Toll of Climate Change on World Food Supply Could Be Worse Than Thought

Global agriculture, already predicted to be stressed by climate change in coming decades, could go into steep, unanticipated declines in some regions due to complications that scientists have so far inadequately considered, say three new scientific reports. The authors say that progressive changes predicted to stem from 1- to 5-degree C temperature rises in coming decades fail to account for seasonal extremes of heat, drought or rain, multiplier effects of spreading diseases or weeds, and other ecological upsets. All are believed more likely in the future. Coauthored by leading researchers from Europe, North America and Australia, they appear in this week’s issue of the Proceedings of the National Academy of Sciences (PNAS).

“Many people assume that we will never have a problem with food production on a global scale. But there is a strong potential for negative surprises,” said Francesco Tubiello, a physicist and agricultural expert at the NASA/Goddard Institute of Space Studies who coauthored all three papers. Goddard is a member of Columbia University’s Earth Institute.

In order to keep pace with population growth, current production of grain-from which humans derive two-thirds of their protein-will probably have to double, to 4 billion tons a years before 2100. Studies in the past 10 years suggest that mounting levels of carbon dioxide in the air-believed to be the basis of human-caused climate change-may initially bolster the photosynthetic rate of many plants, and, along with new farming techniques, possibly add to some crop yields. Between now and mid-century, higher temperatures in northerly latitudes will probably also expand lands available for farming, and bring longer growing seasons. However, these gains likely will be canceled by agricultural declines in the tropics, where even modest 1- to 2-degree rises are expected to evaporate rainfall and push staple crops over their survival thresholds. Existing research estimates that developing countries may lose 135 million hectares (334 million acres) of prime farm land in the next 50 years. After mid-century, continuing temperature rises-5 degrees C or more by then–are expected to start adversely affecting northern crops as well, tipping the whole world into a danger zone.

The authors of the PNAS studies say that much of the previous work is oversimplified, and as a consequence, the potential for bigger, more rapid problems remains largely unexplored. “The projections show a smooth curve, but a smooth curve has never happened in human history,” said Tubiello. “Things happen suddenly, and then you can’t respond to them.” For instance, extreme-weather events of all kinds, including heat waves or sudden big storms, could easily wipe out crops on vast scales if they occur for even a few days during critical germination or flowering times. Tubiello says this is already happening on smaller scales. During a heat wave in the summer of 2003, temperatures in Italy soared 6 degrees C over their long-term mean, and the corn yield in the rich Po valley dropped a record 36%. Nearly all the world’s pastures are rain-fed; in Africa, droughts in the 1980s and 1990s wiped out 20% to 60% of some nations’ herds. Such events on larger scales could arise with little or no warning in the near future, the authors suggest.

Higher temperatures may also prompt outbreaks of weeds and pests, and affect plant or animal physiology-factors also left out of most projections. One of the new PNAS studies, “Crop and Pasture Response to Climate Change,” says that more recent modeling suggests cattle ticks and bluetongue (a viral disease of sheep and cattle) will move outward from the tropics to areas such as southern Australia. Other new models suggest that higher temperatures will limit the ability of modern dairy-cow breeds to convert feed into milk, and lead to declines in livestock fertility and longevity. As temperatures rise in northerly latitudes, the ability of crop pests to survive winters is expected to improve, enabling them to attack spring crops in regions where they were previously kept at bay during this vulnerable time.

The authors say that farmers may temporarily mitigate some effects of changing climate by moving toward adaptations now. Adaptations already being considered or set up include regional climate-forecasting systems that enable farmers to switch to different crops or change the timing of plantings; introduction of new varieties or species that can withstand anticipated conditions; and improved flood-mitigation and water-storage facilities. One of the PNAS studies, “Adapting Agriculture to Climate Change,” says that such adaptations might help tropical farmers cut damages wrought by rises of 1.5 to 3 degrees, and temperate-region farmers, damages from 1- to 2-degree rises. This would buy a few decades of time for nations to agree on ways to slow or reverse the warming itself. “After that, all the bets are off,” said Tubiello.

The other authors are based at the Food and Agriculture Organization, in Rome; Austria’s International Institute for Applied Systems Analysis; France’s National Agronomy Research Institute; Australia’s Commonwealth Scientific and Industrial Research Organization; Pennsylvania State University; Arizona State University; and Wageningen University in the Netherlands.

Pulselike and Cracklike Ruptures in Earthquake Experiments

Lab experiments that mimic the way the ground moves during destructive earthquakes require some sophisticated equipment, and they yield valuable insights. Caltech scientists studying how sliding motion spreads along a fault interface conducted a series of experiments involving ultrafast digital cameras and high-speed laser velocimeters to replicate a range of realistic fault conditions.

The team documented for the first time a systematic variation in earthquake rupture patterns called pulselike and cracklike ruptures. The experiments also revealed that both types of ruptures can transition to a state known as supershear speed, which generates its own characteristic ground shaking. The results appeared in the November 27 issue of the journal Proceedings of the National Academy of Sciences.

The scientists include Xiao Lu, graduate student in aeronautics; Nadia Lapusta, assistant professor of mechanical engineering and geophysics; and Ares Rosakis, the von Kármán Professor of Aeronautics and Mechanical Engineering and director of the Graduate Aeronautical Laboratories.

Simple theoretical models of earthquake ruptures show they slide like a crack–the entire length of the fault slides for just about as long as the earthquake lasts. But slip models used by seismologists to match records of ground motions from past earthquakes have suggested a different mode of rupture, one that moves like a pulse. A pulse of slip would travel down the length of a fault like a ripple passing over the surface of a pond, with all motion contained in the ripple, and the fault surface “healing” in its wake.

The forces that build up on either side of a fault, known as tectonic loading, can vary greatly and lead to different types of fault slip behavior. “Numerical calculations of earthquake ruptures that use friction laws guided by laboratory experiments produce both crack- and pulselike modes, depending on how loaded the fault is,” says Lapusta. “We set out to test the predictions of these calculations in our experimental study.” Pulse modes are predicted by calculations where faults are less loaded, but to make a fault slip under these conditions, models have to assume that fault friction decreases as the fault slip gets faster. This behavior, called rate-weakening friction, has been of long-standing interest to Lapusta and to Thomas Heaton, professor of engineering seismology, whose influential work on slip pulses demonstrated their short duration, and who proposed rate-weakening friction as a likely explanation.

The experiments began with a 9.5-millimeter-thick photoelastic plate sliced at an angle through its length, simulating a fault in Earth’s crust. Pressure on the two sides of the fault was applied incrementally at an angle to build up the different components of loading. To trigger an earthquake rupture, a nickel wire the diameter of a human hair was embedded in the plate interface and then electrically discharged, creating a small explosion followed by a spontaneously spreading rupture. Lasers measured the relative movements on each side of the fault after the shock, and a high-speed camera captured the movements in 5-microsecond intervals. The mini-explosions were repeated for various orientations of tectonic loading.

The experimental setup mimics conditions under which very large earthquakes rupture Earth’s crust along major strike-slip faults like California’s San Andreas fault or the Kunlun fault in northern Tibet. The initial experimental design was devised by Rosakis; Smits Professor of Geophysics, Emeritus Hiroo Kanamori; and their joint graduate student Kaiwen Xia, who is now a professor at the University of Toronto.

The new experimental results support the models that suggest faults can have pulselike ruptures. “This is the first time we observed this spontaneous pulselike rupture in an experiment that mimics crustal earthquakes. We proved its existence,” says Lu.

The experiments also documented under what conditions pulselike ruptures arise. When the plate interface was oriented at a 70-degree angle to the direction of compression, the rupture propagated as a narrow pulse. At smaller angles, the pulses got wider, until they transitioned into cracklike sliding modes. These experimental observations demonstrate the role that tectonic loading plays in how earthquakes rupture, and imply that real faults are governed by rate-weakening friction.

Another experimental result is related to earthquake rupture speeds. Calculations since the 1970s have predicted phenomena known as supershear bursts, which would cause destructive, high-frequency ground motions. Rosakis, Kanamori, and Xia have demonstrated such bursts in their experiments in recent years. Supershear bursts were shown to have caused damage during the 1979 Imperial Valley, 1992 Landers, and 1999 Izmit, Turkey, earthquakes.

In the experiment by Lu, Lapusta, and Rosakis, supershear propagation is seen to arise during both pulselike and cracklike earthquake ruptures. “That’s new–nobody has seen before that either of those modes could transition to supershear,” says Rosakis. Shock waves generated by supershear propagation generate more ground shaking, he adds, and notes that with more details about exactly how earthquakes rupture, scientists can devise more sophisticated ways for buildings to survive the specific types of shaking that arise.

Aurora Borealis breaks new grounds – and old ice

It can crush ice sideways and stay precisely on station to an accuracy of a metre. It can drill a hole 1,000 metres deep into the seabed while floating above 5,000 metres of ocean and it can generate 55 megawatts of power. So far, Aurora Borealis is the most unusual ship that has never been built, and it represents a floating laboratory for European science, a breakthrough for polar research and a very big headache for international lawyers.

Aurora Borealis will be the first ever international ship, the brainchild of the European Science Federation, the Alfred Wegener Institute for Polar and Maritime Research in Germany and the Germany Federal Ministry of Research and Education. Russia has announced that it will be a partner in launching this state-of-the-art research vessel, but other European nations may soon join the project. But a European ship represents a metaphorical voyage into unknown waters, the ESF Science Policy Conference learned.

“We do not have a European flag at the moment so one nation has to be responsible. And if it is internationally owned, you can imagine the difficulty,” said Nicole Biebow, manager of the project, and a scientist at the Alfred Wegener Institute. “We have to agree where this ship should have its home port. And what happens if there is an accident? Who is responsible if you have an oil spill on the ice, for instance?”

The ice over the polar seas masks millions of years of the planet’s history: drilling is difficult in freezing conditions. Aurora Borealis will be the world’s first icebreaker that is also a drilling ship. This sets unusual challenges for marine engineers: a vessel poised on top of 5000 metres of drilling rig cannot afford to move very much in any direction. But ice drifts, and currents and winds can alter in moments. So the ship will be designed not just to break the ice as it moves forward and astern, but also to port and starboard.

“We had some early ice tanks tests and they came up with a design that is able to break ice sideways,” said Paul Egerton, head of the European Polar Board within the European Science Federation. “As the ice continually presses against the side of the ship, the pieces of ice go underneath the hull and are washed away by the propulsion system. There is also a kind of damping system so the ship can raise itself up and down vertically to break the ice. It has a propeller that can turn 360 degrees, linked to satellite navigation. A lot of the cruise ships now have this so they can navigate in a very small area. But the propeller also has to break ice: it has to be strengthened.”

Not only will the diesel-electric ship be the floating equivalent of a 55 megawatt power station, it will be an intellectual powerhouse as well. It will be probe the role of polar waters in global climate change. Drill cores from the sea floor could answer questions about the geological history of the Arctic ocean, and other instruments will measure the transport of contaminants through the air, water and ice. The vessel could be home to 120 people, more than half of them scientists who need to go to sea to study the ice, the ocean beneath and the history of the deep sea floor.

It will be equipped with two “moon pools” in the bottom of the hull to give direct access to the open water beneath the ice, so that drillers can work in freezing conditions and biologists can launch underwater vehicles to study the mysterious processes that trigger an explosion of life in the polar seas every spring. The design and preparation of Aurora Borealis will continue until 2011. Builders could start assembling the hull in 2012, it could be cruising the oceans from 2014 – and it could begin answering some of the great questions of ocean science for the next 40 years.

3D model visualises underground water supplies

A 3D computer model being developed by Queensland University of Technology has the potential to map all the subsurface water supplies within South East Queensland.

Utilising visual 3D technology, QUT scientists are creating a regional hydrogeological model that will make it possible to drill “virtual” bore holes and determine the complexities of underground water systems and the geology of aquifers.

Associate Professor Malcolm Cox, from QUT’s Institute of Sustainable Resources, said groundwater was not only an important resource for water supply but also a vital component of wider, interlinked ecosystems.

“Factors such as rapid population growth and drought are producing significant impacts on groundwater resources, however, in most areas these natural systems and surface links are not well understood,” Professor Cox said.

“The objective of this project is to develop a tool that makes it possible to catalogue where and how groundwater occurs and assess any changes over time.

“The concept is to use real data to produce a computer generated block of ground and incorporate information about its water-bearing properties.”

Professor Cox said the model would include groundwater levels, flow directions, water quality and bore locations and depths.

The area covered by the model will stretch from the NSW border in the south to Noosa in the north, Toowoomba in the west and the bay islands in the east.

“This is one of the faster growing regions in Australia and one within which water resources are becoming inadequate and groundwater is increasingly being utilised,” he said.

“Within this setting many of the groundwater systems are being impacted and some are now coming under stress, especially with continuing drought conditions.”

Professor Cox said with this in mind, it was essential to properly manage groundwater systems, thereby ensuring their integrity.

“Currently no structured management system exists to provide an integrated approach to the region,” he said.

Joint researcher on the project, Dr Joseph Young of the QUT High Performance Computer group, said the project would provide scientists and managers with a regional 3D hydrogeological model that could be used for the strategic management of groundwater resources.

Development of the model, known as HYDROSEQ, is a collaborative venture involving QUT, the Queensland Cyber Infrastructure Foundation, Natural Resources and Water, Geological Survey of Queensland, CSIRO and local councils.

Researchers break new ground in earthquake predictions

Researchers from UQ’s Earth Systems Science Computational Centre (ESSCC) who were able to predict a series of three large Sumatran earthquakes that occurred in September, will present their ground-breaking research at the Fall Meeting of the American Geophysical Union (AGU), held from December 10 to 14.

In this, the Union’s 40th year, the meeting is expected to draw a crowd of over 15,000 of the leading geophysicists from around the world, to present and review the latest breakthroughs on issues affecting the Earth, the planets and their environments in space.

Research team leader, Dr Huilin Xing, said the AGU’s last-minute inclusion of the UQ research in an added special session entitled “The 2007 Sumatra Seismic Sequence” reflected the significance of the work.

The predictions were made using advanced computer simulation software developed as part of a research program under Dr Xing, with researchers utilising the ESSCC’s Altix supercomputer – one of the fastest in Australia – to model scenarios and determine the highest risk areas.

As a result of their simulations, Dr Xing and his colleagues identified the part of the subduction zone where the Eurasian and Indian/Australian tectonic plates meet between latitude S1° and S5.5° as having the highest earthquake risk – exactly the zone in which the series of quakes occurred.

Dr Xing said that in the wake of the 2004 Boxing Day tsunami, the Sumatra region was one of the first areas of application for the modelling software.

“Not too long after we developed the software the 2004 Boxing Day tsunami occurred and as a result, we began a project specially focused on the tsunami generation process induced by earthquakes and from there, we really began the research for the Sumatra area,” he said.

“The region had a lot of data and papers related to it as a very hot topic, and all that information was ideal for helping us conduct the simulations.

“We presented our results as early as last April in Hawaii, highlighting the high earthquake risk in this very specific area… and now already the event has happened with the three earthquakes occurring in exactly the place we had predicted – and this is why we’re very excited but in some ways quite shocked.

“This sort of event is very rare in earthquake history – to have three very large earthquakes occur so close together but also in a very narrow area.”

The three quakes, which occurred in the space of just two days, were measured on the Richter scale at magnitudes of 8.4 and 7.9 (September 12), and 7.0 (September 13) respectively. Residents living around the Indian Ocean were quick to register their shock at the magnitude of the tremors, which were felt as far away as Singapore and Malaysia.

Interestingly, the area was one of very few in the wider Sumatran region that had not experienced earthquake activity for some time. But the extended period of quiescence did not discourage Dr Xing and his colleagues from pinpointing it as high-risk zone.

“It was very strange that even in this region of high earthquake activity and in which the tsunami-inducing earthquake occurred, that this particular area seemed to be locked.

“But while on the one side this could have meant that perhaps this area was very safe because there was no slip, on the other side the lack of any slip meant a significant build-up of force and that the area had a large amount of energy to release.

“When we looked at the earthquake history around this area we found that about 170 years ago there were two very large earthquakes exactly in this area, so we began to think this area might have potential for a large, destructive earthquake in between the relatively long periods of quiet.”

Despite the accuracy of the UQ forecast, Dr Xing was quick to point out that the prediction of earthquakes is not an exact science and said the recent series of earthquakes have in many ways only added to the many questions surrounding the subject.

“For example, from research we know we can expect that if an earthquake is larger than magnitude 6.5 there may be a tsunami, and while this is not directly or linearly related to size, it is very important.

“But in this case the first earthquake was of magnitude 8.4, and there was almost no tsunami…and I think this means we really need to keep looking deeper to work out what kinds of earthquakes can generate tsunamis and how big the tsunami might be.

“If we continue this research, we can help to make the prediction of earthquakes and tsunamis a more accurate process, contributing some further understanding of the factors involved and with respect to this particular area, modelling where the next event might occur.”

And with the third anniversary of the Boxing Day tsunami fast approaching, Dr Xing said researchers were faced with a tragic and timely reminder of just how important any such advances could be.

In the meantime, his finite element crustal dynamics software is currently being applied in the supercomputer simulation of hot fractured rock geothermal reservoir systems in the field of alternative energy, and has demonstrated other significant potential applications in regards to modelling the deep geological disposal of nuclear waste and carbon dioxide.

Dr Xing said it was important to acknowledge the support he has received from the Australian Computational Earth Systems Simulator (ACcESS) – a major national research facility hosted by the ESSCC; as well as the Australian Research Council and industry collaborators, such as Geodynamics Ltd.

The ESSCC conducts research on the mechanics and physics of solid Earth processes on all scales using supercomputer simulation and by applying the methodologies of geophysical fluid and solid mechanics.

New Antarctica research season kicks off

A composed satellite photograph of Antarctica. - Photo: courtesy NASA
A composed satellite photograph of Antarctica. – Photo: courtesy NASA

The approach of winter in the northern hemisphere means that summer is coming to Antarctica – still bitterly cold, but just warm enough to let scientists make progress on ongoing studies.

Among those UW-Madison faculty members who conduct research at the bottom of the word are Jim Bockheim, an expert on Antarctica’s Mars-like soils; Christine Ribic, a wildlife ecologist who studies the super-hardy Adelie penguin; and Charles Bentley, a geologist who is celebrating his 50th anniversary as an Antarctic scientist this year.

This research season also marks the midway point of the International Polar Year (IPY), which extends from March 2007 to March 2009. Organized through the International Council for Science and the World Meteorological Organization, the IPY is a large scientific program dedicated to the Arctic and the Antarctic. The 2007-09 “year” follows previous polar years in 1882-83, 1932-33, and 1957-58.

As visitors soar, scientist maps Antartica’s sensitive soils

Jim Bockheim has trekked to some of the coldest, driest places on earth. As a polar soil scientist, he has spent more than three decades studying glacial cycles and how soils form in these extreme climates. But these days, the ends of the earth are becoming more crowded.

In 2006, almost 30,000 travelers journeyed to Antarctica to see penguins, whales and the South Pole. This kind of adventure doesn’t come cheap. Excursions range from $4,000 to $30,000 per trip. For that price, eco-tourists can play scientist, visit research stations, commune with seals, and even climb unnamed mountains.

Bockheim worries about the impact of this activity on a fragile ecosystem. Polar soils are unique he says. He should know: Bockheim played a key role in naming this soil class-the gelisols-in 1998. Perpetually frozen, Antarctic gelisols have been likened to the soils on Mars. They are also sensitive to human impact.

To that end, Bockheim is collaborating with colleagues from New Zealand and several international organizations to develop comprehensive maps of Antarctica’s permafrost and soils. These maps might soon be used to develop a trail system for visitors.

“If tourism becomes more extensive,” Bockheim says, the maps can show “where the best place would be to lay these trails out with minimum impact.”

But Bockheim isn’t just worried about the impacts of tourists. Research in Antarctica has also increased. McMurdo Station, Antarctica’s largest settlement, now hosts more than 1,000 scientists and support staff year round. And they require amenities such as research labs, dormitories, a bowling alley, satellite television, and a diesel generator for electricity.

Many of these scientists study climate change effects. Bockheim is no exception. Part of his research examines glacial cycles, which he hopes can provide information about future climate events. A better understanding of what caused mass glaciation in the past, he says, can help better predict when it could happen again. The clues are in the soils. And they need protection.

With an increased focus on preserving the ecosystem of the “last continent,” scientists are becoming more careful about how they do business in Antarctica. Each small change is significant.

“Every time I dig a soil pit, I’m conducting some kind of disturbance,” Bockheim says. “So now, we dig the soil layers very carefully and put them on a tarp.” After collecting samples and data, his team gently replaces all the soil and stones. They even pack out their own human waste.

It takes days for Bockheim to get to his remote location in Antarctica’s Dry Valley, but it’s worth it. His benefits include interesting and meaningful research, great scenery, and a mountain with his name on it: Mount Bockheim.

“It’s spectacular,” he says of the experience. “I’m interested in life at the extremes.”

Not so happy feet: Retreating sea ice bad news for penguins

As penguins go, the Adelie is one tough bird. Standing about 2 1/2-feet tall, the diminutive Adelie is one of just a few animals to brave the Antarctic winter, hanging around to feast on krill while other species depart for warmer destinations.

But the Adelie depends on constant sea ice for its successful Antarctic lifestyle, and changes in the marine ice related to global climate change may doom rookeries that have been used by the flightless birds for more than 8,000 years, according to new research.

“The Adelie is integrating all the effects of climate change. They have to deal with it,” explains Christine Ribic, a UW-Madison wildlife ecologist who studies the penguin’s habitat on the western Antarctica Peninsula. “This is a real ice species.”

Ribic and others worry that the Adelie rookeries nearest the U.S. Palmer Antarctic Research Station on Anvers Island will disappear as sea ice retreats south and be replaced by other penguin species – the chinstrap and Gentoo – which are more tolerant of open water. “The fear is that in 5 to 10 years on Anvers Island, the Adelie will go extinct at those sites,” she says.

There are five Adelie rookeries on the peninsula, including those on Anvers Island, and all are within easy reach of an ocean trough where upwelling currents provide nutrients for krill, shrimp-like crustaceans that are the preferred prey for the Adelie.

Recent mapping of the ocean floor, coupled with tracking of satellite-tagged penguins, has revealed the importance of troughs to the rookeries, Ribic says. “Now we know what the ocean floor looks like. For example, the trough at Anvers Island is within 15 to 20 kilometers of where the penguins are. The penguins are limited to regions where prey is available, and that is predictable in terms of centuries.”

The good news, according to Ribic, is that if the Adelie rookeries near Palmer “wink out,” they could return – as long as there is enough sea ice for the penguins to maintain their lifestyle and out-compete their flightless cousins.

Drilling into Antarctica’s past

A team of UW-Madison scientists and engineers is traveling to the West Antarctic Ice Sheet this winter for the inaugural Antarctic run of a powerful new ice-coring drill, called the Deep Ice Sheet Coring (DISC) Drill.

Developed at UW-Madison’s Space Science and Engineering Center by a team led by project manager Alexander Shturmakov, the drill will enable scientists to collect and analyze high-quality cores of the Antarctic ice and bedrock.

Over the course of three work seasons, the team aims to drill through the entire depth of the West Antarctic Ice Sheet, a distance greater than two miles. In subsequent years, they also hope to collect cores from the underlying bedrock – a feat that has never been accomplished in Antarctica.

Ice sheets contain a record of past climates and environments. As layers of snow were compressed into ice, they trapped air bubbles, minute quantities of chemical impurities and biological samples that now offer a look back through Antarctic history.

An interdisciplinary team of scientists from a score of institutions will use the DISC drill cores to study past relationships between geology, biology and climate. They also plan to compare their Antarctic findings to similar data from Greenland ice cores to determine the relationship between environmental changes in the northern and southern hemispheres.

The project team is targeting a region of the West Antarctic Ice Sheet that receives high annual snowfall, which creates thick and more easily analyzed yearly ice layers. Cores from this region should provide a view of past climates with a level of detail unprecedented in Antarctica, with single-year resolution for the past 40,000 to 50,000 years.

Charles Bentley, principal investigator for the DISC drill project and professor emeritus of geology and geophysics, will be traveling to the drilling site from Jan. 12-19, 2008, to see the drill in operation for the first time. This season marks the 50th anniversary of Bentley’s first full field season in Antarctica in 1957-58.

Planting carbon deep in the earth – rather than the greenhouse

Storing carbon dioxide deep below the earth’s surface could be a safe, long-term solution to one of the planet’s major contributors to climate change.

University of Leeds research shows that porous sandstone, drained of oil by the energy giants, could provide a safe reservoir for carbon dioxide. The study found that sandstone reacts with injected fluids more quickly than had been predicted – such reactions are essential if the captured CO2 is not to leak back to the surface.

The study looked at data from the Miller oilfield in the North Sea, where BP had been pumping seawater into the oil reservoir to enhance the flow of oil. As oil was extracted, the water that was pumped out with it was analysed and this showed that minerals had grown and dissolved as the water travelled through the field. (1)

Significantly, PhD student Stephanie Houston found that water pumped out with the oil was especially rich in silica. This showed that silicates, usually thought of as very slow to react, had dissolved in the newly-injected seawater over less than a year. This is the type of reaction that would be needed to make carbon dioxide stable in the pore waters, rather like the dissolved carbonate found in still mineral water. (2)

The study gives a clear indication that carbon dioxide sequestered deep underground could also react quickly with ordinary rocks to become assimilated into the deep formation water.

The work was supervised by Bruce Yardley, Professor in the School of Earth and Environment at the University, who explained: “If CO2 is injected underground we hope that it will react with the water and minerals there in order to be stabilized. That way it spreads into its local environment rather than remaining as a giant gas bubble which might ultimately seep to the surface.

“It had been thought that reaction might take place over hundreds or thousands of years, but there’s a clear implication in this study that if we inject carbon dioxide into rocks, these reactions will happen quite quickly making it far less likely to escape.”

Although extracting CO2 from power stations and storing it underground has been suggested as a long-term measure for tackling climate change, it has not yet been put to work for this purpose on a large scale. “There is one storage project in place at Sleipner, in the Norwegian sector of the North Sea, and some oil companies have actually used CO2 sequestration as a means of pushing out more oil from existing oilfields,” said Prof Yardley.

In the UK the Prime Minister has recently announced a major expansion of energy from renewable sources and the launch of a competition to build one of the world’s first carbon capture and storage plants. (3) The Leeds study suggests the technique has long-term potential for safely storing this major by-product of our power stations, rather than allowing it to escape and further contribute to global warming.


  1. The study covered samples of water pumped out from the Miller oilfield over a seven-year period. The data is routinely collected by BP to assess whether water-borne chemicals are liable to cause costly problems of scale to the drilling equipment. The Leeds scientists compared these with the composition of the water that was there before and the water that was injected. This showed that minerals had grown and dissolved as the water travelled through the field.

  2. Stephanie Houston worked on the project as part of an Industrial Case Studentship, funded by the Natural Environment Research Council and BP. Her work was supervised by Professor Bruce Yardley, who is based in the Institute of Geological Sciences within the School of Earth and Environment at the University of Leeds.


New satellite study shows dramatic melting of Greenland ice during summer of 2007

Newly published research that includes satellite data from three separate sources shows that the seasonal melt on Greenland’s ice sheet during the summer of 2007 was a stunning 60 percent more than the previous high, set in 1998.

The new information, which differs from other studies by including information beginning in the early 1970s, is consistent with other indicators of worldwide global climate change, according to the author of the study, Thomas L. Mote, a climatologist from the University of Georgia.

“What we found was really quite remarkable,” said Mote, a professor in UGA’s department of geography and its Climatology Research Lab. “This work includes the longest satellite record anyone has for Greenland. No one piece of evidence ever tells the whole story, but when you put them together, they point in the same direction.”

Mote’s research was just published in the journal Geophysical Research Letters.

Perhaps just as dramatic as the huge increase in snow melt is that Greenland had as many as 50 more days of melt than average, and the melting season began a full month earlier than normal.

Mote has studied snow melt in Greenland for more than a decade, but even he was unprepared for the dramatic melt that occurred last summer. He compared data from three satellite sources:

  • The Special Sensor Microwave/Imager (SSM/I), which provided information from 1987 to present;

  • The Scanning Multichannel Microwave Radiometer (SMMR), which supplied data from 1979 to 1987; and

  • The Electrically Scanning Microwave Radiometer (ESMR), for data recorded in 1973, 1974 and 1976 respectively.

While other researchers had used data from SSM/I and SMMR, none had reexamined the older information generated from the ESMR satellite, and that longer record allowed Mote to see farther into the recent past of Greenland’s ice-sheet history.

“To be honest, there’s just not much useful satellite data prior to the 1980s,” said Mote.

There have been other warm periods in Greenland’s recent past, Mote says, most notably in the 1930s, though it’s difficult to say how much melt may have occurred then. But a dramatic change is now underway in a land that covers more than 800,000 square miles but has a permanent population of less than 60,000.

Just why the huge increase in melt occurred in the summer of 2007 is not yet entirely clear, said Mote. Certainly, increasing surface temperatures are part of it. Coastal meteorological stations showed higher-than-average temperatures for most of the season. But another culprit may be changes in the surface of the ice sheet itself.

Data show that the average number of melt days has been steadily increasing since 1997, and this may have allowed the ice sheet to become more susceptible to further melting. Large streams of water actually flow through chasms and cracks down to the land’s surface and cause the ice sheet to become unstable.

Another possible mechanism may be an increase in temperature of the snow or less snow accumulation in recent years, said Mote.

He points out that the noticeable summer melt of ice in Greenland is consistent with satellite observations that have pointed to decreasing sea ice across the Northern Hemisphere since 2000.

“The most recent Intergovernmental Panel on Climate Change assessment report concludes that changes in surface melting have contributed to a loss of mass in Greenland,” said Mote, “which they report is ‘very likely’ a contributor to global sea rise level.”

Researchers will be watching Greenland’s ice sheet warily next summer to see if the trend continues.