Cutting warming to 1.5°C could put food supply at risk

Cutting warming to 1.5°C could put food supply at risk

Scientists say meeting the tougher demands of many countries on limiting global temperature rise may be technically feasible, but would risk worsening world hunger.

LONDON, 21 May, 2015 – As world leaders try to agree how to prevent global warming from heating the planet by more than 2°C above pre-industrial levels, scientists have tackled an altogether thornier question: can we keep the rise below 1.5°C?

The lower target − demanded by more than 100 countries as a safer goal − is attainable, they say. But there will be little room for error, and getting there will mean not only cutting greenhouse gas emissions, but actually removing carbon dioxide from the atmosphere.

That is not possible with the technology now available. And even if it could one day be done, it would probably have forbiddingly harmful consequences for world food supplies.

However, limiting temperature rise by 2100 to less than 1.5°C is still feasible, say the researchers from the International Institute for Applied Systems Analysis (IIASA) in Austria, the Potsdam Institute for Climate Impact Research (PIK), Germany, and colleagues. They report their findings in the journal Nature Climate Change.

Similar actions

Not surprisingly, the answer includes doing more, and doing it faster. “Actions for returning global warming to below 1.5°C by 2100 are in many ways similar to those for limiting warming to below 2°C,” says IIASA climate researcher Joeri Rogelj, one of the lead authors of the report.

The authors accept that the economic, political, and technological conditions for achieving even 2°C are “substantial”. The negotiations to be held in Paris in December by member states of the UN Framework Convention on Climate Change (UNFCCC) may show what chance there is of meeting them.

The new study identifies key ways of reaching the 1.5°C target by 2100. One is a tight limit on future carbon emissions.

Gunnar Luderer, PIK senior researcher in sustainable solutions, who co-led the study, says: “In 1.5°C scenarios, the remaining carbon budget for the 21st century is reduced to almost half, compared to 2°C scenarios.

“As a consequence, deeper emissions cuts are required from all sectors, and global carbon neutrality would need to be reached 10-20 years earlier than projected for 2°C scenarios.”

Energy efficiency will also need to improve faster, he says.

“The scenarios we assess keep warming
to the lowest levels currently considered
technologically feasible”

But the study finds that staying below 1.5°C would require a radical step change: some time this century, carbon emissions would have to become negative at a global scale.

That is the scientists’ way of saying that significant amounts of CO2 will have to be actively removed from the atmosphere. And there is at present no known way of doing that.

In theory, it is possible − for example, through bio-energy use, combined with carbon capture and storage. But that is a technology that so far remains untested on a large scale.

It would also increase hunger, as the crops needed to produce enough biofuel would compete for land with food plants.

Another idea is to grow more forests, which would sequester carbon in their trees, but this would be open to the same objection − that it would reduce cropland. The higher temperatures in prospect will themselves affect forest growth and health.

Lowest levels

Rogelj told the Climate News Network: “Increased temperatures can make afforestation efforts harder. However, the scenarios we assess here keep warming to the lowest levels currently considered technologically feasible, and this issue will thus have a relatively smaller impact.”

Whatever happens, the authors expect things to get hotter before they have any chance of cooling down.

Rogelj says: “Basically, all our 1.5°C scenarios first exceed the 1.5°C temperature threshold somewhere in mid-century, before declining to 2100 and beyond as more and more carbon dioxide is actively removed from the atmosphere by specialised technologies.”

Over 100 countries worldwide more than half the members of the UNFCCC, including the Alliance of Small Island States (AOSIS) and the Least Developed Countries (LDCs) have declared their support for a 1.5°C target. – Climate News Network

Share This:

Tree-based farming could deliver abundant benefits

Tree-based farming could deliver abundant benefits

In addition to mitigating the effects of climate change, forests can help alleviate hunger and provide a safety net for some of the world’s poorest people.

LONDON, 8 May, 2015 – Forests may be the green investment with the richest returns for humankind, according to new research.

While one study outlines the ways in which forests provide food, fuel, shelter and a safety net for more than a billion humans, a separate one confirms that a canopy of older, sturdier trees helps protect the saplings and juvenile growths against heat and drought.

An international team of more than 60 scientists collaborated on a report − Forests, Trees and Landscapes for Food Security and Nutrition: a Global Assessment Report − just published by the International Union of Forest Research Organisations (IUFRO).

“Large-scale crop production is highly vulnerable to extreme weather events, which may occur far more frequently under climate change,” says Christoph Wilburger, who co-ordinated the IUFRO initiative. “Science shows that tree-based farming can adapt far better to such calamities.

Key role

“We know that forests already play a key role in mitigating the effects of climate change. This report makes it very clear that they also play a key role in alleviating hunger and in improving nutrition.”

Climate scientists tend to consider forests as “carbon sinks” − agencies that soak up carbon dioxide from the atmosphere and that could help counter the rising levels of the greenhouse gas released by the burning of fossil fuels.

But forests also have a role in water storage and in protecting land from the forces of erosion.

Forest fruits and nuts are an important nutrition source for many. The iron content of the dried seeds of the African locust bean and raw cashew nut can, for instance, match the flesh of chickens. And forests are shelter for sources of wild meat, fish and edible insects.

“Extensive losses of forest canopy . . . will amplify the effects of climate change”

In developing countries, around 2.4 billion households use wood and charcoal for cooking and heating, and forests deliver a multitude of what are sometimes called ecosystem services − such as supporting bees and other crop pollinators, delivering fodder for village livestock, and protecting streams and watersheds.

Worldwide, the lower the levels of prosperity, the higher the dependence on forests. In the Sahel region of Africa south of the Sahara, trees contribute on average four-fifths of household income − mostly through shea nut production.

The report also points out that the expansion of agricultural land accounts for 73% of forest loss worldwide.

Increasing threat

But if forests keep people safe, what keeps a forest in leaf when drought, extremes of heat and the attrition of climate change are also an increasing threat?

Solomon Dobrowski, of the Forest Landscape Ecology Lab at the University of Montana, and colleagues report in Global Ecology and Biogeography that the regeneration of future forests could depend on shelter from the extensive canopy provided by the adult trees in mature woodland.

Juvenile trees are more shallow-rooted and more vulnerable to high winds, intense sunlight, high temperatures and extended drought. Without a shady, protective canopy, they could suffer. And without juvenile trees, a forest could only decline.

Professor Dobrowski warns: “Extensive losses of forest canopy from disturbances such as severe wildfire will amplify the effects of climate change.” – Climate News Network

Share This:

Well drilling has deep impact on Great Plains’ health

Well drilling has deep impact on Great Plains' health

Loss of vegetation on North America’s vast rangelands as a result of a huge increase in oil and gas wells invokes memories of the 1930s Dust Bowl disaster.

LONDON, 27 April, 2015 − Oil wells and natural gas may have made individual Americans rich, but they have impoverished the great plains of North America, according to new research.

Fossil fuel prospectors have sunk 50,000 new wells a year since 2000 in three Canadian provinces and 11 US states, and have damaged the foundation of all economic growth: net primary production − otherwise known as biomass, or vegetation.

Brady Allred, assistant professor of rangeland ecology at the University of Montana’s College of Forestry and Conservation, and colleagues write in the journal Science that they combined years of high-resolution satellite data with information from industry and public records to track the impact of oil drilling on natural and crop growth.

They conclude that the vegetation lost or removed by the expansion of the oil and gas business between 2000 and 2012 added up to 10 million tonnes of dry vegetation, or 4.5 million tonnes of carbon that otherwise would have been removed from the atmosphere.

Loss of fodder

Put another way, this loss amounted to the equivalent of fodder for five million cattle for one month from the rangelands, and 120 million bushels of wheat from the croplands. This wheat equivalent, they point out, adds up to the equivalent of 13% of the wheat exported by the US in 2013.

Net primary production – the biomass that plants make from photosynthesis every day, all over the world – is the basis of all wealth and food security. It underwrites all other human and animal activity.

Human wealth depends ultimately on what grows in the ground, or what can be dug from the ground, and most of the latter – such as coal, oil and peat– was once stuff that grew in the ground.

The same net primary production is the basis of what economists sometimes call ecosystem services on which all civilisation depends: the natural replenishment of the water supply, the pollination of crops, the provision of natural nitrogen fertilisers, and the renewal of natural habitat for wild things.

“It took catastrophic disruption of livelihoods and economies [in the 1930s] to trigger policy reforms that addressed environmental and social risks of land-use change”

And what worries the conservation scientists is that this loss of net primary production is likely to be “long-lasting and potentially permanent, as recovery or reclamation of previously drilled land has not kept pace with accelerated drilling”.

“This is not surprising because current reclamation practices vary by land ownership and governing body, target only limited portions of the energy landscape, require substantial funding and implementation commitments, and are often not initiated until the end life of a well.”

They say that the land actually taken up by wells, roads and storage facilities just between 2000 and 2012 is about 3 million hectares. This is the land area equivalent to three Yellowstone National Parks.

The hydraulic fracturing, or “fracking”, used to extract oil and gas is between 8,000 cubic metres and 50,000 cubic metres per well, which means that the total quantity of water squirted into the ground at high pressure during the 12 years to 2012 could exceed 33,900 million cubic metres. At least half of this was used in areas already defined as “water-stressed”.

New wells

The researchers considered the drilling of new wells in Alberta, Manitoba and Saskatchewan in Canada, and in Colorado, Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, Utah and Wyoming in the US.

Although there is legislation, it is limited to lands subject to federal jurisdiction, and 90% of all drilling infrastructure is now on privately-owned land − at least, in the US.

A tanker drives past a flaring oil well in North Dakota. Image: Tim Evanson via Wikimedia Commons

A tanker drives past a flaring oil well in North Dakota.  Image: Tim Evanson via Wikimedia Commons

The study’s authors want decision-makers to confront the challenges of this kind of ecological disruption. There are lessons from history in all this, they warn.

“In the early 20th century, rapid agricultural expansion and widespread displacement of native vegetation reduced the resilience of the region to drought, ultimately contributing to the Dust Bowl of the 1930s,” they write.

“It took catastrophic disruption of livelihoods and economies to trigger policy reforms that addressed environmental and social risks of land-use change.” – Climate News Network

Share This:

Familiar fish find northern seas too warm for comfort

Familiar fish find northern seas too warm for comfort

Fish accustomed to shallow northern waters will search in vain for cooler depths as climate change warms the seas where they thrive.

LONDON, 18 April, 2015 – Some of Northern Europe’s favourite suppers may be about to swim off the menu altogether. Global warming could change the future catch, according to new research.

British scientists report in the journal Nature Climate Change that popular species such as haddock, lemon sole and plaice could become less common as the climate changes and the North Sea warms.

The North Sea is relatively shallow – during the height of the Ice Age, much of the sea bed was dry land – which means that fish that would otherwise find deeper waters to keep cool have nowhere to go.

The North Atlantic is warming fast. The mean annual North Sea surface temperatures have increased by 1.3°C in the past 30 years. This is four times faster than the global average. But fish evolved to make a living in the temperatures that suit them best, and the evidence is that the North Sea is increasingly host to species that were once characteristic of the Mediterranean.

Changing abundance

Fishing is big business: landings in 2007 in the region reached $1.2 billion, and accordingly the ecology of the North Sea has been intensively monitored. Cold-adapted landings have halved in the last 30 years, but landings of warm-adapted species have increased 2.5 times. With a baseline of very detailed data from the past, the researchers were able to use computer models to build up a picture of things to come in northern waters.

And the result is this: the demersal or bottom-feeding fish that were the basis of fish-and-chip suppers from Cornwall in the UK to northern Norway are likely to dwindle over the next 50 years. Many of them cannot move north to get away from the heat, because there is no suitable habitat, and they can’t go deeper, because there isn’t any depth. So the abundance of species will change with time.

“Our study suggests that we will see proportionately less of some of the species we eat most of as they struggle to cope with warming conditions in the North Sea,” said Louise Rutterford of Exeter University, the first author.

Squeezed out

“We provide new insight into how important local depths and associated habitats are to these commercial species. It’s something that is not always captured in existing models that predict future fish distributions.”

Other studies have found that fish in many regions are changing to new latitudes as climates change in response to greenhouse gas emissions from fossil fuel combustion. The same man-made global warming has brought a greater number of sardines, for instance, to northern waters, and in the US fishermen have had to sail ever further north to pursue the black bass. There has even been a warning that the retreat of the Arctic ice means that Atlantic halibut could actually migrate into the North Pacific.

So the latest message is confirmation of an increasingly familiar finding. “We will see a real changing of the guard in the next few decades,” said Steve Simpson, a marine biologist at Exeter, and another of the authors.

“Our models predict cold water species will be squeezed out with warmer water fish likely to take their place. For sustainable UK fisheries, we need to move from haddock and chips and look to southern Europe for our gastronomic inspiration.” – Climate News Network

Share This:

China ramps up the rhetoric on climate change

China ramps up the rhetoric on climate change

Senior Chinese official warns that climate-related temperature rises could seriously affect the country’s harvests and major infrastructure projects.

LONDON, 28 March, 2015 − Zheng Guogang, head of the China Meteorological Administration, says future variations in climate are likely to reduce crop yields and damage the environment.

In one of the strongest official statements to date on the challenges faced, Zheng told China’s official Xinhua news agency that climate change could have a “huge impact” on the country, with a growing risk of climate-related disasters.

“To face the challenges from past and future climate change, we must respect nature and live in harmony with it,” Zheng said. “We must promote the idea of nature, and emphasise climate security.”

Violent rainstorms

Zheng said temperature rises in China over the past century have been higher than the global average. He warned that river flows and harvests are likely to suffer as the incidence of droughts and violent rainstorms across the country increases.

In turn, this could affect major infrastructure projects such as the Three Gorges Dam on the Yangtze river, the biggest hydroelectric scheme in the world.

Other projects that could be hit by changes in climate are the rail line between the northwestern province of Qinghai and Tibet − the highest railway line in the world, and partly built on permafrost − and a massive project aimed at bringing water from the south of China to the parched towns and cities of the north.

“The safe production and operation of major strategic projects is facing a serious threat,” Zheng said.

Although millions of people in China have benefited from years of double-digit economic growth, damage to the environment has been extensive and has become a major social, health and political issue.

“To face the challenges from past and future climate change, we must respect nature
and live in harmony with it”

China is now the world’s biggest emitter of greenhouse gases − largely due to its continued reliance on coal for power generation.

There are frequent public protests about the state of the environment, particularly water and air pollution. In Beijing and several other cities, air pollution frequently exceeds internationally-recognised health safety limits.

The authorities are taking various measures to tackle the country’s considerable environmental problems, but they are nervous about public protests on the environment getting out of control.

Earlier this month, “Under the Dome” – a documentary on China’s pollution, made by one of the country’s leading investigative reporters − was taken down from the internet by the authorities after having been viewed by an estimated 100 million people.

Green development

Under China’s present five-year plan, which started in 2011, there is a focus on the need to encourage “green, cyclical and low-carbon development”.

The plan claims: “These actions will increase the strategic position of combating climate change in China’s overall economic and social development.”

In an effort to improve its environment and meet international obligations to cut emissions, China is in the midst of a renewable energy programme costing billions of dollars.

Late last year, Beijing announced for the first time a date when the country’s emissions would peak – 2030 – and then taper off in the years following.

China is also involved with the US and other countries in a wide range of energy-saving research projects aimed at combating climate change. – Climate News Network

Share This:

Heat-tolerant beans could help keep millions fed

Heat-tolerant beans could help keep millions fed

Plant researchers say new varieties of a tropical crop essential to people’s survival in Africa and Latin America can withstand the effects of global warming.

LONDON, 26 March, 2015 − Scientists believe they may have found how to safeguard a staple tropical crop, on which hundreds of millions of people depend, from the depredations of climate change.

They have discovered − through conventional breeding rather than genetic modification − 30 new “lines” (varieties) of beans that will thrive in the higher temperatures expected later this century, and which will pose a particular threat to harvests in Africa and Latin America.

The new “heat-beater” beans, an important source of protein for around 400 million people, have been identified by plant breeders with the CGIAR global agriculture research partnership.

Steve Beebe, a senior CGIAR bean researcher, announced at a conference in Ethiopia: “This discovery could be a big boon for bean production because we are facing a dire situation where, by 2050, global warming could reduce areas suitable for growing beans by 50%.

Worst-case scenario

“Incredibly, the heat-tolerant beans we tested may be able to handle a worst-case scenario where the build-up of greenhouse gases causes the world to heat up by an average of 4°C.

“Even if they can only handle a 3°C rise, that would still limit the bean production area lost to climate change to about 5%. And farmers could potentially make up for that by using these beans to expand their production of the crop in countries such as Nicaragua and Malawi, where beans are essential to survival.”

Dr Beebe told the Climate News Network: “So far, so good. Some of the lines are also drought-tolerant, and some are resistant to Bean Golden Yellow Mosaic Virus.

“We are taking these beans into a new environment that we don’t know from the bean perspective. . . Will we find more surprises?

“There are two caveats. First, so far the best lines are small red types for Central America and parts of East Africa, so we have a long road to improve a range of grain types, colours, etc.

“The other issue is that we are taking these beans into a new environment that we dont know from the bean perspective. We have seen that a soil pathogen, pythium, is more severe. Will we find more surprises?”

Rising heat as climate change intensifies is expected to disrupt bean production in central and South American countries, including Nicaragua, Haiti, Brazil and Honduras. African countries thought to be at risk are principally Malawi and the Democratic Republic of the Congo, followed by Tanzania, Uganda and Kenya.

Many of the new heat-tolerant beans developed by the CGIAR scientists are “crosses” of the common bean − which includes pinto, white, black, and kidney beans − and the tepary bean, a hardy survivor cultivated since pre-Columbian times in what is now part of northern Mexico and the southwest US.

Highly nutritious

Beans are often called the “meat of the poor”. They are highly nutritious, providing not only protein but fibre, complex carbohydrates, vitamins, and other micronutrients. In addition to heat tolerance, CGIAR researchers are also breeding lines with a higher iron content, in an effort to tackle malnutrition.

The new beans are the result of CGIAR’s work to develop new crop varieties that can thrive in drastic weather extremes, based on research in its “genebanks”, which preserve the world’s largest seed collections of the most important staple crops.

The heat-beaters emerged from the testing of more than 1,000 bean lines − work that began as an effort to develop beans that could tolerate poor soils and drought.

The focus turned to heat-tolerance following a 2012 report from CGIAR scientists warning that heat was a much bigger threat to bean production than previously believed. − Climate News Network

Share This:

Acid attack on algae damages ocean ecosystem

Acid attack on algae damages ocean ecosystem

Increasing acidity in the Southern Ocean is having a serious effect on the growth of a small but hugely important food source for marine life.

LONDON, 27 February, 2015 − As the planet’s oceans become more acidic, the diatoms − a major group of alga − in the Southern Ocean could grow more slowly.

Nobody expected this. And since tiny, single-celled algae are a primary food source for an entire ocean ecosystem, the discovery seems ominous.

Bioscientist Clara Hoppe and colleagues from the Alfred Wegener Institute [http://www.awi.de/en/home/]at the Helmholtz Centre for Polar and Marine Research in Bremerhaven, Germany, report in the journal New Phytologist that they tested the growth of the Antarctic diatom Chaetoceros debilis under laboratory conditions.

They used two levels of pH – which is an indicator of acidity – and they exposed their tiny volunteers to constant light and to changing light, providing both standard laboratory conditions and lighting levels that approximated to the real world.

Plant growth

In the unblinking glare of light, the diatoms responded well. Their growth levels were consistent with an assumption that more dissolved carbon dioxide – which makes the waters more acidic – would in effect fertilise plant growth.

Under conditions of changing light, however, it was a different story. The algae grew more slowly, which suggests that the oceans could become less efficient at removing carbon from the atmosphere, and perhaps less valuable as a primary food source for the creatures that teem in the Antarctic waters.

“Diatoms fulfil an important role in the Earth’s climate system,” Dr Hoppe says. “They can absorb large quantities of carbon dioxide, which they bind before ultimately transporting part of it to the depths of the ocean.

“Once there, the greenhouse gas remains naturally sequestered for centuries.”

Previous research into the steady acidification of the oceans has tended to concentrate on the consequences for coral reefs,  fisheries, and tourism, but not on the impact on plant life in the seas.

Since carbon dioxide acts as a fertiliser, higher levels dissolved in the water might stimulate more growth.

“We now know that when the light intensity constantly changes, the effect of ocean acidification reverses”

But growth depends not just on more carbon dioxide, but also on reliable sunlight. In the stormy southern seas, this is not steadily supplied.

Dr Hoppe says: “Several times a day, winds and currents transport diatoms in the Southern Ocean from the uppermost water layer to the layers below, and then back to the surface – which means that, in the course of a day, the diatoms experience alternating phases with more and with less light.”

Her co-author, marine biogeochemist Björn Rost, from the Alfred Wegener Institute, says: “Our findings show for the first time that our old assumptions most likely fall short of the mark. We now know that when the light intensity constantly changes, the effect of ocean acidification reverses.

“All of a sudden, lower pH values don’t increase growth, like studies using constant light show. Instead, they have the opposite effect.”

The implication is that, at certain intensities, the photosynthesis chain breaks down. The point at which light becomes too much light is more quickly reached in waters that are more acidic.

Like all such research, the finding has limitations. It applies to one species of single-celled creature in the waters of one ocean, and the tests were in a laboratory on a small scale, and not in a turbulent ocean rich in life. The Alfred Wegener team will continue their studies.

But in the real world, coastal communities in 15 US states could be at long-term economic risk, as ocean acidification starts to take its toll on the commercial oyster fisheries.

Julia Ekstrom, then of the Natural Resources Defense Council and now director of the Climate Adaptation Programme at the University of California, Davis, and George Waldbusser, assistant professor of ocean ecology and biogeochemistry at Oregon State University report with colleagues, in Nature Climate Change, on an unholy mix in the oceans.

Fisheries at risk

They say that a combination of rising greenhouse gas levels, more acid waters, polluted rivers, and upwelling currents put at risk mollusc fisheries from the Pacific Northwest, New England, the Mid-Atlantic states and the Gulf of Mexico – affecting the shellfish industry that is worth at least $1bn to the US.

Oyster larvae are sensitive to changes in ocean water, and more likely to die as pH levels shift towards the acidic.

But acidification is not the only source of stress, as nitrogen-rich nutrients and chemical pollutants cascade from the land into the rivers, and wash through estuaries and fish hatcheries on the coast.

Things can be done. Scientists have been looking at ways in which the industry might be able to adapt to change. But how well the oyster stock can adapt in the long term remains problematic.

“Ocean acidification has already cost the oyster industry in the Pacific Northwest nearly $110 million and has jeopardised about 3,200 jobs,” Dr Ekstrom says.

And Dr Waldbusser adds: “Without curbing carbon emissions, we will eventually run out of tools to address the short term, and we will be stuck with a much longer-term problem.” – Climate News Network

Share This:

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

Share This:

Sardines swim into northern waters to keep cool

Sardines swim into northern waters to keep cool

Fish species in subtropical European waters are migrating north to escape warming seas − leaving fishermen who rely on them for a living with empty nets.

LONDON, 20 February, 2015 − Several important fish species that for centuries have been part of the staple diet of people in the Mediterranean region are abandoning sub-tropical seas because the water is too warm and are heading north.

Sardines, which for generations have been the most abundant commercial fish species in Portugal, are moving away. They are now established in the North Sea, and are being caught in the Baltic – a sea that until recently was normally frozen over in the winter.

Sardines, anchovies and mackerel − three fish species that are important in the diet of many southern European and North African countries − have been studied by scientists trying to discover how climate change and warming seas are affecting their distribution.

Fishing industry

As well as the affect on the fishing industry, the abundance or disappearance of these species is crucial for many other marine species that rely on them for food.

A pioneering study, published in Global Change Biology, analysed 57,000 fish censuses conducted over 40 years, and has tracked the movement of these fish during this period.

It confirms that the continued increase in water temperature has altered the structure and functioning of marine ecosystems across the world. But it also shows that the effect has been greater in the North Atlantic, with increases of up to 1.3 ºC in the average temperature over the last 30 years.

This variation in temperature directly affects the frequency and range of pelagic fish, which live in the middle of the water column and are directly influenced by temperature, rather than habitat. It includes the sardine (Sardina pilchardus), anchovy (Engraulis encrasicolus), horse mackerel (Trachurus trachurus) and mackerel (Scomber scombrus), among others.

Sardines and other fish represent “an exceptional bioindicator to measure the direction and speed of climate change expected in the near future”

They feed off phytoplankton and zooplankton, and are themselves the staple diet of large predators, such as cetaceans, large fish and marine birds. These fish occur off the shores of many coastal countries in the world and are important sources of protein.

Scientists have known that fish were moving to new areas, but did not know whether it was in response to their main food supply plankton moving first or whether it was a simple response to changing temperatures.

The new study has developed statistical models for the North Sea area, and confirms the great importance of sea temperatures.

“Time series of zooplankton and sea surface temperature data have been included to determine the factor causing these patterns,” Ignasi Montero-Serra, lead author of the study and researcher in the department of Ecology at the University of Barcelona, explains to the Scientific Information and News Service.

To demonstrate the consequences of the warming of the seas, the research team analysed fish censuses from commercial fishing performed independently along the European continental shelf between 1965 and 2012, extracted from data provided by the International Council for the Exploration of the Sea.

The study, which is the first to be carried out on such a large timescale and area, allows for the dynamics of this species to be understood in relation to the rapid warming of the oceans that has been happening since the 1980s.

The results reveal that sardines and other fish with fast life cycles, planktonic larval stage and low habitat dependence are highly vulnerable to changes in ocean temperature, and therefore represent, Montero-Serra says, “an exceptional bioindicator to measure the direction and speed of climate change expected in the near future”.

Accelerated increase

Montero-Serra says that accelerated increase in temperature of the continental seas has resulted in sardines and anchovies − with a typically subtropical distribution − increasing their presence in the North Sea and “even venturing into the Baltic Sea”. And the presence of species with a more northern distribution, such as the herring and the sprat, has decreased.

The analysis is therefore a clear sign that species in the North Sea and Baltic Sea are “becoming subtropical”.

This is due to the pelagic fish being highly dependent on environmental temperatures at different stages of their life cycle − from reproductive migrations and egg-laying, to development and survival of larvae.

According to the researchers, the changes in such an important ecological group “will have an effect on the structure and functioning of the whole ecosystem”, although they still do not know the scale of the socio-economic and ecological repercussions. – Climate News Network

Share This:

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

Share This: