Rainforests are left on edge of destruction

Rainforests are left on edge of destruction

Eminent conservationist says climate change’s major threat to the world’s tropical rainforests comes not from heat, but from drought and uncertain rainfall.

LONDON, 23 May, 2015 – Rising temperatures will not themselves spell disaster for the world’s rainforests. It is the droughts and unpredictable rainfall patterns, which climate change is already worsening, that will settle the forests’ fate before the century ends, according to a new book.

Claude Martin, who has worked in tropical rainforest conservation since the 1970s, is author of On the Edge, commissioned by the Club of Rome, which published the seminal Limits to Growth report in 1972. Since then, nearly 50% of the world’s forest cover has disappeared.

Martin, a former director-general of WWF International, recognises that there are many drivers of forest damage and destruction − including the pressures of the global economy for animal feed and food for humans, and the worldwide demand for biofuels.

Essential ecosystem

Acknowledging the progress made in science and conservation, he reminds his readers that the forests are not just huge repositories of biodiversity, but an essential ecosystem providing everyone on the planet with fresh water, clean air and climate regulation.

Evaluating the impact of climate change on rainforests means focusing on the length of dry seasons and water stress, rather than temperature, Martin writes.

The likeliest cause of forest collapse and severe risks of reaching a tipping point is not temperature rise, but the change from the dependable rainfall patterns of the past, and the probability of increasing droughts and forest fires.

He sees a likelihood of drought and fires increasing − not least in the Amazon − because of the way in which climate change is fuelling El Niño and La Niña, the twin periodic temperature disruptions that occur every few years in the eastern Pacific Ocean.

Known together as the El Niño-Southern Oscillation (ENSO), their impacts spread for thousands of miles.

“Lethargy of governments and the impotence of the intergovernmental system make it very unlikely that average global warming will be kept below 2°C

Martin is one of those scientists who are convinced that climate change will intensify ENSOs. As global warming effects become stronger, ENSO events become more frequent, rainfall drops further because of forest loss and fragmentation, and droughts are likely to become more common and more severe. And so the vicious circle becomes a constant downward spiral.

“When the 20th century’s strongest ENSO occurred in 1997/98,” Martin writes, “it was considered to be an unusual phenomenon. . . . [It] caused severe drought in Amazonia, Southeast Asia and Mexico, and had massive effects on the net primary productivity of forests, thus their capacity of carbon storage as well as forest fires.”

After another severe drought in 2001, following another ENSO event, about a third of the Amazon forests stored significantly less carbon and became vulnerable to fire. Two more droughts followed soon after, in 2005 and 2010. The first was estimated to be a once-in-a-century occurrence.

Fastest warming

Martin’s concerns are not confined to Amazonia. He cites modelling by the Intergovernmental Panel on Climate Change, which shows that Africa is expected to warm by 3-4°C by the end of the century − the fastest warming since the end of the last ice age around 11,500 years ago. This would expose the great Congo Basin forest to the risk of severe damage.

Globally, Martin is not hopeful. “The current rate of greenhouse gas emissions, the lethargy of governments and the impotence of the intergovernmental system make it very unlikely that average global warming will be kept below 2°C,” he says.

Under a mid-range emissions scenario, atmospheric CO2 concentrations are likely to rise by the end of the century to levels not seen in the last 50 million years. But he thinks the forest crisis will be developing uncontrollably some decades before then.

He predicts: “The decisive period for the long-term future of the rainforests . . . will be the second half of the century, when global warming is likely to exceed 2°C above the pre-industrial global average.

“It will be too late then to avoid a dangerous tipping point of self-reinforcing climate change.” – Climate News Network

  • On the Edge − The State and Fate of the World’s Tropical Rainforests. A Report to the Club of Rome, by Claude Martin (Greystone Books, £20/US$32.95).

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Heat and drought pose threat to US power supplies

Heat and drought pose threat to US power supplies

Global warming will leave people in the western states of the US exposed to increasingly extreme temperatures that could seriously affect electricity generation.

LONDON, 22 May, 2015 – Climate change could mean that things get really tough for people in the US west in the second half of this century, according to new research.

Higher temperatures and increased intensity of droughts could compromise the electricity grid, while the number of people exposed to extremes of heat is likely to multiply at least fourfold, and perhaps more.

Sustainability scientists Matthew Bartos and Mikhail Chester, of Arizona State University, report in Nature Climate Change that changes in precipitation, air and water temperature, air density and humidity could combine to create problems for electricity generating plant in the western US.

They estimate that around 46% of the generating capacity in 14 US states could experience reductions of up to 3% in the next few decades.

Stream flow

That is because there may not be enough stream flow for hydroelectric stations, and coal and nuclear power plant may not be able to get enough water through the cooling systems to keep generating at peak capacity, especially in the summer months.

Gas turbines, wind turbines and solar cells also could be affected by changes in air temperature.

“Drought and heat-related capacity reductions are especially problematic, because they are likely to occur during periods of high demand,” the researchers warn.

“From 2001 to 2008, a series of droughts caused electricity shortages in the American  southeast, the Pacific  northwest, and continental Europe. As concentrations of atmospheric carbon increase, drought events are anticipated to increase in frequency, duration and intensity.”

“Power providers are not taking into account climate change impacts”

Research such as this is intended to help energy utilities plan for problems ahead. Scientists identify a worst-case scenario, outline the probable  difficulties, and prompt the engineers and managers to take steps to avoid future embarrassments.

As global temperatures rise on average in the coming decades – as carbon dioxide levels in the atmosphere increase with the continued use of fossil fuels – so regions such as the American southwest will experience greater extremes of heat and longer periods of drought.

This will mean that available water will have to be pumped further, and there will be greater demand for cooling and air-conditioning systems.

California and the US  southwest have already been in the grip of extended drought.

“Power providers are not taking into account climate change impacts,” Bartos says. “They are likely overestimating their ability to meet future electricity needs.”

Reduced capacity

The scientists calculated that – if a drought lasted for a decade – capacity in vulnerable power generating stations could be reduced by as much as 8.8%.

Meanwhile, Bryan Jones, a demographer at the City University of New York, and colleagues report in the same issue of Nature Climate Change that the number of people who will want to switch on the air conditioning in the second half of the century will increase dramatically.

“We find that US population exposure to extreme heat increases fourfold to sixfold over observed levels in the late 20th century, and that changes in population are as important as changes in climate in driving this outcome,” they report.

And they add a warning: “Extreme heat is responsible for more deaths in the United States than any other weather-related event, and its frequency and intensity is expected to increase over this century.” – Climate News Network

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Weather events taken to extremes by climate change

Weather events taken to extremes by climate change

Scientists warn that global warming could greatly increase the likelihood of droughts, floods and heatwaves reaching record levels of frequency and intensity.

LONDON, 15 May, 2015 − As temperatures soar to record heights, blame it on global warming − but only about three-quarters of the time. And when the rain comes down by the bucketful, you can attribute one downpour in five to climate change.

Yet another team of research scientists has looked at the probabilities, and has linked extremes of weather with global warming.

Extremes have always happened and are, by definition, rare events. So, for the last 30 years, climate scientists have carefully explained that no particular climate event could be identified as the consequence of a rise in global average temperatures driven by the release of carbon dioxide and other greenhouse gases from the burning of fossil fuels.

But some events that were once improbable have now become statistically more probable because of global warming, according to Erich Fischer and Reno Knutti, climate scientists at ETH Zurich − the Swiss Federal Institute of Technology.

They report in Nature Climate Change that they looked at simulations of probabilities and climate records for the period 1901 to 2005, and projections for the period 2006 to 2100.

Rise in temperatures

Then they settled down to calculate the likelihood that a proportion of past heatwaves or floods could be linked to a measured average rise in planetary temperatures so far of 0.85°C.

They worked out how these proportions would change if the average planetary temperatures reach 2°C above the “normal” of the pre-industrial world, and they found that human-induced global warming could already be responsible for 18% of extremes of rain or snow, and 75% of heatwaves worldwide.

If the temperatures go up to the 2°C that nations have agreed should be the limit, then the probability of precipitation extremes that could be blamed on global warming rises to 40%. They are less precise about heatwaves, but any rise could be sharp.

“If temperatures rise globally by 2°C, we would expect twice as many extreme heat events worldwide than we would with a 1.5% increase,” Dr Fischer says.

“These global warming targets, which are discussed in climate negotiations and which differ little at first glance, therefore have a great influence on the frequency of extremes.”

The researchers are talking about probabilities: it will still be difficult ever to say that one event was a random happening, and another a result of climate change. In such research, there are definition problems. What counts as extreme heat in northern England would not be extreme in India or Saudi Arabia.

But such distinctions could become increasingly academic for people who live in the path of unusual heat and extended drought, or flash floods and catastrophic hailstorms.

A scientist recently told the European Geosciences Union that some regions of the planet will see unprecedented drought, driven once again by climate change, before 2050.

Ignored warnings

Yusuke Satoh, of the International Institute for Applied Systems Analysis, warned that under the notorious business-as-usual scenario −where nations ignore such warnings and just go on burning fossil fuels − 13 of 26 global regions would see “unprecedented hydrological drought levels” by 2050. Some would see this parching much earlier − the Mediterranean by 2027, and the western US as early as 2017.

Such studies are calculated to help provoke governments, states and water authorities into preparing for climate change, but it just may be that the western US is already feeling the heat. California, in particular, has been in the grip of unprecedented drought, and researchers have already linked this to climate change.

Reservoirs and irrigation systems are built on historical data. “But in the next few decades, these historical data may no longer give us accurate information about current conditions,” Dr Satoh says. “The earlier we take this seriously, the better we will be able to adapt.” – Climate News Network

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Climate poses new threat to survival of Arabian oryx

Climate poses new threat to survival of Arabian oryx

Global warming is the suspected cause of the series of dry years in Arabia that have brought starvation to a desert species saved from extinction.

LONDON, 7 April, 2015 − One of conservation’s triumphs – the reintroduction of the oryx to the deserts of Arabia – could be at risk because of climate change, according to a new book.

The animal already beautifully adapted by thousands of years of evolution to an arid environment met a problem on its return: even deserts have droughts.

The Arabian oryx had been hunted almost to extinction before a handful were captured in 1962 and flown to Phoenix, Arizona, as the nucleus of a captive breeding programme.

By 1972, the last wild oryx had been captured or killed in Oman, but the bloodline survived in captivity.

The first reintroductions to the wild began in 1982, and numbers began to increase. There were incursions by poachers, but there were more releases.

However, there have been so many dry years over the last two decades − according to Malcolm Smith, once chief scientist for the Countryside Commission in Wales, in his new book, Back from the Brink − that many of the newly-wild oryx have not been able to find sufficient grazing.

Closely monitored

The animal is one of the most closely monitored in the world. Of all recorded deaths, 19% have occurred in fights between males, 13% have been due to poaching, and 65% have been due to starvation.

The succession of particularly dry years in the region might be due to global warming as a consequence of human combustion of fossil fuels.

Since climate simulations seem to predict that, in general, moist regions will get more rain and dry regions will experience ever drier regimes as greenhouse gas levels build up in the atmosphere, things don’t look good for the oryx − although captive populations for the time being remain secure.

Other recently-rescued species may face even leaner times − once again, because of climate change.

Spanish and Portuguese authorities have established safe territories for the Iberian lynx and, by 2013, more than 300 lived wild in Spain, while 150 lynx paced the enclosures in the breeding centres awaiting reintroduction.

But the wild rabbit makes up 90% of the lynx’s diet, and rabbit numbers are limited by hunting and by outbreaks of myxomatosis and rabbit haemorrhagic disease.

There have been fears too, that southern Spain and Portugal may become too hot and dry to sustain the prey, let alone the predator.

Such threats to biodiversity, and to individual animals, are not new. Climate change has in various ways reportedly threatened Arctic marine mammalscreatures of the Borneo forests,  and chimpanzees in isolated woodland in West Africa.

Whole ecosystems that evolved in geographical climate zones may be doomed to sudden and rapid change.

But Malcolm Smith’s book concerns itself only with the choicest last-minute success stories of conservation bodies: with those creatures that were all but gone when the conservationists stepped in.

They were hunted, their habitats had been destroyed, and their ecosystems were always precarious. But climate change was, at the time of rescue, the least of their problems.

Large Blue butterfly (Maculinea arion). Image: PJC&Co via Wikimedia Commons

Large Blue butterfly (Maculinea arion).
Image: PJC&Co via Wikimedia Commons

One instance he explores shows just how intricate the living arrangements of charismatic species can be, and illustrates the finely-balanced play of climate and ecological stability in preserving a species.

The Large Blue butterfly (Maculinea arion) exists in respectable numbers worldwide, but became all but extinct in the UK − with changes in farming practices and land use the suspected causes.

Peculiar lifestyle

Until 1972, nobody quite understood the peculiar lifestyle of the Large Blue. It lays its eggs on the flower bud of the wild herb, thyme. A larva hatches and, after an initial vegetarian diet, falls off the plant. Thereafter, its life depends on just one species of red ant, Myrmica sabuleti.

The Large Blue grub secretes a fluid that somehow suggests that of a red ant queen grub, so the ants take it home and nurse it. The Large Blue caterpillar turns carnivore and, for 10 months, feeds on red ant larvae.

In pupate form, it makes queen ant noises and the ants continue to protect it. It hatches, gets out to the open − still protected by the ants − and flies off. It then has about a week in which to find a thyme flower bud, mate, and lay its eggs.

But the complexities multiply. The thyme flower bud that bears the eggs must be within metres of the right kind of red ant nest, or the larva perishes.

Dependent on temperature

The grass above the ant nest must be closely grazed because the ants’ survival is dependent on temperature, and if the grass grows even a centimetre ground is shaded, the nest temperature drops by 2°C to 3°C, and the ant colony is at risk − along with any parasitic caterpillars in the nest.

So the thyme has to flower at the right time, very near a red ant nest, the herbage has to be closely cropped, and the temperatures have to stay near the optimum.

If anything goes wrong, there are no surviving Large Blue larvae to pupate. If things go well, and too many Large Blue grubs are taken into a colony, the ant larvae are all consumed, and both ants and butterflies perish.

And then there’s the climate question − one that affects almost all insects.

“Overall, butterfly populations have moved northward by about 75km in the last 20 years as overall temperatures have risen,” Smith writes. “They are likely to move yet further.” – Climate News Network

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“Water Man of India” makes rivers flow again

“Water Man of India” makes rivers flow again

Revival of traditional rainwater harvesting has transformed the driest state in India, and could be used to combat the effects of climate change across the world.

Chennai, 6 April, 2015 − School textbooks in India have been telling children for generations that Rajasthan is an inhospitable state in the northwest of the country, constrained by the hot, hostile sands of the Thar Desert.

But the driest state in India has a softer, humane face as well – that of Rajendra Singh, known as the “Water Man of India”, whose untiring efforts in water conservation in arid Rajasthan have led to him being awarded the Stockholm Water Prize, commonly referred to as the Nobel Prize for Water.

Singh did not attempt to design a new technology to address Rajasthan’s water problems. He began simply by de-silting several traditional surface level rainwater storage facilities – called “johads” in the local Hindi language − that fell out of use during British colonial rule. And, in doing so, he has quenched the thirst of villages that were dying.

Thousands of villages followed his example, and so much water was captured and soaked into aquifers that dry rivers have begun to flow again.

Water wars

Singh believes that water conservation is vital to combat the effects of climate change and to avoid “water wars” in the future.

And such is his reputation on water issues that he received a call from Prince Charles, heir to the UK throne, seeking advice on how to handle the devastating summer floods in England in 2007.

In an interview with Climate News Network, Singh recalled how he began making water flow again in perennially dry Rajasthan by inculcating do-it-yourself initiatives in the villagers.

He explained: “I imbibed Gandhian ideals during my school days that emphasised working for empowerment of villages.

“As an Ayurvedic (traditional medicine system in India) doctor, I went to the Alwar district of Rajasthan early in 1982 to start a clinic and spread awareness among youth about health and hygiene.

“I was perturbed because the majority of young men had already left the village, and the rest were about to leave for green pastures in the cities as they were unable to battle the water scarcity. Besides, they also wanted to earn good money.

“Women, old people and children were left behind in the village. I reworked my doctor plans to address the water scarcity, as that would actually save people from several diseases.

A village johad in arid Rajasthan. Image: LRBurdak via Wikimedia Commons

A village johad in arid Rajasthan. Image: LRBurdak via Wikimedia Commons

“Along with the support of the villagers, I de-silted a couple of johads in Alwar. When rains filled them, people in neighbouring villages trusted my initiative and over 8,000 johads are renovated now.

“Hordes of youth have returned to their villages as water filled tanks and the standard of living in hamlets rose in a big way.”

He said that five rivers in this region had revived and started to flow again.

Johads are simple tanks built across a slope, with a high embankment on three sides and the fourth side left open for rainwater to enter. They hold water during rains and recharge the aquifer below to ensure continuous water supply to the neighbourhood in the dry season.

“Community-based water management yields
long-lasting results and is the only solution for water shortages”

But Singh explained: “After the advent of bore wells and pipelines connecting every hamlet in India, we forgot the traditional water conservation facility used by our ancestors.”

Having won the Stockholm prize, what does the future hold for the Water Man?

“My immediate plans are to take up a global-level campaign on water conservation and peace,” he said. “As predicted by several experts, the next world war will be for water. Unless every one of us starts at least now to save water and protect the water bodies, we face severe conflicts − apart from suffering climate change impacts. I will be leading the global water walk in the UK in August 2015.

“During his two visits (2004 and 2006), Prince Charles told me that he was impressed by the johad model of conservation. He then called me in 2007 to be part of his team of water engineers to work out all possibilities to address the crisis during the floods in England. They listened to my suggestions on creating the johad model on hilltops and downhill to arrest water in the hills and prevent floods in the future.”

In India, however, he is not confident that the government has the right ideas. “Our government is pushing a different idea of inter-linking of rivers, which will only politicise the water crisis. I was part of the national-level body to clean up the holy Ganga River from 2010 to 2012, but I quit as there was lack of accountability and it ended up as a toothless organisation.

“Inter-linking of rivers is not a solution for flood and drought. As far as India is concerned, it will result only in inter-linking of corruption and politics.

Hearts and brains

“What we need is inter-linking of the hearts and brains of people to take up water conservation in their homes and community. If exploitation of river water and polluting the river are stopped, every river will flow. Water engineering should be focused on conservation of each drop, and not on changing the course of rivers, which are designed by Mother Nature.”

Singh is also against the idea of privatising water supplies, and does not believe it would result in people using water more judiciously.

“Water is not a commodity,” he said. “In my own example, johads are de-silted by the people and used by people. Community-based water management yields long-lasting results and is the only solution for water shortages.

“When people realise their need and de-silt lakes and ponds as a group, they can use the water without having to pay for it. Right to water is every man’s right, and monetising water will increase conflicts in the society.

“Helping a community to have access to clean and safe water means helping the community to have a dignified life.” – 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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Warming raises drought’s threat to California

Warming raises drought's threat to California

US researchers say climate change, not random chance, is likely to be causing California’s long drought, one of the worst on record.

LONDON, 3 March, 2015 –  Climate change could be driving the sustained Californian drought. Arid spells have been more frequent in the last two decades than in the preceding century. And warmer global temperatures linked to man-made climate change could be at the heart of it.

Right now, California is in the sustained grip of one of its worst-ever droughts. Noah Diffenbaugh of Stanford University in California and colleagues looked at the patterns of precipitation, temperature and drought in the historical record and report in the Proceedings of the National Academy of Sciences that the latest conditions were not just a random outcome.

In a sunlit landscape with a long record of intermittent drought, researchers make such predictions only cautiously. But the Stanford team worked through 120 years of rainfall, snowfall and temperature data to identify connections.

They found that, puzzlingly, the two sets of measurements were not directly connected: for the first 60 or 70 years of the historical record, it could be wet and warm, or cool and dry. But drought was more likely in those years that by chance were both dry and warm.

Doubled risk

“Of course low precipitation is a prerequisite for drought but less rain and snowfall alone don’t ensure a drought will happen. It really matters if the lack of precipitation happens during a warm or a cool year,” said Dr Diffenbaugh.

“We’ve seen the effects of record heat on snow and soil moisture this year in California and we know from this new research that climate change is increasing the probability of those warm and dry conditions occurring together.”

On the flip-a-coin analogy, the weather could be either wet or dry, and cold or hot. So only one time in four, the weather was both hot and dry. For most of the past two decades, years in California have been either warm, or hot.

“Now the temperature coin is coming up tails most years. So even though the precipitation coin is coming up tails only half the time, it means that over the past two decades we have gotten two tails-warm and dry in half the years, compared with only a quarter of years in the preceding century.”

Most populous

Accordingly, drought frequency has doubled. Model simulations suggest that the risk of any year being both warm and dry will continue. More frequent warm years will also increase the probability of multi-year drought.

The present drought is now in its fourth year, and is one of the longest consecutive periods during which conditions are severely dry and severely warm.

And soon California – home to one in eight Americans, and the country’s most populous state – could enter a climate regime in which the risk that every year will be warmer than the 20th century norm will be almost 100%.

The findings, said Dr Diffenbaugh, provide “very strong evidence that global warming is already making it much more likely that California experiences conditions that are similar to what we have already experienced during the current severe drought.” – 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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Stalagmite links rain reduction to industrial revolution

Stalagmite links rain reduction to industrial revolution

Research shows the explosion of fossil fuel use to power the 19th-century industrial boom began the pattern of lower rainfall affecting the northern tropics. 

LONDON, 17 February, 2015 − Scientists have identified a human-induced cause of climate change. But this time it’s not carbon dioxide that’s the problem − it’s the factory and power station chimney pollutants that began to darken the skies during the industrial revolution.

Analysis of stalagmite samples taken from a cave in Belize, Central America, has revealed that aerosol emissions have led to a reduction of rainfall in the northern tropics during the 20th century.

In effect, the report in Nature Geoscience by lead author Harriet Ridley, of the Department of Earth Sciences at the University of Durham, UK, and international research colleagues invokes the first atmospheric crisis.

Acid rain

Before global warming because of greenhouse gases, and before ozone destruction caused by uncontrolled releases of chlorofluorocarbons, governments and environmentalists alike were concerned about a phenomenon known as acid rain.

So much sulphur and other industrial pollutants entered the atmosphere that raindrops became deliveries of very dilute sulphuric and nitric acid.

The damage to limestone buildings was visible everywhere, and there were concerns – much more difficult to establish – that acid rain was harming the northern European forests.

But even if the massive sulphate discharges of an industrialising world did not seriously damage vegetation, they certainly took a toll on urban human life in terms of respiratory diseases.

Clean-air legislation has reduced the hazard in Europe and North America, but it seems that sulphate aerosols have left their mark.

Researchers in a cave in Belize. Credit: Dr James Baldini/Durham University

Researchers in a cave in Belize.
Image: Dr James Baldini/Durham University

The Durham scientists reconstructed tropic rainfall patterns for the last 450 years from the analysis of stalagmite samples taken from a cave in Belize.

The pattern of precipitation revealed a substantial drying trend from 1850 onwards, and this coincided with a steady rise in sulphate aerosol pollution following the explosion of fossil fuel use that powered the Industrial Revolution.

They also identified nine short-lived drying spells in the northern tropics that followed a series of violent volcanic eruptions in the northern hemisphere. Volcanoes are a natural source of atmospheric sulphur.

Atmospheric pollution

The research confirms earlier suggestions that human atmospheric pollution sufficient to mask the sunlight and cool the upper atmosphere had begun to affect the summer monsoons of Asia, and at the same time stepped up river flow in northern Europe.

The change in radiation strength shifted the tropical rainfall belt, known as the intertropical convergence zone, towards the warmer southern hemisphere, which meant lower levels of precipitation in the northern tropics.

“The research presents strong evidence that industrial sulphate emissions have shifted this important rainfall belt, particularly over the last 100 years,” Dr Ridley says.

“Although warming due to man-made carbon dioxide emissions has been of global importance, the shifting of rain belts due to aerosol emissions is locally critical, as many regions of the world depend on this seasonal rainfall for agriculture.” – Climate News Network

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California is left high and dry by cannabis growers

California is left high and dry by cannabis growers

As California endures its worst drought since records began, illegal marijuana plantations are being blamed for further depleting precious water resources.

MENDOCINO, 4 February, 2015 − Take a flight over the densely forested area in California’s northern coastal region and it’s not hard to spot the marijuana plantations, their bright green plants standing out in clearings in the surrounding vegetation.

But now the big-money cannabis industry is being blamed for adding to water shortage problems caused by a three-year drought that has seriously affected California’s huge agricultural sector.

Although cultivating and using marijuana is illegal under US Federal law, California state law allows marijuana growing – as long as it is for medicinal purposes.

Rules flouted

However, the rules governing who can and cannot grow pot are complex – and openly flouted by thousands of growers, both big and small-time operators.

A report by the California Department of Fish and Wildlife (CDFW) estimates that, in this northern region of the state,  marijuana growing doubled between 2009 and 2012.

Marijuana plants are extremely thirsty, consuming between five and 10 gallons of water per day, depending on the phase of their growing cycle. Officials at the CDFW say that marijuana growers are sucking up precious water resources, exacerbating water shortages and threatening fish in the area’s lakes and streams.

Marijuana growing is particularly prevalent in an area of northern California known as The Emerald Triangle, encompassing Mendocino, Humbolt and Trinity counties. Some estimates say the crop accounts for up to 40% of the region’s economy.

Officials of the CDFW say that the small, well-established marijuana plantations – run by what are described as old time hippies − are not to blame for pumping up excess water.

Illegal marijuana plantations in forest clearings. Image: US Drug Enforcement Agency

Illegal marijuana plantations in forest clearings.
Image: US Drug Enforcement Administration

It is the incomers from outside the area − part of a “green rush” into highly-profitable marijuana growing – that are mainly to blame. These growers are out to make quick profits, and care little about the environment.

Growers of various crops in California are bound by rules stipulating that no more than 10% of the flow of water courses should be diverted for crops, and that such diversions should stop altogether in late summer, when water levels are at their lowest.

The CDFW says the incomers take vast amounts of water in order to harvest their crops as fast as possible. They also use excessive quantities of fertilizer, which leach into water courses, endangering fish stocks and polluting land.

Armed gangs

Fines of up to $8,000 per day are now being imposed for water theft, although monitoring illegal activities is difficult − and, at times, dangerous. Heavily-armed gangs are often involved in the marijuana growing business, and the CDFW has warned that, as the drought continues, conflicts over water resources are likely to increase.

The Emerald Growers Association, a group that represents some of northern California’s marijuana growers, says more regulation is needed to separate the legitimate pot growers from illegal ones.

The drought in California has been going on since 2011 and is described as the worst in the state since records began in the 1850s.

Arguments continue as to whether man-made climate change or natural phenomena are causing the drought.

Although significant amounts of rain last December helped alleviate dry conditions in some parts of the state, experts say more rain is urgently needed to feed watercourses and restock severely depleted aquifers. – Climate News Network

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