Deniers’ voices try to drown out climate scientists

Deniers’ voices try to drown out climate scientists

New study indicates that loud dissent from contrarians may prompt some researchers to soften their language about the threats of climate change.

LONDON, 16 May, 2015 − Climate change denial by contrarians claiming that global warming has stopped, is a natural cycle rather than a consequence of human action, or is simply a hoax or conspiracy can take its toll of climate scientists too.

A new study in Global Environmental Change suggests that the loudest voices of dissent can affect the way researchers who have separately and repeatedly confirmed the reality of global climate change then talk about their own research.

Scoffing by contrarian voices can lead researchers to over-emphasise the inevitable scientific uncertainties, or over-react to claims of alarmism, or even adopt some of the contrarian language – chief of which has been talk of a “pause” or “hiatus” in global warming in the 21st century.

Psychological mechanisms

Stephan Lewandowsky, professor at the University of Bristol School of Experimental Psychology in the UK, and colleagues from the US and Australia call the problem “seepage”. That is, the language of the contrarians has seeped into scientific discourse.

The researchers identify three psychological mechanisms, which they call “stereotype threat”, “pluralistic ignorance” and “third-person effect”.

The first acts as a behaviour response: stereotype climate scientists as alarmist and this triggers a natural reaction to avoid the stereotype and downplay the climate threat, or at least not highlight the risks.

“The public has a right to be informed of risks,
even if they are alarming”

Pluralistic ignorance follows when a noisy minority opinion gets disproportionate play in public debate − that is, when people who thought they were in a majority begin to feel inhibited.

The third-person effect is the assumption that persuasive communications might persuade other people, but not the experts. In fact, there is evidence that even experts can be subtly affected by such talk.

Professor Lewandowsky says: “It seems reasonable to conclude that the pressure of climate contrarians has contributed, at least to some degree, to scientists examining their own theory, data and models, even though all of them permit – indeed expect – changes in the rate of warming over any arbitrarily chosen period.

“We scientists have a unique and crucial role in public policy to communicate clearly and accurately the entire range of risks that we know about. The public has a right to be informed of risks, even if they are alarming.

“Climate scientists have done a great job in pursuing their science under great political pressure, and they have tirelessly rebutted pseudoscientific arguments against their work.

“However, sometimes scientists have inadvertently allowed contrarian claims to frame the language of their scientific thinking, leading us to overstate scientific uncertainty and under-communicate knowledge.”

A second study by US scientists recently confirmed that, in fact, scientists have communicated the knowledge. They have certainly done so to a US legislature rich in Republican representatives who make a point of challenging or dismissing the climate science consensus.

Contrarian voices occasionally claim that the scientific community is “divided” − but such division was not on show in evidence presented to the US Congress.

Expert witnesses

Xinsheng Liu, associate research scientist at Texas A&M University, and colleagues report in the journal Climatic Change that they analysed 1,350 testimonies delivered to 253 congressional hearings from 1969 to 2007.

Of the expert witnesses who expressed a view, 86% said that climate change was happening, and 78% said it was a consequence of human activity. Most significantly, 95% of those scientists who gave testimony supported action to combat climate change.

So a “supermajority” of scientific opinion had presented the facts to Congress, and the near-complete agreement in the science community had been consistently presented.

“Possible explanations for policymakers’ contention must be based on something other than a lack of knowledge or divided scientific information,” the report’s authors conclude. – Climate News Network

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Climate pushes Doomsday Clock close to midnight

Climate pushes Doomsday Clock close to midnight

Scientists warn that the deadly combination of unchecked climate change and nuclear weapons endangers everyone on Earth unless urgent action is taken.

LONDON, 26 January, 2015 − The two main “extraordinary and undeniable threats to the continued existence of humanity” are more acute than at any time in the last 30 years, according to scientists in the US.

One is the possibility of nuclear war − even a limited one. The other is climate change, which the scientists say “looms over all of humanity”. Either means that “the probability of global catastrophe is very high” without urgent action.

The warning comes from the Bulletin of Atomic Scientists’ science and security board, which has moved the hands of the historic Doomsday Clock forward two minutes. They now stand at three minutes to midnight.

Undeniable threats

The board says in a statement: “In 2015, unchecked climate change, global nuclear weapons modernisations, and outsized nuclear weapons arsenals pose extraordinary and undeniable threats to the continued existence of humanity, and world leaders have failed to act with the speed or on the scale required. . .

“These failures of political leadership endanger every person on Earth.”

The statement says: “The board feels compelled to add, with a sense of great urgency: ‘The probability of global catastrophe is very high, and the actions needed to reduce the risks of disaster must be taken very soon.’”

The Doomsday Clock symbolises how close humanity has come to the apocalyptic danger of mass destruction by nuclear weapons, climate change, and emergent technologies.

The clock’s minute hand stood at two minutes before midnight in 1953, and at 17 minutes before midnight in 1991, after the end of the Cold War. The last time it was just three minutes to midnight was 1983, when “US-Soviet relations were at their iciest”, according to the Bulletin.

“This threat looms over all of humanity. We all need
to respond now, while there is still time.”

Sivan Kartha, a member of the Bulletin’s science and security board and a senior scientist at the Stockholm Environment Institute, said: “Steps seen as bold in light of today’s extremely daunting political opposition to climate action do not even match the expectations of five years ago, to say nothing of the scientific necessity.

“Global greenhouse gas emission rates are now 50% higher than they were in 1990. Emission rates have risen since 2000 by more than in the previous three decades combined. Investments have continued to pour into fossil fuel infrastructure at a rate that exceeds $1 trillion per year, with additional hundreds of billions of dollars in continued fossil fuel subsidies.”

Sharon Squassoni, another board member and director of the Proliferation Prevention Programme at the Center for Strategic and International Studies, said: “Since the end of the Cold War, there has been cautious optimism about the ability of nuclear weapon states to keep the nuclear arms race in check and to walk back slowly from the precipice of nuclear destruction.

“That optimism has essentially evaporated in the face of two trends: sweeping nuclear weapons modernisation programmes and a disarmament machinery that has ground to a halt.

Slowed dramatically

“Although the United States and Russia no longer have the tens of thousands of nuclear weapons they had during the Cold War, the pace of reduction has slowed dramatically in recent years, well before the crisis in Crimea. From 2009 to 2013, the Obama administration cut only 309 warheads from the stockpile.”

Richard Somerville, a board member and research professor at Scripps Institution of Oceanography, University of California, San Diego, said: “Efforts at reducing global emissions of heat-trapping gases have so far been entirely insufficient to prevent unacceptable climate disruption. . .  This threat looms over all of humanity. We all need to respond now, while there is still time.”

The board urges action to be taken to cap greenhouse gas emissions at levels that that would keep average global temperature from rising more than 2°C above pre-industrial levels. This is the internationally-agreed limit, which will form the basis of the global agreement that climate negotiators hope to reach at UN talks in Paris in December.

The board also urges sharply reduced planned spending on nuclear weapons modernisation, a revitalised disarmament process, and immediate action to deal with nuclear waste. − Climate News Network

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Small volcanic eruptions are key to warming hiatus

Small volcanic eruptions are key to warming hiatus

Sulphur dioxide hurled in vast amounts from volcanoes is known to cool the atmosphere, but now scientists have identified how even small eruptions have a big effect on climate.

LONDON, 13 January, 2015 − Researchers now have a new explanation for the so-called slowdown in global warming in this century. They blame it on not very dramatic, small-scale volcanic eruptions.

This is a new twist in a puzzling story. In 1991, a catastrophic eruption of Mount Pinatubo in the Philippines hurled 20 million tonnes of sulphur dioxide into the stratosphere − a delivery of aerosols huge enough to block incoming sunlight and actually cool the planet for a couple of years. The assumption since then has been that big volcanic eruptions have enough heft to influence climate.

But in two recent papers, researchers have proposed another hypothesis, and then identified the evidence that a greater number of quite modest eruptions could have the same effect.

Mechanisms at work

To demonstrate such a thing, scientists need to pinpoint the mechanisms at work. In November, David Ridley, an atmospheric scientist at the Massachusetts Institute of Technology, and colleagues focused on the intersection of two atmospheric layers – the atmosphere and troposphere.

They used a mix of ground, air and space-based technology to observe the aerosols in the lower stratosphere, and then they played with a climate model. The conclusions were straightforward: volcanoes could have caused a cooling of between 0.05°C and 0.12°C since 2000.

And the latest study, by a team led by Benjamin Santer, an atmospheric scientist at the Lawrence Livermore National Laboratory in California, has shown that the “signals” of eruptions in the late 20th and early 21st centuries can be positively identified in the atmospheric temperature, moisture and reflected radiation at the top of the atmosphere.

This signal, they report in Geophysical Research Letters, doesn’t explain all the hiatus or slowdown. But it makes a significant contribution.

Uptick in activity

Very roughly, there are 1,500 active volcanoes on the planet and, during 1990, there were 53 recorded eruptions. In 2010, there were 83; in 2013, there were a record 84. So it looks as if an uptick in geothermal activity could have made a difference.

But the climate machine is not a simple thing, and the argument is likely to go on. Other researchers have proposed that the missing heat is concealed in the ocean depths, or that a change in the trade winds may be a factor, or that climate scientists may have misread the signals because the extremes in the last 15 years have been hotter, even if the average has not increased much.

So, all along, the discussion has been not just about what might have been missed, but also about precisely what should or could be measured. And, in any case, words such as “pause”, “hiatus” and even “slowdown” add to the confusion.

Early in December, meteorologists declared 2014 on course to be the warmest year ever. It may not prove so – the calculations will take a few more weeks – but even if it isn’t, 14 of the 15 warmest years ever recorded have all occurred in the 21st century. – Climate News Network

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Atlantic depths may hold key to heat hiatus

Atlantic depths may hold key to heat hiatus

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

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Health alert over fracking’s chemical cocktails

Health alert over fracking’s chemical cocktails

Scientists in the US have established that some chemicals used in the controversial process of fracking to extract gas and oil could represent health and environmental hazards.

LONDON, 19 August, 2014 − Fracking is once again in trouble. Scientists have found that what gets pumped into hydrocarbon-rich rock as part of the hydraulic fracture technique to release gas and oil trapped in underground reservoirs may not be entirely healthy.

Environmental engineer William Stringfellow and colleagues at Lawrence Berkeley National Laboratory and the University of the Pacific told the American Chemical Society meeting in San Francisco that they scoured databases and reports to compile a list of the chemicals commonly used in fracking.

Such additives, which are necessary for the extraction process, include: acids to dissolve minerals and open up cracks in the rock; biocides to kill bacteria and prevent corrosion; gels and other agents to keep the fluid at the right level of viscosity at different temperatures; substances to prevent clays from swelling or shifting; distillates to reduce friction; acids to limit the precipitation of metal oxides.

Household use

Some of these compounds – for example, common salt, acetic acid and sodium carbonate – are routinely used in households worldwide.

But the researchers assembled a list of 190 of them, and considered their properties. For around one-third of them, there was very little data about health risks, and eight of them were toxic to mammals.

Fracking is a highly controversial technique, and has not been handed a clean bill of health by the scientific societies.

Seismologists have warned that such operations could possibly trigger earthquakes, and endocrinologists have warned that some of the chemicals used are known hormone-disruptors, and likely therefore to represent a health hazard if they get into well water.

Industry operators have countered that their techniques are safe, and involve innocent compounds frequently used, for instance, in making processed food and even ice-cream.

But the precise cocktail of chemicals used by each operator is often an industrial secret, and the North Carolina legislature even considered a bill that would make it a felony to disclose details of the fracking fluid mixtures.

So the Lawrence Berkeley team began their research in the hope of settling some aspects of the dispute.

Real story

Dr Stringfellow explained: “The industrial side was saying, ‘We’re just using food additives, basically making ice-cream here.’ On the other side, there’s talk about the injection of thousands of toxic chemicals. As scientists, we looked at the debate and asked, ‘What’s the real story?’”.

The story that unfolded was that there could be some substance to claims from both the industry and the environmentalists. But there were also caveats. Eight substances were identified as toxins. And even innocent chemicals could represent a real hazard to the water supply.

“You can’t take a truckload of ice-cream and dump it down a storm drain,” Dr Stringfellow said. “Even ice-cream manufacturers have to treat dairy wastes, which are natural and biodegradable. They must break them down, rather than releasing them directly into the environment.

“There are a number of chemicals, like corrosion inhibitors and biocides in particular, that are being used in reasonably high concentrations that could potentially have adverse effects. Biocides, for example, are designed to kill bacteria – it’s not a benign material.” – Climate News Network

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China and US boost search for CCS solution

China and US boost search for CCS solution

Capturing carbon emissions from polluting industries has long been touted as a key way of helping to address climate change, but a new China-US agreement looks like giving much-needed stimulus to development of the technology.

LONDON, 18 July 2014 − For years, the energy companies have been telling us not to worry. Yes, mounting carbon emissions threaten to heat up the world – but technology, particularly carbon capture and storage (CCS), will come to the rescue.

The trouble is that there’s been plenty of talk about CCS and little action, with few projects being implemented on a large scale.

That could be about to change as China and the US, who have been leading the way on CCS research in recent years, this month signed a raft of agreements on tackling climate change  − with half of them focusing on CCS.

The idea behind CCS is to capture at source the carbon emissions from big polluters, such as power utilities and cement plants, and either pipe the CO2 down into deep storage cavities below the Earth’s surface or to recycle the emissions to be used in the production of biofuels.

Despite various geopolitical rivalries and disputes over trade, China and the US have shown increasing willingness to co-operate when it comes to climate change issues.

Worsening impacts

In February this year, the two countries issued a joint statement that highlighted the urgent need for cutbacks in fossil fuel use “in light of the overwhelming scientific consensus on climate change and its worsening impacts”.

The agreements signed in Beijing this month establish collaborative research programmes between China’s state energy firms and US universities on a wide range of CCS-related technologies, including CO2 storage techniques and the combining of captured emissions with algae to produce energy.

The implementation of CCS projects around the world has been plagued by various technical problems, high costs, arguments between energy companies and governments about who pays for research and development, and by regulatory uncertainties in many countries.

The Global CCS Institute, an independent, not-for-profit organisation based in Australia, promotes the use of CCS technology. It says that, at present, the 21 large-scale CCS projects either in construction or in operation around the world are capable of capturing in total up to 40 million tonnes of CO2 annually – the equivalent of taking eight million cars off the road each year.

While the use of CCS is expanding, it’s still not being utilised on anything like the scale needed to result in cutbacks of global greenhouse gas emissions. Most CCS projects are in the US, China and Canada, with Europe lagging very much behind.

Big push needed

Brad Page, the head of the Global CCS Institute, says that if we are to meet the generally-agreed target of limiting warming to 2˚C over 1990 levels by mid-century, there has to be a big push into CCS technology.

“For this low-carbon technology to reach a scale needed to reduce carbon dioxide emissions, more countries need to match progress in places like the US, Canada and China, which are bringing CCS projects online at a robust pace,” he says.

Page adds that CCS must be supported by clear government policies − particularly in Europe, where more flexible funding and policy arrangements are urgently needed.

Earlier this month, the International Energy Agency (IEA) called for the implementation of more CCS projects. The IEA said such projects are particularly important at a time when the use of coal – the most polluting of fuels − is increasing rapidly worldwide. – Climate News Network

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Tofu offers a taste of cheaper solar energy

Tofu offers a taste of cheaper solar energy

The discovery by British scientists that a chemical used in making tofu and gritting icy roads is a much cheaper, safer option in the production of solar cells could have huge financial benefits for the renewable energy market.

LONDON, 30 June, 2014 − British researchers have found a new way to cut the cost of solar cell manufacture, and at the same time make the process less hazardous. Ironically, it is also very old way – using a chemical important in turning soy milk into tofu.

Jonathan Major and colleagues at the University of Liverpool report in Nature journal that magnesium chloride − traditionally added to soy milk as a coagulant to make tofu, but also used in gritting roads in winter time, used as bath salts, and sometimes even sold as a health supplement – could replace cadmium chloride as a “doping agent” to increase the efficiency of cadmium telluride solar cells.

Dangerous to handle

Cadmium chloride is very expensive, costing $0.30 (£0.18) per gram. It is also highly toxic and very dangerous to handle, which adds to the process costs. Naturally-occurring magnesium chloride costs only $0.001 per gram, and is one of the substances that makes the ocean salty. Since the planet is two-thirds ocean, there is no danger of running out of supplies.

Photovoltaic solar cells that convert sunlight directly to electricity are now big business, and getting bigger. They can be made of thin slivers of silicon, but the silicon wafer has to be 99.999% pure, and 200 microns thick  (0.2 millimetres). So industry has also started using cadmium telluride to make sheets of photovoltaic cells that have a thickness of only two microns (0.002mm) − so thin and flexible they could even be sold by the roll.

The problem with cadmium telluride is that, to make it efficient enough to compete, it must be washed with a doping agent − an impurity added to a pure substance to produce a deliberate change− and, so far, the industry has relied on cadmium chloride. Cadmium is a dangerous metal, toxic if swallowed, fatal if inhaled, and linked by some researchers to breast cancer, cardiovascular disease, and even gout. It isn’t very good for aquatic life either.

Extra expense

Cadmium telluride is a stable salt and safe to handle, but cadmium chloride separates in solution into cadmium and into chlorine, another toxic substance. So manufacturers have the extra expense of safety during production, and then of safe disposal of waste.

Dr Major and his team at the university’s Stephenson Institute for Renewable Energy are competitors in a worldwide search for ingenious ways to exploit renewable energy and reduce fossil fuel emissions.

They started this latest research by considering what it was about the cadmium chloride that made it effective, and then whether some other salt might serve the same purpose. They found that magnesium chloride had some of the same important physical properties, and then tested it.

“If renewable energy is going to compete with fossil fuels, then the cost has to come down,” Dr Major said. “Great strides have been made, but the findings in this paper have the potential to reduce costs further.” – Climate News Network

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Satellite zooms in on crucial carbon questions

Satellite zooms in on crucial carbon questions

The ability of scientists to make accurate predictions about future effects of CO2 will be boosted by vital data from a US satellite being launched to take a detailed inventory of the planet’s sinks and sources of carbon.

LONDON, 28 June, 2014 − The US space agency NASA is about to send up a satellite that will provide vital data for predicting future effects of CO2 by taking the measure of the planetary carbon budget.

OCO-2, more formally known as Orbiting Carbon Observatory-2, is planned for launch on July 1 and will circle the globe, taking an inventory of those places on the planet that absorb carbon from the atmosphere (the sinks) and those places that release it into the atmosphere (the sources).

Although the satellite’s acronymic name pleasingly evokes CO2, the carbon dioxide greenhouse gas that is now at higher levels in the atmosphere than at any time in the last 800,000 years, this is pure accident. The first attempt to launch an orbiting carbon observatory came to grief when the satellite failed to separate from the launch rocket. OCO-2 is the second attempt.

Future build-up

“Knowing what parts of Earth are helping to remove carbon from our atmosphere will help us understand whether they can keep on doing so in future,” said the project scientist Michael Gunson, of NASA’s Jet Propulsion Laboratory. “Quantifying these sinks now will help us predict how fast CO2 will build up in the future.”

Carbon dioxide exists in the atmosphere only in trace amounts: 400 parts per million. But humans are adding 40 billion tons of the gas a year by burning fossil fuel, destroying forests and quarrying lime for cement.

Less than half of this total stays there: the rest is taken up by forests on land and by algae in the oceans. But quite how much, for how long, and how predictably, remains a puzzle.

Climate scientists need to know more about sinks and sources to make more accurate predictions. And governments, planners and foresters need to know more about the ways the forest world absorbs and emits carbon dioxide.

The new satellite will use onboard spectrometers to take hundreds of thousands of measurements every day to answer these complex questions of supply and demand. Researchers are also likely to match the data with other studies of the planet’s changing forests.

Scientists at Ludwig Maximilian University in Munich − where records show that average temperatures have risen by 1.5°C in the last century − have been observing at ground level, to measure changes in the growing season.

There are around 16,000 species in the Munich Botanical Garden, and researchers have measured changes in leaf-out times for 500 species to establish why the characteristic forests of the region are likely to change with warming temperatures. The answer is that some species burst into leaf when daylight reaches a certain number of hours, while some respond to temperature.

This will put central European species − such as beech, which buds when there are 13 hours of daylight, whether the spring has arrived early or not − at a disadvantage. Southern species, which respond instead to rising temperatures, will gain a growing advantage.

Inexorable change

Meanwhile, in the US, foresters have begun to resign themselves to inexorable change in the iconic forests of Minnesota.

A report by the US Forest Service warns that, in the next 100 years, the evergreen white spruce and balsam fir and cool-climate deciduous trees, such as tamarack and quaking aspen, could give way to black cherry, eastern white pine, sugar maple and white oak.

As temperatures rise, researchers expect to see longer growing seasons, increases in heavy precipitation, more flooding and erosion, more drought stress, increasing risks of forest fire, and many more invasive pest species.

“Our assessment gives forest managers in Minnesota the best possible science on the effects of climate change so they can make climate- informed decisions about management today,” said Stephen Handler, the report’s lead author. – Climate News Network

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Longer flight paths can cut climate impact

Longer flight paths can cut climate impact

British scientists have developed a simple framework that shows how aircraft can become more environmentally friendly by choosing flight paths that reduce the formation of their distinctive vapour trails − even if it means flying further

LONDON, 21 June, 2014 − Air travel is a rapidly-growing source of carbon dioxide and is helping to heat the Earth. It accounted for 6% of the UK’s total greenhouse gas emissions in 2011.

But researchers from the University of Reading, UK, say the CO2 that aircraft emit may be less damaging to the climate than the vapour trails they often leave behind them.

Writing in the journal Environmental Research Letters, the scientists demonstrate that aircraft contribute less to global warming when they avoid the places where the thin-shaped clouds of vapour − called condensation trails, or contrails − are produced, even if that means flying further and emitting more CO2.

Wispy clouds

Contrails form only in parts of the sky with very cold and moist air, often in the ascending air around high pressure weather systems. They sometimes stay in the air for many hours, eventually spreading out to resemble natural, wispy clouds.

Previous research by scientists at Reading has shown that, on average, 7% of the total distance flown by aircraft is in cold, moist air where long-lasting contrails can form − 2.4 billion km out of a global total of 33 billion km flown in 2005.

The new findings from Reading follow research published recently in the journal Nature Climate Change showing that the amount of global warming caused by contrails could be as large as, or even larger than, the contribution from aviation’s CO2 emissions.

The work was carried out by three scientists in Reading’s Department of Meteorology − Dr Emma Irvine, Professor Keith Shine, and Professor Sir Brian Hoskins, who is also chair of the Grantham Institute at Imperial College London.

“It may be possible to mitigate [contrails’] effect
by routing aircraft to avoid them”

Dr Irvine said: “If we can predict the regions where contrails will form, it may be possible to mitigate their effect by routing aircraft to avoid them. Our work shows that, for a rounded assessment of the environmental impact of aviation, more needs to be considered than just the carbon emissions of aircraft.”

Just like natural clouds, contrails reflect some of the sun’s incoming energy, and so produce a cooling effect. But they also trap some of the infra-red energy that radiates from the Earth into space, and so have a warming effect − again, like other clouds. The researchers say detailed calculations show that, generally, the warming influence is greater than the cooling.

But the picture is more complex than that. For a start, the team estimates that smaller aircraft can fly much further to avoid forming contrails than larger ones.

With a small aircraft that is predicted to form a contrail 20 miles long, an alternative route would have a smaller climate impact if it adds less than 200 miles to its journey . For larger aircraft, the alternative route could still be preferable, but only if it added less than 60 miles to the journey.

But there is a further twist. The team had to allow for the varying length of time the different impacts would persist. As Dr Irvine explained: “Comparing the relative climate impacts of CO2 and contrails is not trivial. One complicating factor is their vastly differing lifetimes. Contrails may last for several hours, while CO2 can last for decades.”

Feasible and safe

Nor are the relative climate impacts the only factors for aviators to think about. Air traffic controllers would need to be sure re-routing aircraft flight by flight is both feasible and safe, and weather forecasters would want to know whether they can reliably predict when and where contrails are likely to form.

As well as CO2, aircraft engines emit a number of other gases and particles that can also alter climate – such as oxides of nitrogen and sulphur gases − and their effects might also depend on the route taken.

The researchers have devised a framework to calculate how much further an aircraft could travel in a single flight before the extra CO2 that is emitted causes more warming than the contrail would have caused. It takes into account the characteristics of the aircraft and the prevailing weather conditions, since the altitude at which contrails are formed depends greatly on weather patterns.

They are confident their work has practical implications. “The mitigation targets currently adopted by governments all around the world do not yet address the important non-CO2 climate impacts of aviation, such as contrails,” Dr Irvine said.

“We believe it is important for scientists to assess the overall impact of aviation and the robustness of any proposed mitigation measures in order to inform policy decisions.” − Climate News Network

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Hot rocks are a core asset

Hot rocks are a core asset

New engineering techniques mean that hot rocks in the Earth’s crust are second only to hydroelectric schemes as the most productive source of renewable energy, with huge potential to cut greenhouse gas emissions

LONDON, 15 June − Many countries with volcanoes have long used hot rocks and steam to generate electricity, but new engineering methods promise a boom in geothermal energy.

The deeper you drill into the Earth’s crust, the hotter the rocks get − and the heat that is radiating upwards from the core of the planet is constantly replaced. Japan, Iceland, Italy, New Zealand and the US, among other nations with volcanoes and hot underground water, have long exploited this for generating electricity and heating.

But now engineers have found that they do not need to look for naturally-occurring hot water. They can inject cold liquids into the hot rocks and bring it back to the surface through a second borehole to generate electricity. Unlike other renewables that can be variable, the hot rocks produce constant power 24 hours a day.

Drilling techniques

The temperature increases by 30ºC for every kilometre further underground. At a depth of between 3km and 10km, which can be reached with modern drilling techniques, temperatures exceed 150ºC, depending on location. This is hot enough to power a geothermal power station.

France, Australia, Japan, Germany, the US and Switzerland are already building experimental plants using what is called enhanced geothermal technology. An Atlas of Geothermal Resources of Europe shows that there is potential in 28 countries in Europe to develop plants.

One study just published in Spain by Platforma SINC, using information from the atlas, shows that the country could in theory produce five times the electricity it needs solely from geothermal. A report by the University of Valladolid (UVa), in the journal Renewable Energy, says that while Spain has no geothermal plants at present, the technology could provide all the nation’s needs.

Enhanced geothermal systems involve fracturing hot rocks by injecting cold liquids into them, causing rapid expansion similar to the force of an explosion. Afterwards, the liquid is brought back to the surface and the heat is used to generate electricity.

Once the system is operating, the water or other liquid is cooled on the surface and is then re-injected back into the rock in a closed loop.

Enormous potential

César Chamorro, one of the authors of the study, said the hot rocks in Spain “are distributed widely and uniformly, meaning they have enormous potential and could supply significant power in the medium or long term, 24 hours a day, constantly”.

If Spain used 10km-deep boreholes, Chamorro says, the 700GW of electricity indicated in the study “represent approximately five times the current electrical power installed in Spain, if we add together fossil fuels, nuclear and renewable power”.

The potential for power is reduced considerably for shallower boreholes – 190GW for boreholes 7km deep and 30GW for between 3km and 5km – but this is still the equivalent of 30 large power stations.

A life-limiting factor for the technology is that the constant injection of cold liquid into hot rocks gradually cools them, despite the constant heating from below. This is estimated to be 10ºC heat loss over a 30-year period, which might render the station uneconomic after that time.

If less hot water was extracted, allowing the heat of the rocks to regenerate, the system could be sustainable, although it would produce less power. – Climate News Network

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