Heat-tolerant beans could help keep millions fed

Heat-tolerant beans could help keep millions fed

Plant researchers say new varieties of a tropical crop essential to people’s survival in Africa and Latin America can withstand the effects of global warming.

LONDON, 26 March, 2015 − Scientists believe they may have found how to safeguard a staple tropical crop, on which hundreds of millions of people depend, from the depredations of climate change.

They have discovered − through conventional breeding rather than genetic modification − 30 new “lines” (varieties) of beans that will thrive in the higher temperatures expected later this century, and which will pose a particular threat to harvests in Africa and Latin America.

The new “heat-beater” beans, an important source of protein for around 400 million people, have been identified by plant breeders with the CGIAR global agriculture research partnership.

Steve Beebe, a senior CGIAR bean researcher, announced at a conference in Ethiopia: “This discovery could be a big boon for bean production because we are facing a dire situation where, by 2050, global warming could reduce areas suitable for growing beans by 50%.

Worst-case scenario

“Incredibly, the heat-tolerant beans we tested may be able to handle a worst-case scenario where the build-up of greenhouse gases causes the world to heat up by an average of 4°C.

“Even if they can only handle a 3°C rise, that would still limit the bean production area lost to climate change to about 5%. And farmers could potentially make up for that by using these beans to expand their production of the crop in countries such as Nicaragua and Malawi, where beans are essential to survival.”

Dr Beebe told the Climate News Network: “So far, so good. Some of the lines are also drought-tolerant, and some are resistant to Bean Golden Yellow Mosaic Virus.

“We are taking these beans into a new environment that we don’t know from the bean perspective. . . Will we find more surprises?

“There are two caveats. First, so far the best lines are small red types for Central America and parts of East Africa, so we have a long road to improve a range of grain types, colours, etc.

“The other issue is that we are taking these beans into a new environment that we dont know from the bean perspective. We have seen that a soil pathogen, pythium, is more severe. Will we find more surprises?”

Rising heat as climate change intensifies is expected to disrupt bean production in central and South American countries, including Nicaragua, Haiti, Brazil and Honduras. African countries thought to be at risk are principally Malawi and the Democratic Republic of the Congo, followed by Tanzania, Uganda and Kenya.

Many of the new heat-tolerant beans developed by the CGIAR scientists are “crosses” of the common bean − which includes pinto, white, black, and kidney beans − and the tepary bean, a hardy survivor cultivated since pre-Columbian times in what is now part of northern Mexico and the southwest US.

Highly nutritious

Beans are often called the “meat of the poor”. They are highly nutritious, providing not only protein but fibre, complex carbohydrates, vitamins, and other micronutrients. In addition to heat tolerance, CGIAR researchers are also breeding lines with a higher iron content, in an effort to tackle malnutrition.

The new beans are the result of CGIAR’s work to develop new crop varieties that can thrive in drastic weather extremes, based on research in its “genebanks”, which preserve the world’s largest seed collections of the most important staple crops.

The heat-beaters emerged from the testing of more than 1,000 bean lines − work that began as an effort to develop beans that could tolerate poor soils and drought.

The focus turned to heat-tolerance following a 2012 report from CGIAR scientists warning that heat was a much bigger threat to bean production than previously believed. − Climate News Network

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Climate is now main worry for conservation group

Climate is now main worry for conservation group

The devastating effects of a changing climate have become the biggest challenge faced by a leading protector of the UK countryside.

LONDON, 24 March, 2015 − The head of one of the UK’s best-known conservation groups says the greatest threat to its work is now climate change.

Dame Helen Ghosh, director-general of the National Trust, told BBC Radio that there is devastation of wild Britain and the creatures that live there. “Who would have thought that the house sparrow and hedgehog were going to become rare?” she said.

“For the future and we see this on our coastline, in our countryside, even in our houses climate change, we think, is the big threat to us.”

The Trust is the charity responsible for the care of countryside and historic houses across England, Wales and Northern Ireland (a separate body does the work in Scotland).

It is also one of Britain’s largest landowners, with 600,000 acres (250,000 hectares) and 700 miles (1,125 km) of coastline in its care, and more than 300 historic buildings − all held in trust for the future.

About 20 million people go to the Trust’s houses and gardens annually, but 200 million visit its upland, lowland and coastal sites.

Destruction of habitats

Dame Helen said: “The main challenge to our conservation purpose is the destruction of habitats, of wildlife − the fact that we see precious species 60% in decline.”

She suggested that, apart from climate, the other cause of that was intensive land management.

When it comes to recognising the risks of a warming world, Dame Helen is certainly well qualified. As a former leading civil servant, one of her last jobs before joining the Trust was to head the UK government’s Department for Environment, Food and Rural Affairs, which at that time had climate change as one of its responsibilities.

As part of its efforts to help address climate change, Dame Helen said the Trust would be getting 50% of the energy it uses in its houses and properties from renewable sources by 2020.

For example, she said, there would be “lots of hydro schemes across the country, lots of biomass boilers” as part of the renewable energy policy. The Trust aims to reduce its own energy consumption by about 20%.

It will also be working with its own tenant farmers, she said, “to try to make sure that land is farmed in environmentally-friendly ways that we get production, and also the bees and the butterflies”. Climate News Network

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Changing weather patterns hit Pakistan’s crops

Changing weather patterns hit Pakistan's crops

Torrential rain and hailstorms have raised fears that Pakistan’s winter crops yield could be seriously depleted – and global warming is the likely culprit.

Islamabad, 23 March, 2015 − Anxious farmers in Pakistan waited for weeks for the rains to arrive – but when the skies finally opened, the downpour was so intense it destroyed crops and put the harvest in jeopardy.

“We weather scientists are really in shock, and so are farmers, who have suffered economic losses due to crop damage,” says Muzammil Hussain, a weather forecasting scientist at the Pakistan Meteorological Department (PMD).

“The wind from the southeast has carried moisture from the Arabian Sea. Normally, the northeast wind brings rain during winter, and the southeast wind brings monsoon rains in summer. But the pattern has changed this year because of what is believed to be global warming.”

Unusually heavy

Farmers across much of Pakistan plant winter crops of wheat, oilseed and potato late in the year and wait for rains to water the land. This year, the rains arrived more than three weeks late and were unusually heavy, accompanied by violent hailstorms. Along with the rains, temperatures also dropped.

Ibrahim Mughal, chairman of the Pakistan Agri Forum, says excessive moisture due to heavy bouts of late rain is likely to lead to outbreaks of fungus on crops, and production could be halved.

“If the rains come a month ahead of the harvesting time [April to mid-May], it is always disastrous,” he says. “It can hit production for a crop such as wheat by between 20% and 30%, and if the rain is accompanied by hailstorms and winds then the losses can escalate to more than 50%.”

Arif Mahmood, a former director general at PMD, says the onset of winter across much of Pakistan is being delayed by two to three days every year, and there is an urgent need for farmers to adapt to such changes.

“If the rains come a month ahead of the harvesting time, it is always disastrous”

“Over recent years, winter has been delayed by 25 to 30 days, and also the intensity of the cold has increased, which has affected almost every field of life − from agriculture to urban life.”

This year has also been marked by abrupt changes in temperature. Ghulam Rasul, a senior scientist at PMD, says big swings in temperature are likely to add to the problems being faced by millions of farmers in Pakistan.

“The average temperature during the first two weeks [of March] was between 11 and 13 degrees Celsius, but now it’s on a continuous upward trend and has reached 26˚C over the space of two days,” he reports.

“The winter rains in the north and central area of Pakistan, and the sudden rise and fall in temperature, are related to climate change.”

Serious damage

Similar storms and late winter rains have also caused serious damage across large areas of northern India.

The states of Uttar Pradesh and Maharashtra – the two most populous states in the country – have been particularly badly hit.

In Maharashtra, snow and landslides have blocked roads and cut off towns and villages.

In Uttar Pradesh, there are fears that more than 50% of the wheat crop has been lost in the eastern part of the state. – Climate News Network

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Growing threat to Amazon’s crucial carbon sink

Growing threat to Amazon’s crucial carbon sink

Massive new study shows that pressures on the Amazon rainforest mean it can no longer be relied on to soak up more CO2 from the atmosphere than it puts out.

LONDON, 19 March, 2015 − The Amazon rainforest, for so long one of the vital “green lungs” of the planet, is losing its capacity to absorb carbon from the atmosphere, according to new research.

Two decades ago, the forest drew down a peak of two billion tonnes of carbon dioxide each year from the atmosphere. Now, according to a massive new study in Nature journal by more than 90 scientists, the rate of withdrawal has fallen to around half that total.

Fossil fuel emissions from Latin American countries are now running at more than a billion tonnes of CO2. So the region is putting more greenhouse gas into the atmosphere than it is taking out.

The finding is ominous. The Amazon rainforest has always been a big item in the climate modellers’ carbon budget − the calculation of carbon dioxide from fossil fuels burned, set against the natural absorption of the same trace gases by the biosphere.

Unique research

The implication now is that the forest is no longer a carbon “sink” that that can be relied upon to take up a predictable proportion of fossil fuel emissions.

The conclusion is the outcome of a unique international research network’s 30-year study of 189,000 individual trees in 321 plots of forest dotted across six million square kilometres in eight South American countries. And it has revealed a huge surge in the rate of tree deaths across the Amazon basin.

Locations of Amazon forest plots studied. Image: Georgia Pickavance/RAINFOR

Locations of Amazon forest plots studied.
Image: Georgia Pickavance/RAINFOR

The Amazon is one of the wonders of the planet: its 300 billion trees, and 15,000 species, store one-fifth of all the carbon in the planet’s biomass.

The RAINFOR collaboration involves 57 organisations in 15 nations, and is dedicated to detailed study of the forest and the ecosystems that depend upon it.

“Tree mortality rates have increased by more than a third since the mid-1980s, and this is affecting the Amazon’s capacity to store carbon”

Researchers have repeatedly warned of the consequences of destroying rainforest through logging, land-clearance for plantation,  and other assaults upon the gigantic rainforest, but this finding is of a different magnitude altogether.

Roel Brienen, a geographer at the University of Leeds in England, and the lead author of the study, puts it bluntly: “Tree mortality rates have increased by more than a third since the mid-1980s, and this is affecting the Amazon’s capacity to store carbon.”

Carbon dioxide is not, of itself, the problem. Plants capture it with photosynthesis to build tissues and feed the animal kingdom. And, in a greenhouse world, more carbon dioxide should make vegetation more fertile, and more likely to soak up at least a proportion of the extra carbon dioxide from car exhausts and power station chimneys.

Spurt of growth

But the message from this latest study is that it doesn’t necessarily work out like that. The extra carbon dioxide stimulated a spurt of extra growth, and the trees lived faster, only to die sooner.

The problem has been compounded by drought and unusually high temperatures in the Amazon. The spurt in arboreal death rates began well before 2005, but droughts since then have killed millions of additional trees.

“Regardless of the causes behind the increase in tree mortality, this study shows that predictions of a continuing increase of carbon storage in tropical forests may be too optimistic,” Dr Brienen says.

“Climate change models that include vegetation responses assume that as long as carbon dioxide levels keep increasing, then the Amazon will continue to accumulate carbon. Our study shows that this may not be the case, and that tree mortality processes are critical in this system.” – Climate News Network

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Fertilizers help toxic algae thrive in warming world

Fertilizers help toxic algae thrive in warming world

Scientists warn that excessive use of fertilizers, combined with warmer water in lakes, threatens to poison drinking water supplies.

LONDON, 13 March, 2015 − Blue-green algae blooms that can turn toxic in freshwater lakes and can kill bathers, farm animals and domestic pets that drink the water are becoming more widespread across the world, according to new research.

A combination of excess use of fertilizers containing phosphorus and nitrogen, untreated sewage releases, and warmer water caused by climate change is leading to an increasing threat of poisoning to animals and humans that use the lakes for water supplies.

Researchers from France, Italy, Spain, the UK, Malaysia and Canada contributed to the study aimed at discovering whether the algae known as cyanobacteria, which forms a blue-green scum on the surface of lakes, was really increasing or had simply been more widely reported.

The scientists looked closely at 100 lakes in North America and Europe, but their findings would apply to freshwater bodies worldwide. They showed that algae blooms have been increasing over the past two centuries, but the pace has “sharply accelerated since the mid-20th century”.

Acute exposure

Not all blue-green algae growths release poisons into the water, but when they form a scum they frequently release toxins that cause damage to the liver and nervous systems of animals, and can be deadly.

The most common symptoms in humans of acute exposure to harmful algal blooms are skin rash or irritation, gastroenteritis, and respiratory distress.

Chronic, low-dose exposures over a lifetime may result in liver tumors or endocrine disruption, and have also been linked to longer-term degenerative conditions of the nervous system, such as Alzheimer’s, Parkinson’s and Lou Gehrig’s Disease.

The study says that lakes subject to excess discharge of industrial fertilizers and sewage had seen the largest increase in blue-green algae blooms, but alpine lakes without these problems has also had an increase, indicating that climate change was also a factor.

In North America, lowland lakes had a 61% increase in blue-green algae blooms, and this rose to 70% in Europe. Both were close to agriculture areas, but alpine lakes further away from farming showed only a 36% increase.

Dr. Zofia Taranu, a biologist at McGill University, Canada, and lead author of the study published in Ecology Letters, says: “Further work as a society will therefore be needed to reduce nutrient discharges to surface waters.”

“Partnerships among freshwater scientists and farmers are starting to happen, and more of this needs to take place”

The study says it is possible to treat water by adding chemicals that bind the toxins together, and to remove them before they reach the tap, but many municipalities do not regularly look for the danger because it has previously not been a problem.

Even so, both the UK and Australia are spending $100 million a year monitoring and eliminating blue-green algae from drinking water. Water catchment control to keep fertilizer and sewage away from drinking water sources, which has been imposed by the EU Water Framework Directive, is essential to prevent the danger to the general population, the report concludes.

Dr Suzanne McGowan, head of the University of Nottingham School of Geography, UK, and PhD researchers Heather Moorhouse and Mark Stevenson, based at the university, took sample cores of sediment from bodies of water in the British Isles, including in the English Lake District, the meres of the West Midlands, lochs in Scotland, and upland lakes in Northern Ireland.

Biomarkers

These were then analysed for pigments that are left behind by blue-green algae, and which remain stable over thousands of years − acting as biomarkers that reveal past levels of algae found in the water during the course of decades.

The analysis showed that, during the last 200 years, more than half of the lakes (58%) had seen significant increases in concentrations of blue-green algae pigments, whereas only 3% showed a significant decrease.

“Our work shows that we need to work harder as a society to reduce nutrient discharges to surface waters,” says Irene Gregory-Eaves, an associate professor of biology at McGill, and co-author of the study.

“Because diffuse nutrient loading – as opposed to end-of-pipe effluent –  is the main issue, we need to build collaborations to tackle this complex problem.

“For example, partnerships among freshwater scientists and farmers are starting to happen, and more of this needs to take place, so that we can strike a balance between maximising crop yields and minimising excess fertilizer application.” – Climate News Network

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Heat is on to slow down faster rise in temperatures

Heat is on to slow down faster rise in temperatures

New research warns that emissions will make drought conditions even more extreme as our climate moves into a period of rapid change.

LONDON, 12 March, 2015 – Analysis of temperature records and reconstructions of past climates indicates that the pace of global warming is about to accelerate.

Although the much-debated “pause” in warming during the 21st century is still under debate, climate scientist now warn that the Earth is about to enter a period of change that will be faster than anything in the last thousand years.

Steven Smith, an integrated modelling and energy
scientist, at the US government’s Pacific Northwest National Laboratory, and colleagues decided to take a look at the short history of temperature records and the somewhat longer “proxy” reconstructions of past climates to look for patterns of the past that might be a guide to the future.

Baseline rates

They then matched the past and examined the future using computer model simulations. Climate periods were considered in 40 year blocks, and were compared to establish a baseline for natural rates of change.

The scientists report in Nature Climate Change that rises now in North America and many parts of the world are greater than the natural range for any rate of change.

And when they tested future emissions scenarios, they confirmed that global warming will pick up speed in the next 40 years in all cases − even in those projections in which the world reduced its greenhouse gas emissions. And if the world doesn’t reduce these emissions, the rate of change in warming will remain high for the rest of the century.

“In these climate model simulations, the world is just now starting to enter a new place, where rates of temperature change are consistently larger than historical values over 40-year time spans,” Dr Smith says. “We need to better understand what the effects of this will be, and how to prepare for them.”

The research is based on simulation, and seems inconsistent with the story of the 21st century, which is that, after a relatively rapid decadal rise in global average temperatures between 1970 and 2000, the rate of rise seemed to slow.

Although almost all the years of the new century so far have been warmer than any in the 20th century, and although 2014 was the warmest year on record so far, the notches on the thermometer each year have been smaller.

But as researchers have repeatedly warned, the real rise may be masked by some kind of natural variation. At least one group in 2014 found that the patterns of extremes of heat seem to be accelerating, even if the averages are not.

“The finding is critical to understanding
what the world will be like
as the climate continues to change”

And now Rong Fu, professor of geological sciences at the University of Texas at Austin, US, has looked at a study by research scientists William Lau, of the University of Maryland, and Kyu-Myong Kim, of the NASA Goddard Space Flight Centre, and seen signs of an intensified pattern of extreme droughts in Australia, the southwest and central US, and southern Amazonia.

The Proceedings of the National Academy of Sciences has published both the original research and the commentary  by Professor Fu.

At the heart of the issue is the impact of increased emissions of carbon dioxide on the pattern of wind circulation that overall dictates the climate of each hemisphere.

This pattern is sometimes called the Hadley Circulation, named after the 18th-century English lawyer and amateur meteorologist, George Hadley, who first identified the mechanism behind the all-important Trade Winds that carried sailing ships across the Atlantic.

It can change with global temperatures. And as the winds change – and the prevailing Trade Winds move away from the tropics – they take the rainfall with them.

Ominous consequences

The guess has been that Hadley Circulation varies naturally. And the PNAS study suggests that it is likely to intensify in a warmer world, with ominous consequences for some already naturally dry regions.

That both Australia and the American southwest are already feeling the heat is not news. But the significance of the research lies in more detailed understanding of why even more is on the cards in future.

“This is the first study that suggests a possible intensification of droughts in the tropic-subtropical margins in warmer climate,” Professor Fu says. “The finding is critical to understanding what the world will be like as the climate continues to change.

“Will the Hadley Circulation continue to expand? Could the intensification of droughts over the tropics be a new norm? These are questions that need to be answered.” – Climate News Network

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Serious doubts over Europe’s GHG reduction target

Serious doubts over Europe’s GHG reduction target

Europe has made substantial progress in cutting greenhouse gas emissions, but its long-term reduction aims look unachievable, says a new report.

LONDON, 9 March, 2015 − The 28 countries of the European Union (EU) have set themselves a collective target of cutting emissions of climate-changing greenhouse gases (GHGs) by between 80% and 95% by 2050, but  a major report just released says there’s little hope of achieving that goal.

Every five years, the European Environment Agency (EEA) produces a comprehensive study, and the latest says projected declines in GHG emissions are not nearly enough to reach the long-term target of decarbonising most of Europe’s economy by mid-century.

The report says there has been considerable progress in recent years on reducing Europe’s GHG emissions to 19.2% below 1990 levels. while, at the same time, gross domestic product across the EU has increased by 45%. EU per capita emissions fell from 11.8 tonnes of CO2 equivalent in 1990 to 9 tonnes in 2012.

The trouble is that this progress is very unlikely to be maintained over the long term unless the entire EU economy is revamped and there are very substantial investments in renewables.

Hard part ahead

The cut in GHG emissions was largely achieved through economic restructuring in eastern Europe following the collapse of the old Soviet Union and associated states. Polluting energy and industrial plants were closed, and agricultural practices modernised.

The 2008 economic crisis also caused a dip in emissions, while EU policies aimed at achieving greater energy efficiency have also played an important role in reducing emissions.

That, in many ways, was the easy part. Now comes the big challenge: in order to achieve its long-term emissions reduction objective, Europe needs a wholesale reorganisation of its economy, says the EEA, and also needs to become less resource-hungry.

Fossil fuels still dominate energy production, accounting for 75% of energy supply in 2011 − the most recent year for which comprehensive statistics are available.

Progress achieved

“The EU will need to accelerate its implementation of new policies, while restructuring the ways that Europe meets its demand for energy, food, transport and housing,” the report says.

Short-term goals can be achieved, says the EEA, and the EU is on track to meet its target of producing 20% of its energy from renewable sources by 2020. Renewables accounted for 11% of EU energy production in 2012 – up from 4% in 1990.

It is a similar story across much of the European environment. Progress has been made over recent years in improving water systems, waste collection and recycling, and in rehabilitating some ecosystems.

“In many parts of Europe, the local environment is arguably in as good a state today as it has been since the start of industrialisation,” the report says. “Reduced pollution, nature protection and better waste management have all contributed.”

Worsening air

At the same time, what the report refers to as Europe’s natural capital is being seriously degraded by the activities of agriculture, fisheries, industries and  tourism. Urban sprawl is also having a negative impact.

In some regions, ecosystems are in a dire state, and the EU is not on track to meet its 2020 target on halting biodiversity loss.

Air quality is a particular concern.  The EEA estimates that more than 400,000 people in Europe died prematurely in 2011 due to breathing in toxic fumes. In some areas, air quality is getting worse, not better. And land is under severe pressure.

The report says that “loss of soil functions, land degradation and climate change remain major concerns, threatening the flows of environmental goods and services that underpin Europe’s economic output and well-being”. −  Climate News Network

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Climate change is likely factor in Syria’s conflict

Climate change is likely factor in Syria’s conflict

Researchers say climate change probably caused the savage drought that affected Syria nearly a decade ago − and helped to spark the country’s current civil war. 

LONDON, 2 March, 2015 – In a dire chain of cause and effect, the drought that devastated parts of Syria from 2006 to 2010 was probably the result of climate change driven by human activities, a new study says.

And the study’s authors think that the drought may also have contributed to the outbreak of Syria’s uprising in 2011.

The drought, which was the worst ever recorded in the region, ravaged agriculture in the breadbasket region of northern Syria, driving dispossessed farmers to the cities where poverty, government mismanagement and other factors created the unrest that exploded four years ago. The conflict has left at least 200,000 people dead, and has displaced millions of others.

The study, by scientists from Lamont-Doherty Earth Observatory at Columbia University, US, is published in the Proceedings of the National Academy of Sciences.

The authors are quite clear that the climatic changes were human-driven (anthropogenic) and cannot be attributed simply to natural variability, but are careful to stress that their findings are tentative.

“We’re not saying the drought caused the war,” says Richard Seager, one of the co-authors. “We’re saying that, added to all the other stressors, it helped kick things over the threshold into open conflict.

“And a drought of that severity was made much more likely by the ongoing human-driven drying of that region.”

Link with violence

Their study, although it contains new material, is not the first to suggest a possible link between extreme weather and the likelihood of violence.

Some researchers have investigated whether there may be a link between El Niño and La Niña − the periodic Pacific weather disruptions − and outbreaks of unrest.

Syria was not the only country affected by the drought. It struck the Fertile Crescent, linking Turkey, Syria and Iraq, where agriculture and animal herding are believed to have started around 12,000 years ago.

Suggestions of a global connection between climate change and political instability is being taken seriously by two influential groups − insurers and military planners.

The Levant has always seen natural weather swings. Other research has suggested that the Akkadian empire, spanning much of the Fertile Crescent about 4,000 years ago, probably collapsed during a long drought.

Drought can lead to devastating consequences when coupled with pre-existing acute vulnerability

But the authors of the Lamont-Doherty study, using existing studies and their own research, showed that the area has warmed by between 1°C and 1.2°C since 1900, and has undergone a 10% reduction in wet-season precipitation.

They say this trend is a neat match for models of human-influenced global warming, and so cannot be attributed to natural variability.

Global warming has had two effects, they say. First, it appears to have indirectly weakened wind patterns that bring rain-laden air from the Mediterranean, reducing precipitation during the usual November-April wet season. And higher temperatures have increased the evaporation of moisture from soils during the hot summers.

The authors say an episode of this severity and length would have been unlikely without the long-term changes.

Other researchers have observed the long-term drying trend across the Mediterranean region, and have attributed at least part of it to anthropogenic warming.

The researchers say Syria was especially vulnerable because of other factors − including a huge increase in population from four million in the 1950s to 22 million in recent years.

Water-intensive crops

The government has also encouraged water-intensive export crops such as cotton, while illegal drilling of irrigation wells depleted groundwater, says co-author Shahrzad Mohtadi, an international affairs consultant at the US Department of State.

The drought’s effects were immediate and overwhelming. Agricultural production − typically, a quarter of Syria‘s gross domestic product − fell by a third. In the northeast, livestock was practically wiped out, cereal prices doubled, and nutrition-related diseases among children increased steeply.

As many as 1.5 million people fled from the countryside to cities already strained by waves of refugees from the war in neighbouring Iraq.

“Rapid demographic change encourages instability,” the authors say. “Whether it was a primary or substantial factor is impossible to know, but drought can lead to devastating consequences when coupled with pre-existing acute vulnerability.”

Solomon Hsiang, professor of public policy at the University of California, Berkeley, says the study is “the first scientific paper to make the case that human-caused climate change is already altering the risk of large-scale social unrest and violence”. – Climate News Network

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Big cities head for water crisis as populations explode

Big cities head for water crisis as populations explode

With more than half the world’s population now in cities, scientists warn that inadequate surface water supplies will leave many at increasing risk of drought.

LONDON, 21 February, 2015 − More than 40% of the world’s great cities supplied by surface water could become vulnerable to shortages and drought by 2040, according to new research. And more than three out of 10 were already vulnerable in 2010.

Meanwhile, the vital array of satellites designed to monitor rainfall and to warn of potential flooding is reported to be coming to the end of its shelf life.

For the first time in history, more than half the world’s population is now concentrated in cities, and this proportion is predicted to increase to two-thirds. Cities grow up near plentiful water supplies − and as a population explodes, so does demand. But the flow remains much the same.

Some cities are already under drought stress. Chennai in southern India had to be supplied with tankers in 2004 and 2005, and São Paulo in Brazil is now at crisis point.

Supply analysis

Environmental scientist Julie Padowski and Steven Gorelick, director of the Global Freshwater Initiative at Stanford University in California, report in Environmental Research Letters that they analysed supplies to 70 cities in 39 countries, all of them with more than 750,000 inhabitants, and all of them reliant on surface water.

They defined vulnerability as the failure of an urban supply basin to meet demands from human, environmental and agricultural users, and they set the supply target as 4,600 litres per person per day – which factors in “virtual water”, defined as the total volume of water needed to produce and process a commodity or service.

They proposed three different kinds of measure of supply. If a city failed to meet one or two of these metrics, it was considered threatened. If it failed to meet all three, it was rated as vulnerable.

Importantly, the scientists did not factor in climate change, which is likely to make conditions worse. Instead, they simply considered current demand and supply, and then projected demand in 2040.

Of their 70 cities, they found that 25 (36%) could already be considered vulnerable by 2010. By 2040, this number had grown to 31 (44%).

The six cities that will begin to face water shortages are Dublin in Ireland, Charlotte in the US, Ouagadougou in Burkina Faso, and Guangzhou, Wuhan and Nanjing in China.

Most of the cities that are already vulnerable rely on reservoirs, and the study implies that urban planners will need to think about more reservoirs, deeper wells or desalination plants, or will have to contemplate the diversion of rivers from somewhere else.

Rainfall data

Meanwhile, they cannot rely on rainfall data because – as geological engineer Patrick Reed, professor of civil and environmental engineering at Cornell University, and colleagues report in Environmental Research Letters − the network of dedicated satellites “fails to meet operational data needs for flood management”.

Four of the 10 satellites have exceeded their design life − some by more than a decade. There are already weak spots in the network, especially in developing countries, which means that floods could take people by surprise.

Space-based instruments offer a way of monitoring rainfall and ground moisture upstream, in a way that gives authorities time to predict the moment when the rivers will start to rise and flood the cities. When four fail to deliver, the potential for catastrophe will be even worse.

So the scientists call for better international co-ordination of satellite replacement.

“It is important for us to start thinking as a globe about a serious discussion on flood adaptation and aiding affected populations to reduce their risks,” Professor Reed says. “We want to give people time to evacuate, to make better choices, and to understand their conditions.” – Climate News Network

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Climate impacts on European farmers’ yields per field

Climate impacts on European farmers’ yields per field

Scientists says changes in temperature and snow or rainfall are key factors in the stagnation of wheat and barley yields across Europe since the early 1990s.

LONDON, 19 February, 2015 – Farmers in Europe have already begun to feel the pinch of climate change as yields of wheat since 1989 have fallen by 2.5% and barley by 3.8% on average across the whole continent.

And two Californian scientists now believe that changes in temperature and snow or rainfall during the last quarter of a century are at least partly to blame.

The pinch may be gentle, but environmental scientists Frances Moore and David Lobell, of Stanford University, believe it is real.

They report in the Proceedings of the National Academy of Sciences that although changes in farming and environmental policies explain much of the stagnation of yields in Europe in the last 25 years, at least 10% of this change could be attributed to climate trends.

Sugarbeet and maize harvests have gone up slightly − and that, too, could be pinned on global warming.

Overall trends

It is no small challenge to find an overall trend to crop yields across a continent that stretches from Scotland to the Black Sea, from northern Norway to Sicily, and over a timescale that embraces floods, droughts, forest fires and heat waves that may or may not have been made worse or more frequent by global warming, but which would have occurred anyway.

The other complication is that, in the same 25 years, the patterns of agricultural subsidy and market demand have also changed.

But the Stanford scientists started with conditions on the farms in the 1980s, when Europe’s farmers were, on average, getting 0.12 more tonnes of wheat and barley per hectare than the year before. Yields per field were rising steadily.

“Agriculture is one of the economic sectors most exposed to climate change impacts”

“If they had continued growing at that rate after 1995, wheat and barley yields would be 30% and 37% higher today, respectively,” they write.

Climate trends could perhaps account for around 10% of the stagnation revealed in the statistics. The remaining change could be put down to economic and political shifts and other factors.

One of these would be that crops had been improving to a point called the biophysical limits: just how much weight of grain could one stalk hold anyway? So some change would be expected, and climate must be a component of that.

To arrive at their conclusion, the two scientists looked at the predictions made for climate change – southern Europe was always expected to become drier, but farmers in moist northern climates could benefit from temperature increases – and the available data, and then applied sophisticated mathematical probability techniques to isolate the possible impact of climate change so far.

Social costs

They have looked at the economic and social challenges of global warming before. Last year, they warned that Europe’s farmers were going to have to adapt to climate change in the 21st century, and Moore and a colleague claimed last month that economists had badly underestimated the economic and social costs of each tonne of carbon added to the levels of CO2 in the atmosphere.

The new research is, they argue, important because “agriculture is one of the economic sectors most exposed to climate change impacts, but few studies have statistically connected long-term changes in temperature and rainfall with yields.

“Doing so in Europe is particularly important because yields of wheat and barley have plateaued since the early 1990s ,and climate change has been suggested as a cause of this stagnation.” – Climate News Network

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