AAAS 2011: Climate change poses challenge to food safety

Sid Perkins

WASHINGTON, DC – Climate change will pose a number of challenges to food safety in the coming decades, from boosting the rates of food- and water-borne illnesses to enabling the spread of pathogens, researchers reported Monday at the annual meeting of the American Association for the Advancement of Science.

Depending on the greenhouse gas emissions scenario, global average temperature is expected to rise between 1.1° and 6.8° Celsius by the end of the century. And warmer temperatures are known to increase rates of some diseases: According to a recent study of salmonellosis in Europe, frequency of the ailment rises about 12 percent for every 1°C that air temperature increases beyond a baseline of 6°C, said Cristina Tirado, an environmental scientist at the University of California, Los Angeles. The precise cause for this trend isn’t clear, said Ewen Todd, a bacteriologist at Michigan State University in East Lansing. It’s possible that warmer temperatures cause bacteria to grow more quickly, or people may prepare food differently in warmer weather (grilling outdoors vis-à-vis cooking in a kitchen, for example).

Climate change can increase disease risks in several ways, Tirado added. The concentration of methyl mercury in fish increases about 3.5 percent for every 1°C rise in water temperature. Warmer sea-surface temperatures can boost the frequency of harmful algal blooms, leading to an increased incidence of paralytic shellfish poisoning. Higher water temperatures also enable the spread of pathogens to higher latitudes: An outbreak of vibriosis on an Alaskan cruise ship in 2005, later linked to oysters that had been harvested near one of the ship’s ports of call, represents the spread of the disease-causing Vibrio parahaemolyticus to a locale more than 1,000 kilometers north of its previous known range. Dust storms, which are expected to increase in some regions due to climate change, could wreak their own havoc, because iron-rich mineral dust can drive a 10- to 1,000-fold increase in the growth rate of Vibrio bacteria.

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AAAS 2011: Beyond the “California condor” approach to adaptation

Sid Perkins

WASHINGTON, DC – Although no one knows the ultimate effects of climate change on marine ecosystems, scientists know enough about the oceans to proceed with adaptation, researchers reported Saturday at the annual meeting of the American Association for the Advancement of Science. And while many previous studies have focused on minimizing detriments to single species of economic importance, future efforts should shift to preserving ecosystems and their capacity to adapt, they suggest.

While many people recognize the warming effects of climate change on Earth’s atmosphere, the oceans are sucking up heat too. Only 4 percent of the excess energy absorbed by the planet in the past 40 years has gone into heating the atmosphere, but 84 percent has gone into the oceans, a larger and much more effective reservoir of heat, said Chad English, director of science policy outreach at the Communication Partnership for Science and the Sea (COMPASS) in Silver Spring, Maryland. (The rest of that energy imbalance has gone into warming Earth’s landmasses and melting ice, he notes.) Meanwhile, oceans are acidifying (by the end of this century, they’ll reach a pH lower than any experienced in the last 20 million years), sea levels are rising, and waves are getting bigger, driven by faster winds. The changes seen so far are just a preview of coming attractions, he suggests: “We’ve only seen [Earth’s] transient response to warming, and we don’t yet know at what point ecosystems will break down.”

Indeed, a wide variety of holes exist in scientists’ knowledge about when —and how — ecosystems will respond to climate change. While many studies have assessed the individual effects of warmer waters, increasing levels of ocean acidity, and lower levels of dissolved oxygen on various marine species, the combined effects of multiple stressors are largely unknown, said James Barry of the Monterey Bay Aquarium Research Institute in Moss Landing, California.

Looking to save ecosystems by preserving a single species of importance probably won’t work, said Nancy Knowlton, a marine biologist at the Smithsonian Institution’s National Museum of Natural History in Washington, D.C. Such a “California condor” approach – a massive effort dedicated to preserving just one, usually charismatic species – ignores the fact that ecosystems are finely-tuned biological networks composed of numerous interacting species. In the case of coral reefs, Knowlton’s specialty, those ecosystems are home to more than 1,000 species of corals and between 1 million and 9 million species of fish and other organisms.

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AAAS 2011: Ill effects of climate on ocean fisheries

Sid Perkins

WASHINGTON, DC – Climate change will dramatically alter marine ecosystems, wreaking havoc on many fisheries and exacting a huge economic toll, researchers reported today at the annual meeting of the American Association for the Advancement of Science.

Despite being overexploited, the world’s fisheries are still profitable: In 2003, they generated more than $24 billion in wages for fishermen, profits for companies and payments to resource owners, says Rashid Sumaila, an economist at the University of British Columbia in Vancouver. Yet those profits – and in some cases the fisheries themselves – are threatened by a variety of ill effects brought about by climate change, he notes. Warming seas and rising atmospheric concentrations of carbon dioxide will cause oceans to acidify, the habitable ranges of many species to shift substantially, and the size of adult fish to decline, to name just a few.

Climate models suggest that by the year 2100, sea-surface temperatures will be between 1.9° and 2.8° Celsius higher than they were in the 1890s, says Jorge Sarmiento, a marine biogeochemist at Princeton University in Princeton, New Jersey. As a result, changes in the patterns and rates of upwelling that bring nutrients to the surface, among other factors, will cause primary productivity – the amount of biomass generated by the ocean’s food chain – to decline between 2 and 16 percent by the end of the century. While some areas, such as the Southern Ocean surrounding Antarctica, will see slight increases in biological productivity, many areas, including much of the tropical and temperate seas, will see substantial decreases, the models suggest. For example, he notes, in 2090 the combined productivity of North Atlantic fisheries will be about half what it was in 1860.

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Our pick of the recent literature

Each week on Nature Climate Change, we select three papers published within the last month that we find noteworthy for their novelty and wide interest. Our latest picks are:

Policy: Global cooperation game

International cooperation on technological development might be a crucial part of the much-needed breakthrough in tackling climate change.

Original paper: Golombek, R. & Hoel, M. International cooperation on climate-friendly technologies. Environ. Res. Econ. doi:10.1007/s10640-010-9442-x (2010).

Ecology: Downhill drive

Climate change can cause vegetation to move up- or down-slope depending on water availability.

Original paper: Crimmins, S. M., Dobrowski, S. Z., Greenburg, J. A., Abatzoglou, J. T. & Mynsberge, A. R. Changes in climatic water balance drive downhill shifts in plant species’ optimum elevations. Science doi:10.1126/science.1199040 (2011).

Atmospheric science: Sun’s energy output

Accurately estimating the Sun’s energy output is vital for attributing climate change correctly. Improved measurements have now been obtained from a space-based instrument.

Original paper: Kopp, G. & Lean, J. L. A new, lower value of total solar irradiance: Evidence and climate significance. Geophys. Res. Lett. 38, L01706 (2011).

Corals show complex response to climate change

Sid Perkins

In the coming decades, the world’s coral reefs will suffer a variety of indignities, from global threats such as warming seas and ocean acidification to local and regional problems such as overfishing and nutrient-rich runoff. If carbon dioxide emissions remain high until the end of the century, reef coverage may drop by 50 percent or more even if local threats are addressed aggressively, a new study suggests. Despite this bad news, another study provides a glimmer of hope for long-suffering reefs: In some cases, the coral ecosystems that rise to replace ones blighted by climate change may actually be more resistant to disease.climate_2009_98-i1.jpg

In a paper to be published in Global Change Biology, Kenneth Anthony, a marine ecologist at the University of Queensland in Brisbane, Australia and his colleagues modeled how reefs of branching corals of the genus Acropora would fare under various levels of climate change and fishing. In the team’s model simulations, ocean acidification and warming impair the growth and boost the mortality of corals, elevated nutrients in runoff fuels the growth of coral-stifling Lobophora seaweed, and more intense fishing drives down the numbers of herbivores that help to keep the seaweed under control.

Unsurprisingly, under the most extreme climate scenario — the IPCC’s A1FI scenario, in which atmospheric concentrations of carbon dioxide rise to exceed 900 parts per billion by 2100, compared to around 390 ppb today — reefs suffer the most. By the end of the century, even if fish graze about 60 percent of the seaweed each year and the nutrient content of runoff remains relatively low, the area covered by Acropora corals could drop to half today’s amount. If increased fishing drives the grazing rate below 40 percent, however, coral coverage plummets to near zero and the area occupied by seaweed rises to 40 percent or higher. A rise in nutrient-rich runoff would boost the growth of seaweed even higher, Anthony says.

The new analysis doesn’t include effects of non-nutrient pollution and coral disease, and it doesn’t account for any synergetic effects among global and local threats that would amplify known detriments from individual threats, says Anthony. “In that sense, our figures may quite possibly paint an overly optimistic picture.” Nevertheless, he adds, “coral reefs can survive climate change if they’re treated well at the local scale, but many people would consider a nearly 50 percent drop in coral coverage a significant deterioration.”

If there’s any positive aspect to be seen in the ecological havoc wrought by climate change, it’s this: The coral ecosystems that replace old-growth reefs could, in some instances, be more resistant to disease outbreaks, according to a study published online on January 17 in Proceedings of the National Academy of Sciences. In that paper, Laith Yakob and Peter Mumby of the University of Queensland in Brisbane, Australia propose a model in which climate change affects disease resistance in corals in two contradictory ways.

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Our pick of the recent literature

Each week on Nature Climate Change, we select three papers published within the last month that we find noteworthy for their novelty and wide interest. Our latest picks are:

Media: Reporters get it right

Accurate reporting of sea-level rise is a welcome success story at the sometimes fraught interface of climate science and mass media.

Original paper: Rick, U. K. et al. Effective media reporting of sea level rise projections: 1989–2009. Environ. Res. Lett. (in the press).

Ecology: Pikas’ pain

Rising temperatures may be to blame for the disappearance of a mountain-dwelling mammal.

Original paper: Beever, E. A. et al. Contemporary climate change alters the pace and drivers of extinction. Glob. Change Biol. doi:10.1111/j.1365-2486.2010.02389.x (2010).

Energy: A carbon-free future?

Large-scale deployment of wind, water and solar power could decarbonize our energy system by 2050, academics say.

Original papers: Jacobson, M. Z. & Delucchi, M. A. Providing all global energy with wind, water, and solar power, Part I: Technologies, energy resources, quantities and areas of infrastructure, and materials. Energy Policy. doi:10.1016/j.enpol.2010.11.040 (2010).

Delucchi, M. A. & Jacobson, M. Z. Providing all global energy with wind, water, and solar power, Part II: Reliability, system and transmission costs, and policies. Energy Policy. doi:10.1016/j.enpol.2010.11.045 (2010).

Read these highlights in full on our homepage.

Our pick of the recent literature

Each week on Nature Climate Change, we select three papers published within the last month that we find noteworthy for their novelty and wide interest. Our latest picks are:

Built environment: Cities to suffer

The world’s most populated port cities will be three times more likely to suffer from an extreme weather event by 2070, a study suggests.

Original paper: Hanson, S. et al. A global ranking of port cities with high exposure to climate extremes. Climatic Change doi:10.1007/s10584-010-9977-4 (2010

Agriculture: Insights on adaptation

A historical look at grain growth in North America shows that past generations of farmers have coped with significant climate changes.

Original paper: Olmstead, A. L. & Rhode, P. W. Adapting North American wheat production to climatic challenges, 1839-2009. Proc. Natl Acad. Sci. USA doi:10.1073/pnas.1008279108 (2010).

Ecology: Climate relief

Plant leaf growth is boosted by carbon dioxide, but can, in turn, slow global warming, shows research.

Original paper: Bounoua, L. et al. Quantifying the negative feedback of vegetation to greenhouse warming: A modeling approach. Geophys. Res. Lett. 37, L23701 (2010

Read these highlights in full on our homepage.

Penguins feel the pain

Sid Perkins

A well-designed scientific experiment shouldn’t affect the behavior of its subjects or cause them harm. Yet that’s exactly the result of using flipper bands to identify individual penguins during field studies, one team of researchers now contends.

In recent years, scientists have increasingly looked to penguins as a source of data about climate change. The new evidence comes from a long-term field experiment conducted on a remote island in the southern Indian Ocean that was designed to do just that. From 1998 through 2008, a team led by Yvon Le Maho, an ecophysiologist at the University of Strasbourg in France, monitored 100 king penguins on Possession Island, a 150-square-kilometer landmass in the windswept Crozet archipelago. Le Maho and his colleagues implanted the penguins with transponder tags — similar to those implanted in pet dogs and cats — that allowed researchers to track the comings and goings of the majestic birds in the breeding colony there. But 50 of the birds in this experiment were also tagged with a metallic band around one flipper, the standard technique scientists have used to monitor penguins for decades.

Over the course of the team’s 10-year study, unbanded penguins fared much better than their banded brethren. Birds tagged with flipper bands had a lower long-term survival rate — dropping by 16 percentage points, or about 44 percent overall (note this was incorrectly reported in the original paper, a point picked up by AP journalist Seth Borenstein). Banded birds also had about 40 percent fewer chicks than unbanded birds did, the researchers report in the January 13 issue of Nature.

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A call to contribute

Olive Heffernan

Next spring will bring a much-awaited and exciting new addition to the family of Nature journals. The newest of Nature’s research journals, Nature Climate Change will dedicate its coverage to one of the greatest challenges for science and society.

By and large, society now accepts that climate change is happening. But the science of global climate change is far from settled — large uncertainties remain regarding the rate of change and the scale and distribution of impacts. Less certain still is how we will respond as individuals and collectively to the problem. Although ample cause for concern, such uncertainty also brings the opportunity for new discovery.

Nature Climate Change, which becomes available in print from April 2011, aims to be the world’s leading research journal for documenting new scientific discoveries about how we will experience and respond to the challenges of a changing climate. With our online submission system now open, we are calling for original research articles from the natural and social science communities, in subject areas from atmospheric physics to psychology and policy. Central to the journal’s mission, and to addressing climate change, is reaching beyond traditional academic boundaries, and bringing together diverse expertise and perspectives. As such, Nature Climate Change especially encourages the submission of interdisciplinary climate research. Further details can be found in our Guide to Authors.

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Nature Climate Change website – coming soon

Our regular readers will have noticed that Climate Feedback has been on hiatus over the summer – apologies for the silence. The good news is that taking a break from blogging has allowed us to do all of the ‘behind the scenes’ work on getting Nature Climate Change, our forthcoming journal, underway.

The blog will be back up and running regularly once the journal launches, and in the meantime, our website will go live in October. Once we are live, we will open our doors for submissions from the research community, and will be accepting original research papers, both in article and letter format, on climate change across the natural and social sciences. Until then, readers can find out more about the journal here.

From October right up until the first print issue of Nature Climate Change in April 2011, we will be highlighting the latest developments in climate research on a weekly basis online. We will also be commenting on climate change, its impacts and implications on Twitter, on Facebook, and here.