Two oceans may explain global warming pause

Two oceans may explain global warming pause

Temperatures may be rising more slowly than expected because of two natural oceanic cycles − the latest refutation of the global warming “pause”.

LONDON, 1 March, 2015 − US scientists have suggested yet another explanation for the so-called pause in global warming. They think it might all be down to the juxtaposition of two independent natural climate cycles – each with periods of half a century or more – one of which is blowing cold, and the other not very hot.

Between them, the phenomena known to meteorologists as the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation could account for the seeming slowdown in predicted temperature rises.

Any pause or hiatus in global warming is only apparent: in fact, 14 of the warmest years on record have happened in the last 15 years and 2014 was scored separately, by the World Meteorological Organisation, the US National Oceanic and Atmospheric Administration, and the US space agency Nasa,  as the warmest on record.

But overall, the palpable increases in average temperatures per decade recorded in the last 30 years of the 20th century have not been maintained, and climate scientists and meteorologists have been trying to work out why.

The latest proposal is from Byron Steinman, a geologist at the University of Minnesota Duluth, and Michael Mann and Sonya Miller of Pennsylvania State University.

Multiple theories

Professor Mann is the scientist who, much to the fury of people who deny climate change, first formulated the famous “hockey-stick graph” which highlights the magnitude of change that threatens to overtake global climate as greenhouse gas levels rise because of human activity.

They report in Science that the northern hemisphere is warming more slowly, not because of the Atlantic oscillation, which has been relatively flat, but because of a second, different but still natural downward trend in the Pacific cycle.

This is not the only explanation on the table. In the past two years Climate News Network has reported that climate scientists certainly expected a slowdown, but just not right now; or that planetary measurements might be incomplete or misleading; or that even though average levels were down, this masked a series of hotter extremes.

The oceans have certainly been under suspicion. One group has already identified the cooling Pacific as a damper on global warming. Another has suggested that in fact the “missing heat” is collecting in the Atlantic depths.

Yet another has questioned the role of the trade winds, while still another has pointed to an upswing in volcanic activity that could have delivered a fine smear of sunblock aerosols to the atmosphere.

“The North Atlantic and North Pacific Oceans appear to be drivers of substantial natural… climate variability on timescales of decades”

Any or all of these could have some role in the big picture. The climate would vary anyway, and the question in every case is: how much would any or all natural variation affect the overall path of change because of increasing carbon dioxide levels in the atmosphere?

The latest study is based on sophisticated climate models that match the predicted impact of the great ocean-atmosphere cycles with the pattern of climate shifts recorded in the past.

“We know that it is important to distinguish between human-caused and natural climate variability so we can assess the impact of human-caused climate change, including drought and weather extremes,” Professor Mann said.

“The North Atlantic and North Pacific Oceans appear to be drivers of substantial natural, internal climate variability on timescales of decades.” – Climate News Network

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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

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Satellite link puts sharper focus on ocean acidity rise

Satellite link puts sharper focus on ocean acidity rise

Global data network could provide scientists with an easy and cheaper way of finding answers to crucial questions on the oceans’ changing chemistry.

LONDON, 25 February, 2015 − Climate scientists are looking for a new perspective on the increasingly acidic oceans through a suite of satellites 700 km out in space, watching over parts of the seas that research ships cannot reach.

They report in the journal Environmental Science and Technology that thermal cameras could measure ocean temperatures, while microwave sensors could measure ocean salinity. Together, the two sets of data could help answer, cheaply and easily, questions about the chemistry of the oceans – and in particular changes in pH, the index of acidity.

Until now, researchers have depended on specialist instruments or shipboard samples to provide answers to huge questions about the oceans’ increasing uptake of carbon dioxide. Such research is costly and limited.

But ocean science has become ever more important. Each year, 36 billion tonnes of CO2 are released into the atmosphere, and about a quarter of this gets into the oceans.

Greenhouse gas

That’s a good thing: if it did not, global warming would accelerate at an even greater rate. But the same global transfer of greenhouse gas also delivers a stronger solution of carbonic acid to the oceans, and ocean acidity levels have risen by 26% over the last 200 years.

The consequences for all those sea creatures that evolved to exploit ocean chemistry to build shells or skeletons are uncertain, but the evidence so far is that changes can affect fish behaviour, shellfish reproduction, and coral growth.

The changes could almost certainly affect fisheries in the short term, and in the long term could possibly alter the continuous and vital exchanges between atmosphere and ocean that controls the climates of continents.

So marine scientists launched a Global Ocean Acidification Observing Network to assemble worldwide expertise and find new ways to monitor change.

“We are pioneering these techniques so that we can monitor large areas of the Earth’s oceans”

“Satellites are likely to become increasingly important for the monitoring of ocean acidification especially in remote and dangerous waters like the Arctic,” says one of the report’s authors, Jamie Shutler, an oceanographer at the University of Exeter. UK.

“It can be difficult and expensive to take year-round direct measurements in such inaccessible locations. We are pioneering these techniques so that we can monitor large areas of the Earth’s oceans, allowing us to quickly and easily identify those areas most at risk from the increasing acidification.”

The European Space Agency’s SMOS satellite in orbit. Image: ESA

The European Space Agency’s SMOS satellite in orbit.
Image: ESA

The new approach will exploit a number of existing satellites, along with the European Space Agency’s Soil Moisture and Ocean Salinity sensor (SMOS), launched in 2009, and the US space agency NASA’s Aquarius satellite, launched in 2011.

The satellites cannot, of course, directly measure ocean pH values, but the capacity of CO2 to dissolve in water is controlled by ocean temperatures.

Salinity levels

On the other hand, salinity levels play into the capacity to form carbonates. Chlorophyll levels in the oceans also indicate the rates at which biology can exploit any of the dissolved carbon dioxide.

If the scientists have temperature and air pressure data as well, they have enough to begin to calculate the rates at which any stretch of sea might be acidifying.

Although such measurements are indirect, and involve complex mathematical calculation, the results can be checked in some places against real-time data from a network of autonomous instruments called Argo, and by shipboard laboratory studies.

But satellites are about the only way of making consistent measurements of the desolate and hostile Arctic and Indian Oceans. They could also help researchers understand the changes taking place in complex stretches of sea such as the Bay of Bengal and the Greater Caribbean.

The research is in its infancy. But the authors say that satellite studies − supported by good measurements taken directly at sea − could become a key element in understanding and assessing the acidification of the oceans. – Climate News Network

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New ideas give energy boost to wave power

New ideas give energy boost to wave power

Scientists and engineers in Scandinavia reveal new plans to harness the huge potential of waves to produce commercially viable renewable energy.

LONDON, 22 February, 2015 − All along the coasts of Europe where the Atlantic waves crash onto the shore there are experimental wave power stations producing electricity.

Now engineers in Norway and Sweden − two of the countries trying hardest to develop this technology − have announced “breakthroughs” in their methods, which the inventors believe will make wave power competitive.

At present, most wave power stations are small-scale. All of them work, but making them commercially viable to compete economically with other renewables and fossil fuels has so far eluded their inventors.

The latest Norwegian experiment has been installed in a redundant fishing vessel in the Stadthavet area of West Norway, an area designated for renewable energy testing.

Bicycle pump principle

Like all the best ideas, it is simple. “In principle, it works almost like a bicycle pump,” explains engineer and project manager Edgar Kvernevik, of Kvernevik Engineering AS.

The makers have installed four large chambers in the vessel’s bow. As the waves strike the vessel, the water level in the chambers rises. This creates an increase in air pressure, which in turn drives four turbines – one for each chamber.

The pitch of the vessel also contributes by generating additional air pressure in the chambers when the wave height is large. The design of the chambers is such that they work in response to different wave heights, which means that the energy is exploited very effectively.

“The plant thus produces electricity with the help of what is called a fluctuating water column,” says Kvernevik, who has spent much of his working life designing and building vessels.

Our aim is to . . . produce hydrogen at a competitive price – based on an infinite resource and involving no harmful emissions”

“All we have to do is to let the vessel swing at anchor in a part of the ocean with sufficient wave energy. Everything is designed to be remotely-controlled from onshore.

“This floating power plant has also been equipped with a special anchoring system, which means that it is always facing into the incoming waves. This ensures that the plant is in the optimal position at all times.”

A former fishing vessel converted to a wave power plant. Image: Sintef

A former fishing vessel that has been converted to a wave power plant.
Image: Sintef

The turbines on the deck of the vessel continue to work regardless of whether the chambers are inhaling or exhaling air as the wave runs past the vessel.

In the same area, which has a high average wind velocity, researchers have been studying the idea of floating wind turbines.

The project is now looking at combining wind turbines and wave power plants on the same vessel and using the electricity to create hydrogen gas – a way of storing the energy.

“We see this project as a three-stage rocket,” Kvernevik says. “The first stage is to test the model we have just built to make sure that electricity generation can be carried out as planned.

Production plant

“Next, a hydrogen production plant will be installed on board the vessel so that the electricity generated can be stored in the form of hydrogen gas.

“We have high hopes that hydrogen will be the car fuel of the future. Our aim is to work with others to produce hydrogen at a competitive price – based on an infinite resource and involving no harmful emissions.

“The plan is then to construct a plant with a nominal capacity of 1000kW (1MW). We will do this by installing five production modules similar to the current plant, either on a larger vessel or a custom-built barge. Finally, we will build a semi-submersible platform designed to carry a 4MW wave power plant with a 6MW wind turbine installed on top.”

The Norwegian Marine Technology Research Institute (MARINTEK) is one of the project partners that have contributed towards the development of the wave power plant.

Reliable source

Meanwhile, a Swedish company claims to have cracked the problem of scaling-up wave energy with a gearbox that generates five times as much power per tonne of device at one third of the cost.

One of the obvious problems with wave power is the height and timing of the waves, making it difficult to convert the power into a reliable energy source. But CorPower Ocean’s new wave energy system claims to produce three to four times more power than traditional systems.

The new system that helps to solve this problem is based in a buoy that absorbs energy from the waves − a scaled-up version of a heart surgeon’s research into heart pumping and control functions.

Patrik Möller, CorPower’s chief executive, says the wave energy converter – in contrast to competing systems − can manage the entire spectrum of waves.

He says: “We can ensure that it always works in time with the waves, which greatly enhances the buoy’s movement and uses it all the way between the wave crest and wave trough and back in an optimal way, no matter how long or high the waves are.”

The buoys are compact and lightweight and can be manufactured at a relatively low cost. A buoy 8 metres in diameter can produce 250-300 kilowatts in a typical Atlantic swell. A wave energy park with 100 buoys can generate 25 to 30 megawatts. – Climate News Network

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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

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Arctic melting opens sea route to more pollution

Arctic melting opens sea route to more pollution

Increasing loss of Arctic sea ice is likely soon to mean more ships being able to use the polar passage affecting climate, health and air quality.

LONDON, 14 February, 2015 − As Arctic sea ice continues to melt at an alarming rate, maritime traffic is set to increase − and with it the pollution emitted by ships’ engines.

A paper published by the International Council on Clean Transportation (ICCT) says emissions of pollutants from vessels in the US area of the high Arctic could increase by between 150% and 600% by 2025.

Ships typically burn bunker fuel with a high sulphur content. As well as various greenhouse gases (GHGs), the engines also emit soot, or black carbon. And when this covers snow and ice, it reduces their ability to reflect sunlight away from the Earth, and so raises temperatures.

Human health

The ICCT paper says ship-borne pollutants − which include carbon dioxide, nitrous oxide (NOX), oxides of sulphur, particulate matter (PM) and soot − affect local air quality and human health, as well as the global climate.

Without new pollution controls, it is estimated that global soot emissions from shipping may more than quintuple from 2004 to 2050, to a total of more than 744,000 tonnes, because of increased shipping demand.

A growing share of those emissions will occur in the Arctic, because of vessels being diverted to the much shorter Northwest Passage and Northeast Passage to cut the length of voyages.

Earlier studies of increased shipping in the Arctic concentrated on infrastructure needs and estimates of shipping growth, based on potential oil and gas exploration and other development, but did not address air pollution or its effects.

The paper says: “The potential increases in vessel activity associated with oil and gas exploration . . . would increase emissions from vessels beyond those estimated in this paper.”

It also says that a change to higher quality low-sulphur fuel would cut pollution significantly.

“The lack of regional restrictions in the Arctic leaves the area vulnerable to increasing emissions from international traffic . . .”

Mark Jacobson, professor of civil and environmental engineering at Stanford University, US, advised as long ago as 2011 that controlling soot could reduce warming in the Arctic by about 2°C within 15 years.

“That would virtually erase all of the warming that has occurred in the Arctic during the last 100 years,” he said. “No other measure could have such an immediate effect.”

He said soot emissions were second only to carbon dioxide in promoting global warming, accounting for about 17% of the extra heat. But its contribution could be cut by 90% in five to 10 years with aggressive national and international policies.

The International Maritime Organisation (IMO], a UN body, said in the final report of its GHG Study 2014 that, by 2050, emissions of NOX could increase globally by as much as 300%, and PM by 280%.

The IMO has two sets of emission and fuel quality requirements, one for global shipping and the other a more stringent set of rules for ships in Emission Control Areas.

The global requirements include a limit on marine bunker fuel sulphur content, which is currently 3.5%, compared with an actual global average of 2.7%. This limit is due to be cut to 0.5% in 2020, although parts of the shipping industry are urging the IMO to delay the reduction until at least 2025.

International regulations do not directly restrict the emission of soot from vessels, although it is generally understood that improving fuel quality also controls soot.

Increasing impact

The ICCT paper says that, combined with the potential increases in marine emissions, “the current lack of regional environmental requirements for vessels transiting and operating in the US Arctic may lead to an increasing impact on human health for Arctic communities and for the global climate.

“Additional emissions of climate-forcing pollutants such as black carbon and carbon dioxide, combined with emissions of PM and NOX, which can be linked with respiratory health issues, may place additional stress on the Arctic environment and Arctic communities.

“The lack of regional restrictions in the Arctic leaves the area vulnerable to increasing emissions from international traffic that is less tightly regulated than under US law.”

There have also been calls to find alternatives to the many diesel generators currently in use throughout Arctic communities, and which are known to produce large amounts of greenhouse gases and soot. − Climate News Network

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Ancient shells offer evidence of how Ice Age ended

Ancient shells offer evidence of how Ice Age ended

Ocean sediment reveals that release of carbon stored deep in the sea is linked to the rise in atmospheric CO2 that caused the world to warm.

LONDON, 13 February, 2015 − Scientists believe they may have cracked the mystery of the end of the last ice age. The temperatures suddenly soared, and the glaciers went into retreat, because the deep southern ocean released huge quantities of carbon dioxide.

And the convincing answers have been delivered by analysis of the composition of calcium carbonate shells of ancient marine organisms.

The link between human burning of fossil fuels and the steady rise in atmospheric carbon dioxide levels was proposed more than a century ago and firmly established in the last 30 years.

But the ups and downs of planetary temperatures before the emergence of human civilisation are harder to explain. Fossil evidence suggests a link with carbon dioxide levels, but not necessarily a cause.

Bygone climates

Now paleoceanographer Miguel Martínez-Botí, from the University of Southampton, UK, and ocean and climate change researcher Gianluca Marino, from the Australian National University, report in Nature that they found their evidence in sediment cores – in effect, annual records of bygone climates – rich in the shells of tiny foraminifera called Globigerina bulloides.

This is a species that flourishes in conditions of high nutrients, acting as a kind of biological pump, gulping carbon from the atmosphere.

They found that high concentrations of carbon dioxide dissolved in surface waters of the southern Atlantic Ocean and the eastern equatorial Pacific coincided with rises in atmospheric CO2 at the end of the last ice age.

The implication is that these regions were the source of the carbon dioxide to the atmosphere.

“Our findings support the theory that a series of processes in the Southern Ocean changed the amount of carbon in the deep sea”

At their coldest, during the ice ages, carbon dioxide levels fell to 185 parts per million. During the interglacials, when the world warmed and lions and hyenas roamed the plains of Europe, the carbon dioxide levels rose to 280 ppm.

Right now, thanks to human activity, CO2 levels are rising ominously towards 400 ppm.

The oceans are home to about 60 times more carbon than the atmosphere and can, it seems, surrender it rapidly.

“The magnitude and rapidity of the swings in atmospheric CO2 across the ice age cycles suggest that changes in ocean carbon storage are important drivers of natural atmospheric CO2 variations,” Dr Martínez-Botí says.

“Our findings support the theory that a series of processes operating in the southernmost sector of the Atlantic, Pacific and Indian oceans, a region known as the Southern Ocean, changed the amount of carbon in the deep sea.

Into the abyss

“While a reduction in communication between the deep sea and the atmosphere in this region potentially locks carbon away from the atmosphere into the abyss during ice ages, the opposite occurs during warm interglacial periods.”

To arrive at their conclusion, the scientists had to analyse subtle evidence from the isotopic composition of the carbonate shells, and then use mathematical techniques to reconstruct a story of a great, faraway sigh of carbon dioxide from the ocean to the atmosphere.

The finding, based on calculated probabilities, is incomplete as there may have been other forces also at play.

Gavin Foster, associate professor in isotope geochemistry at the University of Southampton, says: “While our results support a primary role for the Southern Ocean processes in these natural cycles, we don’t yet know the full story. Other processes operating in other parts of the ocean, such as the north Pacific, may have an additional role to play.” – Climate News Network

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Climate data gives mixed message on storm forecasts

Climate data gives mixed message on storm forecasts

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

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

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

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

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

Heat engine

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

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

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

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

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

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

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

Energy budget

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

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

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

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

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Climate change triggers threats to marine ecosystems

Climate change triggers threats to marine ecosystems

A two-way migration of fish species between the northern Pacific and Atlantic as oceans warm could have drastic ecological and commercial impacts.

LONDON, 7 February, 2015 − The Atlantic halibut is about to go where no Atlantic halibut has gone before – into the Pacific. And it could meet the Alaska pollock coming in the other direction.

Just as marine commerce could soon exploit the opening of the fabled north-west or north-east passages between the two great oceans, so could at least 80 species of fish.

Mary Wisz, an ecologist now with the Danish DHI group, but formerly at the Arctic Research Centre of Aarhus University in Denmark, reports with colleagues in Nature Climate Change that as sea temperatures increase, and food sources begin to flourish at the highest latitudes, shoals of fish from the Atlantic could reach the Pacific along once almost impassable seaways north of Arctic Canada and Siberia.

Northerly species

The last such large-scale transfer was nearly three million years ago, with the opening of the Bering Strait. But climate conditions that were once harsh have begun to open migration opportunities for the northerly species in both oceans, the researchers say.

Such changes have happened before. Since the opening of the Suez Canal in 1869, the Mediterranean has been invaded by 55 Red Sea species, with a “drastic impact” on commercial fisheries.

Fish are already moving north in response to climate change, and Dr Wisz and her colleagues modelled what would happen to 515 species of fish under predicted conditions of global warming later this century.

By 2050, the scientists believe, trans-Arctic traffic will accelerate, and by 2100, 41 Atlantic species − among them cod and herring − could reach the Pacific, while 44 species could get into the Atlantic.

They warn: “This exchange of fish species may trigger changes in the North Atlantic and the North Pacific, with ecological and economic consequences to ecosystems that at present contribute 39% to global marine fish landings.”

Changes to marine chemistry also threaten the balance of power in the oceans

The Danish-led team was essentially modelling temperature, currents and spawning strategies to see which species were most likely to find new grounds. But changes to marine chemistry also threaten the balance of power in the oceans.

The seas are predicted to become more acidic as more carbon dioxide gets into the atmosphere, and this change in water chemistry is likely to affect not just fish and shellfish but also entire communities of creatures.

Scientists have tested the fauna that foul ships’ hulls. These are the tiny barnacles and squirts that attach themselves to hard surfaces wherever they can in the oceans.

Lloyd Peck, a biologist with the British Antarctic Survey, and colleagues report in Global Change Biology that they tested creatures from a lagoon off the Algarve in Portugal, in aquarium tanks.

One set of tanks was filled with normal sea water; in the other set, the sea water was set at levels of acidity predicted to be normal within the next 50 years. Within 100 days, in the more acid tanks, the make-up of the community that colonised the hard surfaces had begun to change.

Worms with hard shells in the more acidic tanks were reduced to a fifth of their normal levels, but sponges and sea squirts multiplied twofold and even fourfold.

“Our experiment shows the response of one biofouling community to a very rapid change in acidity,” said Professor Peck. “What’s interesting is that the increased acidity at the levels we studied destroys not only the building blocks in the outer shell of the worms itself, but the binding that holds it together.

“Many individuals perish, but we also showed their larvae and juveniles are also unable to establish and create their hard exoskeletons.”

Altered behaviour

Climate change could also alter the behaviour of the green sea turtle, Chelonia mydas, according to an international team led by Professor Kyle Van Houtan, of the Nicholas School of the Environment and Earth Sciences at Duke University, US.

The researchers studied six years of turtle observations off Oahu, Hawaii, and 24 years of satellite data for sea surface temperatures in regions that are home to 11 populations of the turtle.

They report in Biology Letters that they know why the turtles crawl up onto the beach to bask. Not all populations bask, but the ones that do tend to sprawl in the sand do so to regulate body temperatures, and were least likely to bask when local winter sea temperatures stayed above 23°C. When the seas stayed warm, the turtles stayed in the water.

Given the predicted ocean temperature rises over the next century, the scientists calculate that green turtles may stop basking altogether by 2100. – Climate News Network

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Greenland’s hidden meltwater lakes store up trouble

Greenland’s hidden meltwater lakes store up trouble

Scientists find evidence of vast “storage tanks” of water deep below the melting Greenland ice sheet that could have a major effect on sea level rise.

LONDON, 5 February, 2015 − One small mystery that surrounds Greenland’s melting ice is a little closer to being solved as scientists in the US confirm that surface meltwater can drain all the way down to fill concealed lakes under the ice.

This means that atmospheric warming can reach thousands of metres below the ice sheet − warming the glacial base and potentially increasing its rate of flow.

One group, led by geologist Michael Willis, of Cornell University, and another team led by glaciologist Ian Howat, of Ohio State University, report in two different journals on separate but related studies of Greenland’s plumbing system: what happens to meltwater.

The ice sheet of Greenland adds up to about four-fifths of the mass of the vast frozen island, and there is evidence that, as a consequence of global warming, the rate of melting has begun to accelerate.

Measurable difference

This has already begun to make a measureable difference to global sea levels, and were the entire island to shed its burden of ice – a process that would take a considerable time − then sea levels would rise by seven metres or more.

So what exactly happens to the water that forms on the surface and collects in lakes each summer, and how much of it gets into the sea, has become an important but perplexing problem. Surface lakes are now appearing much further inland, and at higher altitudes, than recorded in the past.

Dr Howat and his colleagues report in The Cryosphere that they measured a two kilometre-wide depression 70 metres deep in the icecap of southwest Greenland, which they then identified as “the first direct evidence for concentrated long-term storage and sudden release of meltwater at the bed”.

The slumped crater suggested a holding capacity of more than 30 million cubic metres of water, which had suddenly drained away.

“If we are going to do something to mitigate sea level rise, we need to do it earlier rather than later”

“The fact that our lake appears to have been stable for at least several decades, and then drained in a matter of weeks – or less – after a few very hot summers, may signal a fundamental change happening to the ice sheet,” Dr Howat said.

The Cornell team worked in northeast Greenland, and in 2011 found a collapsed basin 70 metres deep. Dr Willis and colleagues report in Nature journal that between 2011 and 2014 they watched as summer meltwater made its way down fissures in the depression and refilled a lake basin at the base of the icecap. When this in turn emptied, the researchers calculated that the flow from the subglacial lake was at a rate of 215 cubic metres per second.

“We’re seeing surface meltwater make its way to the base of the ice where it can get trapped and stored at the boundary between the bedrock beneath the ice sheet and the ice itself,” they say.

“As the lake beneath the ice fills with surface meltwater, the heat released by this trapped meltwater can soften surrounding ice, which may eventually cause an increase in ice flow.”

Glacial flow

The researchers do not yet know whether the draining water is increasing glacial flow, and nor can they be sure how many such depressions in the Greenland ice mask buried meltwater storage tanks.

But melting of glacial ice is likely to accelerate anyway, according to new research in the journal Climate Dynamics.

Earth scientist Patrick Applegate, of Penn State University, reports that computer models confirm that the more temperatures increase, the faster the ice will melt.

Were all Greenland’s ice to melt, sea levels would rise catastrophically. At least one billion people live on coasts and estuaries vulnerable to a mere one metre rise.

The Arctic is already the fastest warming place in the northern hemisphere, and the Penn State scientists wanted to see how present warming could play back into future warming. Engineers call this positive feedback.

“If we are going to do something to mitigate sea level rise, we need to do it earlier rather than later,” Dr Applegate said. “The longer we wait, the more rapidly the changes will take place and the more difficult it will be to change.” − Climate News Network

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