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UCLA research makes possible rapid assessment of plant drought tolerance

UCLA. Used under Creative Commons License. Photo by:Rictor Norton & David Allen

UCLA life scientists, working with colleagues in China, have discovered a new method to quickly assess plants' drought tolerance. The method works for many diverse species growing around the world. The research, published in the journal Methods in Ecology and Evolution, may revolutionize the ability to survey plant species for their ability to withstand drought, said senior author Lawren Sack, a UCLA professor of ecology and evolutionary biology.

"This method can be applied rapidly and reliably for diverse species across ecosystems worldwide," he said of the federally funded research by the National Science Foundation.

Droughts, which are a major threat to plants worldwide, are expected to become both more frequent and more severe with climate change, Sack said. Assessing species' vulnerabilities to drought is essential to predict their responses to climate change and plan their conservation, he said.

Earlier this year, Sack and his research team resolved a decades-old debate about what leaf traits best predict drought tolerance for diverse plant species worldwide. However, these leaf traits are too difficult and time-consuming to measure, often taking up to two days for one species, Sack said.

The UCLA team worked with collaborators at the Xishuangbanna Tropical Botanical Gardens (XTBG) in Yunnan, China, to develop a method for measuring leaf drought tolerance that is 30 times faster. It is based on an important trait known as "turgor loss point." During drought, the leaf cells' water becomes harder to replace. The turgor loss point is reached when leaf cells become so dehydrated their walls become flaccid. This cell-level loss of turgor — or swollenness — causes the leaf to become limp and wilted, and the plant cannot grow, Sack said.

The new method, based on a technique called "osmometry," requires only about 10 minutes per leaf, sufficient to make a fast estimate for a given species.

Plant growth depends on the ability to withstand enormous losses of water to evaporation when they open their pores, or stomata, to take in carbon dioxide for photosynthesis. The amount of evaporation a plant can tolerate depends on the water pressure inside of its cells, which in turn depends on its turgor potential; the pushing force of water against the inside of the cell walls; and the osmotic potential inside the cell, which is to say, the pulling force of dissolved salt molecules on the water molecules — the same force that makes water with salt added boil at a higher temperature.

Plant cells need to maintain their turgor pressure to hold up their cell walls, but as evaporation dries out the cells, they lose turgor pressure, said co-author Christine Scoffoni, a UCLA graduate student in the Department of Ecology and Evolutionary Biology.

At the turgor loss point, saltier cells have a stronger pulling force holding the water molecules inside the cell. Plants with saltier cells can keep their stomata open in drier conditions, Sack said.

The turgor loss point, which varies widely among species, is a powerful determinant of the plant's drought tolerance. The UCLA team previously showed that the turgor loss point can predict the dryness of the ecosystem from which a plant species comes.

"Drought-tolerant plants typically have low turgor loss points and saltier sap," said lead author Megan Bartlett, a UCLA graduate student in the Department of Ecology and Evolutionary Biology. "Some plant species even load more salt into their cells when they experience a drought to lower their turgor loss point and improve their drought tolerance."

Researchers have been measuring turgor loss point and osmotic potential, or cell saltiness, for decades. Once the UCLA team demonstrated that these are the key traits to predict drought tolerance, they realized that a stumbling block to their use is the difficulty of their measurement. These traits are typically measured by generating a relationship called the pressure-volume (p-v) curve. To produce a p-v curve, a leaf is dried slowly. Leaf water pressure and water mass are repeatedly measured, requiring nearly constant attention from a researcher for up to two days for a single species.

"After we identified these traits for measuring drought tolerance, our next challenge was to make it possible to measure them quickly for many diverse species," Bartlett said.

To hasten the process, the UCLA team and XTBG froze small discs of leaf tissue in liquid nitrogen to break the cell walls and mix the cell sap. The saltiness of the cell sap could then be measured with an instrument called an osmometer, which is typically used to measure osmotic potential in urine or blood. (Earlier studies compared osmotic potential measured by p-v curves with those from the osmometer, but the method had not been refined enough to produce reliable results for turgor loss point.)

The UCLA-XTBG team refined the method so that it can be applied in 10 minutes. They made measurements for 30 species from very different ecosystems, including tropical forest in China and the California chaparral. From this comparison, they developed the first equations for predicting p-v curve turgor loss point and cell saltiness from osmometer measurements.

"This approach has great potential for determining drought tolerance for thousands of species that are threatened by climate change, and to answer important questions about the relationship between drought tolerance and plant evolution and ecology that were just not feasible before," Sack said.

UCLA is California's largest university, with an enrollment of nearly 38,000 undergraduate and graduate students. The UCLA College of Letters and Science and the university's 11 professional schools feature renowned faculty and offer 337 degree programs and majors. UCLA is a national and international leader in the breadth and quality of its academic, research, health care, cultural, continuing education and athletic programs. Six alumni and five faculty have been awarded the Nobel Prize.

Contact: Stuart Wolpert
swolpert@support.ucla.edu
310-206-0511
University of California - Los Angeles

 

 

First of Its Kind Multimillion Dollar Trust Fund Launched to Protect Guyana's Forests

The governments of Guyana and Germany along with Conservation International launch fund to protect critical ecosystems, maintain global carbon stocks and benefit local communities.

Kaieteur Falls, Guyana. © Conservation International/photo by John Martin

The Guyanese government today launched a US$8.5 million trust fund called the Conservation Trust Fund, the first of its kind for the country. The fund will provide long-term financing for the management of Guyana’s intact protected areas system (PAS) and will support efforts by the government, along with local communities, to manage the country’s PAS. The fund was established in part to recognize the outstanding contribution of the PAS initiative for Guyana, the region and the world.

Financing for the trust comes from the German government through their development bank, KfW, which provided US$5 million with another US$3.5 million coming from Conservation International’s (CI) Global Conservation Fund, made possible by a grant from the Gordon and Betty Moore Foundation.

According to Honorable Robert M. Persaud, Guyana’s Minister of Natural Resources and the Environment, “Guyana is globally recognized for its unique biodiversity and for having one of the lowest deforestation rates in the developing world. We have recently made significant strides in establishing a national protected areas system as a tool to conserve this natural heritage, while at the same time contributing to our sustainable development. The creation of the Conservation Trust Fund, and the commitments made by Germany and CI’s Global Conservation Fund, therefore represents an important piece of this puzzle, as it offers a valid option for the long-term, sustainable financing of Guyana’s Protected Areas.”

The trust fund will greatly enhance Guyana’s conservation efforts by supporting the on-the-ground efforts for the country’s protected areas including the implementation of management and monitoring plans and funding for park rangers and scientific research.

Guyana established its national PAS with the passing of the national Protected Areas Act in July 2011. This was quickly followed by the November 2011 creation of two new protected areas: the Kanuku Mountain Protected Area located in southwestern Guyana, and the Shell Beach Protected Area, which is located along the country’s northwest coast. These two areas now join the existing Kaieteur National Park, Iwokrama Rainforest Reserve, and the Community Owned Conservation Area at Konashen, collectively protecting almost 9 percent of Guyana’s landmass.

Following the appointment of the Board of Directors of the Protected Areas Commission in February 2012, the Ministry of Natural Resources and the Environment is moving to establish the Protected Areas Commission, and recruit key officers within the Commission. The Ministry is also implementing Phase II of the KfW funded Guyana Protected Areas System Project, which provides US$1.5 million for the establishment of the Protected Areas Commission offices, the development of a Shell Beach Protected Area management plan, and additional support for community livelihood projects.

Protected areas are also a key component of Guyana’s green economy, as described in its national Low Carbon Development Strategy (LCDS). The LCDS seeks to promote low-carbon economic development using revenues generated through the maintenance of the climate and biodiversity assets found in the country’s intact ecosystems, such as forest carbon offsets, primarily located in the areas that the new fund will help to conserve. The trust fund, along with the creation of a national system of protected areas, will ensure long-term conservation of tropical forests and other ecosystems and help maintain critical carbon stock.

Dr. Russell Mittermeier, President of Conservation International said: “This is a major achievement for Guyana. It represents a long-term commitment to conserving the country’s unique biodiversity and forest resources, and recognizing them as central to the success of the Low Carbon Development Strategy that the country has embarked upon.” He stressed that, “Guyana is one of the very few places in the world where one can still find such huge areas of intact wilderness, which represent the country’s renewable natural capital and will enable Guyana to develop a model green economy for the future. The Conservation Trust Fund will help to provide the financial support necessary to ensure the protection of critical ecosystems and to ensure that they continue to provide the wide range of ecosystem services necessary for the long-term well-being of Guyana’s people.”

More than 90 percent of Guyana’s natural wealth remains intact including tropical forests, wetlands, rivers, shrub and grassland savannahs. In addition, Guyana’s ecosystems harbor a range of extraordinary environmental values such as offering natural protection to the wealth of biodiversity and producing enormous volumes of fresh water that make it the fourth most water-rich country in the world.  The country’s tropical ecosystems, especially its forests, contribute irreplaceably to ensuring a stable global climate. These tropical ecosystems also provide a number of local, national and global benefits.

Stefan Schlueter, the German Ambassador in Trinidad and Tobago, accredited to Guyana, in explaining the significance of the process of setting up the Trust Fund stated, “The recent achievements in the establishment of the Guyana Protected Areas System represent a compelling example of joint collaboration between national governments, international nongovernmental organizations and official development assistance under the umbrella of a comprehensive national policy. The German government is looking forward to further support this process.”

Peter Hilliges, head of the Competence Center for Agriculture and Natural Resource Management in KfW said, “The development of sustainable and innovative financing mechanisms for nature conservation are worldwide a crucial challenge in order to ensure that also future generations can benefit from the beauty and services provided by protected areas. The establishment of the Conservation Trust Fund is a fundamental step towards this sustainability. KfW with its current and future support will help to further develop and broaden the scope of this financial mechanism.”

By December, the trust fund will be rolled into the statutory National Protected Areas Trust Fund under Guyana’s Protected Areas Act. Meanwhile, the next several months will be spent convening stakeholder consultations to develop the strategic and operational plan, which will guide the operation and grant-making portfolio of the trust fund for the years ahead.  This effort will include development of a  fundraising strategy in order to attract more national and international donors to jointly support the conservation of Guyana’s abundant biodiversity and nature. 

Macushi boy & Giant Otter (Pteronura brasiliensis), an endangered species. © Pete Oxford/iLCP

Conservation International (CI) - Building upon a strong foundation of science, partnership and field demonstration, CI empowers societies to responsibly and sustainably care for nature, our global biodiversity, for the long term well-being of people. Founded in 1987 and marking its 25th anniversary in 2012, CI has headquarters in the Washington DC area, and 900 employees working in nearly 30 countries on four continents, plus 1,000+ partners around the world.  

Global Conservation Fund (GCF) — Conservation International's GCF finances the creation, expansion and long-term management of protected areas. Made possible by a grant from the Gordon and Betty Moore Foundation, GCF provides financial and strategic assistance to enable local communities, nongovernmental organizations and governments to protect their biological riches.

Ministry of Natural Resources and the Environment, Guyana – Established in 2011, the Ministry is responsible for the development and implementation of policies in Guyana’s mining, forestry, land administration and environmental sectors. The Ministry also provides administrative oversight to a number of sector agencies, including the Protected Areas Commission.

Kreditanstalt für Wiederaufbau (KfW) - A German government – owned development bank formed in 1948. As one of the leading and most experienced promotional banks in the world, KfW supports change and encourages forward-looking ideas – in Germany, Europe and throughout the world. 

Contact:
Patricia Malentaqui, International Media Manager, Conservation International

 

 

When the world burned less

Study: Cool climate, not population loss, led to fewer fires

		This is University of Utah researcher Mitchell Power with refrigerated sediment samples in a lab at the Natural History Museum of Utah. Charcoal in such sediments was the key evidence used in a new study by Powers and colleagues suggesting that the Little Ice Age – a period of global cooling – explains why there were fewer fires after about 1500. Credit: Lee J. Siegel, University of Utah

In the years after Columbus' voyage, burning of New World forests and fields diminished significantly – a phenomenon some have attributed to decimation of native populations by European diseases. But a new University of Utah-led study suggests global cooling resulted in fewer fires because both preceded Columbus in many regions worldwide.

"The drop in fire [after about A.D. 1500] has been linked previously to the population collapse. We're saying no, there is enough independent evidence that the drop in fire was caused by cooling climate," says the study's principal author, Mitchell Power, an assistant professor of geography at the University of Utah.

"The implication is that climate is a large-scale driver of fire. That's a key finding. Climate is driving fire on global and continental scales," says Power, who also is curator of the Garrett Herbarium at the Natural History Museum of Utah, which is part of the University of Utah.

The new study analyzed worldwide charcoal samples spanning 2,000 years. It will be published online during August in the journal The Holocene, which is the name of the geological epoch covering roughly the last 11,500 years of Earth's history. It was funded by the National Science Foundation and the Natural History Museum of Utah.

The study deals with the Little Ice Age, a period when Earth's climate cooled, causing New York Harbor to freeze over in 1780, among other effects. Estimates of when the Little Ice Age started range from the 1200s to the 1500s. It ended in the early 1800s. Possible causes include some combination of increased dust from volcanic eruptions, decreased solar activity, and changes in circulation of the ocean and atmosphere.

"The decrease in fire on a very large scale – globally and in the Americas – was controlled by this cooling climate, which began prior to the population collapse, and climate alone is sufficient to explain large scale changes in burning," says Power.

"In a cooler atmosphere, you tend to get reduced convection, so you get reduced thunderstorms and ignition from lightning," he says. "Cooler climate also tends to maintain high levels of fuel moisture and soil moisture."

Today, warming climate and drought have been tied to increasing fires in the U.S. West and elsewhere. "In a world where climate is rapidly changing we need to pay more attention to this relationship between climate and fire," Power says

Power conducted the study with 19 other scientists, including paleoecologist Frank Mayle at the University of Edinburgh, U.K., and climatologist Patrick Bartlein at the University of Oregon. Other coauthors – who provided charcoal data or samples – are from University of Wisconsin, Madison and Oshkosh; Northern Arizona University; University of Gottingen, Germany; Canadian Forest Service; University of Montpellier, France; University of Bern, Switzerland; University of Calgary, Canada; University of Tennessee; Virginia Tech; University of North Carolina; University of Chile; Laval University, Quebec; Fordham College, New York; and Central Washington University.

		Mitchell Power, of the University of Utah and Natural History Museum of Utah, pulls a sediment core out of Spring Lake near Delta, Utah. The sediment core showed a reduction in charcoal – and thus fire – in the area during the Little Ice Age, a time of global cooling that began sometime between that A.D. 1200s and 1500s and ended in the early 1800s. A new study led by Powers suggests the Little Ice Age led to a worldwide reduction in fires after 1500, and that reduction was not caused by decimation of New Word populations by European diseases in the wake of Columbus. Credit: University of Utah.

Cooling Climate or Population Collapse?

After Columbus reached the New World in 1492, explorers brought European diseases such as smallpox that "decimated populations in the Americas – 10 million to 100 million dead, with most estimates in the 60 million range," Power says.

"All these people died abruptly – Mayans, Incas, Aztecs and down in Patagonia – they were all affected," he adds. "Agriculture was sharply reduced. Landscapes that had been cleared for agriculture started a process of plants growing back and infilling those abandoned fields. In terms of greenhouse gases, when you change from maintained cropland to woodlands, plants take up more carbon dioxide and there is less in the atmosphere. This has been pointed to as one mechanism for causing the Little Ice Age."

Power agrees population collapse may have led to reduced biomass burning in some local regions of the Americas. But the new study indicates the reduction in fire was actually global and began before Columbus in most areas, suggesting the Little Ice Age triggered most of the reduction in burning – not the other way around, Power says.

"If you look at independent climate records, cooling from the Little Ice Age was happening about 200 years before the population collapse," or about A.D. 1300, he says.

Power notes there is room for debate because the Little Ice Age varied in time and space, and didn't affect all parts of the world equally, although most places cooled.

A Record of Fire Left in Charcoal

The study used existing records and-or new samples of charcoal – burnt wood or other biomass – found in sediment cores from lake bottoms and bogs from some 600 sites around the world, about half in the Americas, and dated within the past 2,000 years.

"Whatever was burning, we see a record of that fire in lake sediments, from either aerial transport or erosion" of burned material, Power says.

Power manages the Global Charcoal Database that compiles data from all the existing studies that date charcoal samples and describe where they came from. The new study included 498 existing charcoal records and 93 new samples.

"We have gone back in and calculated the ages of all these charcoal samples," except for some dated independently in other recent studies, and then used recent radiocarbon dating calibrations to make sure all data are consistent, Power says.

"Greater than 80 percent of biomass burning records show a decline post-1500 in the Americas, he says. The other 20 percent may be from areas that were still fire-prone despite cooling or that simply had burning declines for which there are inadequate charcoal samples, he adds.

The study compared the charcoal records with previously published ancient climate records and population reconstructions. It found:

• Clumping all the charcoal data in two groups – from the Americas or the Eastern Hemisphere – shows that in the Americas, biomass burning declined between 1500 and 1650 and stayed at a minimum until 1700, the same time as the peak of the Little Ice Age. That period was the lowest level of burning in the past 6,000 years.
• In the Eastern Hemisphere, there was a prominent decline in burning that began about 1400 – well before the population collapse in the Americas. Power says cooling also started about a century earlier in the Eastern Hemisphere than in the Americas – more evidence cooling caused reduced burning. There was no parallel population collapse large enough to explain the reduction in burning, although a small downward blip in burning is noted in Europe around the time of the bubonic plague or Black Death.
• In tropical Middle America – the Caribbean Basin, Mexico and Central America – climate cooling starting around 1350, when burning also begins to decline. Population collapse didn't begin until around 1500.
• In tropical South America, climate changed around 1350 to 1400. There is debate whether it warmed or cooled. The population collapsed after 1500. Power says neither climate nor population strongly influenced post-Columbian biomass burning in that region, which declined only subtly and not until 1700. It also is possible the population that collapsed didn't use fire very much in agriculture – something a recent study coauthored by Power found in French Guiana.
• In southern South America, ice-core and tree-ring growth studies show cooling began about 1450, well before an abrupt decline in burning in 1550. That would seem to support the theory that population collapse reduced burning – except that the region had little population, certainly not enough for any decline to trigger a reduction in burning.
• Ice cores from Greenland show cooling started about 1450, and fire started to decline about 1500, according to charcoal for boreal Canada and the western United States. Cooling and reduced burning stopped about 1800. Despite the 50-year lag, Power says that is more evidence tying climate cooling to reduced biomass burning, particularly since the region had relatively few people at the time.

Contact: Lee Siegel
lee.siegel@utah.edu
801-581-8993
University of Utah

Chronic 2000-04 drought, worst in 800 years, may be the 'new normal'

Pinyon pine forests near Los Alamos, N.M., had already begun to turn brown from drought stress in the image at left, in 2002, and another photo taken in 2004 from the same vantage point, at right, show them largely grey and dead. (Photo by Craig Allen, U.S. Geological Survey)

The chronic drought that hit western North America from 2000 to 2004 left dying forests and depleted river basins in its wake and was the strongest in 800 years, scientists have concluded, but they say those conditions will become the "new normal" for most of the coming century.

Such climatic extremes have increased as a result of global warming, a group of 10 researchers reported today in Nature Geoscience. And as bad as conditions were during the 2000-04 drought, they may eventually be seen as the good old days.

Climate models and precipitation projections indicate this period will actually be closer to the "wet end" of a drier hydroclimate during the last half of the 21st century, scientists said.

Aside from its impact on forests, crops, rivers and water tables, the drought also cut carbon sequestration by an average of 51 percent in a massive region of the western United States, Canada and Mexico, although some areas were hit much harder than others. As vegetation withered, this released more carbon dioxide into the atmosphere, with the effect of amplifying global warming.

"Climatic extremes such as this will cause more large-scale droughts and forest mortality, and the ability of vegetation to sequester carbon is going to decline," said Beverly Law, a co-author of the study, professor of global change biology and terrestrial systems science at Oregon State University, and former science director of AmeriFlux, an ecosystem observation network.

"During this drought, carbon sequestration from this region was reduced by half," Law said. "That's a huge drop. And if global carbon emissions don't come down, the future will be even worse."

This research was supported by the National Science Foundation, NASA, U.S. Department of Energy, and other agencies. The lead author was Christopher Schwalm at Northern Arizona University. Other collaborators were from the University of Colorado, University of California at Berkeley, University of British Columbia, San Diego State University, and other institutions.

It's not clear whether or not the current drought in the Midwest, now being called one of the worst since the Dust Bowl, is related to these same forces, Law said. This study did not address that, and there are some climate mechanisms in western North America that affect that region more than other parts of the country.

But in the West, this multi-year drought was unlike anything seen in many centuries, based on tree ring data. The last two periods with drought events of similar severity were in the Middle Ages, from 977-981 and 1146-1151. The 2000-04 drought affected precipitation, soil moisture, river levels, crops, forests and grasslands.

Ordinarily, Law said, the land sink in North America is able to sequester the equivalent of about 30 percent of the carbon emitted into the atmosphere by the use of fossil fuels in the same region. However, based on projected changes in precipitation and drought severity, scientists said that this carbon sink, at least in western North America, could disappear by the end of the century.

"Areas that are already dry in the West are expected to get drier," Law said. "We expect more extremes. And it's these extreme periods that can really cause ecosystem damage, lead to climate-induced mortality of forests, and may cause some areas to convert from forest into shrublands or grassland."

During the 2000-04 drought, runoff in the upper Colorado River basin was cut in half. Crop productivity in much of the West fell 5 percent. The productivity of forests and grasslands declined, along with snowpacks. Evapotranspiration decreased the most in evergreen needleleaf forests, about 33 percent.

The effects are driven by human-caused increases in temperature, with associated lower soil moisture and decreased runoff in all major water basins of the western U.S., researchers said in the study.

Although regional precipitations patterns are difficult to forecast, researchers in this report said that climate models are underestimating the extent and severity of drought, compared to actual observations. They say the situation will continue to worsen, and that 80 of the 95 years from 2006 to 2100 will have precipitation levels as low as, or lower than, this "turn of the century" drought from 2000-04.

"Towards the latter half of the 21st century the precipitation regime associated with the turn of the century drought will represent an outlier of extreme wetness," the scientists wrote in this study.

These long-term trends are consistent with a 21st century "megadrought," they said.

Contact: Beverly Law
bev.law@oregonstate.edu
541-737-6111
Oregon State University

 

 

New discovery of how carbon is stored in the Southern Ocean

A team of British and Australian scientists has discovered an important method of how carbon is drawn down from the surface of the Southern Ocean to the deep waters beneath. The Southern Ocean is an important carbon sink in the world – around 40% of the annual global CO2 emissions absorbed by the world's oceans enter through this region.

Reporting this week in the journal Nature Geoscience, scientists from British Antarctic Survey (BAS) and Australia's national research agency, the Commonwealth Scientific and Industrial Research Organisation (CSIRO), reveal that rather than carbon being absorbed uniformly into the deep ocean in vast areas, it is drawn down and locked away from the atmosphere by plunging currents a thousand kilometres wide.

Winds, currents and massive whirlpools that carry warm and cold water around the ocean – known as eddies – create localised pathways or funnels for carbon to be stored.

Lead author, Dr Jean-Baptiste Sallée from British Antarctic Survey says,

"The Southern Ocean is a large window by which the atmosphere connects to the interior of the ocean below. Until now we didn't know exactly the physical processes of how carbon ends up being stored deep in the ocean. It's the combination of winds, currents and eddies that create these carbon-capturing pathways drawing waters down into the deep ocean from the ocean surface.

"Now that we have an improved understanding of the mechanisms for carbon draw-down we are better placed to understand the effects of changing climate and future carbon absorption by the ocean."

CSIRO co-author, Dr Richard Matear says the rate-limiting step in the anthropogenic carbon uptake by the ocean is the physical transport from the surface into the ocean interior.

"Our study identifies these pathways for the first time and this matches well with observationally–derived estimates of carbon storage in the ocean interior," Dr Matear says.

Due to the size and remote location of the Southern Ocean, scientists have only recently been able to explore the workings of the ocean with the help of small robotic probes – known as Argo floats. In 2002, 80 floats were deployed in the Southern Ocean to collect information on the temperature and salinity. This unique set of observations spanning 10 years has enabled scientists to investigate this remote region of the world for the first time. The floats are just over a metre in length and dive to depths of 2km. Today, there are over 3,000 floats in the oceans worldwide providing detailed information used in oceanic climate models.

The team also analysed temperature, salinity and pressure data collected from ship-based observations since the 1990s. The instrument used for this is called a CTD profiler which is a cluster of sensors taking measurements as it's lowered deep down into the ocean to depths of more than 7km.

Reference:  Localised subduction of anthropogenic carbon dioxide in the Southern Hemisphere oceans - is published in the August edition of Nature Geoscience (and online on 29th July) by Jean-Baptiste Sallée; Richard J. Matear and Andrew Lenton from CSIRO Marine and Atmospheric Research in Australia; and Stephen R. Rintoul from Antarctic Climate and Ecosystems Cooperative Research Centre in Australia.

This study compliments a paper published in Nature 487, 313-319 (19 July 2012) – Deep carbon export from a Southern Ocean iron-fertilized diatom bloom – by Victor Smetacek, Christine Klaas, Volker H. Strass et al, which outlines the biological processes involved in how carbon is absorbed in the Southern Ocean.

• Eddy – A massive whirlpool carrying warm and cold water around the ocean that may be formed when a bend in a surface ocean current lengthens and eventually makes a loop which separates from the main current.
• CTD Profiler – An oceanographic instrument with a cluster of sensors that measure continuous data of depth, salinity and temperature of the ocean. It is deployed from the deck of a research vessel and lowered down deep into the ocean to depths exceeding 10,000m.
• Argo floats – Small, robotic probes that collect high-quality temperature, pressure and salinity data. There are more than 3,000 underwater robots swimming in the Earth's oceans at this moment. The probes dive as deep as 2,000m into the ocean for 10 days at a time, after which they re-surface and transmit the data they have collected via satellites. Each float is designed to make around 150 such cycles. 
• British Antarctic Survey (BAS), a component of the Natural Environment Research Council (NERC), delivers and enables world-leading interdisciplinary research in the Polar Regions. Its skilled science and support staff based in Cambridge, Antarctica and the Arctic, work together to deliver research that uses the Polar Regions to advance our understanding of Earth as a sustainable planet. Through its extensive logistic capability and know-how BAS facilitates access for the British and international science community to the UK polar research operation. Numerous national and international collaborations, combined with an excellent infrastructure help sustain a world leading position for the UK in Antarctic affairs.
• The Natural Environment Research Council (NERC) is the UK's main agency for funding and managing world-class research, training and knowledge exchange in the environmental sciences. It coordinates some of the world's most exciting research projects, tackling major issues such as climate change, environmental influences on human health, the genetic make-up of life on earth, and much more. NERC receives around £320 million a year from the government's science budget, which it uses to fund independent research and training in universities and its own research centres. 
• CSIRO is Australia's national science agency and one of the largest and most diverse research agencies in the world. CSIRO's marine research – delivered through the Wealth from Oceans National Research Flagship – focuses on understanding our oceans and their biodiversity, resources and relationships with the climate system. The Flagship delivers practical science that enables governments, industries and communities to make informed decisions about the sustainable management of marine and coastal resources. Taking a whole-of-system approach to marine science, the Flagship contributes to national and international challenges where oceans play a central role. 
• Antarctic Climate & Ecosystem Cooperative Research Centre is a multidisciplinary partnership of 21 national and international organizations based at the University of Tasmania, Hobart. It provides science, knowledge and understanding to help Australia meet the challenges of climate change by understanding the crucial role played by Antarctica and the Southern Ocean in global climate, and the impacts of climate change on Australia and the world. The Centre informs governments, the community and scientists about climate change to guide Australia's future.

Contact: Audrey Stevens
auev@bas.ac.uk
44-012-232-21230
British Antarctic Survey