Category Archives: Warming

Warmer Atlantic widens invader’s hunting ground

Moving home: an Indo-Pacific lionfish on a reef off the North Carolina coast Image: NOAA
Moving home: an Indo-Pacific lionfish cruises on a reef off the North Carolina coast
Image: NOAA

By Tim Radford

The exotic lionfish, already a long way from the reefs of its Indo-Pacific home, is heading further north up the US coast as global warming causes big changes to ocean habitats.

LONDON, 28 September, 2014 − The venomous lionfish is on the move. This invasive species has been observed in deeper waters off the North Carolina coast since the turn of the century, but new research suggests it may now be expanding its range into the shallower levels.

Since the lionfish (Pterois volitans) is actually native to the Indo-Pacific region, it is already a long way from home. But what now gives it licence to hunt further north is warmer sea temperature.

Global warming has already begun to make huge differences to ocean habitat. The bluefin tuna is a temperate zone fish that has already been observed in Arctic waters off the coast of Greenland, and commercial species such as red mullet, a creature of the Mediterranean, has been seen in the North Sea and even in Norwegian waters.

Now researchers in the US have reported that the lionfish – an invader first observed off the Florida coast in the 1980s − is spreading through the north-west Atlantic.

Temperature is the key determinant for a fish on the move. Fisheries biologist Paula Whitfield, of the National Oceanic and Atmospheric Administration’s National Centres for Coastal Ocean Science, and colleagues report in the journal Marine Ecology Progress Series that they surveyed 40 species of fish off the reefs of North Carolina.

Tropical species

These reefs have always been home both to temperate and tropical species, at the limits of their ranges. But now the reefs are becoming more tropical − and so is the local population.

“Along the North Carolina coast, warming water temperatures may allow the expansion of tropical fish species, such as lionfish, into areas that were previously uninhabitable due to cold winter temperatures,” Whitfield says.

“The temperature thresholds collected in this study will allow us to detect and estimate fish community changes related to water temperature.”

The lionfish tends to prefer water warmer than 15.2°C, and so normally inhabits the warm currents of the deeper waters in the temperate Atlantic. It is a carnivore that seems to enjoy a wide range of prey. It makes itself at home in a wide variety of habitat, and is considered a serious threat to other species of reef fish. – Climate News Network

California burning points to more intense wildfires

Burning issue: a wildfire raging this month in California’s Yosemite National Park Image: PBJamesPhoto via Wikimedia Commons
Razed alarm: wildfire rages through part of California’s Yosemite National Park this month
Image: PBJamesPhoto via Wikimedia Commons

By Kieran Cooke

As the forest fires season peaks in the western US, a new report predicts that climate-led temperature rise will lead to millions more acres across the world being burned to the ground.

LONDON, 27 September, 2014 − Smoke from fires burning at present in northern California has been detected as far north as Canada, as thousands of firefighters battle to contain blazes that together cover nearly 300,000 acres of forest and shrub wood. And it looks like things are going to get worse.

A new report by the US-based Cost of Carbon Pollution project forecasts that such fires are going to become ever more intense in the years ahead – not just in the western US, but elsewhere round the world, and particularly in areas of southern Europe and in Australia.

The ongoing drought across much of the western US has had a serious impact on the region’s agricultural industry, and has resulted in the build-up of vast amounts of tinder-dry material on the land.

“We haven’t been out of fire season for a year and a half,” a leading fire official told the Washington Post. “There is no end in sight.”

Incidence doubles

The new report says the incidence of wildfires – unrestrained fires that burn predominantly in areas of forests, woodlands, grasslands, peat or shrubs – has doubled in the US since the 1990s.

In total, between seven and nine million acres in the US are burned as a result of wildfires every year – an area equivalent to one-and-a-half times the size of the state of Massachusetts.

“These amounts are expected to increase significantly due to climate change and other factors,” the report says. And, overall, there is likely to be a 50% increase by 2050 in the area of North America burned, with more large and potentially catastrophic wildfires.

Not only will more valuable forest be lost, the fires will also have an increasing impact on the economy − with important industries such as tourism suffering serious losses.

More and more people have been migrating to the western US. In 1960, California’s population was 15 million: it’s now nearly 40 million, and is expected to increase to 50 million by 2030. The study says the fires are already taking their toll on people’s health.

Forests and peat lands function as carbon sinks – sucking up volumes of greenhouse gases (GHGs). But the report says an increase in wildfires could mean that, in time, these areas would become net emitters of GHGs, adding to problems of global warming.

Mistaken policies

Dr Wallace Covington, director of the Ecological Restoration Institute at Northern Arizona University, is an internationally-recognised expert on forest restoration. He says that the growth in wildfires in the western US is due, to a large extent, to mistaken forest policies over the past 100 years.

Dense forests were planted, while natural fires – which form a normal part of nature’s cycle, and can regenerate growth in some trees and plants – were suppressed.

“Forests became unhealthy, and an excessive amount of fire fuel was allowed to build up,” Covington told the Climate News Network. “Natural fires can be easily controlled, but once fires spread over thousands of acres they are virtually impossible to contain.”

Covington says that climate change has exacerbated the situation. “We’re seeing wider swings from very dry to very wet conditions, and wind speeds, which fan the forest flames, have been building up across the region over recent years.”

Forest specialists at Northern Arizona University and elsewhere are now pressing for radical changes in forestry policy, including the thinning of densely-wooded areas and the reintroduction of controlled, natural fires at various times of the year. – Climate News Network

Ice melt dilutes Arctic sea’s CO2 clean-up role

Cutting edge: climate scientist Dorte Haubjerg Søgaard studies the sea ice in Greenland Image: Søren Rysgaard,  Arctic Research Centre, Aarhus University
Cutting edge: climate scientist Dorte Haubjerg Søgaard studies the sea ice in Greenland
Image: Søren Rysgaard, Arctic Research Centre, Aarhus University

By Tim Radford

New scientific research confirms that global warming is melting increasingly larger areas of Arctic sea ice − and reducing its vital function of removing CO2 from the atmosphere.

LONDON, 26 September, 2014 − The Arctic ice cap has just passed its summer minimum – and it’s the sixth lowest measure of sea ice recorded since 1978, according to scientists at the US space agency NASA.

For three decades, the shrinking Arctic ice – and the growing area of clear blue water exposed each summer – has been a cause of increasing alarm to climate scientists.

Polar seasonal changes are measured annually by NASA, but reliable satellite data goes back only to 1978, For much of the 20th century, the Arctic was part of the Cold War zone, so only Soviet naval icebreakers and US nuclear submarines took consistent measurements − and neither side published the data.

But studies of 17th and 18th century whaling ships’ logbooks and other records make it clear that the ice once stretched much further south each summer than it does today.

Steady decline

In the last 30 years, the thickness and the area of the ice have both been in steady decline, with predictions that in a few decades the Arctic Ocean could be virtually ice free by September, opening up new sea routes between Asia and Europe.

This year could have been worse, although the area of ice fell to little more than 5 million square kilometres − significantly below the 1981-2010 average of 6.22 million sq km.

“The summer started off relatively cool, and lacked the big storms or persistent winds that can break up ice and increase melting,” said Walter Meier, a research scientists at NASA’s Goddard Space Flight Centre. “Even with a relatively cool year, the ice is so much thinner than it used to be. It is more susceptible to melting.”

Warming in the Arctic is likely to affect climate patterns in the temperate zones, and the state of the polar ice has become of such concern that researchers are using ground-based and sea-based monitors to explore the physics of the phenomenon.

But there is another reason for the attention: as polar ice diminishes, so does the planet’s albedo − its ability to reflect sunlight back into space.

So, as the ice shrinks, the seas warm, making it more difficult for new ice to form. And greater exposure to sunlight increases the probability that permafrost will thaw, releasing even more greenhouse gases locked in the frozen soils.

Now researchers have found another and unexpected example of climate feedback that could affect the cycle of warming. Climate scientist Dorte Haubjerg Søgaard, of the Greenland Institute of Natural Resources and the University of Southern Denmark, and research colleagues have discovered that sea ice itself is an agency that removes carbon dioxide from the atmosphere.

That the oceans absorb the stuff, and tuck it away as calcium carbonate or other marine minerals, is old news.

“But we also thought that this did not apply to ocean areas covered by ice, because the ice was considered impenetrable,” Søgaard said. “However, new research shows that sea ice in the Arctic draws large amounts of CO2 from the atmosphere into the ocean.”

The research is published in four journals, Polar Biology, The Cryosphere, The Journal of Geophysical Research: Atmospheres and Marine Ecology Progress Series.

Two-stage pattern

The Danish research team observed a complex, two-stage pattern of gas exchange as ice floes formed off southern Greenland. They measured the role of atmospheric carbon dioxide in the formation and release of calcium carbonate crystals form in the sea ice, and kept a tally during a 71-day cycle of the carbon dioxide budget.

In the course of this complicated bit of natural cryo-chemistry, they found that some CO2 was carried deep into the ocean with dense, heavy brines, as the ice froze and some was captured by algae in the thawing ice.

They also identified a third factor: the “frost flowers” that formed on the new ice had an unexpectedly high concentration of calcium carbonate.

The profit-and-loss accounting meant that every square metre of ice effectively removed 56 milligrams of carbon from the atmosphere during the 71-day cycle. Over an area of 5 million sq km, this would represent a significant uptake.

But the real importance of the discovery is that scientists have identified yet another way in which the ice – while it is there – helps keep the Arctic cold, and yet another way in which carbon dioxide is absorbed by the oceans.

“If our results are representative, then the sea ice plays a greater role than expected, and we should take account of this in future global CO2 budgets,” Søgaard said. – Climate News Network

Croplands changed by climate’s ups and downs

Arid areas such as Patagonia have become wetter rather than drier Image: Rolf Hengel via Wikimedia Commons
Arid areas such as Patagonia have unexpectedly become wetter rather than drier
Image: Rolf Hengel via Wikimedia Commons

By Tim Radford

New research shows that the complex balance of gains and losses caused by climate change could mean more land being available for agriculture − but fewer harvests.

LONDON, 25 September, 2014 − With climate change, you win some, you lose some. New research shows that suitable new cropland could become available in the high latitudes as the world warms − but tropical regions may become less productive.

Florian Zabel and two fellow-geographers from Ludwig Maximilians University in Munich, Germany, report in the journal Public Library of Science One that they made judgments about the climate, soil and topography to suit the 16 most important food and energy crops. They then compared data for the period 1981-2010 with simulations of a warming world for the period 2071-2100.

The results looked good: in northern Canada, China and Russia, they found that a notional additional land area of 5.6 million sq km became available for crops.

Significant losses

Less happily, in the Mediterranean and sub-Saharan Africa there were significant losses of agricultural productivity – if no additional irrigation was factored in. Also, the chances of multiple harvests in tropical Brazil, Asia and Central Africa would be reduced.

Altogether, the land suitable for agriculture by 2100 would total 54 million sq km. But of this, 91% is already under cultivation.

“Much of the additional area is, however, at best only moderately suited to agricultural use, so the proportion of highly fertile land suited to agricultural use will decrease,” Dr Zabel says.

“In the context of current projections, which predict that the demand for food will double by the year 2050 as the result of population increase, our results are quite alarming.”

The Munich calculations were essentially mathematical projections based on climate models that are, in turn, based on broad conclusions of change. But what if those broad conclusions are too sweeping?

Climate researcher Peter Greve, of the Swiss Federal Institute of Technology (ETH) in Zurich, and colleagues report in Nature Geoscience that the rule of thumb for climate change – that wet regions will tend to get wetter, and already dry regions will in general become more arid – may not always hold.

So they looked at the calculations again, and began to search for trends towards increasing humidity or aridity.

In effect, they were trying to see if they could predict what should have happened in the past, so they chose two periods − 1948 to 1968, and 1984 to 2004 − and examined the patterns of change.

Clear trends

They could find no obvious trend towards either a wetter or a drier climate over about three-quarters of the land area under consideration. There were clear trends for the remaining quarter, but, once again, the answers were not simple. In about half of this land area, the dry-gets-drier, wet-gets-wetter rule seemed to hold. In the other half, the trends seemed to be contradictory.

In the past, parts of the Amazon, Central America, tropical Africa and Asia should have got wetter, but instead became less moist. Patagonia, central Australia and the US Midwest were all dry areas that became wetter.

The wet-gets-wetter rule held good for the eastern US, northern Australia and northern Eurasia, and the already dry Sahel, Arabian Peninsula and parts of central Asia and Australia became more parched.

The lesson is not that climate projections are wrong, but that climate systems are very complex. “Our results emphasise how we should not overly rely on simplifying principles to assess past developments in dryness and humidity,” Greve says. – Climate News Network

Clean urban transport can drive emissions cuts

Making public transport cleaner and more accessible can reap major benefits Image: Ilya Plekhenov via Wikimedia Commons
Making public transport cleaner and more accessible will lead to major social benefits
Image: Ilya Plekhenov via Wikimedia Commons

By Tim Radford

Researchers’ urgent message to world leaders at the UN climate summit: save 1.4 million lives and trillions of dollars by controlling vehicle pollution, improving public transport and shifting away from the car culture.

LONDON, 24 September, 2014 − Here’s a way to save $100 trillion and stop 1,700 million tonnes of carbon dioxide from getting into the atmosphere every year by 2050: cycle, walk or take public transport.

A new report by the University of California Davis and the Institute for Transportation and Development Policy (ITDP) estimates that such a policy would also prevent 1.4 million premature deaths a year from lung cancer and cardiopulmonary diseases.

The report, aimed to coincide with the current UN climate change summit in New York, sees sustainable public transport as a key factor in economic development.

Pollution  controls

However, according to parallel analysis by the International Council on Clean Transportation, the planet’s governments must also demand the strongest vehicle pollution controls and push for ultra-low sulphur fuels.

The ITDP message is, of course, one that city planners, health chiefs, traffic analysts, atmospheric scientists and environmental campaigners have been urging for decades. The difference is that the new report, called A Global High Shift Scenario, attempts to estimate the money saved, the greenhouse gases not emitted, and the lives saved by a switch from the “business-as-usual” approach to transport.

This would require governments everywhere to invest in clean, safe and swift public transport by bus and rail, and at the same time make the streets safe for cyclists and pedestrians.

If authorities also moved investment away from road construction, garages and parking lots, then enormous savings would follow over the next 35 years.

“Transportation, driven by rapid growth in car use, has been the fastest-growing source of CO2 in the world,” says Michael Replogle, ITDP’s founder and managing director for policy.

His co-author, Lew Fulton, co-director of the NextSTEPS (Sustainable Transportation Energy Pathways) programme within the Institute of Transportation Studies at the University of California Davis, adds: “The analysis shows that car-centric development will cut urban CO2 dramatically and also reduce costs, especially in rapidly expanding economies.”

Under the ITDP scenario, access to public transport would more than triple for the lowest income groups, and double for the next lowest income group. Overall, mobility tends to provide the poorest people with better access to employment and to services that will improve livelihoods.

Fulton says: “Today, and out to 2050, lower income groups will have limited access to cars in most countries under almost any scenario, so improving access to modern, clean, high-capacity public transport is crucial.”

Growing inequality

And Replogle warns: “Unmanaged growth in motor vehicle use threatens to exacerbate growing income inequality and environmental ills, while more sustainable transport delivers access for all, reducing these ills.”

Motor traffic in urban areas accounted for 2,300 megatonnes of carbon dioxide in 2010 –about a quarter of emissions from all parts of the transport sector. Rapid urbanisation in China, India and other fast-developing countries threatens to double these emissions.

Right now, the US is the world leader in carbon dioxide emissions from urban passenger transport, with 670 megatonnes a year. But the report calculates that this could be reduced to 280 megatonnes.

In China, the emissions from city transport are expected to rise from 190 megatonnes a year now to 1,100 megatonnes as the nation’s economy booms. Under the high shift scenario, this could be slashed to 650 megatonnes, with help from extensive investment in public transport.

Currently, Indian cities emit 70 megatonnes. This could rise to 540 megatonnes by 2050, but the report says that these could be contained at 350 megatonnes by addressing crucial deficiencies in India’s public transport. – Climate News Network

Political will is only barrier to 100% renewables

Wind turbines in Germany's Rhein-Hunsrück district, a world leader in renewables Image: Markus Braun via Wikimedia Commons
Germany’s Rhein-Hunsrück district already exceeds100% electricity from renewables
Image: Markus Braun via Wikimedia Commons

By Paul Brown

A report published ahead of next week’s UN Climate Summit illustrates that poor and prosperous nations, tiny islands and great cities, can achieve all their energy needs from renewables.

LONDON, 20 September, 2014 − A new handbook shows how forward-looking communities around the world are already moving away from reliance on fossil fuels and generating their own power with 100% renewables − while also becoming more prosperous and creating jobs.

The report, How to Achieve 100% Renewable Energy, is being released today, ahead of the UN Climate Summit in New York next Tuesday (September 23), when the UN Secretary-general, Ban Ki-Moon, will call on world leaders to make new commitments to cut fossil fuel use.

The World Future Council, based in Hamburg, Germany, has issued the report to show that it is only lack of political will that is preventing the world switching away from fossil fuels. It believes that the leaders at the UN summit need to set ambitious targets and timetables to achieve the switch to renewables.

Technologies exist

Using case histories − from small islands in the Canaries to great commercial cities such as Frankfurt in Germany and Sydney in Australia − the report makes clear that the technologies to go 100% renewable exist already.

In many cases, the switch has the combined effect of saving money for the community concerned and creating jobs, making everyone more prosperous. In all cases, improvements in energy efficiency are essential to meeting targets.

Where the100% renewable target is adopted, it gives the clearest signal to business that investments in clean technologies will be secure. The report says: “The benefits range from savings on fossil fuel imports, improved energy, and economic security, as well as reduced energy and electricity costs for governments, local residents and businesses.”

There is no case made for nuclear power. Indeed, the report says that the uranium needed for nuclear fuel is − like coal, oil and gas − a finite resource that will soon be running out.

One of the case histories in the report is the Fukushima Prefecture in Japan. In March 2011,  it sustained the world’s worst nuclear accident since the 1986 Chernobyl disaster in Ukraine, and has now opted to go for 100% electricity from renewables by 2040.

Some of the 100% renewable targets detailed in the report are just for electricity production. The authors − Toby Couture, founder of the Berlin-based energy consultancy E3 Analytics, and Anna Leidreiter, climate and energy policy officer at the World Future Council − point out that heating and cooling, and particularly transport, without fossil fuels is far more challenging, but still equally possible. Some countries are already committed to it.

Denmark, a pioneer in the field, has a target of achieving all its electricity and heating needs from renewables by 2035, and all energy sectors − including transport − by 2050. This includes an expansion of wind and solar power, biogas, ground source heat pumps, and wood-based biomass. Because of its investments, the country expects to have saved €920 million on energy costs by 2020.

At the opposite end of the scale, El Hierro, a small island in the Canaries, has a 100% energy strategy, using a wind farm and a volcanic crater. When excess electricity is produced by the wind farm, water is pumped into the volcanic crater, which acts as a storage lake for a hydroelectric plant. This supplements the island’s electricity supply when the wind drops or when demand is very high.

A future component of El Hierro’s strategy is to replace the island’s entire stock of 4,500 cars with electric vehicles, so cutting the need to import fuel.

Surplus electricity

Some places have already exceeded 100% electricity from renewables. The Rhein-Hunsruck district west of Frankfurt, Germany, managed this in 2012, and expects by the end of this year to be producing 230% of its needs, exporting the surplus to neighbouring areas through the national grid. It hopes to use the surplus in future for local transportation, hydrogen or methane production.

There are many other examples in the report, including from San Francisco in the US, Cape Verde island in West Africa, Bangladesh, Costa Rica, and Tuvalu island in the Pacific. These show that both rich and poor communities can share the benefits of the renewable revolution – and, in the case of the 3 billion people still without electric power in the world, bypass the need for fossil fuels altogether.

Jeremy Leggett, a pioneer of solar power and author of a foreword to the report, says: “We are on the verge of a profound and urgently necessary shift in the way we produce and use energy.

“This shift will move the world away from the consumption of fossil resources towards cleaner, renewable forms of power. Renewable energy technologies are blowing the whistle on oil dependency and will spark an economic and social renaissance.

“The question is: Do we make this transition from fossil resources to renewables on our own terms, in ways that maximise the benefits to us today and to future generations, or do we turn our heads away and suffer the economic and social shocks that rising prices and market volatility will create?” – Climate News Network

Climate action and economies can grow together

Investing in renewables such as solar energy can spur economic activity Image: Alex Snyder/Wayne National Forest via Wikimedia Commons
Working together: investing in renewables such as solar energy can spur economic activity
Image: Alex Snyder/Wayne National Forest via Wikimedia Commons

By Kieran Cooke

A new global commission report by major political and business figures refutes the claim that economic expansion and tackling climate change can’t both be achieved at the same time.

LONDON, 17 September, 2014 − We can have our cake and eat it. That’s the main message of a new study that says the idea that we have to choose between battling against climate change or promoting growth in the world’s economy is a “false dilemma”.

The report, The New Climate Economy, was produced by the Global Commission on the Economy and Climate, chaired by Felipe Calderón, the former president of Mexico, and including eminent economist Lord [Nicholas] Stern.

Calderon, addressing what he describes as a “false dilemma”, says: “The message to leaders is clear. We don’t have to choose between economic growth and a safe climate. We can have both.”

Lord Stern, author of the 2006 Stern Review, which comprehensively detailed, for the first time, the economic consequences of not taking action on climate change, says decisions being made now will determine the future of both the economy and the climate.

High-quality growth

“If we choose low-carbon investment, we can generate strong, high-quality growth – not just in the future, but now,” he says. “But if we continue down the high-carbon route, climate change will bring severe risks to long-term prosperity.”

The commission’s report, released at the United Nations in New York shortly before a major UN climate summit, says there are now big opportunities for achieving strong economic growth and, at the same time, lowering emissions across three sectors:

  • Building more compact, better connected cities will improve the quality of life of urban dwellers, improve economic performance, and lower emissions.
  • Improved land use can cut emissions resulting from deforestation. Restoring 12% of the world’s degraded land would dramatically raise farmers’ incomes.
  • More and more of the world’s energy is likely to be generated by renewables, cutting dependence on highly-polluting coal. Renewables is now a big growth industry, spurring on various economic activities.

The report says that about US$90 trillion is likely to be invested in infrastructure in the world’s cities, agriculture and energy systems over the next 15 years, and spending should be directed towards low-carbon growth that would not only benefit the climate but also business productivity.

The study calls for the phasing out of huge amounts spent worldwide on subsidies for fossil fuels – currently US$600 billion, compared with US$100bn for renewable, the report says. Competitive energy markets, consistent government policy, a strong price for carbon, and greatly expanded research in low carbon technologies are also needed.

If fully implemented, the report’s authors calculate, a reduction of up to 90% in emissions could be achieved by 2030, and dangerous climate change would be averted.

Meaningful action

Although the report’s findings have been endorsed by a wide range of leading politicians, business figures and economists, there are those who would argue against the idea that economic growth can be achieved alongside meaningful action on climate change.

For example, the New Economics Foundation (NEF), a UK thinktank, contends that indefinite global economic growth is unsustainable.

In a 2010 report, Growth Isn’t Possible, the NEF said economic growth is constrained by the finite nature of the planet’s natural resources. “Growth forever, as conventionally defined, within fixed though flexible limits, is not possible,” it said. “Sooner or later, we will hit the biosphere’s buffers.”

Others would point out that although a carbon market has been in operation for several years, the price of carbon has failed to rise. The introduction of market forces and competition in the energy sector in many countries has done little to lessen greenhouse gas emissions.

In many countries, including India, China, Australia and some states in Europe, a central role in driving economic growth is still played by coal, the most polluting of all energy sources. – Climate News Network

Warming will leave drought-hit California reeling

 

The treeline below Tells Peak in California’s Sierra Nevada mountains Image: Nick Ares via Wikimedia Commons
The treeline below Tells Peak in California’s Sierra Nevada mountains
Image: Nick Ares via Wikimedia Commons

By Tim Radford

Researchers in the US warn that climate change could worsen California droughts by drastically reducing water flow from the Sierra Nevada mountains − and also threatens the extinction of a rare species of fish.

LONDON, 16 September, 2014 − Things could soon get worse for drought-hit California. New research predicts that, by the close of the century, global warming could have reduced the flow of water from the Sierra Nevada mountains by at least a quarter.

Michael Goulden, associate professor of earth system science at the University of California Irvine, and Roger Bales, director of the Sierra Nevada Research Institute at the University of California Merced, publish their alarming findings in the Proceedings of the National Academy of Sciences.

Plant growth

Their research looked not at the long-term projections for precipitation in the US south-west, but simply at the effect of higher average temperatures on plant growth.

Mountains in many ways mimic hemispheres: just as trees become more stunted at higher latitudes, so they get smaller and less frequent at higher altitudes. Temperature ultimately controls plant growth.

But a projected warming of 4.1°C by 2100 would make a big difference to plant growth in the Arctic tundra and around the present alpine treeline everywhere in the world.

The scientists contemplated snow and rain conditions in the King’s River Basin in the Sierra Nevada range. They looked at how much flows downstream to local communities, and how much goes back into the atmosphere as water vapour. Then they did their sums.

They calculated that the 4.1°C temperature rise in the region would increase the density of vegetation at high elevations, with a 28% increase in evapotranspiration − the process that draws water up through the roots to the leaves, and then releases it as vapour through the pores. And what was true for one river basin, they thought, should be true for the whole area. River run-off could drop by 26%.

“Scientists have recognised for a while that something like this was possible, but no one has been able to quantify whether it could be a big effect,” said Professor Goulden. “It’s clear that this could be a big effect of climate warming and that managers need to recognise and plan for the possibility of increased water losses from forest evaporation.”

Endangered fish

MEANWHILE, climate change threatens to wipe out an endangered species of fish in a remote area of Nevada.

The Devils Hole pupfish (Cyprinodon diabolis) is not just rare, it is very rare: the population has fallen as low as 35 individuals. It lives in the geothermally-warmed waters of a limestone cavern in the Devils Hole in the Mojave desert, and its existence was probably always precarious. The fish are little more than 2cms long, iridescent blue, and they have made their home in the upper 25 metres of the cavern’s waters for at least 10,000 years.

Devils Hole pupfish are only 2cms long Image: Nevada Fish & Wildlife Office
Devils Hole pupfish are only 2cms long
Image: Nevada Fish & Wildlife Office via Wikimedia Commons

But Mark Hausner, a hydrogeologist at the Desert Research Institute in Las Vegas, Nevada, and colleagues report in the journal Water Resources Research that there is only a 10-week window in which the water temperatures are optimal, and there is enough food available, for new larvae to hatch.

Climate change is bringing the already-warm water to dangerous temperature levels, and this has already shortened by at least one week the brief opportunity to restore the population. When counts began in 1972, there were more than 500 of the fish. A decade ago there were 171, and at the last count there were only 92.

“This is a fish that does live in a fishbowl, an incredibly hostile fishbowl, and you can’t move the fishbowl,” said one of the report’s authors, Scott Tyler, professor in the Department of Geological Sciences and Engineering at the University of Nevada, Reno. “This is a species that can’t adapt or change or leave to go to a better environment.” − Climate News Network

Drowned tropical forests add to climate change

Dead trees poke out of the Nam Theun 2 dam reservoir, Laos. Image: Dominique Serça/CNRS
Dead trees poke eerily out of the Nam Theun 2 dam reservoir in Laos
Image: Dominique Serça/CNRS

By Paul Brown

New scientific data supports the belief that methane emissions from big hydroelectric dams in the tropics outweigh the benefits that this form of renewable energy provides.

LONDON, 11 September, 2014 − Big dams built in the tropics to produce hydroelectricity have long been highly controversial − and data gathered in Laos by a French team studying methane emissions confirms that dams can add to global warming, not reduce it.

In many rocky regions low on vegetation and population, such as in Iceland and other northern mountainous regions, the production of electricity from hydropower is clearly a net gain in the battle against climate change.

In Asia, Africa and South America, however, masses of methane are produced from dams by the drowning of tropical forests in them. As long ago as 2007, researchers at Brazil’s National Institute for Space Research calculated that the world’s largest dams emitted 104 million tonnes of methane annually and were responsible for 4% of the human contribution to climate change.

Short-term threat

Since methane has an impact 84 times higher over 20 years than the same quantity of carbon dioxide, this is a serious short-term threat to pushing the planet towards the danger threshold of increasing temperatures by 2˚C .

Despite the warnings that big dams in the tropics might be adding to climate change, governments go on building them − while often claiming that large dams equal clean energy.

The new research shows that the methane discharges are probably even worse than current calculations.

In an attempt to find out exactly what the perils and benefits of big dams in the tropics can be, a French team from the National Centre for Scientific Research (CNRS) has been studying the Nam Theun 2 reservoir in Laos − the largest in Southeast Asia − prior to its filling, in May 2008, right up to the present to calculate the total methane emissions.

Methane is produced by bacteria feeding on the plant material drowned when the dam is filled. This is added to by more organic matter that is washed into it by rivers and rains.

Measuring the methane produced is the tricky bit as it reaches the atmosphere in three ways. Some is dissolved in the water and reaches the atmosphere by diffusion, some goes through the turbines and is released downstream, and the third way is called ebullition – which means bubbles of methane coming directly to the surface and going straight into the atmosphere.

It is these last gas emissions that have been so hard to measure, but the team has developed automatic measuring devices that work 24 hours a day.

The measurements carried out on the Nam Theun 2 reservoir enabled the scientists to show that ebullition accounted for between 60% and 80% of total emissions from the reservoir in the first years following filling.

Maximum emissions

In addition, ebullition intensity varies at night and seasonally. During the four months of the hot dry season (mid-February to mid-June), emissions reach their maximum because water levels are low. Daily variations are controlled by atmospheric pressure: during the two daily pressure drops (in the middle of the day and the middle of the night), methane (CH4) ebullition increases.

With the help of a statistical model, day-to-day data related to atmospheric pressure and water level was used by the researchers to reconstruct emissions by ebullition over a continuous four-year period (2009-2013).

The results obtained highlight the importance of very frequent measurements of methane fluxes. They also show that the ebullition process − and therefore the amount of methane emitted from tropical reservoirs during their first years of operation − has most certainly been underestimated until now.

For the researchers, the next stage will be to quantify diffusion at the surface of the reservoir and emissions downstream from the dam to the same level of accuracy. This will enable them to complete the assessment of methane emissions from this reservoir, and better assess the contribution they make to the global greenhouse effect. – 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