their catalytic cell and see it powered by solar or wind energy. “But we have a lot more work to do to make a device that is practical,” said Matthew Kanan of Stanford.

Meanwhile, scientists in Oregon report in the Royal Society of Chemistry journal RSC Advances that they have tested a new way to tap the sun’s rays, and to use that power to make solar energy materials at the same time.

Once again, the match of nanoscience and copper has provided unexpected consequences. By focusing light continuously on a continuous flow micro-reactor, the researchers have synthesized copper indium nanoparticle inks that could make thin-film solar cells in minutes. Other processes might take hours to deliver the same materials.

“It could produce solar energy materials anywhere there’s an adequate solar resource and in this chemical manufacturing process, there would be zero energy impact,” said Chih-Hung Chang of Oregon State University. – Climate News Network

Fish on acid lose fear of predators

April 15, 2014 in Adaptation, Carbon Dioxide, Marine ecology, Ocean acidification

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Reef species like this clown fish are at higher risk of succumbing to predators in more acid seas Image: Ritiks via Wikimedia Commons

Reef species like this clown fish are at higher risk of succumbing to predators in more acid seas
Image: Ritiks via Wikimedia Commons

By Tim Radford

As carbon dioxide makes the seas more acidic and poses physical problems for some species of fish, it can also rob them of their inhibitions, which helps their predators.

LONDON, 15 April – Coral reef fishes exposed to acid oceans lose their sense of smell – and their sense of caution – and are more likely to fall prey to natural enemies, according to new research in Nature Climate Change.

The finding is based on observations of the behaviour of four species at a reef off the coasts of Papua New Guinea where natural carbon dioxide seeps out of the rock, and confirms a series of other such studies in the last year.

A cool volcanic discharge in the reef has served as a natural laboratory for years: water in the region reaches an average pH of 7.8. This standard measure of acidity is co-incidentally the level predicted for all the world’s oceans by 2100, as atmospheric carbon dioxide levels continue to rise, according to the Intergovernmental Panel on Climate Change. www.ipcc.ch/

Australian and US scientists observed the fishy behaviour from a boat moored above the reef, and also tested the fish on board the vessel. What they observed was that, away from the volcanic bubbles of carbon dioxide, in conditions of more normal ocean chemistry, damsel fish and cardinal fish seemed able to smell predators and stayed in sheltered places in the reef to avoid becoming prey.

Fish from the waters richer in carbonic acid seemed not to sense the presence of predators, and were more likely to venture into dangerous waters.

Survival threat

After a sudden scare that sent all the fish racing for cover, the fish from the bubble reef ventured forth much sooner. In normal circumstances, such fish spend 80% of their time under cover.

The bubble reef fish spent at most only 12% of their time in hiding. Mortality accordingly was five times higher.
“Their sense of smell was acutely affected in CO2-rich waters in ways that gravely threaten their survival,” said Alistair Cheal of the Australian Institute of Marine Science.

“We were able to test long-term realistic effects in this environment,” said another author, Danielle Dixson of the Georgia Institute of Technology in the US. “One problem with ocean acidification research is that it’s all laboratory-based, or you’re testing something that’s going to happen in 100 years’ time with fish that are from the present day, which is not actually accurate.”

The reasoning is that the change in pH levels disrupts a neuroreceptor in the fishes’ brains and affects faculties or alters behaviour. Similar experiments with Californian rockfish have demonstrated much the same effect.

Acid spreading

But increased acidification of the oceans is also likely to affect shellfish and corals in other ways, and research in the Great Barrier Reef region of Australia has documented a dramatic behaviour change in a jumping snail that suggested impaired decision-making capability as pH levels alter.

Sea water is already 30% more acidic that it was at the start of the Industrial Revolution 200 years ago. The rate of change is at least 100 times faster than at any time in the last 650,000 years.

The bubbling waters of the reef under test are not unique – such localized carbonic acid seeps occur in many places all over the world – and the fact that predators might find easy pickings in such places makes no real difference to population levels in the vastness of the rest of the ocean. But such experiments raise the question: can ecosystems adapt to changing water chemistry?

“Continuous exposure does not reduce the effect of high CO2 on behaviour in natural reef habitat and this could be a serious problem for fish communities in the future when ocean acidification becomes widespread as a result of continued uptake of anthropogenic CO2 emissions,” the authors conclude. - Climate News Network

More CO2 limits plants’ protein output

April 12, 2014 in Agriculture, Carbon Dioxide, Soil, Uncategorized, Vegetation changes, Warming

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The Mojave desert: As CO2levels rose, it took up unexpectedly large amountsofthe gas Image: Rennett Stowe via Wikimedia Commons

The Mojave desert: As CO2 levels rose, it took up unexpectedly large amounts of the gas
Image: Rennett Stowe via Wikimedia Commons

By Tim Radford

With increasing warmth drying more of the Earth, arid soils may absorb more carbon dioxide – but that in turn is likely to limit protein production.

LONDON, 12 April – As global temperatures rise, more than one third of the land surface may become more arid. Although there will be changes in rainfall patterns, heat – and the attendant evaporation of the soil – could extend ever drier conditions to more and more farmland and cities, according to research in the journal Climate Dynamics.

The new study – which excludes Antarctica – is led by Benjamin Cook, a climate scientist both with the University of Columbia’s Lamont-Doherty Earth Observatory and the US space agency Nasa. It is based on climate simulation, and forecasts that 12% of the land surface will be subjected to drought by 2100 just through changes in rainfall. Throw in the increased heat, though, and the drying effect will be spread to 30% of the land.

Even those regions that might be expected to get more rain will be at greater risk of drought. This would be very bad news for the wheat, corn and rice belts of the south-western US and south-eastern China.

“For agriculture, moisture in the soil is what really matters,” said Cook’s co-author, Jason Smerdon. The research confirms previous studies, and the more recent warnings from the Intergovernmental Panel on Climate Change, and other studies, have predicted that extremes of temperature will be bad news for farmers anyway, with yields  likely to be affected.

But nothing in climate research is simple. The extra warming will be a direct consequence of ever-higher levels of carbon dioxide in the atmosphere. A study in Nature Climate Change has just revealed that arid zones offer an unexpected source of what engineers call negative feedback.

Carbon sink

A 10-year experiment in the Mojave desert in the US has shown that as carbon dioxide levels increase, arid areas take up unexpectedly large amounts of the gas.

“They are a major sink for atmospheric carbon dioxide, so as CO2 levels go up, they’ll increase their uptake of CO2 from the atmosphere. They’ll help take up some of that excess CO2 going into the atmosphere. They can’t take it all up, but they’ll help,” says Dave Evans, a biologist at Washington State University.

All land surfaces absorb some carbon. Until now, most attention has been paid to the role of forests as major “sinks” of carbon. But the US experimenters marked out nine octagonal plots of the desert and blew air with current levels of CO2 over three of them, and air with 550 parts per million of CO2, the expected level by 2050, over another three. Three received no extra air at all.

Then the researchers excavated the soils to a depth of a metre to measure the absorbed carbon and were surprised by the gain in carbon during a relatively short exposure in the plots exposed to the extra carbon dioxide.

Arid and semi-arid soils account for a large proportion of the planet’s land surface: overall, they could increase carbon uptake to account for between 15% and 28% of the amount currently being absorbed by land surfaces.

Less protein

This sounds like good news, on balance. It may not be, as far as food supplies are concerned. In the same issue of Nature Climate Change a second study reports on experiments into the effects of elevated levels of carbon dioxide on wheat.

Carbon dioxide is seen as a fertiliser of plants and indeed, without it, there would be no plants. But Arnold Bloom, a plant scientist at the University of California Davis reports that, according to his experiments, elevated levels of carbon dioxide also inhibit the conversion of nitrate into protein in crops.

Wheat provides nearly one fourth of all protein in the global human diet. Other studies have shown the same effect with wheat – and also with rice, barley and potato tubers.

“When this decline is factored into the respective portion of dietary protein that humans derive from these various crops, it becomes clear that the overall protein available for human consumption may drop by about three per cent as atmospheric carbon dioxide reaches the levels anticipated to occur during the next few decades,” Bloom said. – Climate News Network

Bricks on wheels face road closure

March 23, 2014 in Carbon Dioxide, Economy, European Union, Road Transport, Safety, Technology, United Kingdom

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A brick on wheels? The traditional British lorry may before lone give way to a new and perhaps safer design Image: By Adrian S Pye via Wikimedia Commons

A brick on wheels? The traditional British lorry may before long give way to a new and perhaps safer design
Image: By Adrian S Pye via Wikimedia Commons

By Kieran Cooke

The European Parliament has voted in favour of changing the design of goods lorries throughout the EU – from their present brick shape to a more streamlined-looking vehicle. The idea is not only to increase fuel efficiency and cut back on CO2 emissions, but also to reduce accidents.

LONDON, 23 March – It’s one of those small steps that could help in the battle against greenhouse gas emissions and climate change.

Lorry design in the European Union at present is governed by legislation dating back to the mid-1990s, stipulating total maximum lengths for cabs and trailers.

This has resulted in the general adoption by road hauliers of a brick-shaped design for cabs on lorries: by making the cab more upright and shorter, transport companies have more space for goods.

But according to Transport & Environment (T&E), a Brussels-based group which campaigns for more sustainable and environmentally friendly transport policies within the EU, lorries have lagged seriously behind other vehicles in terms of environmental performance over the past 20 years.

“Whilst only three per cent of vehicles (in the EU), lorries account for a quarter of Europe’s road transport emissions. That share is expected to grow as traffic increases further”, it says.

Improving protection

T&E says the brick-shaped design is not only inefficient in terms of fuel consumption – it is also dangerous: “Lorries also have a dreadful safety record: every year 15% of all fatal collisions – around 4,200 deaths – involve lorries.”

About 75% of freight in Europe is delivered by lorry. Studies indicate road freight transport is one of the fastest-growing sources of CO2 emissions in the EU, with emissions from the sector likely to increase by more than 20% over the next 15 years. The EU imports 500 million barrels of oil each year, wortharound €60bn, to power its freight fleet.

European Parliament members say relatively simple changes in design can bring about advances in fuel efficiency and cut back on CO2 emissions. Under the Parliament’s proposals, the brick-shaped cab design would be replaced by a more streamlined, aerodynamic nose. The rear of the vehicle would also have aerodynamic flaps and shaping.

T&E says giving lorries a rounder front and putting in place other improvements could improve fuel economy by between seven and ten per cent. It says a more curved cab front would also give drivers greater visibility, eliminate blind spots and so avoid accidents.

Powerful backing

“Today is a good day for pedestrians, cyclists, drivers, hauliers and the environment”, said William Todts of T&E following the EU Parliament vote. “This vote brings the end of the brick-shaped cab closer. It’s a key decision that will reduce road deaths and kickstart progress on lorry CO2 emissions after 20 years of stagnation.”

After a spate of fatal accidents involving lorries and cyclists, London’s mayor, Boris Johnson, has joined the call for changes in lorry design.

The era of more fuel-efficient, safer lorries in Europe is likely to be delayed for some time. Hauliers and truck manufacturers object to the costs of design changes.  To compensate for the haulage space lost due to any new shapes for lorries, the trucking industry is likely to press for bigger, longer vehicles.

The Parliament’s vote still needs to be confirmed by the full parliamentary body. It then goes forward to be considered by all member states. The brick on wheels could be charging down Europe’s roads for some time yet. – Climate News Network

Biofuels from waste ‘need EU backing’

March 3, 2014 in Adaptation, Agriculture, Biofuels, Business, Carbon Dioxide, Energy, European Union, Forests

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The bales head  for the farm: Straw is an agricultural waste suitable for making biofuel Image: Ian Kirk from Broadstone, Dorset, UK via Wikimedia Commons

The bales head for the farm: Straw is an agricultural waste suitable for making biofuel
Image: Ian Kirk from Broadstone, Dorset, UK via Wikimedia Commons

By Alex Kirby

The countries of the European Union could slash their greenhouse gas emissions and save significant amounts of oil by making fuel from waste, researchers say. But they think policymakers should give a lead.

LONDON, 3 March – Europe has the technology and the raw material to make a big cut in the amount of oil its transport uses, researchers say. But it will fail to reap the benefits on offer unless the European Union comes up with more radical policies.

A report, Wasted: Europe’s Untapped Resource, says the continent has significant unexploited potential to convert waste from farming, forestry, industry and households into advanced low-carbon biofuels, saving more than a sixth of the EU’s expected total fuel consumption for road transport 16 years from now.

But it says the conversion will not happen unless EU policymakers give greater priority to sustainability and to the need to lower the dependence of transport on high-carbon fuels by 2030.

The research which produced the report was carried out by the International Council on Clean Transportation (ICCT) and NNFCC, a UK research consultancy. The project was supported by a group of companies interested in introducing new technology, including two airlines, British Airways and Virgin, and by WWF, BirdLife Europe and several other environment NGOs.

The report says that if all sustainable waste from farms, forests, households and industry is used for transport fuels, that could make enough to replace about 37 million tonnes of oil annually by 2030 – the equivalent of 16% of the EU’s road transport fuel demand by then.

Safeguards needed

It also says that so long as the new fuels came from sustainable sources, they would produce less than 40% of the carbon dioxide emissions from fossil fuels. Using them would inject up to €15 billion (US$21 bn) of extra revenue into the rural economy every year and create up to 300,000 new jobs by 2030.

The sorts of wastes that could be used include straw and other crop left-overs, forestry residues, municipal solid waste and used cooking oil.

But the report carries a warning too: safeguards would be needed to ensure the waste was obtained sustainably, including land management methods to protect biodiversity, water and soil.

And the benefits of biofuel from waste would have to be paid for. The report says some combinations of feedstock and technology would need short-term financial incentives, although others are already close to being competitive and would need little more than certainty about policy.

Easier challenge

The authors say cautiously that the research shows it is possible to develop a biofuel industry based on farm and forest wastes “which in the case of the cheapest feedstocks could become cost-competitive with only modest incentives…” Biofuel from other wastes might need different levels of subsidy.

Chris Malins led the analysis for the ICCT. He said: “Even when taking account of possible indirect emissions, alternative fuels from wastes and residues offer real and substantial carbon savings. The resource is available, and the technology exists – the challenge now is for Europe to put a policy framework in place that allows rapid investment.”

David Turley of the NNFCC, who led the economic analysis, said advanced biofuels from agricultural and forest wastes would require “little or only a modest additional incentive” to stimulate production at prices comparable to those of current fuels made from specially-grown crops.

The report concludes that while trying to use all the available waste might be thought optimistic, achieving just 2% of current EU road transport fuel use in 2020, as suggested by the European Parliament, would be less challenging.

Even that more modest aim, the report says, would still add about €163 million (US$224 m) in net revenues to the agricultural sector and €432 m (US$594 m) to the forestry sector. It would also generate an extra 37,000 permanent jobs in the rural economy, and 3,500 more in biofuel refineries. – Climate News Network

Tree roots ‘are natural thermostat’

February 18, 2014 in Carbon Dioxide, Forests, Mountains, Palaeoclimatology, Soil

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In sight of the Carpathians: Mountain forests can cool - and warm - the Earth Image: Horia Varlan from Bucharest, Romania, via Wikimedia Commons

In sight of the Carpathians: Mountain forests can cool – and warm – the Earth
Image: Horia Varlan from Bucharest, Romania, via Wikimedia Commons

By Tim Radford

Trees can influence the climate in unexpected ways, and British researchers say their roots are an important way of helping rocks to weather and drawing carbon dioxide from the atmosphere.

LONDON, 18 February – Trees have become a source of continuous surprise. Only weeks after researchers demonstrated that old forest giants actually accumulate more carbon than younger, fast-growing trees, British scientists have discovered that the great arbiters of long-term global temperatures may not be the leaves of an oak, a pine or a eucalypt, but the roots.

The argument, put by a team from Oxford and Sheffield Universities in the journal Geophysical Research Letters, begins with temperature. Warmer climates mean more vigorous tree growth and more leaf litter, and more organic content in the soil. So the tree’s roots grow more vigorously, say Christopher Doughty of Oxford and colleagues.

They get into the bedrock, and break up it up into its constituent minerals. Once that happens, the rock starts to weather, combining with carbon dioxide. This weathering draws carbon dioxide out of the atmosphere, and in the process cools the planet down a little. So mountain ecosystems – mountain forests are usually wet, and on conspicuous layers of rock – are in effect part of the global thermostat, preventing catastrophic overheating.

The tree is more than just a sink for carbon, it is an agency for chemical weathering that removes carbon from the air and locks it up in carbonate rock.

That mountain weathering and forest growth are part of the climate system has never been in much doubt: the questions have always been about how big a forest’s role might be, and how to calculate its contribution.

Keeping climate stable

US scientists recently studied the rainy slopes of New Zealand’s Southern Alps to begin to put a value on mountain ecosystem processes. Dr Doughty and his colleagues measured tree roots at varying altitudes in the tropical rain forests of Peru, from the Amazon lowlands to 3,000 metres of altitude in the higher Andes.

They measured the growth to 30 cms below the surface every three months and did so for a period of years. They recorded the thickness of the soil’s organic layer, and they matched their observations with local temperatures, and began to calculate the rate at which tree roots might turn Andean granite into soil.

Then they scaled up the process, and extended it through long periods of time. Their conclusion: that forests served to moderate temperatures in a much hotter world 65 million years ago.

“This is a simple process driven by tree root growth and the decomposition of organic material. Yet it may contribute to the Earth’s long-term climate stability. It seems to act like a thermostat, drawing more carbon dioxide out of the atmosphere when it is warm and less when it is cooler”, Dr Doughty said.

If forests cool the Earth, however, they might also warm it up. A team from Yale University in the US has reported in Geophysical Research Letters that forest fires might have had an even greater impact on global warming during the Pliocene epoch about three million years ago than carbon dioxide.

Rapid rise expected

Nadine Unger, an atmospheric chemist, and a colleague have calculated that the release of volatile organic compounds, ozone and other products from blazing trees could have altered the planet’s radiation balance, by dumping enough aerosols into the atmosphere to outperform carbon dioxide as a planet-warmer.

In fact, the Pliocene was at least 2°C or 3°C warmer than the pre-industrial world. The Pliocene is of intense interest to climate scientists: they expect planetary temperatures to return to Pliocene levels before the end of the century, precisely because humans have cleared and burned the forests, and pumped colossal quantities of carbon dioxide into the atmosphere. The greater puzzle is why a rainy, forested and conspicuously human-free world should have been so much warmer.

“This discovery is important for better understanding climate change through Earth’s history, and has enormous implications for the impacts of deforestation and the role of forests in climate protection strategies”, Dr Unger said.

All this scholarship is concerned with the natural machinery of ancient climate change, and the Yale research was based on powerful computer simulations of long-vanished conditions that could not be replicated in a laboratory.

Meanwhile, ironically, forest scientists have had a chance to test the levels of volatile organic discharges from blazing forests because freakish weather conditions in Norway have seen unexpected wild fires in tracts of mountain forest. December was one of Norway’s warmest winter months ever. In one blaze, 430 residents were forced to evacuate. – Climate News Network

Carbon output ‘will climb 29% by 2035′

February 7, 2014 in Carbon Dioxide, Coal, Energy, Forecasting, Greenhouse Gases, Renewables, Shale Gas

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Spelling it out: A French "non" to the prospect of shale oil and gas Image: Eva Joly 2012 via Wikimedia Commons

Spelling it out: A French “non” to the prospect of shale oil and gas
Image: Eva Joly 2012 via Wikimedia Commons

By Alex Kirby

Climate scientists agree that global carbon dioxide emissions need to be sharply cut. A prominent player in the energy industry predicts they will go in the opposite direction.

LONDON, 7 February – The good news, from the climate’s standpoint, is that while global demand for energy is continuing to grow, the growth is slowing. The bad news is that one energy giant predicts global carbon dioxide emissions will probably rise by almost a third in the next 20 years.

The Intergovernmental Panel on Climate Change says greenhouse gas emissions need to peak by 2020 and then decline if the world is to hope to avoid global average temperatures rising by more than 2°C over pre-industrial levels. Beyond 2°C, it says, climate change could become dangerously unmanageable.

But BP’s Energy Outlook 2035 says CO2 emissions are likely to increase by 29% in the next two decades because of growing energy demand from the developing world.

It says “energy use in the advanced economies of North America, Europe and Asia as a group is expected to grow only very slowly – and begin to decline in the later years of the forecast period”.

But by 2035 energy use in the non-OECD economies is expected to be 69% higher than in 2012. In comparison use in the OECD will have grown by only 5%, and actually to have fallen after 2030, even with continued economic growth. The Outlook predicts that global energy consumption will rise by 41% from 2012 to 2035, compared with 30% over the last ten.

Nor does it offer much hope that the use of novel energy sources will help to cut emissions. It says: “Shale gas is the fastest-growing source of supply (6.5% p.a.), providing nearly half of the growth in global gas.”

Renewables shine

Burning gas produces much lower CO2 emissions than using coal, but the sheer volume of shale production is expected to cancel out any possible emissions reductions. In fact the Outlook says of its predictions:  “…emissions [of CO2] remain well above the path recommended by scientists…Global emissions in 2035 are nearly double the 1990 level.”

An advantage claimed by some supporters of shale gas is that it will increasingly replace a much more polluting fossil fuel, coal. But at the moment many coal-producing countries are finding markets overseas for those they have lost to shale gas at home.

Oil, natural gas and coal are each expected to make up around 27% of the total mix by 2035, with the remaining share coming from nuclear, hydroelectricity and renewables. Among fossil fuels gas, conventional as well as shale, is growing fastest and is increasingly being used as a cleaner alternative to coal.

Bob Dudley, BP Group chief executive, said the Group was “optimistic for the world’s energy future”. Europe, China and India would become more dependent on imports, he said, while the US was on course to become self-sufficient in energy.

The Outlook does provide encouragement to the producers of renewables, which are expected to continue to be the fastest growing class of energy, gaining market share from a small base as they rise at an average of 6.4% a year to 2035. – Climate News Network

Woodman, spare that tree!

January 26, 2014 in Carbon Dioxide, Forests, Vegetation changes

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By Tim Radford

It may seem unlikely, but an international team of researchers has found that most large trees keep absorbing atmospheric carbon dioxide even in old age.

LONDON, 26 January – Giant trees could play a giant role in fixing carbon dioxide from the atmosphere. This counter-intuitive discovery – surely, young faster-growing trees would be more efficient at soaking up carbon?  – emerges from a study of more than 403 species by a consortium of 38 scientists in 16 countries who report in Nature.

Nathan Stephenson of the US Geological Survey and his 37 colleagues between them studied data collected from more than 650,000 individual trees on six continents over a span of 80 years to show that the world’s oldest trees actually grow more quickly, and also accumulate carbon more rapidly than younger, smaller trees.

Some trees are known to reach vast heights and masses. But acknowledged giants such as the Australian mountain ash Eucalyptus regnans and the coastal redwood Sequoia sempervirens are not just lonely examples of spectacular weight gain.

The researchers observed continuing gains in 97% of the trees surveyed. “Rapid growth in giant trees is the global norm and can exceed 600 kg per year in the largest individuals”, they reported.

“In human terms it is as if our growth just keeps accelerating after adolescence, instead of slowing down”, Stephenson said. “By that measure, humans would weight half a ton by middle age and well over a ton by retirement.”

Continued utility

The research matters for three reasons. The first is that it is a tribute to the power of patient data collection over decades: much of it by amateur naturalists and natural history and conservation groups.

The second is that it adds significantly to the chances of making more complete sense of the great carbon conundrum – where, when carbon disappears from the atmosphere, does it go, and how long does it stay there?

A large western white pine in California: Trees as large and old as this will still absorn CO2 from the atmosphere Image: Dcrjsr via Wikimedia Commons

A large western white pine in California: Trees as large and old as this will still absorn CO2 from the atmosphere
Image: Dcrjsr via Wikimedia Commons

And the third is that it helps resolve the open question of whether established forests can continue to serve as reservoirs of atmospheric carbon. In August, researchers published a study in Nature Climate Change that suggested that Europe’s forests, for instance, might have reached saturation point.

Previous studies have tended to measure forest growth at the level of the leaf, and the level of the forest as a whole. Stephenson and his colleagues considered the tree as the agency that mattered most, and observed a different outcome.

They calculated that a single large, old tree could add as much carbon to the forest in one year as was contained in an entire middle-sized tree. Even though individual leaf level productivity declined with age, the tree’s total leaf area increased to outpace this decline.

More questions

So even though each leaf might be less efficient at absorbing carbon, the tree kept on growing because it was bigger and therefore had more leaves with which to soak up nourishment from the atmosphere.

It’s a question of scale: in the language of mathematics, total tree leaf mass increases as the square of trunk diameter. So a tree that makes a tenfold increase in diameter will make a 100-fold increase in leaf mass, and at least a 50-fold increase in total leaf area.

To put it another way, in old western US forests, individuals more than a metre across comprised 6% of the tree population, but contributed 33% of the annual forest growth in terms of mass.

But, as usual, such research raises more questions that must be settled. The authors themselves warn that what is true for individual trees might not hold for stands of trees in a block of woodland. As trees age, some will die, leaving fewer individuals occupying an area of forest, and therefore possibly less carbon overall.

“Our results are relevant to understanding and predicting forest feedbacks to the terrestrial carbon cycle and global climate system”, the authors write. – Climate News Network

Shellfish feel impact of more acid seas

January 22, 2014 in Adaptation, Algae, Carbon Dioxide, Fish, Greenhouse Gases, Marine ecology, Ocean acidification, Predation, USA

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Low oxygen and rising acidity in the oceans spell trouble for some species of scallop Image: By Jeremy Keith from Brighton & Hove, UK

Low oxygen and rising acidity in the oceans spell trouble for some species of scallop
Image: By Jeremy Keith from Brighton & Hove, UK, via Wikimedia Commons

By Tim Radford

Researchers in the US have discovered that several more marine species are being damaged by the effects of the increasing acidity of the oceans, a direct consequence of greenhouse gas emissions.

LONDON, 22 January – Ocean acidification brings fresh problems for Californian native oysters. Like some creature from a horror movie, a driller killer threatens Ostrea lurida, the Olympia oyster that dwells in the estuaries of western North America.

Many species are likely to face problems as pH levels (which measure how acid a liquid is) change and ocean chemistry begins to alter as the world warms and ever more dissolved carbon dioxide flows into the sea and adds to its acidity.

Researchers have observed that coral skeletons are affected and larval oysters find it more difficult to build their first shell structures. The change towards greater acidity seems to trigger learning difficulties in juvenile rockfish  and make it harder for the conch snail to leap out of the way of a predator’s poisoned dart. And three separate research papers bring yet more bad news for yet more sea creatures.

Eric Sanford and colleagues at the University of California, Davis, report in the Proceedings of the Royal Society B that under more acid water conditions, the Olympia oyster experiences a 20% increase in drilling predation.

Researchers conducted a direct experiment involving oysters reared in normal conditions, oysters reared in water high in dissolved carbon dioxide, and an invasive predator from a distant ocean called Urosalpinx cinerea, the Atlantic oyster drill. Their assumption was that bivalves (creatures with a hinged shell) in more acid water would grow thinner shells, and that drilling predators would selectively choose the victims that would be easiest to drill into.

Problems multiply

It didn’t work quite like that – the experimental oysters did not have thinner shells. But these oysters were victims all the same. They were 30% to 40% smaller than the control group of oysters in the other tank “and these smaller individuals were consumed at disproportionately greater rates”, the authors say. The invasive snails, on the other hand, were not bothered by the change in water pH.

The results indicate, say the researchers, that ocean acidification “can negatively affect the early life stages of Olympia oysters.” They have been subjected already to overfishing, disease, habitat loss, pollution and hypoxia, when water is so rich in nutrients that it becomes starved of oxygen and turns into a dead zone where nothing much can survive for long. Extra vulnerability to an invasive driller killer is, the scientists carefully say in non-emotive language, “a relatively novel stressor for this species.”

Hypoxia, too, turns out to be a problem made worse by carbon dioxide. Low oxygen waters are already acidified waters, say Christopher Gobler of Stony Brook University in the US and colleagues in the Public Library of Science journal PLOS One.

They report that a combination of low oxygen and low pH led to higher rates of death and slower growth for young bay scallops and hard clams than expected from either individual factor. “Low oxygen zones in coastal and open ocean ecosystems have expanded in recent decades, a trend that will accelerate with climatic warming”, says Gobler.

Threat to algae

“There is a growing recognition that low oxygen regions of the ocean are also acidified, a condition that will intensify with rising levels of atmospheric CO2 due to the burning of fossil fuels causing ocean acidification. Hence the low oxygen, low pH conditions used in this study will be increasingly common in the world’s oceans in the future.”

And ocean acidification is not just making life good for predators and bad for the prey, it could be threatening to alter the basic biodiversity of the sea. Sophie McCoy of the University of Chicago reports in Ecology Letters that she and Cathy Pfister looked at the dynamics of coralline algae that live around Tatoosh Island, Washington, on the Pacific coast of the US.

These little creatures, like oysters, grow calcium carbonate skeletons. In previous observations in which four species were transplanted to these waters, one species called Pseudolithophyllum muricatum emerged as the undisputed winner. In the 1980s, its skeleton grew twice as thick as its competitors’.

In the latest round of tests, there was no clear winner: no species was dominant, and P. muricatum won less than 25% of the time – a response, the authors think, to changes in the pH of the sea water just in the last 12 years.

The total energy available to the organisms was the same, but their responses were different: those that needed to make more calcium carbonate tissue were under more stress than those that did not.

This experiment was a “real world” test rather than a laboratory experiment. “Field sites like Tatoosh are unique because we have a lot of historical ecological data going back decades,” said McCoy. “I think it is really important to use that in nature to understand what is going on.” – Climate News Network

Rainy mountains speed CO2 removal

January 19, 2014 in Carbon Dioxide, Mountains, New Zealand, Rainfall, Soil

FOR IMMEDIATE RELEASE

The rainswept Southern Alps are young mountains and growing fast Image: Philip Capper from Wellington NZ via Wikimedia Commons

The rainswept Southern Alps are young mountains and growing fast, providing new rock for weathering
Image: Philip Capper from Wellington NZ via Wikimedia Commons

By Tim Radford

The speed at which soil is produced by rain falling on mountain slopes proves to be much faster than science had realised – with significant implications for carbon in the atmosphere.  

LONDON, 19 January – US scientists have measured the rate at which mountains make the raw material for molehills – and found that if the climate is rainy enough, soil gets made at an astonishing speed. And in the course of this natural conversion of rock to fertile farmland and forest loam, carbon is naturally removed from the atmosphere.

Isaac Larsen of the University of Washington in Seattle and colleagues from California and New Zealand took a closer look at rates of weathering on the western slopes of the Southern Alps in New Zealand. They report in Science that, according to their measurements, rock is being transformed into soil more than twice as fast as previously believed.

On the ridge tops of the NZ mountains, soil was being manufactured by chemical weathering (which is scientific shorthand for rain splashing on rock) at the rate of up to 2.5mm a year.

“A couple of millimeters a year sounds pretty slow to anyone but a geologist”, said David Montgomery, one of the authors. “Isaac measured two millimeters of soil production a year, so it would take just a dozen years to make an inch of soil. That’s shockingly fast for a geologist, because the conventional wisdom is it takes centuries.”

The research matters because – once again – it throws new light on one of the dark regions of the climate machine: how carbon dioxide is removed from the atmosphere, at what rate, and where it goes and where it all ends up.

Temperature drop

The Southern Alps of New Zealand are in geological terms young, and still going up in the world: they include some of the fastest-uplifting mountains on the planet. They are also among the rainiest: more than 10 metres of precipitation a year, on average.

Uplift – the process of mountain-building – provides fresh new rock for weathering to work on. Rainclouds arrive on the prevailing winds from the Tasman Sea, hit the mountain sides, rise, condense and release their burden on the western slopes, to generate colossal run-off, lots of silt and rock fragments and dissolved silica, and to nourish dense, vigorous forests at the bottom of the slope.

And along with all this trickling water and new soil is a steady delivery of carbon, removed from the atmosphere’s carbon dioxide.

The hypothesis that mountains play a role in chemical weathering, carbon dioxide removal and climate change is not new. Decades ago scientists argued that when the continent of India slammed into Asia and lifted up the Himalayas and the Tibetan plateau more than 50 million years ago, this process generated conditions for monsoon rainfall that accelerated the removal of carbon dioxide from the atmosphere at such a rate that global temperatures dropped dramatically and ushered in the Ice Ages.

Such an argument is difficult to clinch, but the latest research from NZ certainly lends support to the reasoning that new mountain chains are influential components in the climate machine.

Strenuous research

Larsen and colleagues calculate that the young, wet mountain chains of the world make up only 14% of the land area that drains into the ocean, but account for 62% of the sediment, 38% of the total dissolved solids and 60% of the dissolved silica delivered down the rivers and into estuaries and deltas and ultimately to the sea, where huge quantities of this run-off settle to become carbonate rock.

Mountains, in effect, are agencies that turn carbon dioxide from the air into limestone beneath the sea, and the evidence from the Southern Alps is that this happens more speedily than anyone first thought.

To complete the research, the scientists had repeatedly to take helicopter rides to the highest ridges, hike down to collect a burden of new soil, and then climb the steep mountain slopes again to await the return flight.

Back in Washington, they tested their soil samples for levels of beryllium-10, an isotope made at the Earth’s surface by cosmic rays, and therefore an indicator of the newness of the soil, and the rate at which it formed.

“I’ve worked in a lot of places,” said Larsen. “This was the most challenging fieldwork I have ever done.” – Climate News Network