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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World needs early warning of climate-linked disasters

World needs early warning of climate-linked disasters

A leading French government minister says the number of natural disasters connected to climate change has doubled in two decades, and is urging a global early warning system.

LONDON, 15 March, 2015 − A senior French political leader, foreign minister Laurent Fabius, has told an international conference on how to reduce the risk from natural disasters that 70% of them are now linked to climate change, twice as many as twenty years ago.

Mr. Fabius is the incoming president of this year’s round of negotiations by member states of the UN climate change convention, to take place in Paris in December. He said disaster risk reduction and the struggle against climate change went hand in hand: “It is necessary to tackle these problems together and not separately.”

He was speaking against the background of two events which occurred thousands of miles apart on 14 March, linked by nothing except tragic coincidence.

In the Japanese city of Sendai the third UN world conference on disaster risk reduction began a five-day meeting. In the South Pacific Cyclone Pam brought death and devastation to the 83-island nation of Vanuatu on a scale seldom recorded in the region.

Vivien Maidaborn, executive director of Unicef New Zealand, said the disaster could prove one of the worst in Pacific history. “The sheer force of the storm, combined with communities just not set up to withstand it, could have devastating results for thousands across the region,” she said.

Hope shattered

A Unicef worker in Vanuatu described the cyclone as “15 to 30 minutes of absolute terror” for “everybody in this country” as it passed over.

The president of Vanuatu, Baldwin Lonsdale, told the UN meeting: “I am speaking with you today with a heart that is so heavy… All I can say is that our hope for prospering into the future has been shattered.”

The UN Secretary-General, Ban Ki-moon, opened the Sendai meeting, attended by 4,000 people from 186 countries, with a reminder that annual economic losses from natural disasters are now estimated to exceed US$ 300 billion annually.

He said: “We can watch that number grow as more people suffer. Or we can dramatically lower that figure and invest the savings in development. Six billion dollars allocated each year can result in savings of up to US$360 billion by 2030.”

A report released at the meeting, United for Disaster Resilience, prepared by insurance companies working with the UN Environment Programme’s Finance Initiative, said: “In the past decade, average economic losses from disasters were about US$190 billion per year, while average insured losses were about US$60 billion per year. This century, more than one million people have already lost their lives to disasters.”

Alert system

The UN Office for Disaster Risk Reduction, UNISDR, says global climate-related disasters between 1980 and 2011 included:

  • 3,455 floods
  • 2,689 storms
  • 470 droughts
  • 395 episodes of extreme temperature.

Mr Fabius said the creation of a worldwide early warning system for climate disasters could provide the most vulnerable countries, including small island developing states, with access to real-time weather and climate updates, information and communications technology, and with support for an SMS-based alert system. UNISDR’s PreventionWeb already links those working to protect communities against disaster risk.

Since the last such disaster risk conference in 2005, the UN says, at least 700,000 people have died, 1.7 billion more have been affected, and economic losses from major reported disasters total US$1.4 trillion.

The conference is working to prepare a new plan for reducing the risks of disasters. Margareta Wahlström, head of UNISDR, said: “After three years of consultation on a post-2015 framework which updates the current Hyogo Framework for Action, there is general agreement that we must move from managing disasters to managing disaster risk.” She said the framework would help to reduce existing levels of risk and avoid the creation of new ones. − Climate News Network

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Forecast of less stormy weather is not good news

Forecast of less stormy weather is not good news

Scientists say intense droughts and heatwaves are the likely climate-related outcome of less frequent summer storms in recent decades.

LONDON, 14 March, 2015 − Storms on fine summer days might be unwelcome to many, but at least the rain and winds does act like a big brush on the weather system − bringing fresh air and relief from oppressive heat.

And scientists now warn that a decrease in the frequency of such storms across much of the US, Europe and Russia in recent decades − with climate change the probable cause – could mean that summer heat waves and droughts are likely to become ever more persistent and intense.

Scientists from the Potsdam Institute for Climate Impact Research (PIK) in Germany report in Science journal that storm activity data they collected from weather stations and satellites shows a clear reduction in the frequency and intensity of summer storms in the mid-latitudes of the northern hemisphere over recent decades.

Heat extremes

This makes heat extremes – such as the period of intense heat that hit Russia in 2010, causing widespread crop failure and multiple wildfires – ever more likely.

“While you might expect reduced storm activity to be something good, it turns out that this reduction leads to a greater persistence of weather systems in the northern hemisphere mid-latitudes,” says Dim Coumou, an Earth systems analyst at PIK and lead author of the study.

“In summer, storms transport moist and cool air from the oceans to the continents, bringing relief after periods of oppressive heat. Slack periods, in contrast, make warm weather conditions endure, resulting in the build-up of heat and drought.”

The PIK study looks at a particular set of turbulences − called synoptic eddy − in weather systems over the summer months, and calculates the total energy of their wind speeds.

“Climate change disturbs airstreams that are
important for shaping our weather”

It shows that the level of this energy, which measures the interplay between the intensity and frequency of high and low pressure systems in the atmosphere, has dropped by approximately 10% over the past 35 years.

Previous studies have focused mostly on winter storms, which tend to do more damage than those in summer. The PIK study found that average storm activity in the winter months in many regions is largely unchanged.

The Arctic region probably holds the key to the drop in summer storm activity, say the scientists.

Temperatures around the globe are rising due to greenhouse gas emissions caused by the burning of fossil fuels, but the rate of warming is faster in the Arctic.

As the sea ice cover in the Arctic shrinks, the surface reflects less sunlight and absorbs more heat. The warmer waters then warm the air, setting in motion a process through which the relative difference in temperature is reduced between the cold polar region and the rest of the northern hemisphere.

Air circulation

Temperature differences drive air circulation. As the difference in temperatures between the two regions decreases, so does the rate of summer storm activity.

The study also found that this reduction in the temperature differential weakens the polar jet stream, which − often travelling at speeds of more than 200 miles per hour high up in the troposphere − acts as a boundary between the cold polar air and warmer air further south.

“From whichever angle we look at the heat extremes, the evidence we find points in the same direction,” Dim Coumou says.

“The heat extremes do not just increase because we’re warming the planet, but because climate change disturbs airstreams that are important for shaping our weather.

“The reduced day-to-day variability that we observed makes weather more persistent, resulting in heat extremes on monthly timescales. So the risk of high-impact heat waves is likely to increase.” – 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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Ancient landscapes point to dramatic climate change

Ancient landscapes point to dramatic climate change

Scientists believe Chinese civilisation could have been founded by climate refugees after the collapse of an Inner Mongolian culture over 4,000 years ago.

LONDON, 26 February, 2015 − Chinese and US scientists have uncovered prehistoric evidence of mass migration triggered by climate change.

Something occurred 4,200 years ago – a collapse of the monsoon system, the sapping of the groundwater, the sudden drainage of a lake – that brought a Neolithic culture to an end and left nothing but sandy landscapes in China’s Inner Mongolia region.

Archaeological evidence has revealed the jade carvings that once marked the Hongshan culture, along with evidence of hunting, fishing and even commercial traffic with Mongolian shepherds. And then the artefacts stop.

There is a 600-year period marked by no evidence of human settlement at all. Where there had once been streams, lakes grassland and forest, and a flourishing new Stone Age culture, only shifting sand dunes remained.

Recent origin

Xiaoping Yang, professor in the Institute of Geology and Geophysics at the Chinese Academy of Sciences, Beijing, and research colleagues from China, New Mexico, Hawaii and Texas report in the Proceedings of the National Academy of Sciences that they used a new laboratory technique to show that the northern Chinese deserts were not – as many had thought – millions of years old.

Instead, they are of very recent origin, and the researchers found evidence of dramatic change during human settlement.

In addition, the exploration of artefacts in the region – and the discovery, among other things, of a jade object that might be a dragon − now suggests that Chinese culture and identity may have its origins in the far north, rather than in the Yellow River basin, which has been the archaeologists’ working hypothesis until now.

“This study has far-reaching implications for understanding how human populations respond and adapt to drastic climate change”

If that was so, then one of the world’s great civilisations was founded by climate refugees.

Extraordinary claims require extraordinary evidence. The Beijing team used space-based radar topography measurements to show that the dunes and depressions of the Hunshandake region of northern China had once been home to lakes fed by a system of streams and rivers.

This was then confirmed with fossil evidence of tree pollens and algae that typically float in freshwater lakes.

The scientists built up a timetable of events by dating sediment samples with a technique called optically-stimulated luminescence, which reveals when minerals were last exposed to sunlight.

They started with the proposition that an extraordinary series of droughts occurred in the northern hemisphere around 4,200 years ago, in North Africa, the Middle East and the Mediterranean.

Something similar happened in Hunshandake at around that time. The monsoon rainfall weakened, the lake levels dropped dramatically, and the water table was lowered drastically − and perhaps finally.

The researchers call it a “rapid and catastrophic shift”. And they warn that their research suggests that attempts to reverse the advance of the deserts in the region are likely to have limited success, because the change in the hydrological system is irreversible. Any water that fell there would just trickle away.

Human departure

Such discovery of links between climate and human departure is not isolated. In the last two years, meteorologists and archaeologists have identified climate change as a factor in the collapse of the Bronze Age Mediterranean culture, the implosion of the Assyrian empire at Nineveh in the 7th century BC, and the end of the Indus Valley civilisation 4,000 years ago.

Climate has also been implicated in the advance of the armies of Genghis Khan in the 13th century.

While climate change cannot explain everything about such shifts in ancient history, it is a factor.

But, say the Beijing scientists, “our evidence suggests that Hongshan culture was devastated by combined regional green/desert vegetation shift”, and that the change was intensified and made final by a sudden and final sapping of the groundwater table below the lakes and pastures in the region.

The scientist who used the optically-stimulated luminescence technique, geologist Steven Forman, of Baylor University in Texas, says: “This study has far-reaching implications for understanding how human populations respond and adapt to drastic climate change.” – 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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Arid areas of US face prospect of ‘megadroughts’

Arid areas of US face prospect of ‘megadroughts’

Scientists in the US predict droughts worse than the extreme conditions believed to have played a part in ending a once-flourishing medieval culture.

LONDON, 15 February, 2015The Central Plains and Southwest region of the US face “unprecedented” droughts later this century, according to new research.

While Midwest states have experienced ever more flooding over the last 50 years, the regions already suffering from extremes of aridity are being warned to expect megadroughts worse than any conditions in the last 1,000 years.

Climate scientist Benjamin Cook, of NASA’s Goddard Institute for Space Studies, New York, and colleagues report in a new journal, Science Advances, that they looked at historical evidence, climate projections and ways of calculating soil moisture.

They found that the drought conditions of the future American west will be more severe than the hottest, most arid extended droughts of the 12th and 13th centuries, which are thought to have played a role in ending the once-flourishing Pueblo culture of the American Southwest.

Computer predictions

The growth rings of trees provided the evidence for reconstructions of what climatologists call the warm Medieval period, and the researchers matched the picture from the past with 17 different computer model predictions of the climate later in the 21st century.

The conclusions were ominous: nearly all the models predicted that the Plains and the Southwest would become drier than at any time in the last 1,000 years.

Even though winter rain and snowfall could increase in parts of California – currently in the grip of calamitous drought – in the decades to come, overall there will be lower cold season precipitation and, because of higher temperatures, ever more evaporation and ever more water demand for the surviving vegetation.

The authors conclude: “Ultimately, the consistency of our results suggests an exceptionally high risk of a multidecadal megadrought occurring over the Central Plains and Southwest regions during the late 21st century, a level of aridity exceeding even the persistent megadroughts that characterised the Medieval era.”

“I was honestly surprised at just how dry the future is likely to be”

Co-author Toby Ault, head of the Emergent Climate Risk Lab at Cornell University, warned of future megadroughts only last year. He says: “I was honestly surprised at just how dry the future is likely to be.”

But to the north, in the American Midwest, conditions have begun to change in a different way. Iman Mallakour and Gabriele Villarini, of the Department of Civil and Environmental Engineering at the University of Iowa, collected evidence from 774 stream gauges in 14 states from 1962 to 2011.

Flood events

They report in Nature Climate Change that a third of them had recorded a greater number of flood events, and only one in 10 recorded a decrease.

The pattern of increase extended from North Dakota south to Iowa and Missouri, and east to Illinois, Indiana and Ohio.

The region was hit by economically-disastrous, billion-dollar floods in 1993, 2008, 2011, 2013 and 2014. The researchers wanted to see whether flooding was really on the increase, or whether perception of greater flooding was what they called “an artefact of our relatively short collective memory”.

The result is a confirmation of perceived increase. It was not an artefact.

“It’s not that big floods are getting bigger, but that we have been experiencing a larger number of big floods,” Dr Villarini says. – Climate News Network

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Climate data gives mixed message on storm forecasts

Climate data gives mixed message on storm forecasts

New research suggests that climate change won’t after all lead to more storms − but the bad ones could be even more devastating.

LONDON, 8 February, 2015 − Keep calm and hold on to your hat. The atmosphere will not become increasingly stormy as the planet warms and the climate changes.

The downside is that while the number of storms will probably remain unchanged, and weak storms could even become weaker, new research warns that the strongest storms could become significantly stronger.

For at least three decades, researchers have worked on the assumption that as the average energy of the atmosphere increased with warming, so would the potential for extremes of heat and drought, flood and cyclone, typhoon or hurricane.

Frederic Laliberté, of the University of Toronto in Canada, and atmospheric physicist colleagues don’t exactly disagree: they just took a closer at the way in which some things are likely to change.

Heat engine

They report in the journal Science that they considered the interplay of weather, moisture and temperature around the globe as an atmospheric heat engine – which it is – and compared it to a famous 19th-century theoretical model of energy and output known to engineers, physicists and meteorologists everywhere as the Carnot Cycle.

The engine works like this: air warmed by the sun moves across the ocean and takes up water through evaporation. The warmer the air, the more water it takes up. The air current gets to the Equator and then ascends through the atmosphere, cooling as it rises.

As the air cools, the burden of water condenses and releases heat. When enough heat is released, the air rises even further, pulling more air behind it to produce a thunderstorm.

A more vigorous water cycle could actually take yet more steam out of the atmospheric circulation.
The winds could run out of puff.

So the atmospheric engine’s output is the amount of heat and moisture it distributes between the Equator and the Poles.

“By viewing the atmospheric circulation as a heat engine, we were able to rely on the laws of thermodynamics to analyse how the circulation would change in a simulation of global warming,” Dr Laliberté said. “We used these laws to quantify how the increase in water vapour that would result from global warming would influence the strength of the atmospheric circulation.

To do this, they had to build on climate models, examine climate records for the last 30 years, and simulate the planet’s climate from 1982 to 2098.

Energy budget

They worked out that although the atmosphere is a machine, it isn’t a perfectly efficient one. At least a third of the atmosphere’s energy budget was dedicated simply to evaporating water and then dropping it as rain, and this drain on the overall energy available actually reduced the potential intensity of the winds around the planet, which is why the weather is, quite often, pleasant.

Like all science, the findings will be tested − first by other scientists and then by the planet itself. Time will tell. But the conclusion is that a more vigorous water cycle could actually take yet more steam out of the atmospheric circulation. The winds could run out of puff.

This wouldn’t work smoothly, though. Air masses that didn’t get to the top of the atmosphere would be weakened, but those that did get to the top would be more tempestuous.

“Powerful storms are strengthened at the expense of weaker storms,” Dr Laliberté says. “We believe atmospheric circulation will adapt to this less efficient form of heat transfer and we will see either fewer storms overall, or at least a weakening of the most common, weaker storms,” – 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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