Chimps’ survival hopes jeopardised by climate change

Chimps’ survival hopes jeopardised by climate change

One of our closest animal relatives is at risk of being wiped out as changing rainfall patterns threaten to destroy its Central African habitat.

LONDON, 30 January, 2015 − Climate change is a challenge for chimpanzees, too. New research warns that a primate subspecies – one of humanity’s closest animal relatives – could become endangered within five years

The threatened subspecies of the common chimpanzee is Pan troglodytes ellioti, and there are only 6,000 remaining individuals, surviving in two populations in Cameroon.

Field biologist Paul Sesink Clee, of Drexel University, US, and colleagues report in BMC Evolutionary Biology that they combined climate, environmental and population data to model how the chimpanzees’ preferred habitats would change with climate under a “business as usual” scenario in which the world went on burning fossil fuels.

Habitat change

Underlying such research is the larger question of how variation in habitat drives evolutionary change: why are there four subspecies of chimpanzee, and how much does geography and habitat have to do with it?

So the scientists made a chimpanzee population map, and imposed it on a map of habitats.

They found two distinct populations of the chimpanzee − one in the mountainous rainforests of western Cameroon, and one in a distinctive region of grassland, forest and woodland in central Cameroon.

Then they simulated how these habitats would change under global warming scenarios by 2020, 2050 and 2080.

“Preliminary projections suggest that rainfall patterns will change dramatically in this region of Africa”

Their findings were that the mountain rainforest habitat would survive, but the lowland dwellers would decline quickly under all scenarios by 2020, and could disappear almost entirely under the worst case scenario by 2080.

Since half of the entire population of Nigeria-Cameroon chimpanzees survive in this habitat, the suggestion is that the chimpanzees are particularly vulnerable to climate change.

Severely affected

The researchers did not take into account the opportunities for the chimpanzees to migrate, or to adapt to new circumstances. They point out that Central Africa in particular, and the continent in general, is likely to be severely affected by climate change.

“Preliminary projections suggest that rainfall patterns will change dramatically in this region of Africa, which will result in significant alterations of forest and savanna habitats,” the report says.

“Models of global climate change also have been used to show that 30% of plant and animal species are at risk of extinction if the rise in mean global temperature exceeds 1.5°C − an increase that is nearly certain to occur under future climate scenarios.” – Climate News Network

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California rains bring little relief from harsh drought

California rains bring little relief from harsh drought

Unless substantial rain falls soon, California’s worst drought on record threatens dire consequences for the state’s massive agricultural industry.

DAVIS, CALIFORNIA, 29 January, 2015 − Doing the right thing in the environs of the University of California, Davis – one of the foremost agricultural institutions in the US – means driving a carbon efficient car. And having a lawn that’s burned dry.

California’s worst drought on record is forcing people to cut back radically on water use – and that means letting lawns die. There was considerable rainfall last month, but it was not nearly enough to replenish the badly-depleted water resources.

“If we don’t have rain in significant amounts by early March, we’ll be in dire straits,” says Professor Daniel Sumner, director of the Agricultural Issues Center at Davis.

Water restrictions

Higher than average temperatures – particularly during the winter months – have combined with a lack of rainfall to produce severe drought conditions across much of the state. Water restrictions have been brought in following the imposition of a drought emergency in January last year.

“Historically, California’s water has been stored in the snow pack in the mountains, but warmer winter temperatures have meant the pack has been melting.” Sumner says.

“The agricultural sector has made considerable advances in limiting water use, and new, more drought resistant, crops and plant varieties have been introduced, but aquifers have been pumped and they are not being replenished.

“In the past, massive projects were undertaken to distribute water round the state, but now there’s not the money available to do any more big-time plumbing work. Also, the regulations on diverting water for agriculture use are very tight – rivers can’t be pumped if it means endangering fish stocks or other wildlife.”

“California is still growing – and exporting – rice, which is a real water drinker. How crazy is that?”

Whether or not climate change is causing the drought is a matter of considerable debate. A recent report sponsored by the US government’s National Oceanic and Atmospheric Administration (NOAA) says natural oceanic and atmospheric patterns are the primary drivers behind the drought.

A high pressure ridge that has hovered over the Pacific off California’s coast for the past three years has resulted in higher temperatures and little rainfall falling across the state, the report says.

However, a separate report by climate scientists at Stanford University says the existence of the high pressure ridge, which is preventing rains falling over California, is made much more likely by ever greater accumulations of climate-changing greenhouse gas emissions in the atmosphere.

Whatever the cause of the drought, the lack of rain is doing considerable environmental and economic damage. The Public Policy Institute of California, a not-for-profit thinktank, estimates that $2.2 billion in agricultural revenues and more than 17,000 jobs have been lost as a result of the drought.

Severely depleted

Thousands of acres of woodland have been lost due to wildfires, while fisheries experts are concerned that severely depleted streams and rivers could lead to the disappearance of fish species in the area, such as coho salmon and steelhead trout.

The drought is not limited to California. Adjacent states are also affected, and over the US border to the south, in Mexico’s Chihuahua state, crops have been devastated and 400,000 cattle have died.

Frank Green, a vineyard owner in the hills of Mendocino County, northern California, says: “The vines are pretty robust and, despite the drought, our wines have been some of the best ever over the past two years.

“But there’s no doubt we need a lot more rain, and plenty more could be done on saving and harvesting water. Farmers have cut back on growing water-hungry crops like cotton, but California is still growing – and exporting – rice, which is a real water drinker. How crazy is that?” – Climate News Network

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Climate’s impact on agriculture could lead to calamity

Climate’s impact on agriculture could lead to calamity

Widespread hunger and poverty are predicted unless strategies are developed to cope with the drop in crop yields climate change will cause.

LONDON, 22 December, 2014 – New research predicts that climate change will transform agriculture, with a drop in yields of up to 18% by 2050 in terms of calories harvested. By then, the global population will have risen by more than 18%, so the consequences could be calamitous.

That’s the worst projected outcome. By the same date, the researchers say, yields in terms of calories could have risen by 3%, but that would still mean widespread hunger and poverty.

The difference in projected outcomes may say more about the sheer complexity of global agriculture and the uncertainties of the future than anything else.

David Leclère, a researcher at the International Institute for Systems Analysis (IIASA) in Austria, and colleagues report in the journal Environmental Research Letters that they used computer simulations to explore nine different climate scenarios and their impact on 18 selected crops and four crop management systems.

Human adaptations

They also factored in human adaptations that might be necessary, chief among them being new management systems for water and for irrigation.

Also explored were the benefits of a warmer world − some temperate regions will certainly become more productive – as well as the fertilisation effect of increased carbon dioxide in the atmosphere.

They had to balance these against the expectation of extremes of heat, which can affect yield, and the overall change in rainfall patterns expected with climate change.

This is already having an effect on productivity, they say, and things will get worse.

“The challenge we face is to find a strategy that fits a hundred scenarios at the same time”

“Yields of major crops will decrease in low latitude areas even under a local increase in temperature below 2°C, and worldwide losses are expected for larger temperature increases,” the study warns. “This will precipitate significant adjustments throughout the global food supply chain.”

In a large part of the world, demand for irrigation may grow by as much as 25%.

Since, over the centuries, agriculture has been adapted very precisely to local climate patterns, and since climate models aren’t precise enough to predict quite where precipitation will change, there is still a great deal of uncertainty.

The new research explores this uncertainty, and how humans and their economies will cope.

“Our new study is the first to examine at a global scale whether the adaptations required from agricultural systems are in the transformational range, and whether these transformations are robust across certain plausible scenarios,” says Dr Leclère.

Transformations

“By looking at where, when, why and which transformations are required, but also in how many scenarios, it lays the groundwork for countries to better plan for the impacts of climate change.”

Agriculture has always adapted. How well it can adapt to global climate change depends not just on temperature and rainfall and the choice of crops, but also on international trade and on the decisions governments may take.

Computer models are a way of helping analysts think about a choice of possible outcomes, across a wide range of cultures and climates.

“Our models show that there is an effective global adaptation strategy to any single climate change scenario,” says Petr Havlik, an IIASA researcher, who is one of the report’s authors.

“The challenge we face is to find a strategy that fits a hundred scenarios at the same time.” – Climate News Network

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Fall of ancient civilization offers climate warning

Fall of ancient civilization offers climate warning

Prolonged drought – a familiar climate-related issue in the modern world – is believed by scholars to have been a key factor in the implosion of the powerful Assyrian empire 2,700 years ago.

LONDON, 19 November, 2014 − Two scholars have a new explanation for the collapse of one of the great Bronze Age civilizations. The Assyrian empire of the 7th century BC – based in Nineveh, in what is now northern Iraq – may have collapsed at least in part because of a population explosion and climate change in the form of sustained drought.

And, they point out, there are lessons in ancient history for the modern world as well.

Adam Schneider, an anthropologist at the University of California, San Diego, and Selim Adali, of the Research Centre for Anatolian Civilizations at Koç University in Istanbul, Turkey, put forward their proposal in the journal Climatic Change.

They say that demographic and climatic factors played an indirect but significant role in the collapse of a civilization chronicled not just in clay tablets and archaeological marvels but in the Hebrew scriptures and the Christian Old Testament.

Historic links

The climate change theory of history is now well established. In the last two years, researchers have linked both the dissolution of the Minoan empire in the ancient Mediterranean and the collapse of Levantine civilizations of the near East and the Harappan civilization of the Indus Valley to sustained drought.

Others have identified seasons of plentiful rainfall as the impetus for the conquest of Russia, China and Persia by the Mongol horsemen of Genghis Khan.

The connections with modern conflict, too, have been made before. In 21 studies of upheaval and conflict in modern societies, researchers have found clear links with rises in temperatures.

And just days after the Assyrian study was published in Climatic Change, research in the Proceedings of the National Academy of Sciences identified a link between temperature and rainfall anomalies in sub-Saharan Africa and violence in the region during the last 30 years.

“Hindsight . . . allows us to piece together from the past what can go wrong if we choose not to enact policies that promote longer-term sustainability”

Schneider and Adali looked through what climate scientists call “proxy evidence” of rainfall patterns in the Tigris Valley of northern Iraq more than two and a half millennia ago.

They considered the evidence of lake sediments and confirmed that many parts of the region experienced a “short but widespread dry phase” during the mid-to-late 7th century BC.

They also unearthed written evidence from 666 BC that welcomed “copious rains, huge floods, a fine rate of exchange…” to mark a new accession to the throne. But by 657 BC, another letter stated that “this year’s rains were diminished and no harvest was reaped”.

In fact, Assyrian engineers had established an impressive series of canals, waterways, cisterns and reservoirs to conserve water, and archaeological finds reveal that the imperial farmers grew barley and wheat, grapes, cucumbers, pomegranates, flax and cotton among many other crops.

But demand, too, was on the increase. The empire of built by Sennacherib, a king identified in biblical chronicles, had ambitions for the local populations. In at least 20 known acts of mass deportation, half a million people were resettled in the heartland.

Nineveh grew fivefold in area, and the population growth, the scientists think, placed significant strains on the immediate supplies of food in the region.

Conflict and insurrection

Within five years of the 657 BC drought, the Assyrian economy was struggling, and conflict and insurrection had broken out. By 609 BC, a remarkable civilization had been destroyed.

A multi-year drought, the researchers argue, “would have placed serious stress on the agricultural economy of the Assyrian state and, by extension, upon the imperial political system”.

They see parallels with today, as the fate of the Assyrian empire offers lessons for modern society about the hazards of valuing short-term economic growth over long-term security and sustainability.

“The Assyrians can be ‘excused’ to some extent,” they conclude, “for focusing on short-term economic or political goals that increased their risk of being negatively impacted by climate change, given their technological capacity and their level of scientific understanding about how the natural world works.

“We, however, have no such excuses, and we also possess the additional benefit of hindsight, which allows us to piece together from the past what can go wrong if we choose not to enact policies that promote longer-term sustainability.” – Climate News Network

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Climate threatens striking change to US weather

Climate threatens striking change to US weather

Global warming is expected to have an explosive effect across America as scientists predict that there could be a 50% increase this century in the frequency of lightning strikes.

LONDON, 17 November, 2014 − Climate scientists foresee a brighter future for America − but no one will thank them for it, as global warming is expected to increase the total number of lightning strikes across the US this century by 50%.

David Romps, assistant professor in the Department of Earth and Planetary Science at the University of California, Berkeley, and colleagues report in Science journal that they looked at predictions of rainfall, snow, hail and cloud buoyancy in 11 different climate models. They concluded that the outcome could only be more atmospheric electrical action.

Right now, the continental US is hit about 25 million times a year by lightning.

But Dr Romps said: “With warming, thunderstorms become more explosive. This has to do with water vapour, which is the fuel for explosive deep convection in the atmosphere. Warming causes there to be more water vapour in the atmosphere, and if you have more fuel lying around, when you get ignition, it can go big time.”

More evaporation

Warmer weather means more evaporation. But higher temperatures also mean that the atmosphere’s capacity to hold water vapour increases as well, with a potential for more clouds, more flow of air, and more precipitation.

The volume of water hitting the ground – as hail, snow, sleet or rain – offers a measure of the convection properties of the atmosphere, and convection generates lightning.

Hundreds of people are struck by lightning each year, and scores are killed, but these remain a very small proportion of accidental deaths in any year. The real hazard might lie far from populated areas: half of all wildfires are caused by lightning strikes.

Lightning also generates more nitrous oxides in the atmosphere, which could also affect atmospheric chemistry. So it makes sense to know what to expect as the planet warms.

“We already know that . . . the more precipitation,
the more lightning”

The scientists examined US Weather Service data for 2011, and the counts from the National Lightning Detection Network, to see if they could confirm a link between cloud buoyancy and precipitation as a predictor of lightning. They also looked at data from balloon-borne instruments released every day in the US to measure the rate at which clouds rise.

As a result, they calculate that 77% of the variation in lightning strikes could be predicted from knowledge of the two conditions.

“Lightning is caused by charge separation within clouds, and to maximise charge separation you have to loft more water vapour and heavy ice particles into the atmosphere,” Dr Romps said. “We already know that the faster the updrafts, the more lightning, and the more precipitation, the more lightning.”

Potential energy

Their climate models predicted, on average, an 11% increase in convective available potential energy for every extra degree Celsius rise in average temperatures. They calculated that if average planetary temperatures were to rise by 4°C, the potential for lightning strikes would go up by 50%.

Their calculations are limited to the US mainland and may not apply equally to other parts of the planet. Overall conditions, and therefore the potential for thunderstorms, tend to vary widely.

But the continental US – the predictions do not include Hawaii or Alaska − is flanked by two oceans and with a subtropical sea to its south. It is distinguished by a sharp temperature gradient and dramatic topography, and is already a forge for fierce and destructive tornadoes, and a target for frequent hurricanes.

So the barometer remains set for future storms, with added lightning. – Climate News Network

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Salt’s poisonous effect is growing threat to crops

Salt’s poisonous effect is growing threat to crops

As global warming increases the world’s arid areas, scientists warn that restoring productivity to salt-affected agricultural land will be essential to feed an expanding population.

LONDON, 1 November, 2014 − Salt is poisoning around 2,000 hectares of irrigated farm land every day – and has been doing so for the last 20 years, according to new research.

Think of an area about the size of 3,000 football fields that can no longer be used to produce food each day. And then remember that the global population actually grows by around 200,000 people every day.

Manzoor Qadir, senior research fellow at the United Nations University’s Institute for Water, Environment and Health, and colleagues report in the journal Natural Resources Forum that an area of farmland the size of France – 62 million hectares – has been affected by the build-up of salts in irrigated soil. This is one-fifth of all irrigated land.

“To feed the world’s anticipated nine billion people by 2050, and with little new productive land available, it’s a case of all lands needed on deck,” says Dr Qadir. “We can’t afford not to restore the productivity of salt-affected lands.”

Ancient hazard

Salts degradation is an ancient hazard in arid and semi-arid lands, where groundwater is pumped from aquifers below the bedrock and used to grow crops.

Evaporation and transpiration leave precipitated salts around the roots of each crop and – since there is no fresh rainwater to wash away the salts − sooner or later the levels build up to intolerable scales, and the land becomes increasingly unproductive.

The UN Food and Agriculture Organisation warns that to feed the projected 2050 population, farmers will need to grow 70% more food. Cereal production alone will have to increase by 50%, to a total of three billion tonnes a year. But, each week, the world loses an area of land the size of Manhattan to salt degradation, thanks to poor soil management, bad drainage and other problems.

The researchers, from Canada, Jordan, Pakistan and Sri Lanka, based their estimates on more than 20 studies in the last two decades in Australia, India, Pakistan, Spain, Central Asia and the US.

They also totted up the estimated economic losses: more than $27 billion a year.

In the Indo-Gangetic basin of India, the build-up of soil salts could reduce wheat harvests by 40%, and cotton by more than 60%.

Employment losses could be as much as 50-80 man days per hectare, and human health problems could be between 20% and 40% greater because of the effect. Animal health problems could increase by anywhere between 15% and 50%.

In the Indus basin in Pakistan, the average overall wheat grain loss has been put at 32%, and the average rice yield has fallen by 48%.

The worst affected regions of the world are the Aral Sea basin in Central Asia, the Indo-Gangetic basin in India, the Indus Basin in Pakistan, the Yellow River basin in China, the Euphrates basin in Syria and Iraq, the Murray-Darling in Australia, and the San Joaquin Valley in the US.

The researchers warn that their calculations concern only crop-yield losses.

“Salt-affected degraded lands emit more greenhouse gases, thus contributing to global warming”

“However, the crop yields from irrigated areas not affected by salinisation have increased since 1990 due to factors such as improved crop varieties, efficient on-farm practices, better fertilizer use, and efficient water management practices,” they say.

“Consequently, there may be larger gaps in crop yields harvested from salt-affected and non-affected areas under similar agro-ecosystems, suggesting an underestimation of the economic cost of salt-induced land degradation.”

“These costs are expected to be even higher when other cost components − such as infrastructure deterioration (including roads, railways, and buildings), losses in property values of farms with degraded land, and the social cost of farm businesses − are taken into consideration.

“In addition, there could be additional environmental costs associated with salt-affected degraded lands as these lands emit more greenhouse gases, thus contributing to global warming.”

Some yield could be recovered. For example, farmers could irrigate more sparingly, plough deeply, dig drains, plant trees, select salt-tolerant crops, and dig in the stubble and plant waste.

An essay in the journal Trends in Plant Sciences also notes that around three hectares of farmland are lost every minute.

But plant science itself could help. Sergey Shabala, professor of crop physiology and plant nutrition at the University of Tasmania in Australia,  points out that millions of years of evolution have already devised a possible answer.

He says: “We should learn from nature and do what halophytes, or naturally salt-loving plants, are doing: taking up salt but depositing it in a safe place – external balloon-like structures called salt-bladders.”

Over-riding problem

New approaches to plant breeding could certainly provide part of the solution. The over-riding problem, however, is that water is already being used on a prodigal scale, in a globally-warming world in which some regions are in any case predicted to become even more arid.

Nine-tenths of the Aral Sea – once the world’s fourth largest lake − in Central Asia is now a sandy desert. The dust blown from it has salted half of Uzbekistan’s soil, and 70% of Turkmenistan has become desert, according to a report in the journal Nature.

But the cotton and wheat farmers in the republics that border the Aral Sea are among the highest users of water in the world. A Turkmen, on average, consumes four times the water used by a US citizen, and 13 times that of a Chinese one.

And although the Western hemisphere is in the grip of a calamitous and sustained drought, the real problem, according to Marcia McNutt, the former director of the US Geological Survey, and now the editor-in-chief of Science magazine, is that underground aquifers in the south-western US have been emptied for irrigation at such a rate that the contours on the land itself have started to change.

Californian mountains have risen up to 15 millimetres because of the water loss.

“It is high time we started managing our precious water supplies in harmony with the laws of nature,” she warns. – Climate News Network

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Towering ambition to help protect Amazon rainforest

Towering ambition to help protect Amazon rainforest

A new 325-metre observatory soaring above the Amazonian tree canopy will capture vital data on how climate change is impacting on a delicate environment that is also under threat from encroachment by lawless urban settlements.

SÃO PAULO, 24 October, 2014 − In the Amazon, everything is big – the trees, the rivers, the snakes, and the statistics that measure everything in numbers of football fields or areas the size of entire countries.

Now one of the biggest towers in the world – taller than the Eiffel Tower in Paris and the Chrysler Building in Chicago − is about to rise above the rainforest.

The purpose of the 325-metre (1,066 feet) Amazon Tall Tower Observatory (ATTO) is to gather vital information on how climate change is affecting the Amazon ecosystem and other humid tropical areas, using climate models.

The research project is being run by Brazil’s National Institute for Amazonia Research (INPA), and the Max Planck Institute for Chemistry, Germany. As one of the project directors, Paulo Ataxo, of the University of São Paulo, explains: “The tower will help us answer innumerable questions related to global climate change.”

Jointly financed by the Brazilian and German governments, the ATTO – which has taken seven years to plan and build − is located 100 miles from the city of Manaus. The steel girders had to be transported 4,000 km by road and river from the factory in southern Brazil, and finally up a dirt track into the heart of the forest.

Monitoring network

The ATTO, adding to a network of smaller observation towers already in the area, will be able to monitor − without direct human influence − changes in air masses over an area of hundreds of miles.. It is expected to be in operation for at least 20 years, measuring the wind, humidity, carbon absorption, cloud formation and meteorological patterns in the soil, tree tops, and the air above, adding to the growing body of research showing how vital it is to stop deforestation.

Philip Fearnside, INPA research professor who has been studying the rainforest for over 40 years, says that the loss of natural tree cover is influencing the delicate environmental equilibrium of the region, and of the rest of the country. He says: “Among other services, the forest recycles water, which is critical for the rains in São Paulo , stores carbon, avoiding the worsening of global warming, and maintains biodiversity.”

A recent study by Brazilian, Canadian and German scientists from São Paulo Universities UNESP and USP, Toronto University, and the Hemholtz Centre for Environmental Research in Germany concluded that the deforestation of tropical forests emits at least 20% more CO2 than previously thought.

“Among other services, the forest recycles water,
which is critical for the rains in São Paulo”

The study, published in the Nature Communications magazine, used remote sensoring, the ecology of the countryside, and modelling of the forest dynamic to develop a new approach that included the previously uncalculated loss of biomass on the edges of forest fragments.

The Brazilian government claims it is reducing deforestation. But, according to Environment Ministry figures, the vast area known as Amazônia Legal, which covers the whole of the Amazon basin, has already lost almost a fifth (18.2%) of its total area of 5 million sq km  − that is, around 900,000 sq km.

Another recent study −  a three-year Amazalert research project begun in 2011 by 14 European and South American institutes, including the Universities of Leeds and Edinburgh and the UK Met Office − has concluded that if present policies continue, the future will be chaotic

Amazalert project looked at the impacts of deforestation and climate change on the Amazon up to 2050.

Human impacts

While there is a constant stream of research on the climate and vegetation of the rainforest, to which ATTO will be contributing, there is much less research and information about the role of human beings and society in the Amazon.

Amazalert found that violence and unplanned growth in the towns on the edges of the Amazon region are also threatening its integrity.

Among Brazil’s 50 towns and cities with the highest murder rates per 100,000 inhabitants, 12 are located in the so-called Arc of Deforestation, which runs around the southern and eastern borders of the rainforest. The report says that violence in these towns has reached the “level of civil war”.

For Amazalert collaborator Andrea Coelho, researcher at the Institute for the Economic, Social and Environmental Development of Pará state (IDESP), the problem is that large-scale mining projects, the paving of roads, and the construction of hydroelectric dams attract lots of people, for whom there is no infrastructure.

When the projects are finished, the workers stay on and become goldminers, extractivists, or land-grabbers. Many are living in miserable conditions, and so criminality erupts.

The huge Belo Monte dam, being built on the Xingu river, is an example. In 2007, there were four cases of drug trafficking in surrounding areas. Last year, there were 238. – Climate News Network

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Climate renews famine risk to Africa’s Sahel

Climate renews famine risk to Africa’s Sahel

With population increasing and food demand far outstripping supply, the Sahel is vulnerable to a new humanitarian crisis − and researchers warn that rising temperatures will only make matters worse.

LONDON, 20 October, 2014 − The Sahel, the arid belt of land that stretches from the Atlantic to the Red Sea and separates the Sahara desert from the African savanna, is no stranger to drought and famine.

Now scientists in Sweden say the Sahel faces another humanitarian crisis even than in the recent past − with the changing climate partly responsible.

Writing in the journal Environmental Research Letters, the researchers from Lund University say people in the Sahel need more food, animal feed and fuel every year. But demand, which has more than doubled over a recent 10-year period, is growing much faster than supply.

Fewer resources

Data from 22 countries shows the result: fewer resources per capita and a continued risk of famine in areas with low primary production – that is, the availability of carbon in the form of plant material for consumption as food, fuel and feed.

Human numbers are part of the reason. Between 2000 and 2010, the population of the Sahel grew from 367 million to 471 million people − an annual rise of 2.2% over the decade.

But crop production remained essentially unchanged, so the margin between supply and demand for primary production is shrinking every year, while the Sahel’s population is forecast to total nearly a billion people by 2050.

Children's graves at a refugee camp in Kenya during the famine in 2011 Image: Andy Hll/Oxfam via Wikimedia Commons
Children’s graves at a Kenyan refugee camp during the 2011 famine
Image: Andy Hall/Oxfam via Wikimedia Commons

Some studies suggest that modern plant strains can withstand the effects of drought better than traditional cultivars, although this was not a focus of the Lund team.

They were mainly concerned with the staple crops grown regionally − such as sorghum and millet, which are used as food for people, with the residues used as fodder for livestock − and with the dry woodlands that provide fuel.

They used remote analysis and satellite images to calculate annual crop production in the 22 countries they studied, and compared the figures with data on population growth and consumption of food, animal feed and fuel. This relationship helps to measure a region’s vulnerability.

The study shows that 19% of the Sahel’s total primary production in 2000 was consumed. Ten years later, consumption had increased to 41%.

Reduced harvest

It says several forecasts suggest that harvests will be reduced as a result of the higher air temperatures the region is now experiencing, even though climate change is predicted to result in the Sahel receiving more rain in future.

So, the researchers say, climate change can only increase the vulnerability of the Sahel.

Asked by the Climate News Network whether higher air temperatures alone were likely to cancel the gains from increased rainfall, one of the study’s authors, Hakim Abdi, a doctoral student in physical geography and ecosystem science at Lund, said: “The short answer is yes. Studies indicate that higher temperatures offset both increased rainfall and CO2 fertilisation.

“Additionally, a recent study found that increase in future rainfall in the Sahel, a region where the soil generally receives little nutrient input and is over-exploited, causes nutrient leaching, and hence induces nitrogen stress.

“When we were in our study site in North Kordofan in Sudan, the most common complaint we received from the villages we visited was the lack of water.

“I think that if a drought occurs with an impact that matches or exceeds the ones in 1972/73 or 1982/83, we will see serious consequences − worse impacts than past ones.” − Climate News Network

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Australia gets early blast of more extreme heat

Australia gets early blast of more extreme heat

Summer has come early across much of Australia – and as temperatures soar to record seasonal levels in many areas, the bushfire season has started well ahead of schedule.

LONDON, 14 October, 2014 − It’s the time of year when many Australians start to think about eating outdoors or heading for the beach after work. Early spring, and the temperatures are rising – particularly this year.

The Australian Government’s Bureau of Meteorology (BOM) says maximum temperatures in September across much of the country were higher than average, with central and south-western areas experiencing their warmest September on record.

Australia is considered to be particularly vulnerable to the effects of a climate change, and 2013 was the country’s hottest year since records began, with average temperatures 1.2˚C above the long-term average.

In one seven-day period in early January last year, record national average temperatures exceeded 39˚C.

Unprecedented levels

September started off cool in Sydney, Australia’s most populated city, but then heated up to unprecedented levels for this time of year. For the first time, temperatures climbed to more than 32˚C for two consecutive days in the month.

Meanwhile, overall September rainfall was 27% below the monthly average − and the dry conditions mean the bushfire season has come early. The south of the island of Tasmania has fared particularly badly, with fires fuelled by dry conditions and high winds.

Areas round Sydney and throughout New South Wales – the country’s most populous state − have also been hit by bushfires, with fire warnings going out to more than a million homeowners.

Despite growing evidence that human-induced climate change is a major reason for Australia heating up, the Liberal-National coalition government led by Prime Minister Tony Abbott has taken little action on the issue.

It has abolished a carbon tax introduced by the previous Labour government, abolished a Climate Commission that gave advice on the impact of warming, and is seeking to downgrade modest renewable energy targets.

Polluting fuel

Australia is one of the world’s leading producers of coal – the most polluting fuel, which is responsible for a significant portion of climate changing greenhouse gas emissions (GHGs). The country’s per capita GHG emissions are among the highest in the world.

A recent report on Australia’s climate, produced by BOM and the Commonwealth Scientific and Industrial Research Organisation (CSIRO), the national science agency, predicts temperatures rising across the country by between 0.6˚C and 1.5C by 2030, compared with the rise of 0.6˚C between 1910 and 1990.

The report says: “Data and analysis from BOM and CSIRO show further warming of the atmosphere and oceans in the Australian region. . . this warming has seen Australia experiencing warm weather and extreme heat, and fewer cool extremes.

“There has been an increase in extreme fire weather, and a longer fire season, across large parts of Australia.” – Climate News Network

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Solar dimming reflects complexity of climate change

Solar dimming reflects complexity of climate change

Reduced monsoon rainfall and increased river flow are two extremes that new research has linked to man-made impacts on climate caused by air pollution.

LONDON, 13 October, 2014 − Two separate studies have confirmed the extent of human influence on climate change – and, for once, carbon dioxide is not the usual suspect.

One team has just found that air pollution dimmed the skies of northern Europe, reflected sunlight back into space, reduced evaporation, and increased river flow.

The second group reports that similar aerosol pollution had a quite different effect on the Asian monsoons: in the second half of the 20th century, the darkening skies reduced temperatures and cut the summer monsoon rainfall by 10%.

The two seemingly contradictory findings underscore two clear conclusions. One is that climate science is complex. The other is that human activity clearly influences the climate in different ways.

Worldwide concern

Both studies are concerned with an era when there was, worldwide, more concern about choking smog, sulphuric aerosol discharges and acid rain than about man-made global warming. They also both match complex computer simulation with observed changes in climate during the second half of the 20th century

Nicola Gedney, a senior scientist at the UK’s Meteorological Office, and colleagues report in Nature Geoscience that she and colleagues looked at the growth in aerosol pollution, especially in the Oder river catchment area of central-eastern Europe, that followed the increased burning of sulphurous coal in Europe right up till the late 1970s.

The consequence of that burning was a reduction in sunlight over the hemisphere. But this began to reverse with clean air legislation and a widespread switch to cleaner fuels. River flows, which had been on the increase, were reduced.

“We estimate that, in the most polluted central Europe river basin, this effect led to an increase in river flow of up to 25% when the aerosol levels were at their peak, around 1980,” Dr Gedney said. “With water shortages likely to be one of the biggest impacts of climate change in the future, these findings are important in making projections.”

Aerosol pollution

Meanwhile, a group led by Debbie Polson, a researcher in the University of Edinburgh’s School of Geosciences, Scotland, focused on aerosol pollution and the Asian summer monsoons, which provide four-fifths of the annual rainfall of the Indian subcontinent.

They report in Geophysical Research Letters that they calculated annual summer rainfall between 1951 and 2005, used computer simulations to quantify the impact of increasing aerosol emissions and greenhouse gases during that time, and factored in natural variations, such as volcanic discharges.

They found that, overall, levels of rain during the monsoon fell by 10%, and this change could only be explained by the influence of aerosols from car and factory exhausts.

“This study has shown for the first time that the drying of the monsoon over the past 50 years cannot be explained by natural climate variability, and that human activity has played a significant role in altering the seasonal monsoon rainfall on which billions of people depend,” Dr Polson said. – Climate News Network

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