Big cities head for water crisis as populations explode

Big cities head for water crisis as populations explode

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

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

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

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

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

Supply analysis

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

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

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

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

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

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

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

Rainfall data

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

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

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

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

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

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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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US coastal cities warned of daily high tide floods

US coastal cities warned of daily high tide floods

Scientists report that many cities near the coasts of the US should prepare for daily flooding at high tide by mid-century because of rising sea levels.

LONDON, 5 January, 2015 − Oceanographers have just identified the US coastal regions likely to experience 30 days or more of “nuisance” flooding every year. And the answer is that most of the American coast will experience high waters that are 30-60 cms above local high tides, at least 30 times a year.

Nuisance flooding means just that − somewhere between an inconvenience and modest damage. But climate change, and its attendant sea-level rise, will make them much more frequent, and possibly more damaging.

William Sweet and Joseph Park, scientists at the National Oceanic and Atmospheric Administration (NOAA), report in the journal Earth’s Future that sea level rise has accelerated from 1.7mm a year in the last century to 3.2mm a year in the last two decades, and flooding events that were once extreme could become the mean.

The oceanographers wanted to establish what they call “regional tipping points” – places where extra high waters would wash across streets and promenades normally above water and start to do so frequently.

Detailed picture

New York was inundated when Superstorm Sandy hit the city in 2012, and studies have repeatedly warned that coastal inundations will cost communities colossal sums each year by 2050, and even more by 2100. Nor is the US alone in this respect. There have been ominous calculations for the UK as well.

The NOAA scientists add detail to the big picture. They started with the projections for global sea level rise delivered by the Intergovernmental Panel on Climate Change and then included the more local factors such as land subsidence or settlement, and cyclic weather patterns that exacerbate the tidal highs. Such floods have already increased, and are now five to 10 times more likely than 50 years ago.

They looked at all those tidal stations with a continuous 50-year record of measurement. This does not include the city of Miami, where the tide stations were destroyed in 1992 by Hurricane Andrew.

Coastal changes

And they warn that Boston, New York City, Philadelphia, Baltimore and many other places along the Atlantic Coast, Galveston and Port Isabel in the Gulf of Mexico, and San Francisco Bay and San Diego along the Pacific Coast will all see a lot more seawater in city streets.

“Coastal communities are beginning to experience sunny-day nuisance flooding, much more so than in decades past,” said Dr Sweet. “This is due to sea level rise.

“Unfortunately, once impacts are noticed, they will become commonplace rather quickly. We find that in 30 to 40 years, even modest projections of global sea level rise – 1.5 feet by the year 2100 – will increase instances of daily high tide flooding to a point requiring an active and potentially costly response.

“And by the end of the century, our projections show that there will be near-daily nuisance flooding in most of the locations that we reviewed.” – Climate News Network

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US must face up to the dark side of climate change

US must face up to the dark side of climate change

As global temperatures rise, scientists warn that more cities in the US face the threat of power blackouts caused by fierce and frequent hurricanes.

LONDON, 29 December, 2014 − Climate change could leave more Americans in the dark as hurricanes become more intense or more frequent.

Researchers in the US have identified 27 cities that are likely to become more vulnerable to blackouts as a result of floods and high winds hitting the power grid.

They report in the journal Climatic Change that they matched evidence from the past – historic hurricane information – with scenarios for future storm behaviour throughout the US as global temperatures rise. And then they looked at those cities most vulnerable.

Big increase

Top of the list were New York, Philadelphia, Jacksonville, Virginia Beach and Hartford, which all could see a big increase in future risk of power cuts.

The cities most likely to keep the lights burning are Memphis, Dallas, Pittsburgh, Atlanta, and Buffalo.

In fact, there is no certainty about how global warming will affect hurricane patterns. As sea surface temperatures rise above 28°C, hurricanes tend to become more likely, and there is evidence that tropical cyclones in the Northern hemisphere are increasingly likely to threaten cities once considered beyond the hazard zone.

But hurricanes are capricious monsters, and how their characteristics will change with warmer atmosphere is still debated. So the scientists looked at a range of possibilities.

Cities already at risk – such as Miami and New Orleans – will remain at risk. But New York and Philadelphia, and even some inland urban areas, could become susceptible to increasing storm activity.

For New York – devastated by Superstorm Sandy in 2012 – and Philadelphia, the probability of the kind of storm previously considered a once-a-century event is likely to increase by 50%. More people would lose power more often, and the worst storms could be substantially more intense.

Future hazards

The point of the research is to make civic authorities more aware of potential future hazards.

“We provide insight into how power systems along the Gulf and Atlantic coasts may be affected by climate changes, including which areas should be most concerned and which ones are unlikely to see substantial change,” said Seth Guikema, a geographer at Johns Hopkins University in Baltimore.

“If I’m mayor of Miami, we know about hurricanes, we know about outages, and our system has been adapted for it. But if I’m mayor of Philadelphia, I might say: ‘Whoa, we need to be doing more about this.’” – Climate News Network

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Climate change’s threat of space centre invasion

Climate change's threat of space centre invasion

Rising sea levels and repeated storm damage to natural coastal defences pose an increasing threat to the famous Cape Canaveral rocket launch site in Florida.

LONDON, 15 December, 2014 − Climate change has begun to make its mark on one of America’s most iconic sites – the Kennedy Space Centre at Cape Canaveral in Florida.

Within a decade, according to geologists, the combination punch of rising sea levels and increasing wave energy could start to affect operations at the site where, more than five decades ago, astronauts were launched towards a landing on the Moon.

Peter Adams and John Jaeger, of the University of Florida, have since 2009 been studying the dunes and the beach at Cape Canaveral that historically screened the launch site from even the worst tropical storms.

These dunes were levelled in 2008 during Tropical Storm Fay, in 2011 during Hurricane Irene, and again in 2012 during Hurricane Sandy.

Washed away

Storm waves repeatedly covered a stretch of railroad track built by the US space agency NASA during the 1960s. The line is no longer used, and part of it has been removed to make room for a protective man-made dune. NASA’s own prediction in 2010 was that the line could be permanently breached by 2016.

Hurricane Sandy, the superstorm  that brought catastrophic flooding to New York and caused damage along almost all the US Atlantic seaboard, washed away a section of Cape Canaveral shoreline so close to a US Air Force launch pad that the surrounding fence was left near collapse.

“When you put immovable infrastructure right next to a dynamic environment, something has to give”

Coastal erosion is an enduring fact of life, but during the 1960s the Cape seemed a secure site for one of the great 20th-century adventures.

The two geologists, working as partners with NASA and the US Geological Survey, began looking at a problem that seemed to have been getting worse since 2004: chronic erosion of a six-mile stretch between the two launch pads used for the Apollo missions and space shuttle launches.

According to Dr Adams, the slow rise in sea levels and the increased energy of the ocean’s storm waves – both symptoms of global warming – are almost certainly to blame. He said: “Is it affecting NASA’s infrastructure? The answer’s yes.”

Although man-made dunes will protect the site for the immediate future, the space agency has already spoken of a “managed retreat”. And Dr Jaeger  said: “When you put immovable infrastructure right next to a dynamic environment, something has to give.”

Evidence of flooding

As a coastal facility, Cape Canaveral is naturally vulnerable to hurricanes, which tend to lose their energy as they hit the coasts. But University of Iowa scientists report in the Bulletin of the American Meteorological Society that they have found evidence of flooding by tropical cyclones as far inland as Iowa, in the Midwest.

Gabriele Villarini, a civil and environmental engineer, found the evidence in 30 years’ worth of discharge records from more than 3,000 US Geological Survey stream measurement stations.

Between 1981 and 2011, the US was hit by more than 100 tropical cyclones or hurricanes that did their worst damage at the coast, but could also be linked with major flooding far inland.

“Our results indicate that flooding from tropical cyclones affects large areas of the US and the Midwest, as far inland as Illinois, Wisconsin and Michigan,” Villarini said. – Climate News Network

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Plea for South Asia to unite in fight against climate risks

Plea for South Asia to unite in fight against climate risks

South Asia, one of the world’s most populous and disaster-prone regions, faces dire impacts from climate change. So why are its nations not working together to tackle the many shared threats they face?

LIMA, 8 December, 2014 − The countries of South Asia need to stand together in their efforts to push for more finance from the developed world to help them adapt to and mitigate the impacts of climate change,  a prominent regional expert says.

Saleemul Huq, from Bangladesh, a lead negotiator for the group of Least Developed Countries told a fringe meeting at the UN climate change conference in Lima, Peru, that South Asia countries face a range of climate-related events.

“Countries in the region must co-ordinate climate action to cope with adverse climate impacts, such as flash floods, forest fires, cyclones, migration and sea-level rise.” said Huq, senior fellow in the Climate Change Group at the International Institute for Environment and Development.

The South Asia region is home to more than one-fifth of the globe’s population, but is also regarded as one of the most disaster-prone regions in the world, Huq told delegates.

Substantial rise

Temperature projections for the region for the 21st century indicate a substantial rise in warming, with recent modelling showing that the warming would be particularly significant in the high Himalayas, on the Tibetan Plateau, and across arid regions of Asia.

“Extreme weather events are also forecast across the region” said Huq. “This is likely to include an increase in the interannual variability of precipitation during the Asian summer monsoon period.”

In turn, Huq said, this will negatively impact on crop yields throughout the region, as already crops in many areas are already being grown at close to their temperature tolerance threshold.

In its latest assessment, the UN’s Intergovernmental Panel on Climate Change identified the South Asia region as one of the areas most vulnerable to warming.

“Developing states have to have technical support in order to hammer out their climate adaptation plans”

In the high Himalayas and on the Tibetan Plateau, rates of glacial melting are increasing. The incidence of flooding is likely to grow, although there is the possibility, over the long term, of drought affecting billions of people in one of the most densely-populated areas on Earth.

Co-operation between the region’s countries on climate change is minimal. Pakistan and India, for example, remain deeply suspicious of each other, and data on such key issues as river flows and erosion rates are classified as state secrets.

China and India are competing for water resources, and large-scale dam building programmes in both countries are creating environmental tensions in the region.

Competing interests

Less powerful countries in the area – such as Bangladesh and Nepal – are squeezed between the competing interests of their powerful neighbours.

Harjeet Singh, a New Delhi-based representative of the Action Aid  charity, told delegates that South Asian countries must use their combined influence to pressure world leaders to reach a legally-binding climate agreement in 2015.

Singh told the Climate News Network that a new agreement was a matter of urgency, and  that developed countries must also fulfill their commitments to help developing countries with adaptation measures.

Manjeet Dhakal, a director of the Clean Energy Nepal research organisation, said a new agreement must address the needs of the vulnerable. “The regional countries and other developing states,” he said, “have to have technical support in order to hammer out their climate adaptation plans. They also need the financial support to put those plans into action.” – Climate News Network

  • Saleem Shaikh is a freelance climate change and science journalist based in Islamabad, Pakistan.

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Ocean heat drives surge to global warming record

Ocean heat drives surge to global warming record

Climate scientists say this year looks likely to enter the record books as the world’s hottest, with the warming of the oceans causing striking changes.

LONDON, 3 December 2014 − It’s official, even though it won’t be conclusive for a few months yet: if present trends continue, 2014 will be one of the hottest years on record − and quite possibly the hottest of them all.

Preliminary estimates by the World Meteorological Organisation (WMO) − published to provide information to the UN Framework Convention on Climate Change annual round of negotiations, currently being held in Lima, Peru − show this year is set to be a record breaker largely because of record high global sea surface temperatures.

These, combined with other factors, helped to cause exceptionally heavy rainfall and floods in many countries and extreme drought in others.

Christiana Figueres, executive secretary of the Convention, said: “Our climate is changing, and every year the risks of extreme weather events and impacts on humanity rise.”

Above normal

It is the warming of the oceans − which the WMO says “will very likely remain above normal until the end of the year” − that is chiefly perplexing the scientists.

The WMO’s provisional statement − to be finalised in March next year − on the Status of the Global Climate in 2014 shows that the global average air temperature over the land and sea surface from January to October was about 0.57°C above the average of 14°C for the 1961-1990 reference period, and 0.09°C above the average for 2004 to 2013.

If November and December follow the same trend, the WMO says, then 2014 will probably be the hottest on record, ahead of 2010, 2005 and 1998. This confirms the underlying long-term warming trend.

“The provisional information for 2014 means that 14 of the 15 warmest years on record have all occurred in the 21st century,” said the WMO secretary-general, Michel Jarraud. “There is no standstill in global warming.

“Record-breaking heat, combined with torrential rainfall and floods, destroyed livelihoods
and ruined lives”

“What we saw in 2014 is consistent with what we expect from a changing climate. Record-breaking heat, combined with torrential rainfall and floods, destroyed livelihoods and ruined lives. What is particularly unusual and alarming this year are the high temperatures of vast areas of the ocean surface, including in the northern hemisphere.

“Record-high greenhouse gas emissions and associated atmospheric concentrations are committing the planet to a much more uncertain and inhospitable future.”

Weather patterns

The high January to October temperatures occurred in the absence of a full El Niño-Southern Oscillation (ENSO). An ENSO occurs when warmer than average sea-surface temperatures in the eastern tropical Pacific combine, in a self-reinforcing loop, with atmospheric pressure systems, affecting weather patterns globally.

Among the remarkable features of 2014’s first 10 months are land surface temperatures. The WMO says they averaged about 0.86°C above the 1961-1990 average, the fourth or fifth warmest for the same period on record.

Global sea-surface temperatures were unequivocally the highest on record, at about 0.45°C above the 1961-1990 average. Temperatures were particularly high in the northern hemisphere from June to October for reasons, the WMO notes, that “are subject to intense scientific investigation”.

The ocean heat content for January to June was estimated to depths of 700m and 2000m, and both were the highest recorded. Around 93% of the excess energy trapped in the atmosphere by greenhouse gases from fossil fuels and other human activities ends up in the oceans, so the heat they contain is essential to understanding the climate system.

The early part of 2014 saw global-average measured sea level reach a record high for the time of year. Arctic sea-ice extent was the sixth lowest on record, according to the National Snow and Ice Data Centre, in the US, but Antarctic daily sea ice reached a new record for the third consecutive year.

Some impressively anomalous rainfall and floods made 2014 a year to forget as fast as possible. The UK winter was the wettest on record, with 177% of the long-term average precipitation. In May, devastating floods in south-east Europe affected more than two million people, and in Russia, in late May and early June, more than twice the monthly average precipitation fell in parts of southern Siberia.

In September, southern parts of the Balkan peninsula received over 250% of the monthly average rainfall, while parts of Turkey had more than 500%. Heavy rains caused severe flooding in northern Bangladesh, northern Pakistan and India, affecting millions of people.

Searing drought

In contrast, parts of north-east China, large areas of the western US, Australia, and Brazil experienced searing drought.

But the incidence of tropical storms and cyclones recorded was lower than the 1981-2010 average in much of the world.

The WMO Global Atmosphere Watch Programme shows that atmospheric levels of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) reached new highs in 2013  − the most recent data processed to date.

Globally-averaged atmospheric levels of CO2 reached 396.0 parts per million (ppm), approximately 142% of the pre-industrial average. The increase from 2012 to 2013 was 2.9 ppm, the largest year to year increase.

Atmospheric CH4 concentrations reached a new high of 1,824 parts per billion (ppb) in 2013, about 253% of the pre-industrial level, and concentrations of N2O reached 325.9 ± 0.1 ppb, a rise of 121%. − Climate News Network

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Warming world spells trouble for growing and ageing populations

Warming world spells trouble for growing and ageing populations

As average temperatures rise an increasing global population – with many more elderly people – is going to be more vulnerable to extreme weather, UK scientists say.

LONDON, 28 November 2014 – Life is about to become more hazardous for more people in more places. As atmospheric carbon dioxide levels grow and the planet inexorably warms, there will be more frequent and more damaging floods, droughts and heat waves than ever before.

And since human numbers continue to soar, and the average age of many populations starts to increase, there will be more people, and a greater proportion will be increasingly vulnerable to climate extremes.

A new report by Britain’s Royal Society – one of the oldest and most prestige-laden scientific academies in the world – presents new maps that show the combined impact of climate change upon a global population that is both growing, and growing older.

Climate change is likely to be accompanied by more extremes of weather, with greater risks of flood and drought in East, West and Central Africa, India and South-east Asia. There will also be more, and more protracted heat waves: the number of such events each year could multiply threefold by 2100.

In 2003, in temperate Europe, a heat wave claimed 52,000 lives. People who are 65 or older are naturally more vulnerable to heat extremes. But because of falling birth rates and increasing lifespans, the number of 65-year-olds is also likely to increase.

So by the end of the century the combination punch of climate and demography could mean that the heat wave events experienced by older citizens could multiply by a huge range. Flood losses worldwide recently estimated at US$6bn a year could rise by 2050 to US$1trillion a year.

Harvests affected

But climate change and the weather extremes that go with it will impose another cost: at certain times it could become increasingly difficult for people to work outdoors in Africa, Asia and parts of North, South and Central America. Since the people most likely to work outdoors are farmers and farm workers, this could have an impact on the food harvest – which will anyway be at risk from flood, drought and extremes of heat.

Georgina Mace, who led the working group that produced the report, said: “We are not resilient to the extremes of weather that we experience now and many people are already extremely vulnerable.

“If we continue on our current trajectory the problem is likely to get much worse as our climate and population change. By acting now, we can reduce the risks to our children and grandchildren. National governments have a responsibility to do everything in their ability to protect their people from the devastation caused by extreme weather events.”

Climate scientists have repeatedly and for more than two decades argued that, with greater average warming, populations could expect greater extremes of temperature.

Heat waves are a serious health risk and claim many lives each year. They are already on the increase  and a World Bank report just published has warned that events that once occurred once in a hundred years could become the new “normal”.

Poor are most vulnerable

Between 1980 and 2004, according to the Royal Society, the total cost of extreme weather events added up to US$1.4 trillion: only one quarter of this was insured.

People in those countries with a low human development index make up only 11% of those exposed to hazards but they account for 53% of disaster mortality. The poorest are, as usual, also the most at risk.

The report also considers what can be done: there are engineered options – dams, sea walls, wells and so on – that can reduce the impact of any particular hazard, but these solutions are also always more expensive, and when they fail, they fail catastrophically.

So, once again, the report argues for ecosystem-based or “natural” approaches to protect against floods and storm surges: the restoration of mangrove forests, the protection of flood plains, and greater investment in forests, all of which will deliver benefits wider than simple protection against bad weather.

It also warns that financial organisations must play a crucial role in creating economic systems that can adapt to the new extremes.

“One thing is for sure – what once was an extreme weather event will become more normal”

Nancy Grimm of Arizona State University, a member of the working group, said: “In the developed world we have been heavily reliant on some key large-scale engineering projects, which have been pushed to their limits during recent events.

“By using a combination of engineering and more natural approaches, we can accept occasional small ‘failures’ while limiting the detrimental impact of a large, catastrophic event. We call this a safe-to-fail approach.”

The report has been widely welcomed. Stephan Harrison of the University of Exeter, UK, said: “Even in developed nations the last few years of unusual snowfalls, extreme heat waves and floods have shown us that society is not able to deal with the extremes of weather we are experiencing at present.

“Our vulnerability to the likely climate changes we will see over the century will therefore grow and the developing world will be particularly at risk.”

And Grant Allen, a physicist at the University of Manchester, UK, said: “The science here is easy to understand. As temperatures climb, there will be more energy and more water vapour in the atmosphere.

“Although this affects different regions of the planet differently, one thing is for sure – what once was an extreme weather event will become more normal.” – Climate News Network

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Weather extremes will be the norm as world warms

Weather extremes will be the norm as world warms

The World Bank says the Earth is on an unavoidable path towards a 1.5˚C heat rise by mid-century – but it could reach 4˚C by 2100 unless immediate action is taken to avoid dire impacts for millions of people.

LONDON, 26 November, 2014 − As the planet continues to warm, heat waves and other weather extremes that happen perhaps once in hundreds of years − if ever − would become the “new climate normal”, a World Bank report says.

The consequences for development would be severe: failing harvests, shifting water resources, rising sea-levels, and millions of people’s livelihoods put at risk.

The World Bank report, the third in its Turn Down the Heat series, says even very ambitious mitigation action taken today will not stop global average temperatures reaching about 1.5˚C above their pre-industrial level by the middle of this century. They are already 0.8˚C higher, and likely − on present trends − to reach about 4˚C by 2100.

Poor and vulnerable

“Today’s report confirms what scientists have been saying – past emissions have set an unavoidable course to warming over the next two decades, which will affect the world’s poorest and most vulnerable people the most,” said Jim Yong Kim, President of the World Bank Group.

“We’re already seeing record-breaking temperatures occurring more frequently, rainfall increasing in intensity in some places, and drought-prone regions like the Mediterranean becoming drier. These changes make it more difficult to reduce poverty. . . They also have serious consequences for development budgets.”

“Tackling climate change is a matter of reason,
but also of justice”

The report was prepared for the Bank by the Potsdam Institute for Climate Impact Research (PIK), and the UK independent thinktank, the Overseas Development Institute.

The report’s lead author, Professor Hans Joachim Schellnhuber, director of PIK, said: “Tackling climate change is a matter of reason, but also of justice. Global warming impacts in the next decades are likely to hit those hardest that contributed least to global greenhouse gas emissions: the global poor.”

Chain of impacts

Dr Bill Hare, founder and CEO of the Berlin-based not-for-profit organisation, Climate Analytics, is another lead author of the report. He said: “Assessing the entire chain of climate impacts − for example, how heat waves trigger crop yield declines, and how those trigger health impacts − is key to understanding the risks that climate change poses to development.”

Many of the worst projected impacts can still be avoided by holding warming below 2˚C, the report says. It analyses the probable impacts of 0.8˚C, 2˚C and 4˚C of extra heat on agricultural production, water resources, ecosystem services and coastal vulnerability across Latin America and the Caribbean, the Middle East and North Africa, and parts of Europe and Central Asia.

A common threat across the three regions is the risk posed by heat extremes. State-of-the-art climate modelling shows that “highly unusual” extremes − similar to the heat waves in the US in 2012 and in Russia and Central Asia in 2010 − would increase rapidly under a 4˚C emission pathway. It also shows that the risks of reduced crop yields and production losses increase significantly above 1.5˚C to 2˚C.

Key findings across the regions include:

  • Latin America and the Caribbean: Heat extremes and changing rainfall will damage harvests, water supplies and biodiversity. In Brazil, without further adaptation, crop yields could decrease by 2050 by up to 70% for soya and 50% for wheat with 2˚C of warming. Ocean acidification, sea level rise, cyclones and temperature changes will affect coastal livelihoods, tourism, health, food and water security, particularly in the Caribbean.
  • Middle East and North Africa: A large increase in heat waves, combined with warmer average temperatures, will put intense pressure on already scarce water resources, seriously affecting human consumption and regional food security. In Jordan, Egypt, and Libya, harvests could fall by up to 30% with 1.5˚ to 2˚C warming by 2050. Migration and climate-related pressure on resources may increase the risk of conflict.
  • Western Balkans and Central Asia: Melting glaciers and shifts in the timing of water flows will lead to less water resources in summer months and high risks of torrential floods in Central Asia. In the Balkans, a higher drought risk will affect harvests, urban health and energy generation. In Macedonia, yield losses are projected of up to 50% for maize, wheat, vegetables and grapes at 2˚C warming by 2050.

The report adds that forest damage and thawing permafrost in northern Russia could release carbon and methane. With 2˚C warming by 2050, methane emissions could increase by 20% to 30% across Russia. − Climate News Network

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Sea rise may still pose a man-sized threat

Sea rise may still pose a man-sized threat

Although new research discounts the likelihood of a two-metre sea rise this century, the predicted impacts of global warming are still bad news for the many millions of people living at or near sea level.

LONDON, 21 October, 2014 − For those who think climate change means deep trouble, some comfort: there is a limit to how deep. Danish-led researchers have looked at all the projections and satisfied themselves that, at the very worst, sea levels this century will rise by a maximum 1.8 metres − roughly the height of an average man.

They report in Environmental Research Letters that they contemplated rates of melting in Greenland and Antarctica, the retreat of mountain glaciers worldwide, and the impact of groundwater extraction for agriculture and industry.

They also looked at all the projections for thermal expansion of the oceans, because warmer water is less dense than colder water and therefore occupies a greater volume. Then they began to calculate the band of possibilities.

“We have created a picture of probable limits for how much global sea levels will rise this century,” said Aslak Grinsted, assistant professor in the Niels Bohr Institute’s Centre for Ice and Climate at the University of Copenhagen. “Our calculations show that seas will likely rise by around 80cm. An increase of more than 180 cm has a likelihood of less than 5%. We find that a rise in sea levels of more than 2 metres is improbable.”

Critical infrastructure

The worst-case scenario, he says, is something that it would be wise to consider for critical infrastructure, such as the Delta Works, a series of construction projects that protect a large area of land in the south-west of the Netherlands, or the Thames Barrier, which aims to prevent London from being inundated by exceptionally high tides and storm surges from the North Sea.

The finding comes with two important provisos: one is that any significant rise remains extremely bad news for people in those regions of the planet that are already more or less at sea level − among them the coral atolls of the tropical oceans, the Netherlands, the Nile Delta, Bangladesh, Venice in Italy, and some of the world’s great maritime cities.

The other is that the man-high limit extends only to 2100, and researchers have repeatedly warned that, once begun, sea level rise will continue for centuries.

The Danish calculations fall into the category of things that could happen: melting in polar waters inevitably means even warmer equatorial waters, and another ominous projection for the near future is that commercially valuable fish could desert the tropics by 2050.

William Cheung, head of the Changing Ocean Research Unit at the University of British Columbia, Canada, and Miranda Jones, an environmental scientist at the same university, considered what would happen if the world warmed by 3°C by 2100.

“The tropics will be the overall losers. This area has
a high dependence on fish for food, diet and nutrition”

They report in ICES Journal of Marine Science that, under such a scenario, tropical fish could move away from their present habitats at a rate of 26 kilometres a decade. Even with a 1°C warming, they would desert their home waters at 15 km a decade.

Altogether, the two scientists considered the possibilities for 802 commercially important species, concluding that such a set of migrations might introduce new potential catches in Arctic waters, but could be very bad news for tropical fishermen, and for the hundreds of millions who depend on fish as a source of protein.

“The tropics will be the overall losers,” Dr Cheung said. “This area has a high dependence on fish for food, diet and nutrition. We’ll see a loss of fish populations that are important to the fisheries and communities in these regions.”

Accelerated rates

Paradoxically, as researchers consistently forecast accelerated rates of melting in polar waters, the Antarctic sea ice in September occupied a greater area than ever before, with the five-day average on September 19 reaching 20 million sq km, according to the US National Snow and Ice Data Centre.

That means that while most of the planet continued to warm, the Antarctic continent and the seas around it were icier, for one season at least.

Such measurements ultimately depend on satellite and aerial surveillance, and according to Claire Parkinson, climate change senior scientist at  the NASA Goddard Space Flight Centre, the anomaly simply reflects the complexity of climate dynamics and the diversity of the Earth’s environments.

“The planet as a whole is doing what was expected in terms of warming,” she says. “Sea ice as a whole is decreasing as expected, but just like with global warming, not every location with sea ice will have a downward trend in ice extent.”

But, overall, the planet is still saying goodbye to ice. The Antarctic’s gain is roughly a third in area of the loss of ice in the Arctic. – Climate News Network

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