Tag Archives: Greenhouse gases

Dietary effect on GHG emissions is hard to swallow

High-fibre breakfasts such as muesli could be bad for your planet's health Image: Cyclonebill via Wikimedia Commons
Eating more high-fibre cereals such as muesli could be bad for your planet’s health
Image: Cyclonebill via Wikimedia Commons

By Tim Radford

Controversial new research findings say that US government guidelines on a better diet might be good for Americans’ health, but would be far from healthy for the climate.

LONDON, 13 September, 2014  − The news is enough to make climate campaigners choke on their high-fibre breakfast cereal: if Americans adopted the dietary guidelines suggested by their own Department of Agriculture, greenhouse gas emissions (GHGs) would actually go up by 12%.

And even if Americans did what dietary campaigners urge and restricted themselves to a healthier 2000 calories a day, GHGs would not fall significantly.

Martin Heller and Gregory Keoleian, scientists at the University of Michigan’s Centre for Sustainable Systems, publish these findings in the Journal of Industrial Ecology.

And their conclusion  is liable to prove controversial, if only because other agriculturalists and economists have already argued that changes in human diet and more intelligent ways of promoting agriculture could simultaneously deliver better nutrition, greater food security, and less damage to global climate.

Contentious conclusions

Cynics will remind each other that all scientific conclusions about diet, health, environment and nutrition tend to become contentious shortly after publication.

Others are likely to agree with Paul Palmer, of the University of Edinburgh, and Matthew Smith, of the University of Cambridge, who argue in Nature journal that it makes no sense to speculate on climate change without considering how people will respond to that change. “Omitting human behaviour is like designing a bridge without accounting for traffic,” they say.

Social commentators will also point out that in a society in which one-third of all Americans are classed as clinically obese and another third are overweight − and in which, paradoxically, 49 million are also “food insecure” or just plain hungry − there might be something irrelevant about the US government’s dietary guidelines.

But the study by Heller and Keoleian, at bottom, simply addresses the problems associated with bureaucratic advice on subjects as personal as breakfast, lunch and dinner.

Direct emissions from agriculture make up between 10% and 12% of overall greenhouse gas emissions. If you throw in factors such as fertilizer and chemical production, fuel use and agricultural land-use change, the proportion rises – along with the uncertainty – to between 17% and 32%.

Researchers may enhance yields and farmers may use resources more efficiently, but populations will increase − and so will demand for meat and dairy products.

So the two scientists looked at greenhouse gas emissions associated with 100 foods. They considered the losses and waste in the food business: around a third of all food globally is lost or thrown away, and emissions from wasted food in the US add up to the equivalent of an extra 33 million cars on American roads.

Costs and losses

They added into the mix the potential effects of social change − looking at studies from Germany and Switzerland, at EU targets, and at calculations of the demand for water and fertilizer in Asia and Africa − to get a surer picture of the costs and losses and emissions associated with agriculture.

They then examined the particular case of the US, where, they say, “repeated assessments find that Americans do not meet the federal dietary recommendations”.

Those guidelines recommend that Americans eat more fruits, vegetables, whole grains, fat-free and low-fat dairy products, and seafood, and also consume less salt, saturated fat, trans fats, cholesterol, added sugar and refined grains.

Their calculation is that even if US citizens consumed less beef and thus reduced greenhouse gas emissions – beef makes up 4% by weight of available food, but 36% of emissions − the increased use of dairy products would have the opposite effect.

If Americans followed the recommendations and continued to consume the same number of calories on average, greenhouse gas emissions would rise by 12%. If the nation reduced its intake to 2000 calories a day on average, the reduction would be only 1%.

“These findings emphasise the need to consider environmental costs in formulating recommended food patterns,” Heller and Keoleian conclude. – Climate News Network

Drowned tropical forests add to climate change

Dead trees poke out of the Nam Theun 2 dam reservoir, Laos. Image: Dominique Serça/CNRS
Dead trees poke eerily out of the Nam Theun 2 dam reservoir in Laos
Image: Dominique Serça/CNRS

By Paul Brown

New scientific data supports the belief that methane emissions from big hydroelectric dams in the tropics outweigh the benefits that this form of renewable energy provides.

LONDON, 11 September, 2014 − Big dams built in the tropics to produce hydroelectricity have long been highly controversial − and data gathered in Laos by a French team studying methane emissions confirms that dams can add to global warming, not reduce it.

In many rocky regions low on vegetation and population, such as in Iceland and other northern mountainous regions, the production of electricity from hydropower is clearly a net gain in the battle against climate change.

In Asia, Africa and South America, however, masses of methane are produced from dams by the drowning of tropical forests in them. As long ago as 2007, researchers at Brazil’s National Institute for Space Research calculated that the world’s largest dams emitted 104 million tonnes of methane annually and were responsible for 4% of the human contribution to climate change.

Short-term threat

Since methane has an impact 84 times higher over 20 years than the same quantity of carbon dioxide, this is a serious short-term threat to pushing the planet towards the danger threshold of increasing temperatures by 2˚C .

Despite the warnings that big dams in the tropics might be adding to climate change, governments go on building them − while often claiming that large dams equal clean energy.

The new research shows that the methane discharges are probably even worse than current calculations.

In an attempt to find out exactly what the perils and benefits of big dams in the tropics can be, a French team from the National Centre for Scientific Research (CNRS) has been studying the Nam Theun 2 reservoir in Laos − the largest in Southeast Asia − prior to its filling, in May 2008, right up to the present to calculate the total methane emissions.

Methane is produced by bacteria feeding on the plant material drowned when the dam is filled. This is added to by more organic matter that is washed into it by rivers and rains.

Measuring the methane produced is the tricky bit as it reaches the atmosphere in three ways. Some is dissolved in the water and reaches the atmosphere by diffusion, some goes through the turbines and is released downstream, and the third way is called ebullition – which means bubbles of methane coming directly to the surface and going straight into the atmosphere.

It is these last gas emissions that have been so hard to measure, but the team has developed automatic measuring devices that work 24 hours a day.

The measurements carried out on the Nam Theun 2 reservoir enabled the scientists to show that ebullition accounted for between 60% and 80% of total emissions from the reservoir in the first years following filling.

Maximum emissions

In addition, ebullition intensity varies at night and seasonally. During the four months of the hot dry season (mid-February to mid-June), emissions reach their maximum because water levels are low. Daily variations are controlled by atmospheric pressure: during the two daily pressure drops (in the middle of the day and the middle of the night), methane (CH4) ebullition increases.

With the help of a statistical model, day-to-day data related to atmospheric pressure and water level was used by the researchers to reconstruct emissions by ebullition over a continuous four-year period (2009-2013).

The results obtained highlight the importance of very frequent measurements of methane fluxes. They also show that the ebullition process − and therefore the amount of methane emitted from tropical reservoirs during their first years of operation − has most certainly been underestimated until now.

For the researchers, the next stage will be to quantify diffusion at the surface of the reservoir and emissions downstream from the dam to the same level of accuracy. This will enable them to complete the assessment of methane emissions from this reservoir, and better assess the contribution they make to the global greenhouse effect. – Climate News Network

Weather patterns show climate is changing US

Streams feeding the Verde River in Arizona may be drying up Image: Jennifer Horn via Wikimedia Commons
Streams feeding the Verde River in Arizona may be drying up
Image: Jennifer Horn via Wikimedia Commons

By Tim Radford

Fiercer tornadoes, more prolonged periods of drought and loss of native fish species are some of the damaging impacts predicted for the US as greenhouse gas emissions continue to rise.

LONDON, 10 September, 2014 − The climate is changing . . . and America’s heartland and southwest are changing with it.

In the southwestern state of Arizona, the streams may be drying up − and that could mean that native fish species will die out.

In the midwest states that citizens call Tornado Alley, the evidence is that there are fewer tornado days per year, but the density and strength of those tornadoes that do form is growing as greenhouse gas emissions continue to rise.

And in the west, which is in the grip of a prolonged drought, things are looking up − but not in a good way. Relieved of the weight of water they normally bear – the 240 billion tonnes of snow and rain that have not fallen since the drought began – the land is starting to rise, with mountains as much as 15 millimetres higher.

More arid

The current drought may not be evidence of climate change – there is a long history of periodic drought in the region – but in general the US southwest is expected to become steadily more arid as planetary temperatures soar.

Kristin Jaeger, assistant professor at Ohio State University’s School of Environment and Natural Resources, reports in the Proceedings of the National Academy of Sciences of the USA that she and colleagues decided to model the surface flow of the Verde River Basin in Arizona by 2050.

Fish that live in these waters are already threatened or endangered, their survival depending on being able to move around the watershed to eat, to spawn and to raise offspring. But the computer simulations for the future suggest that there will be a 17% increase in dried-up streams and a 27% increase in days when there will be no flow of water at all.

What this will do is sever connections between streams, and the deeper pools will become isolated. Native species, such as the speckled dace, the roundtail chub and the Sonora sucker, will increasingly have nowhere to go.

Dr Jaeger calls the estimates conservative. She and her fellow researchers did not take account of the groundwater that will be removed to support the expected 50% increase in human population in Arizona by 2050.

In the US, tornadoes are a fact of life – and death. In 2011, for example, it experienced 1,700 storms during the tornado season, and 550 people died. But scientists have begun to detect a pattern of change. In 1971, there were only 187 days with tornadoes, and in 2013, there were only 79 days, according to James Eisner, a geographer at Florida State University, and colleagues in a report in the journal Climate Dynamics.

But the tornadoes that do form are distinguished by what the scientists call “increasing efficiency”. They are more severe, and there are more of them on a given day.

“We may be less threatened by tornadoes on a day-to-day basis, but when they do come, they come like there’s no tomorrow,” said Professor Eisner.

Meanwhile, Adrian Borsa  and other researchers at Scripps Institution of Oceanography in San Diego report in the journal Science that they have been looking at data from GPS satellite ground stations, to discover that – thanks to the current drought – all of them are on the move.

Highest uplift

Overall, the surface of the arid west has gained 4mm in altitude since the drought began, and the highest uplift, 15mm, has been measured in the mountains.

They put it down to the water that has not fallen and which would normally have covered the mountains as heavy snow. Altogether, the water deficit is 240 gigatonnes, or 62 trillion gallons − the equivalent of a 10cm layer of water across the entire west of the US.

This is roughly the equivalent of the mass of ice lost each year from the Greenland ice sheet.

The crustal movement is not expected to have any impact on the likelihood of earthquakes in, for example, California, but the study could offer researchers a new way of measuring fresh water resources over very large regions.

It could be a case of don’t worry about all those rainfall gauges, just watch how the earth moves. Or, in the researchers technical language, such observations “have the potential to expand dramatically the capabilities of the current hydrological observing network”. – Climate News Network

Ocean acidification and GHGs hit record levels

Reef grief: corals, fisheries and tourism will all be damaged by  ocean acidification Image: Ritiks via Wikimedia Commons
Reef stricken: corals, fisheries and tourism will all be damaged by ocean acidification
Image: Ritiks via Wikimedia Commons

By Alex Kirby

New scientific evidence of the highest greenhouse gas concentrations on record is compounded by the revelation that oceans are acidifying faster than at any time in the last 300 million years.

LONDON, 9 September, 2014 – The World Meteorological Organisation (WMO) reports that the amounts of atmospheric greenhouse gases reached a new high in 2013, driven by rapidly rising levels of carbon dioxide.

The news is consistent with trends in fossil fuel consumption. But what comes as more of a surprise is the WMO’s revelation that the current rate of ocean acidification, which greenhouse gases (GHGs) help to cause, appears unprecedented in at least the last 300 million years.

The details of growing GHG levels are in the annual Greenhouse Gas Bulletin, published by the WMO – the United Nations specialist agency that plays a leading role in international efforts to monitor and protect the environment.

They show that between 1990 and 2013 there was a 34% increase in radiative forcing – the warming effect on our climate – because of long-lived greenhouse gases such as carbon dioxide (CO2), methane and nitrous oxide.

Complex interactions

The Bulletin reports on atmospheric concentrations – not emissions − of greenhouse gases. Emissions are what go into the atmosphere, while concentrations are what stay there after the complex system of interactions between the atmosphere, biosphere (the entire global ecological system) and the oceans.

About a quarter of total emissions are taken up by the oceans and another quarter by the biosphere, cutting levels of atmospheric CO2.

In 2013, the atmospheric concentration of CO2 was 142% higher than before the Industrial Revolution started, in about 1750. Concentrations of methane and nitrous oxide had risen by 253% and 121% respectively.

The observations from WMO’s Global Atmosphere Watch network showed that CO2 levels increased more from 2012 to 2013 than during any other year since 1984. Scientists think this may be related to reduced CO2 absorption by the Earth’s biosphere, as well as by the steady increase in emissions.

Although the oceans lessen the increase in CO2 that would otherwise happen in the atmosphere, they do so at a price to marine life and to fishing communities − and also to tourism. The Bulletin says the oceans appear to be acidifying faster than at any time in at least the last 300 million years.

“We know without any doubt that our climate is changing and our weather is becoming more extreme due to human activities such as the burning of fossil fuels,” said the WMO’s secretary-general, Michel Jarraud.

“We are running out of time. The laws
of physics are non-negotiable.”

“The Greenhouse Gas Bulletin shows that, far from falling, the concentration of carbon dioxide in the atmosphere actually increased last year at the fastest rate for nearly 30 years. We are running out of time. The laws of physics are non-negotiable.

“The Bulletin provides a scientific base for decision-making. We have the knowledge and we have the tools for action to try to keep temperature increases within 2°C to give our planet a chance and to give our children and grandchildren a future. Pleading ignorance can no longer be an excuse for not acting.”

Wendy Watson-Wright, executive secretary of the Intergovernmental Oceanographic Commission of UNESCO, said: “It is high time the ocean, as the primary driver of the planet’s climate and attenuator of climate change, becomes a central part of climate change discussions.

“If global warming is not a strong enough reason to cut CO2 emissions, ocean acidification should be, since its effects are already being felt and will increase for many decades to come.”

The amount of CO2 in the atmosphere reached 396.0 parts per million (ppm) in 2013. At the current rate of increase, the global annual average concentration is set to cross the symbolic 400 ppm threshold within the next two years.

More potent

Methane, in the short term, is a far more powerful greenhouse gas than CO2 − 34 times more potent over a century, but 84 times more over 20 years.

Atmospheric methane reached a new high of about 1,824 parts per billion (ppb) in 2013, because of increased emissions from human sources. Since 2007, it has started increasing again, after a temporary period of levelling-off.

Nitrous oxide’s atmospheric concentration in 2013 was about 325.9 ppb. Its impact on climate, over a century, is 298 times greater than equal emissions of CO2. It also plays an important role in the destruction of the ozone layer that protects the Earth from harmful ultraviolet solar radiation.

The oceans currently absorb a quarter of anthropogenic CO2 emissions − about 4kg of CO2 per day per person. Acidification will continue to accelerate at least until mid-century, according to projections from Earth system models. − Climate News Network

Less snow won’t end blizzard hazard

Clearing a station platform in Brookly, New York, during the snowstorms in January this year Image: Patrick Cashin/MTA via Wikimedia Commons
Clearing a train station in New York during snowstorms in January this year
Image: Patrick Cashin/MTA via Wikimedia Commons

By Tim Radford

New research predicts that while there will be less snow in a warming world, the sort of severe snowstorms that caused chaos in the US this year will remain a serious hazard.

LONDON, 6 September, 2014 − There’s still a chance that some people who dream of a white Christmas will get their wish. While there may be less snow falling overall in a warming world, there will still be blizzards.

Paul O’Gorman, an atmospheric scientist at the Massachusetts Institute of Technology in the US, reports in Nature that he studied daily snowfall in the northern hemisphere through the prism of 20 different climate models. Each of these projected climate change over a century, according to various emissions of greenhouse gases.

He also looked at seasonal average and extreme snowfall events, both under current conditions and as the planet warms. And the conclusion is that the kind of snowstorms that hit the US in 2014 will remain a hazard, even though there may be fewer of them.

Climate models

“Many studies have looked at average snowfall over a season in climate models, but there’s less known about these very heavy snowfalls,” Dr O’Gorman said. “In some regions, it is possible for average snowfall to decrease but the snowfall extremes actually increase.”

Climate scientists have consistently warned that a rise in average planetary temperatures is likely to be accompanied by a rise in the frequency or intensity of extreme events.

By these, they usually mean windstorms, floods and heat waves. But ice storms remain part of the picture too. That is because even as temperatures on average creep up, there will be places and seasons where the rain could still turn to snow.

The study found that, under high warming scenarios, those low-lying regions with average winter temperatures normally just below freezing would see a 65% reduction in average winter snowfall. But in these places, the heaviest snowstorms on average became only 8% less intense. In the higher latitudes, extreme snowfall became more intense, with 10% more snow, even under scenarios of relatively high average warming.

Heaviest falls

There is a relatively narrow temperature range − just below freezing point − at which the heaviest snowfalls seem to occur.

“People may know the expression, ‘It’s too cold to snow,’” Dr O’Gorman said. “If it’s very cold, there is too little water vapour in the air to support a very heavy snowfall, and if it’s too warm, most of the precipitation will fall as rain.

“Snowfall extremes still occur in the same narrow temperature range with climate change, and so they respond differently to climate change compared to rainfall extremes or average snowfall.” – Climate News Network

China may be ready to kick coal habit

A coal-fired power station at Yangzhou in China's central Jiangsu province Image: Vmenkov via Wikimedia Commons
A coal-fired power station at Yangzhou in China’s central Jiangsu province
Image: Vmenkov via Wikimedia Commons

By Kieran Cooke

Signs are hopeful that China, the world’s No.1 emitter of greenhouse gases, aims to become less reliant on the polluting coal that powered its rapid economic rise.

LONDON, 5 September, 2014 − There are still doubts. The statistics might be proved wrong. But it looks as if China might be starting to wean itself off its coal consumption habit.

China produces and consumes nearly as much coal as the rest of the world combined. Coal, the most polluting of all energy sources, has powered the growth of China’s flyaway economy. But as incomes have risen, so has pollution. The country is now the world’s No.1 emitter of greenhouse gases.

Latest figures indicate that change is on the way, spurred on by a much-vaunted government “war on pollution” campaign. The state-run National Development and Reform Commission reports that domestic coal output shrank over the first five months of 2014 – the first such decline since the start of China’s rapid economic expansion back in the late 1980s.

Virtual halt

Greenpeace, the environmental NGO, said in a recent analysis of China’s coal sector that growth in coal imports, which had been going up at an annual rate of between 13% and 20% in recent years, has come to a virtual halt.

Meanwhile, the official Xinhua news agency says Beijing – a city of nearly 12 million people – will ban the sale and use of coal in its six main districts by 2020.

Coal-fired factories and power plants around the Chinese capital are being shut down and replaced by natural gas facilities. Coal generated 25% of Beijing’s energy in 2012, and the aim is to bring that figure down to less than 10% by 2017. Other cities and regions are following Beijing’s lead.

Just how meaningful these cutbacks in coal use are is difficult to gauge. Air pollution – much of it caused by the burning of low-grade thermal coal − is not only a big environmental issue in China but also a political one as well.

China’s leaders have promised a population increasingly angry about the low quality of the air they breathe and the water they drink that the government is determined to tackle pollution.

Yet coal-fired power plants are still being built at a considerable pace, and many more are planned.

Some analysts argue that the present slowdown in China’s coal consumption is only temporary, the result of a dip in industrial output that will be reversed as soon as the economy roars ahead again.

Less reliant

Others say the decline in coal consumption is part of a long-term trend. As China’s economy matures, becoming less dependent on heavy industrial goods and embarking on more hi-tech and service-oriented projects, the country will become ever more energy efficient – and less reliant on coal.

China might be the world’s biggest emitter of fossil fuel emissions, but it also has fast become a global leader in hydro, wind and solar power.

No one is suggesting that coal is going to be absent from China’s energy mix anytime soon. The lung-jarring pollution of many of China’s cities is likely still to be evident for some years yet. But coal is no longer king.

That’s bad news for big coal exporters to China, particularly Australia and Indonesia. But it’s potentially good news for millions in China who crave clean air. And it’s very good news for the planet. – Climate News Network

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

Waves wash against the runway at Nauru airport, where sea level rise is a daily reality Image: Dept of Foreign Affairs and Trade via Wikimedia Commons
The runway at Nauru island’s airport in the South Pacific, where sea level rise is a daily reality
Image: Matt Robertson/Australian DFAT via Wikimedia Commons

By Paul Brown

The UN secretary-general is attempting to prevent world leaders sleepwalking into disaster by asking them to make new pledges at a climate summit this month on cutting greenhouse gases.

LONDON, 3 September, 2014  It is widely acknowledged that the planet’s political leaders and its people are currently failing to take enough action to prevent catastrophic climate change.

Next year, at the United Nations climate change conference in Paris, representatives of all the world’s countries will be hoping to reach a new deal to cut greenhouse gases and prevent the planet overheating dangerously. So far, there are no signs that their leaders have the political will to do so.

To try to speed up the process, the UN secretary-general, Ban Ki-moon, has invited world leaders to UN headquarters in New York on 23 September for a grandly-named Climate Summit 2014.

He said at the last climate conference, in Warsaw last year, that he is deeply concerned about the lack of progress in signing up to new legally-binding targets to cut emissions.

If the summit is a success, then it means a new international deal to replace the Kyoto Protocol will be probable in late 2015 in Paris. But if world leaders will not accept new targets for cutting emissions, and timetables to achieve them, then many believe that political progress is impossible.

Danger threshold

Ban Ki-moon’s frustration about lack of progress is because politicians know the danger we are in, yet do nothing. World leaders have already agreed that there is no longer any serious scientific argument about the fact that the Earth is heating up and  if no action is taken  will exceed the 2°C danger threshold.

It is also clear, Ban Ki-moon says, that the technologies already exist for the world to turn its back on fossil fuels and cut emissions of greenhouse gases to a safe level.

What the major countries cannot agree on is how the burden of taking action should be shared among the world’s 196 nations.

Ban Ki-moon already has the backing of more than half the countries in the world for his plan. These are the most vulnerable to climate change, and most are already being seriously affected.

More than 100 countries are currently meeting in Apia, Samoa, at the third UN Conference on Small Island Developing States, which ends tomorrow. In their draft final statement, they note with “grave concern” that world leaders’ pledges on the mitigation of greenhouse gases will not save them from catastrophic sea level rise, droughts, and forced migration.

“We express profound alarm that emissions
of greenhouse gases continue to rise globally”

Many of them have long advocated a maximum temperature rise of 1.5°C to prevent disaster for the most vulnerable nations, such as the Marshall Islands and the Maldives.

The draft ministerial statement says: “Climate change is one of the greatest challenges of our time, and we express profound alarm that emissions of greenhouse gases continue to rise globally.

“We are deeply concerned that all countries, particularly developing countries, are vulnerable to the adverse impacts of climate change and are already experiencing an increase in such impacts, including persistent drought and extreme weather events, sea level rise, coastal erosion and ocean acidification, further threatening food security and efforts to eradicate poverty and achieve sustainable development.”

Devastating consequences

Speaking from Apia, Shirley Laban, the convenor of the Pacific Islands Climate Action Network, an NGO, said: “Unless we cut emissions now, and limit global warming to less than 1.5°C, Pacific communities will reap devastating consequences for generations to come. Because of pollution we are not responsible for, we are facing catastrophic threats to our way of life.”

She called on all leaders attending the UN Climate Summit in New York to “use this historic opportunity to inject momentum into the global climate negotiations, and work to secure an ambitious global agreement in 2015”.

This is a tall order for a one-day summit, but Ban Ki-moon is expecting a whole series of announcements by major nations of new targets to cut greenhouse gases, and timetables to reach them.

There are encouraging signs in that the two largest emitters – China and the US – have been in talks, and both agree that action is a must. Even the previously reluctant Republicans in America now accept that climate change is a danger.

It is not yet known how many heads of state will attend the summit in person, or how many will be prepared to make real pledges.

At the end of the summit, the secretary-general has said, he will sum up the proceedings. It will be a moment when many small island states and millions of people around the world will be hoping for better news.  Climate News Network

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