Tag Archives: Weather

Ice loss sends Alaskan temperatures soaring

Scientists studying Arctic sea ice and melt ponds on the Chuckchi Sea Image: NASA/Kathryn Hansen
Melting point: researchers study Arctic sea ice and melt ponds on the Chuckchi Sea
Image: NASA/Kathryn Hansen via Wikimedia Commons

By Alex Kirby

Scientists analysing more than three decades of weather data for the northern Alaska outpost of Barrow have linked an astonishing 7°C temperature rise to the decline in Arctic sea ice.

LONDON, 17 October, 2014 − If you doubt that parts of the planet really are warming, talk to residents of Barrow, the Alaskan town that is the most northerly settlement in the US.

In the last 34 years, the average October temperature in Barrow has risen by more than 7°C − an increase that, on its own, makes a mockery of international efforts to prevent global temperatures from rising more than 2°C above their pre-industrial level.

A study by scientists at the University of Alaska Fairbanks analysed several decades of weather information. These show that temperature trends are closely linked to sea ice concentrations, which have been recorded since 1979, when accurate satellite measurements began.

The study, published in the Open Atmospheric Science Journal, traces what has happened to average annual and monthly temperatures in Barrow from 1979 to 2012.

Most striking

In that period, the average annual temperature rose by 2.7°C. But the November increase was far higher − more than six degrees. And October was the most striking of all, with the month’s average temperature 7.2°C higher in 2012 than in 1979.

Gerd Wendler, the lead author of the study and a professor emeritus at the university’s International Arctic Research Center, said he was “astonished”. He told the Alaska Dispatch News: “I think I have never, anywhere, seen such a large increase in temperature over such a short period.”

The study shows that October is the month when sea ice loss in the Beaufort and Chukchi Seas, which border northern Alaska, has been highest. The authors say these falling ice levels over the Arctic Ocean after the maximum annual melt are the reason for the temperature rise. “You cannot explain it by anything else,” Wendler said.

They have ruled out the effects of sunlight because, by October, the sun is low in the sky over Barrow and, by late November, does not appear above the horizon.

Instead, they say, the north wind picks up stored heat from water that is no longer ice-covered in late autumn and releases it into the atmosphere.

At first sight, the team’s findings are remarkable, as Barrow’s 7.2°C rise in 34 years compares with a global average temperature increase over the past century of up to about 0.8°C. But what’s happening may be a little more complex.

Warming faster

The fact that temperatures in and around Barrow are rising fast is no surprise, as the Arctic itself is known to be warming faster than most of the rest of the world.

The Intergovernmental Panel on Climate Change says observed warming in parts of northern Alaska was up to 3°C from the early 1980s to the mid-2000s. It also concludes that about two-thirds of the last century’s global temperature increase has occurred since 1980.

But Barrow’s long-term temperature rise has not been uniform, the Fairbanks study says. Its analysis of weather records between 1921 and 2012 shows a much more modest average annual rise, of 1.51°C. In 2014, the city experienced the coolest summer day recorded − 14.5°C.

So one conclusion is to remember just how complex a system the climate is − and how even 34 years may be too short a time to allow for any certainty. − Climate News Network

Australia gets early blast of more extreme heat

A bushfire rages in the hills near Lithgow, New South Wales, last year Image: Lithgowlights via Wikimedia Commons
Hot spot: a bushfire rages in the hills close to Lithgow, New South Wales, last year
Image: Lithgowlights via Wikimedia Commons

By Kieran Cooke

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

Solar dimming reflects complexity of climate change

 

Ominous signs: monsoon clouds roll in over Visakhapatnam in south-east India Image: Adityamadhav83 via Wikimedia Commons
Monsoon clouds roll in over Visakhapatnam, south-east India, but rainfall is reducing
Image: Adityamadhav83 via Wikimedia Commons

By Tim Radford

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

Oxford is rewriting ancient weather record books

The dried-out and rutted Port Meadow in Oxford at the end of September Image: Radcliffe Meteorological Station
The dried-out and rutted Port Meadow in Oxford at the end of September
Image: Radcliffe Meteorological Station

By Alex Kirby

New data added to the unique archive documenting Oxford’s weather since 1767 shows that the university city has just had its second driest September on record – following close on its wettest January.

LONDON, 8 October, 2014 – Several parts of the world like to claim that their unpredictable weather allows you to experience spring, summer, autumn and winter in the space of a single day. The city of Oxford, in the English Midlands, cannot make that boast, but it has broken a surprising number of weather records in a fairly short time.

In its latest bout of meteorological exuberance, Oxford has just had its second driest September since records began almost 250 years ago. It recorded 4.1mm of rainfall over last month, with 1929 the only previous year to have had a month with a lower total − just 2.5mm.

This follows hard on the heels (climatically speaking, at least) of the first month of 2014, which was, by contrast, the wettest January the city has recorded, with total rainfall of 146.9 mm − almost three times the normal and 35 times September’s paltry figure.

Rainiest stretch

Go back a little further, though, for wet weather that really meant business: the nine months from 1 April to 31 December 2012 proved the rainiest nine-month stretch in Oxford’s recorded experience.

Yet the people of Oxford might at that point have been lulled into expectations of balmier weather, because 2011 had turned out to be the city’s joint second-warmest year on record. Six of the top 10 warmest years recorded have occurred since 2000, the warmest being 2006.

Oxford, home of the oldest university in the English-speaking world, knows the details of its weather peaks and troughs so well because it possesses a unique archive.

The Radcliffe Meteorological Station, based at Oxford University’s Green Templeton College and maintained by the university’s School of Geography and the Environment, holds the longest series of temperature and rainfall records for one site in Britain, with records dating back to 1767.

Of nearly 3,000 monthly records since Oxford’s measurements began, only 30 have been drier than last month. This puts September 2014 in the top 1% of the city’s driest ever months.

Dr Ian Ashpole, who collects the daily measurements for Radcliffe, said of the latest record to fall: “Based on analysis of variability around the mean September rainfall over the last 248 years, we can say that no Septembers since 2000 have been unusually wet, but three have been unusually dry.”

Emerging trend

Only one of the other 30 driest months has occurred in the autumn (September to November); 14 have been in spring (March to May), eight in summer (June to August), and the remaining seven during the winter. Four of the driest months have occurred this century.

This year’s September record may be part of an emerging trend in the month since 2000. The 248-year long-term average for September is 60mm, but since the turn of the century 12 have been below this average, including six under 50% of expected rainfall. Only two years have been above the 60mm average − 2008 (72.9mm) and 2006 (90.8mm).

September 2014’s temperature was not quite as extreme as the low rainfall, but still came in at equal seventh (with 1998) at 15.9°C, compared with the long-term average of 13.7°C. Five of the warmest eight Septembers since 1767 have been recorded since 1998.

However, the data from Radcliffe applies only to the city of Oxford and a short distance around it, and can tell us nothing about weather elsewhere in the UK or further afield. – Climate News Network

Surfers fear climate will wipe out big waves

Breaking up: surfers may have to settle for smaller waves in future Image:  Brocken Inaglory via Wikimedia Commons
Breaking up: surfers may have to settle for riding much smaller waves in future
Image: Brocken Inaglory via Wikimedia Commons

By Kieran Cooke

Dedicated surfers, deeply involved with monitoring the natural coastal environment around the world, warn that climate change now poses a major threat to this booming leisure industry.

LONDON, 5 October, 2014 − The world’s oceans are alive with surfers enjoying one of the fastest growing leisure activities. It is estimated there are now at least 35 million people around the globe who regularly ride the waves, and many thousands of people are employed in what has grown into a multi-billion dollar industry.

A warming world should be good news for all those artists of the waves. Warming oceans mean more storms, and the theory goes that more storms will lead to ever bigger waves. So why then are surfing websites – the internet is waterlogged with them – full of concern about changes in the climate?

Two studies appearing in the journal Nature Climate Change have made surfers stand up on their boards and reconsider the situation.

A study led by Dr Andrew Dowdy, a researcher at the Centre for Australian Weather and Climate Research (CAWCR) predicts that rising temperatures will in fact reduce the number of storms causing big waves by the end of the century on the central east coast of Australia.

Potentially destructive

The storms that do occur could be more intense and potentially destructive – but the consistency of wave patterns will be reduced.

That’s bad news for surfers of the future in that area – one of the world’s surfing hotspots. They’ll just have to move elsewhere. Dowdy told the Climate News Network that his projections only relate to that particular region, and they are not necessarily applicable to other coastal regions.

But another study, led by Mark Hemer, a senior research scientist at CAWCR, indicates that surfers might be having to ride smaller waves in future in other parts of the world as well.

Using ocean modelling techniques, Hemer and his colleagues predict a decrease in annual wave height over more than 25% of the global ocean area by the end of the century. The North Atlantic is likely to see a decrease in wave heights during all seasons, and waves are likely to be smaller in the winter months in the North Pacific and Indian Ocean.

But all is not lost. The study predicts that some regions − including  the waters off the south coast of Australia and New Zealand − will see bigger waves of between 5% and 10% above present size averages during winter months.

Surfers are worried about other climate change related threats to their activities. There are fears that rising sea levels could threaten key surfing areas.

Surfers regularly monitor water conditions – everything from acidity levels to rubbish content and sewage levels in the seas.

Surf zone

The Save the Waves Coalition − a US-based group that lobbies to protect the coastal environment, with a particular focus on what it calls the surf zone − monitors development activities in surfing areas worldwide.

Its “endangered waves” campaign lists projects that threaten key surfing areas – from plans to construct a nuclear power station on the coast of South Africa to a series of coal-fired power plants proposed for the coast of Chile.

And Climate change is seen as a major challenge facing the surfing industry.

“The unfortunate truth is that the threats to surfing habitat are now growing exponentially due to the impacts of man-made climate change,” says the California-based Sustainable Surf organisation. – Climate News Network

Human handprint marks Australia’s hottest year

Australian weather stations recording temperatures of 45°C or above in January 2013 Image: Squidman18559 via Wikimedia Commons
Australian weather stations recording temperatures of 45°C or above in January 2013
Image: Squidman18559 via Wikimedia Commons

By Tim Radford

Despite the Australian prime minister’s climate science scepticism, research funded by taxpayers has unanimously found man-made climate change guilty of causing the country’s record-breaking temperatures last year.

LONDON, 4 October, 2014 − Scientists are fond of saying that it is difficult to pin the blame for any one climate event onto climate change. But they have just made an exception by reporting that many things that happened in Australia in 2013 bore the signature of man-made climate change.

In that one year, Australia recorded its hottest day ever, its hottest month in the history books, its hottest summer, its hottest spring, and its hottest year overall.

Extreme events

And in a special edition of the Bulletin of the American Meteorological Society, examining extreme events around the world during 2013, a series of papers home in on the Australian heat waves, and identify a human influence.

“We often talk about the fingerprint of human-caused climate change when we look at extreme weather patterns,” said David Karoly, professor of meteorology at the University of Melbourne’s School of Earth Sciences. “This research across four different papers goes well beyond that.

“If we were climate detectives, then Australia’s hottest year on records in 2013 wasn’t just a smudged fingerprint at the scene of the crime, it was a clear and unequivocal handprint showing the impact of human-caused global warming.”

In general, the world’s meteorologists have found nothing unequivocal to suggest that global warming due to greenhouse gas emissions from fossil fuel combustion caused, for example, the Californian drought, extreme snow in the Spanish Pyrenees or an October blizzard in South Dakota in the US.

But they did find that global warming doubled the chance of severe heat waves in Australia − making extreme summer temperatures five times more likely, increasing the chance of drought conditions sevenfold, and making hot temperatures in spring 30 times more probable.

And they reckoned that the record hot year of 2013 would have been virtually impossible without global warming. At a conservative calculation, the science showed that the heat of 2013 was made 2,000 times more likely by global warming.

Different picture

Paradoxically, Australia’s prime minister, Tony Abbott, was one of the world leaders who pointedly stayed away from the recent United Nations climate change summit in New York, and in the past has taken a sceptical stance on climate science. Yet research funded by Australian taxpayers has consistently painted a different picture.

“When it comes to what helped cause our hottest year on record, human-caused climate change is no longer a prime suspect − it is the guilty party,” said Dr Sophie Lewis, a paleoecologist at the Australian National University.

And her colleague, Sarah Perkins, a climate scientist at the Australian Research Council’s Centre of Excellence for Climate System Science, warned that 2013 was only the beginning.

She said: “If we continue to put carbon into our atmosphere at the currently accelerating rate, years like 2013 will quickly be considered normal, and the impacts of future extremes will be well beyond anything modern society has experienced.” – Climate News Network

Early warning for US states in Tornado Alley

Dark destroyer: a tornado tears through Kansas, one of the US states in ‘Tornado Alley’ Image: Goodland/US National Weather Service via Wikimedia Commons
Dark destroyer: a tornado tears through Kansas, one of the US states in ‘Tornado Alley’
Image: Goodland/US National Weather Service via Wikimedia Commons

By Tim Radford

Research showing that tornadoes are gradually forming earlier in the US could help states in the frontline to prepare better to withstand the storms’ devastating effects.

LONDON, 21 September, 2014 − The terrifying whirlwinds that punctuate the mid-Western summer in the US so frequently as to earn the nickname “Tornado Alley” for the southern plains region states such as Nebraska, Kansas, Oklahoma and northern Texas are forming up to two weeks earlier than they did 60 years ago.

John Long and Paul Stoy, research scientists at Montana State University, report in the journal Geophysical Research Letters that, on average, the tornado season advanced by one week between 1954 and 2009. For many states, the shift is almost 14 days. Peak activity on average used to occur on 26 May, but this century the peak has shifted to 19 May.

On the plus side, the tornado season is also ending earlier than it did in the 1950s.

Tornadoes happen in every continent except Antarctica, but particularly in America. There are on average around 1,300 in the US every year, and on average they kill about 60 people.

They are graded according to the punch they pack: the Fujita scale of tornado rating ranges from F1, with winds at 117 kilometres per hour to 180 kph, to F5, at between 420 kph and 511 kph.

Increase in ferocity

Long and Stoy are not the first to note a change in the pattern of storms. Recently, researchers calculated that, overall, the number of tornadoes each year may be dwindling, but their ferocity seems to be on the increase.

Some researchers think climate change is a factor, but the two Montana scientists are more cautious. They say it takes a mix of topography, temperature, wind patterns and other factors to set in motion the swarms of storms that can slam into a town and wreck tens of thousands of homes in a matter of minutes.

“Observed climate trends cannot fully account for observations,” they say in the formal language demanded by science journals.

But they also point out that if the tornado season is occurring earlier in the year, then it might help individuals, local authorities, emergency services and state governments to know this, and to be prepared. – Climate News Network

Weather patterns show climate is changing US

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

By Tim Radford

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

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

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

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

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

More arid

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

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

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

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

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

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

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

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

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

Highest uplift

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

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

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

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

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

Less snow won’t end blizzard hazard

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

By Tim Radford

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

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

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

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

Climate models

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

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

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

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

Heaviest falls

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

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

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

Elections sideline São Paulo drought crisis

Drought has now hit dams on rivers such as the Paranapanema Image: José Reynaldo da Fonseca via Wikimedia Commons
Past prime: drought has now hit dams on rivers such as the Paranapanema
Image: José Reynaldo da Fonseca via Wikimedia Commons

By Jan Rocha

As South America’s biggest city suffers its worst drought in over a century, São Paulo state politicians are putting re-election prospects ahead of the need to introduce measures to address a desperate situation for millions of people.

SÃO PAULO, 25 August, 2014 − Outside the semi-arid area of the north-east, Brazilians have never had to worry about conserving water. Year in, year out, the summer has always brought rain.

But that has changed dramatically. São Paulo, the biggest metropolis in South America, with a population of almost 20 million, is now in the grip of its worst drought in more than a century − a water crisis of such proportions that reports on the daily level of the main reservoir arefollowed as closely as the football results.

The lack of rain is also affecting the dams that produce most of Brazil’s energy, highlighting the urgent need to diversify power sources.

And yet the state governor, wary of the effects on his prospects in forthcoming elections, has refused to introduce measures to ration, or even conserve, water.

Mighty rivers

Brazil is blessed not only with the mighty Amazon and all its huge tributaries, but also with dozens of other lengthy, broad rivers − once the highways for trade and slaving expeditions, but now providing waterways for cargo, power for dams, and water for reservoirs.It has at least 12% of the world’s fresh water supply.

But five of the principal rivers – the Tiete, Grande, Piracicaba, Mogi-Guaçu and Paraiba do Sul − that cross or border São Paulo, Brazil’s wealthiest state, have less than 30% of the water they should have at this time of year, according to data from the regional Hydrographic Basin Committee and from the National Electric System Operator (ONS).

Other major water sources – such as the Paraná, South America’s second biggest river, and the Paranapanema − are also suffering from the long dry period. The ruins of towns flooded for dam reservoirs have reappeared, fishermen’s boats are beached because the fish have disappeared, and navigation is at a standstill.

The transport of grain and other cargos to the port of Santos, via the river network, had to be suspended after the water level fell by up to eight metres. The equivalent of 10,000 lorryloads of cargo have been transferred by road so far.

Many industries have suspended their activities because of lack of water, and the drought has resulted in the loss of part of the coffee, sugar cane and wheat crops in one of Brazil’s most important agricultural states.

The hydrological period lasting from October 2013 to March 2014 was the driest for 123 years, according to the Agronomic Institute of Campinas, the oldest institute of its kind in Latin America .

Lowest volume

The federal government’s energy research company, EPE, found that in the first three months of 2014 the volume of rain was the third lowest since the 1930s.

It was the third consecutive year of reduction for the reservoirs of the hydroelectric dams that make up the South-east/Centre-West System, where many of Brazil’s biggest cities are located. From 88% in 2011, the volume of water in them had fallen to 38% by April 2014 – the month in which the dry season begins in this region.

By mid-August, the reservoirs of the Cantareira system, which supplies the water for almost 8.5 million of São Paulo’s inhabitants, had fallen to just 13.5% of capacity.

Yet the state government of São Paulo has so far refused even to admit that there is a crisis. The problem is the October elections, when Governor Geraldo Alkmim is running for re-election. Like most politicians, he does not want to be associated with a crisis. The word “rationing” is taboo.

Instead, unofficial rationing – what might be called rationing by stealth – is in operation. At night, the São Paulo Water Company, Sabesp, is reducing the pressure in the water system by 75%, leaving residents in higher areas of the city with dry taps.

Over 80% of the country’s energy comes from hydroelectric power, and dozens more giant dams are under construction or planned, mostly in the Amazon basin. The government has been strangely reluctant to invest in, or even encourage, other sources of abundant renewable energy, such as wind, solar and biomass.

The over-reliance on hydropower has already led to a distortion. The back-up system of thermo-electric plants, run on gas and diesel, and designed for emergencies, has had to increase production from 8% in 2012 to cover 25% of energy demand this year − thus contributing to higher carbon emissions.

Politics have also interfered with the special crisis committee set up to monitor the drought situation, with representatives from local and federal agencies unable to agree on what to do.

The Sao Paulo energy company, CESP, unilaterally decided this month to reduce the volume of water released from the shared Jaguari reservoir to the neighbouring state of Rio de Janeiro for electricity generation, in order to keep more for its own water needs.

Dangerous precedent

For Marcio Zimmerman, executive secretary of the Ministry of Mines and Energy, CESP’s action creates a dangerous precedent. “There will be chaos if everyone decides to rebel against the ONS,” he said.

The realisation that climate change is already leading to major changes in weather patterns has sounded alarm bells among the business community about the need to diversify energy sources and conserve water.

Early this month, at a seminar organised by the Brazilian Business Council for Sustainable Development, the chief executives of more than 20 top companies drew up a list of 22 crisis-related proposals to be put to the presidential candidates in October’s election.

Newspaper editorials are now urging the politicians to take their heads out of the sand and involve the population in a serious discussion on the crisis and its effects on the water supply, energy generation, and food production .

The Rio newspaper O Globo declared: “They belittle the potential for efficiency available in a society accustomed to waste. When they act, it might be too late.” – Climate News Network