Constantine Alexander's blog

"Fish thermometer" reveals long-standing, global impact of climate change

Credit: The Pew Ocean Science Division of The Pew Charitable Trusts

Climate change has been impacting global fisheries for the past four decades by driving species towards cooler, deeper waters, according to University of British Columbia scientists.

In a Nature study published this week, UBC researchers used temperature preferences of fish and other marine species as a sort of "thermometer" to assess effects of climate change on the world's oceans between 1970 and 2006.

They found that global fisheries catches were increasingly dominated by warm-water species as a result of fish migrating towards the poles in response to rising ocean temperatures.

"One way for marine animals to respond to ocean warming is by moving to cooler regions," says the study's lead author William Cheung, an assistant professor at UBC's Fisheries Centre. "As a result, places like New England on the northeast coast of the U.S. saw new species typically found in warmer waters, closer to the tropics.

"Meanwhile in the tropics, climate change meant fewer marine species and reduced catches, with serious implications for food security."

"We've been talking about climate change as if it's something that's going to happen in the distant future – our study shows that it has been affecting our fisheries and oceans for decades," says Daniel Pauly, principal investigator with UBC's Sea Around Us Project and the study's co-author. "These global changes have implications for everyone in every part of the planet."

• Download "Warming Oceans Are Reshaping Fisheries" (PDF)

Contact: William Cheung
w.cheung@fisheries.ubc.ca
778-837-7252
University of British Columbia

Carbon Dioxide at NOAA’s Mauna Loa Observatory reaches new milestone: Tops 400 ppm

NOAA's Mauna Loa Observatory after a snowstorm. Courtesy of Mary Miller, Exploratorium

On May 9, the daily mean concentration of carbon dioxide in the atmosphere of Mauna Loa, Hawaii, surpassed 400 parts per million (ppm) for the first time since measurements began in 1958. Independent measurements made by both NOAA and the Scripps Institution of Oceanography have been approaching this level during the past week. It marks an important milestone because Mauna Loa, as the oldest continuous carbon dioxide (CO2) measurement station in the world, is the primary global benchmark site for monitoring the increase of this potent heat-trapping gas.

Carbon dioxide pumped into the atmosphere by fossil fuel burning and other human activities is the most significant greenhouse gas (GHG) contributing to climate change. Its concentration has increased every year since scientists started making measurements on the slopes of the Mauna Loa volcano more than five decades ago. The rate of increase has accelerated since the measurements started, from about 0.7 ppm per year in the late 1950s to 2.1 ppm per year during the last 10 years.

“That increase is not a surprise to scientists,” said NOAA senior scientist Pieter Tans, with the Global Monitoring Division of NOAA’s Earth System Research Laboratory in Boulder, Colo. “The evidence is conclusive that the strong growth of global CO2 emissions from the burning of coal, oil, and natural gas is driving the acceleration.” 

Before the Industrial Revolution in the 19th century, global average CO2 was about 280 ppm. During the last 800,000 years, CO2 fluctuated between about 180 ppm during ice ages and 280 ppm during interglacial warm periods. Today’s rate of increase is more than 100 times faster than the increase that occurred when the last ice age ended.

It was researcher Charles David Keeling of the Scripps Institution of Oceanography, UC San Diego, who began measuring carbon dioxide at Mauna Loa in 1958, initiating now what is known as the “Keeling Curve.” His son, Ralph Keeling, also a geochemist at Scripps, has continued the Scripps measurement record since his father’s death in 2005.

“There’s no stopping CO2 from reaching 400 ppm,” said Ralph Keeling. “That’s now a done deal. But what happens from here on still matters to climate, and it’s still under our control. It mainly comes down to how much we continue to rely on fossil fuels for energy.”

NOAA scientists with the Global Monitoring Division have made around-the-clock measurements there since 1974. Having two programs independently measure the greenhouse gas provides confidence that the measurements are correct.

Moreover, similar increases of CO2 are seen all over the world by many international scientists. NOAA, for example, which runs a global, cooperative air sampling network, reported last year that all Arctic sites in its network reached 400 ppm for the first time. These high values were a prelude to what is now being observed at Mauna Loa, a site in the subtropics, this year. Sites in the Southern Hemisphere will follow during the next few years. The increase in the Northern Hemisphere is always a little ahead of the Southern Hemisphere because most of the emissions driving the CO2 increase take place in the north.

Once emitted, CO2 added to the atmosphere and oceans remains for thousands of years. Thus, climate changes forced by CO2 depend primarily on cumulative emissions, making it progressively more and more difficult to avoid further substantial climate change. 

Related Links:

• NOAA carbon dioxide data

• Scripps Institution of Oceanography carbon dioxide data

• NOAA’s Maua Loa Observatory

Time history of atmospheric carbon dioxide from 800,000 years ago until January, 2012.

 

Scientists find impact of open-ocean industrial fishing within centuries of bird bones

A Hawaiian petrel flies over part of its Pacific Ocean foraging grounds. Credit: Jim Denny

The impact of industrial fishing on coastal ecosystems has been studied for many years. But how it affects food webs in the open ocean―a vast region that covers almost half of the Earth's surface―has not been very clear. So a team of Smithsonian and Michigan State University scientists and their colleagues looked to the ancient bones of seabirds for answers, revealing some of the dramatic changes that have happened within open-ocean food webs since the onset of industrial fishing. The team's research is published this week in the Proceedings of the National Academy of Sciences.

Few records of species that live in the open ocean date back more than 60 years, and the sheer size of open-ocean regions makes their food webs difficult to study. The Hawaiian petrel (Pterodroma sandwichensis), a crow-sized oceanic bird, offered the team a solution. These birds range widely over the northeast Pacific, and their diets integrate food webs from that vast area.

400 to 1,000-year-old bones from an endangered seabird, the Hawaiian petrel. These bones represent a small fraction of those collected from the species. They offer a window into the lives of seabirds before and after the arrival of humans in the open ocean environments of the Pacific. Credit: Brittany Hance, Smithsonian Institution

What the petrels have eaten is recorded in the chemistry of their bones. By extracting protein from bones and feathers and studying stable isotopes of carbon and nitrogen in the protein, the scientists were able to assess the birds' diet and how it changed over centuries. What they found from bones 100 to 4,000 years old were nitrogen isotope ratios that were consistently high, indicating a diet of relatively large prey. Those less than a century old, after industrial fishing started, had low ratios, revealing a shift to smaller fish, squid and other prey.

"The question is, have the effects of open-ocean fishing gone beyond targeted species, like tuna," said Anne Wiley, lead author, Smithsonian postdoctoral researcher and former MSU doctoral student. "Our study is among the very first to show that it has, and because Hawaiian petrels eat such a wide variety of prey over a large area, our results suggest that fishery influence may be widespread and profound in the Pacific. Understanding the influence of fisheries on open-ocean food webs has been one of the great mysteries of biological oceanography."

The team's isotope records are unusual because they are from all the known populations of the species, which breed on different Hawaiian Islands. The records show that separate populations of Hawaiian petrels hunted in different areas of the open ocean for thousands of years. The scientists revealed a foraging shift in multiple Hawaiian petrel populations, emphasizing that the petrels' diets changed across a very broad expanse of the ocean. This sudden shift in the past 100 years suggests a relatively rapid change in the composition of oceanic food webs in the Northeast Pacific.

"Conservation efforts for endangered seabirds take place mainly on land at breeding colonies where there are obvious threats like introduced predators," said Helen James, coauthor and research zoologist at Smithsonian's National Museum of Natural History. "Our study suggests we should pay more attention to the lives of these birds at sea."

Further studies are needed to explore how the change in foraging is affecting the Hawaiian petrel. Similar shifts down the food chain in other species have been associated with decreases in population size―potentially a bad sign for the Hawaiian petrel, which already has a small population restricted to the Hawaiian islands and is listed as "vulnerable" by the International Union for Conservation of Nature and Natural Resources.

Contact: John Gibbons
gibbonsjp@si.edu
202-633-5187
Smithsonian

Land management options outlined to address cheatgrass invasion

This intact rangeland community, some distance from water, has little cheatgrass but abundant native bunchgrasses and forbs that help resist cheatgrass invasion. Photo courtesy of Oregon State University

A new study suggests that overgrazing and other factors increase the severity of cheatgrass invasion in sagebrush steppe, one of North America's most endangered ecosystems.

The research found that overgrazed land loses the mechanisms that can resist invasion. This includes degradation of once-abundant native bunchgrasses and trampling that disturbs biological soil crusts. The work was published today in the Journal of Applied Ecology by researchers from Oregon State University, Augustana College and the U.S. Geological Survey.

"We think there are ways to assess the risks these lands face to reduce the impact of cheatgrass invasion," said Paul Doescher, professor and head of the OSU Department of Forest Ecosystems and Society, and co-author on the study.

"In the future we should work cooperatively with ranchers and land managers to promote a diverse sagebrush and bunchgrass ecosystem," Doescher said. "That type of community will protect the native plant and wildlife species and benefit sustainable rangeland use at the same time."

Researchers suggested that one of the most effective restoration approaches would be to minimize the cumulative impact of grazing, by better managing the timing, frequency of grazing and number of animals.

The researchers also determined that, contrary to some previous suggestions, grazing does not reduce cheatgrass abundance. Cheatgrass was found by this study to be extremely tolerant of even intensive grazing, and the findings "raise serious concern" about proposals to use cattle grazing to help control its spread in areas where native bunchgrasses still persist.

The study outlines the complex ecological processes that can promote cheatgrass invasion and the indirect role overgrazing plays in that process. Increasing gaps and connection of gaps between once-abundant native bunchgrasses allow "a dramatic increase" in cheatgrass invasion, the study concluded. Such gaps could serve as a valuable "early warning indicator" and allow for management approaches that could help conserve and restore the land.

Cheatgrass threatens vast regions of the American West, especially the Great Basin in Nevada and surrounding states. These are areas which were once carpeted by millions of acres of native sagebrush, perennial bunchgrasses and associated wildlife that had evolved with little herbivore pressure. Cheatgrass displaces native grasses and wildlife, can increase fire frequency and ultimately cause an irreversible loss of these native shrub-steppe communities.

This also has grazing implications: cheatgrass is a short-lived annual grass that dries out quickly and provides lower quality forage for much of the year, compared to perennial bunchgrasses.

"Cheatgrass changes the fire regime, and as it spreads, can reach a tipping point," said Michael Reisner, now an assistant professor at Augustana College who led this study as a doctoral student at OSU.

"After you cross that threshold, a major rangeland fire will come through that takes out the sagebrush, and in most cases the native ecosystem never recovers," Reisner said. "Many of the plant and animal species that were there can disappear, mostly replaced by cheatgrass that offers poor forage for cattle."

In a more resistant system, abundant native bunchgrasses can limit the size and connectivity of gaps, which minimizes the water and nutrients available to cheatgrass. Using data from 75 study sites, researchers found that high levels of cattle grazing were associated with reduced bunchgrass cover, with wider and more connections between the gaps that provided an opportunity for cheatgrass to invade.

Cattle grazing in a rangeland site near water has led to reduced native bunchgrasses and a higher level of cheatgrass invasion. Photo courtesy of Oregon State University

Cattle trampling also appeared to disturb biological soil crust that offers a second defensive barrier against cheatgrass, and further speeds the invasion. Impacts are greater on the drier and warmer sites within this region.

If the level and amount of gaps indicates that it's necessary, changes in grazing could help restore bunchgrass cover, maintain a diversity of native grass species and provide much better resistance to cheatgrass invasion, the study concluded. Continued research is needed to quantify the threshold levels of cattle grazing that would still maintain a healthy native ecosystem.

Contact: Paul Doescher
paul.doescher@oregonstate.edu
541-737-6583
Oregon State University

GBIF enables global forecast of climate impacts on species

Study uses data on 50,000 common plants and animals to predict worldwide range losses without urgent action to limit emissions

Pacific Northwest Rainforest. Credit: Constantine Alexander

Climate change could dramatically reduce the geographic ranges of thousands of common plant and animal species during this century, according to research using data made freely available online through the Global Biodiversity Information Facility (GBIF).

Research published today in the journal Nature Climate Change looked at nearly 50,000 globally widespread and common species and found that nearly two-thirds of the plants and almost half of animal species could lose more than half of their climatic range by 2080 if nothing is done to limit greenhouse gas emissions.

However, acting quickly to mitigate climate change could reduce losses by 60 per cent and buy an additional 40 years for species to adapt, the research concludes.

The study, by researchers in the United Kingdom, Australia and Colombia, defined the climate 'niche' occupied by each species, based on temperature and rainfall where they live now, and mapped the areas that would remain suitable for them according to various scenarios of future climate change.

The information on the current location of common species of plants, mammals, birds, reptiles and amphibians was taken from around 170 million individual data records published freely online through GBIF by some 200 different institutions around the world. The records include museum specimens, data from scientific expeditions and the observations of thousands of volunteer 'citizen scientists'.

One of the co-authors of the study, Jeff Price of the University of East Anglia's School of Environmental Sciences, United Kingdom, said: "Without free and open access to massive amounts of data such as those made available online through GBIF, no individual researcher is able to contact every country, every museum, every scientist holding the data and pull it all together. So this research would not be possible without GBIF and its global community of researchers and volunteers who make their data freely available."

According to the research, plants, reptiles and especially amphibians are expected to be at highest risk from climate change. The climate will become especially unsuitable for both plant and animal species in Sub-Saharan Africa, Central America, Amazonia and Australia. A major loss of plant species is also projected for North Africa, Central Asia and South-eastern Europe.

The lead author of the study, Dr Rachel Warren, also from UEA's School of Environmental Sciences and the Tyndall Centre, said: "While there has been much research on the effect of climate change on rare and endangered species, little has been known about how an increase in global temperature will affect more common species.

"This broader issue of potential range loss in widespread species is a serious concern as even small declines in these species can significantly disrupt ecosystems.

"Our research predicts that climate change will greatly reduce the diversity of even very common species found in most parts of the world. This loss of global-scale biodiversity would significantly impoverish the biosphere and the ecosystem services it provides.

"The good news is that our research provides crucial new evidence of how swift action to reduce CO2 and other greenhouse gases can prevent the biodiversity loss by reducing the amount of global warming to 2 degrees Celsius rather than 4 degrees. This would also buy time – up to four decades - for plants and animals to adapt to the remaining 2 degrees of climate change."

Quantifying the benefit of early climate change mitigation in avoiding biodiversity loss' is published online by the journal Nature Climate Change on Sunday May 12, 2013. Contributing authors are from the Tyndall Centre, School of Environmental Sciences, University of East Anglia, UK; School of Marine and Tropical Biology, James Cook University, Townsville, Australia; International Centre for Tropical Agriculture (CIAT), Cali, Colombia; School of Earth and Environment, University of Leeds, UK; School of Biological Sciences, University of Queensland, Australia; the Met Office Hadley Centre, UK; and Department of Meteorology, University of Reading, UK.

Contact: Tim Hirsch
thirsch@gbif.org
45-28-75-14-85
Global Biodiversity Information Facility

The Global Biodiversity Information Facility was founded in 2001 as an intergovernmental scientific infrastructure aimed at providing free and open access to biodiversity data, via the Internet. It currently offers a single online access point to 400 million biodiversity records from over 10,000 datasets published by 460 institutions, ranging from museum specimens collected from the earliest days of natural history exploration, to current observations by 'citizen scientists' and monitoring from research expeditions. GBIF operates through a network of national and thematic 'nodes', and a secretariat based in Copenhagen, Denmark.

Plastic litter found in fish guts

Tiny pieces of plastic are being taken up by a range of different fish species with unknown effects on their health, according to a new study. Researchers examined the gut contents of ten different species of fish found in UK waters and showed that so-called 'microplastics' were found in all species.

Between 60 and 80% of marine litter is plastic. Although larger items are well documented, much less is known about distribution or effects of microplastics - fragments below 5mm in size. Such microlitter is given special consideration under the Marine Framework Strategy Directive and in a recent report experts recommended that approaches for sampling this marine litter should be standardised, both in terms of methods and coverage.

There is particular concern that these particles could clog or carry harmful pollutants into the guts of marine animals. Sea creatures, including crustaceans and mussels, have been shown to ingest these microplastics in the laboratory, but studies in natural environments are rare.

For this study, researchers examined the guts of 504 individual fish of ten species caught in the English Channel. Over a third of the fish (184) were found to contain microplastics, which made up 92% of all plastic material found. Five of the species included were pelagic fish, which are bottom-dwellers, and five species were demersal fish, which live higher up the water column.

Researchers found microplastics in the guts of all species, with no difference in amounts between pelagic and demersal species. Across all species, the average number of pieces of microplastic per fish was just less than two, although there were examples of fish ingesting up to 15 pieces.

The quantities per individual fish were, on average, very low, and probably do not present a hazard to the fish. Neither do the results suggest a risk linked to human consumption, as the plastic was found in the gut - which we do not normally eat. However, the research does demonstrate that the problem of microplastics is widespread, not only in natural habitats but also in marine organisms.

To analyse the types of plastic swallowed by fish, the researchers used a technique called Fourier transform infrared spectroscopy (FT-IR), which identifies what samples are made of based on how they absorb different wavelengths of light. More than half of the microplastic litter was rayon and around a third was polyamide, with polyester, polystyrene, polyethylene and acrylic making up the remainder.

Polyester and polyamide are commonly used by the fishing industry (in ropes, nets and lines), whilst rayon could have come from textiles or via sewage, hygiene products or nappies. Polystyrene, polyethylene and acrylic were only found in pelagic fish. These are less dense than polyester and rayon and it is not clear from the results why they are being taken up more by bottom-dwelling fish.

Further studies will be necessary to understand the extent of the problem at larger scales. In particular, it will be important to consider the age of fish to understand whether microplastic waste accumulates or passes through the digestive tract naturally over time. The length of time that microplastics spend in the gut is also crucial to determining the severity of any physical or toxic effects.

Source: Lusher, A.L., McHugh, M. and Thompson, R.C. (2013). Occurrence of microplastics in the gastrointestinal tract of pelagic and demersal fish from the English Channel. Marine Pollution Bulletin, 67, 94-99. DOI: 10.1016/j.marpolbul.2012.11.028

Contact: R.C.Thompson@plymouth.ac.uk

Marine Pollution Source Example in the Mediterranean

Zeal to ensure clean leafy greens takes bite out of riverside habitat in California

Perceived food safety risk from wildlife drives expensive and unnecessary habitat destruction around farm fields

Meticulous attention to food safety is a good thing. As consumers, we like to hear that produce growers and distributers go above and beyond food safety mandates to ensure that healthy fresh fruits and vegetables do not carry bacteria or viruses that can make us sick.

But in California's Salinas Valley, some more vigorous interventions are cutting into the last corners of wildlife habitat and potentially threatening water quality, without evidence of food safety benefits. These policies create tensions between wildlife preservation and food safety where none need exist, say scientists for The Nature Conservancy, writing in the Ecological Society of America's journal Frontiers in Ecology and the Environment. The study will be published online ahead of print on Monday, May 6th, 2013.

"Farming practices for food safety that target wildlife are damaging valuable ecological systems despite low risk from these animals," said lead author Sasha Gennet.

Check the back of your bag of spinach or prepackaged salad greens, and you'll probably find that they came from the Salinas Valley. Salad is big business in California.

In the aftermath of a deadly 2006 Escherichia coli serotype O157:H7 outbreak traced to California spinach, growers and distributers of leafy greens came together to create the California Leafy Green Handler Marketing Agreement (LGMA) on best practices for the industry, enforced by third-party auditors and inspectors. The LGMA established standards for farm work hygiene, produce processing and transport, and proximity to livestock. About 99 percent of California leafy greens now come from participating farms.

But produce farmers in the Salinas Valley report pressure from some powerful buyers to take additional precautions not mandated by government or industry standards. These buyers insist that swathes of bare ground wider than a football field is long separate the leafy greens from rivers, wetlands and other wildlife habitat.

Other precautions include treating irrigation water with chemicals toxic to fish and amphibians, and setting poisoned bait for rodents.

"The California Leafy Green Hander agreement is transparent, flexible and science based," said Gennet. "Going above and beyond it just creates costs for farmers and doesn't improve safety."

It also creates costs for wildlife. Although scant evidence exists of risk of food-borne disease spread by wildlife, the risk of rejection of produce by major buyers is too much for most growers to bear, say Gennet and her co-authors. They measured changes in wetlands and riverside habitat in the Salinas Valley between 2005 and 2009, finding 13.3 percent converted to bare ground, crops or otherwise diminished. Widespread introduction of fencing blocked wildlife corridors. Low barriers even kept out the frogs.

Unlike the LGMA standards, individual corporate requirements for farm produce are generally not transparent to the public. But in surveys, farmers report pressure from auditors to implement fences and bare ground buffers around spinach, lettuce, and other leafy greens.

Such pressures have set back years of collaboration between growers and environmental advocates to make farm edges slim sanctuaries for wildlife, as well as buffers between agricultural fields and waterways. Fallow strips along streams and rivers provide corridors for migrating animals and birds.

"This is an area that is already 95 percent altered – the habitat that remains is critical," said Gennet. "Removing 13 percent of what is already heavily-impacted habitat and cutting off wildlife corridors is a significant loss."

The Salinas River and its tributaries are an important rest stop on the Pacific Flyway, a major migration route for neotropical songbirds, and home to raptors and shorebirds. The waterways are also corridors for deer and other big animals moving between the high country of the Diablo Range and coastal Big Sur mountains that flank the valley.

Wetlands and buffers of trees, grasses, and shrubs help to keep runoff from fields out of the waterways, slowing erosion of soil and blooms of algae downstream. An overabundance of fertilizer has created problems for domestic drinking water as well as the ecosystems of the Salinas River watershed and its outlet, Monterey Bay.

"California has a big problem with concentrated nutrients in waterways, and there is a lot of pressure on growers to reduce those inputs – so to the extent that riverside wildlife habitat could be a benefit all around, a coordinated approach to agricultural management and policy makes the most sense," said Gennet.

"The policies that these distributors are forming are very narrow," said Lisa Schulte Moore, an agricultural ecologist at Iowa State University who is not affiliated with the Nature Conservancy study. Nervous distributers are looking at specific risks in isolation, she said, and not asking "does the food system create a healthy human environment?"

Schulte Moore works with Iowa farmers to incorporate native grassland habitat alongside corn and soy fields. Her experiments look for native grass mixtures that don't tend to invade the crops and are highly attractive to beneficial native insects, including the natural enemies of agricultural pests. "If we design the systems right there could be substantial benefits to the agricultural system as a whole," she said.

The key word, Gennet says, is "co-management." As a community, we need to approach food health, wildlife health, and water health in the Salinas Valley as parts of an integrated system. She would like to see California growers, buyers, and consumers rely on standards like the LGMA. "We think it's been a good process, using the newest science and trying to take a constructive approach. If everybody stuck to those standards, that would be a good outcome," said Gennet.

Citation: Farm practices for food safety: an emerging threat to floodplain and riparian ecosystems. (2013) Sasha Gennet, Jeanette Howard, Jeff Langholz, Kathryn Andrews, Mark D Reynolds, and Scott A Morrison. Frontiers in Ecology and the Environment doi:10.1890/1202443

Contact: Liza Lester
llester@esa.org
202-833-8773 x211
Ecological Society of America

More hurricanes for Hawaii?

Hurricane Flossie is approaching the Big Island of Hawaii in August 2007. Credit: NASA

News of a hurricane threat sends our hearts racing, glues us to the Internet for updates, and makes us rush to the store to stock up on staples. Hawaii, fortunately, has been largely free from these violent storms in the recent past, only two having made landfall in more than 30 years.

Now a study headed by a team of scientists at the International Pacific Research Center, University of Hawaii at Manoa, shows that Hawaii could see a two-to-three-fold increase in tropical cyclones by the last quarter of this century. The study, which appears in the May 5, 2013, online issue of Nature Climate Change, though, leaves open the question, how worried Island residents should get.

"Computer models run with global warming scenarios generally project a decrease in tropical cyclones worldwide. This, though, may not be what will happen with local communities," says lead author Hiroyuki Murakami.

To determine whether tropical cyclones will become more frequent in Hawaii with climate change, Murakami and climate expert Bin Wang at the Meteorology Department, University of Hawaii at Manoa, joined forces with Akio Kitoh at the Meteorological Research Institute and the University of Tsukuba in Japan. The scientists compared in a state-of-the-art, high-resolution global climate model the recent history of tropical cyclones in the North Pacific with a future (2075–2099) scenario, under which greenhouse gas emissions continue to rise, resulting in temperatures about 2°C higher than today.

This image shows the projected change in number of tropical cyclones per year by the last quarter of this century. The green stippling indicates statistical significance at the 99 percent confidence level. Credit: Hiroyuki Murakami, Nature Climate Change

"In our study, we looked at all tropical cyclones, which range in intensity from tropical storms to full-blown category 5 hurricanes. From 1979 to 2003, both observational records and our model document that only every four years on average did a tropical cyclone come near Hawaii. Our projections for the end of this century show a two-to-three-fold increase for this region," explains Murakami.

The main factors responsible for the increase are changes in the large-scale moisture conditions, the flow patterns in the wind, and in surface temperature patterns stemming from global warming.

Most hurricanes that might threaten Hawaii now are born in the eastern Pacific, south of the Baja California Peninsula. From June through November the ingredients there are just right for tropical cyclone formation, with warm ocean temperatures, lots of moisture, and weak vertical wind shear. But during the storms' long journey across the 3000 miles to Hawaii, they usually fizzle out due to dry conditions over the subtropical central Pacific and the wind shear from the westerly subtropical jet.

Surprisingly, even though fewer tropical cyclones will form in the eastern Pacific in Murakami's future scenario, we can expect more of them to make their way to Hawaii.

The upper-level westerly subtropical jet will move poleward so that the mean steering flow becomes easterly. Thus, storms from Baja California are much more likely to make it to Hawaii. Furthermore, since the climate models also project that the equatorial central Pacific will heat up, conditions may become more favorable for hurricane formation in the open ocean to the south or southeast of Hawaii.

"Our finding that more tropical cyclones will approach Hawaii as Earth continues to warm is fairly robust because we ran our experiments with different model versions and under varying conditions. The yearly number we project, however, still remains very low," reassures study co-author Wang.

Citation: Hiroyuki Murakami, Bin Wang, Tim Li, and Akio Kitoh: Projected increase in tropical cyclones near Hawaii. Nature Climate Change, May 5, 2013, doi:10.1038/nclimate1890

Contact: Gisela Speidel
gspeidel@hawaii.edu
808-956-9252
University of Hawaii ‑ SOEST

Researchers calculate the global highways of invasive marine species

The risk of marine bio-invasion caused by global shipping around the world. The brighter colour and thicker line indicates a higher bio-invasion risk.  Image by Dr Michael Gastner

Globalisation, with its ever increasing demand for cargo transport, has inadvertently opened the flood gates for a new, silent invasion. New research has mapped the most detailed forecast to date for importing potentially harmful invasive species with the ballast water of cargo ships.

Scientists from the Universities of Bristol, UK, and Oldenburg, Germany, have examined ship traffic data and biological records to assess the risk of future invasions. Their research is published in the latest issue of Ecology Letters.

Animals and plants can hitch a ride on cargo ships, hiding as stowaways in the ballast tanks or clinging to the ship's hull. Upon arrival in a new port, alien species can then wreak havoc in formerly pristine waters. These so-called invasive species can drive native species to extinction, modify whole ecosystems and impact human economy.

Some regions, such as the San Francisco Bay or Chesapeake Bay, have even reported several new exotic species per year. The knock-on effects to fishermen, farmers, tourism and industry create billions of US dollars in damage every year. Conservationists and ship engineers are now trying to prevent the next big invasion. But without knowing when and where it may occur, their possibilities remain limited.

As part of the research project, funded by the Volkswagen Foundation, the team obtained detailed logs of nearly three million ship voyages in 2007 and 2008. Depending on the particular route travelled by each ship, the researchers estimated the probability that a species survives the journey and establishes a population in subsequent ports of call. Although this probability is tiny for any single voyage, the numbers quickly add up because modern cargo traffic volumes are enormous.

Professor Bernd Blasius from the University of Oldenburg and one of the researchers involved in the study, said: "Our model combines information such as shipping routes, ship sizes, temperatures and biogeography to come up with local forecasts of invasion probabilities."

The final tally reveals the hotspots of bioinvasion. Large Asian ports such as Singapore and Hong Kong but also US ports like New York and Long Beach are among the sites of highest invasion probability. These waterways are notoriously busy, but, traffic is not the only important factor.

The North Sea, for example, does not rank among the top endangered regions despite intense shipping. Temperatures here are lower, making it more difficult for alien species to survive. However, arrivals from the other side of the Atlantic pose a serious threat to the North Sea. Most invaders are predicted to originate from the North American east coast.

Hanno Seebens from the University of Oldenburg said: "We also compared our model results to field data. And, indeed, most of the alien species actually do originate from there."

As severe as the risk of future invasions may be, the study also contains a hopeful message. If ship engineers could prevent at least some potential invaders from getting on board, the total invasion risk could be substantially mitigated.

By successfully removing a species from 25 per cent of the ballast tanks arriving at each port (eg with filters, chemicals or radiation), the overall invasion probability decreases by 56 per cent. The reduction is so disproportionately large because the effect of ballast water treatment multiplies at successive stopovers.

Bioinvasion is, as the researchers admit, a complex process, and records of past invasions are far from comprehensive. Facing these uncertainties, they simulated various different scenarios. Interestingly, the key results are comparable for different models, predicting the same hotspots and global highways of bioinvasion. The traffic on the main shipping routes plays the greatest role for the calculation.

Dr Michael Gastner, Lecturer in Engineering Mathematics at the University of Bristol, added: "Ship movements in the past few years are well documented, but there are many unknowns about future trade routes."

For example, the future of the world economy remains uncertain, and Arctic passages may become navigable as a consequence of global warming. Future simulations will also have to take into account which engineering solutions for ballast water treatment will eventually be adopted by port authorities.

Paper: The risk of marine bioinvasion caused by global shipping, Hanno Seebens, Michael T. Gastner, Bernd Blasius, Ecology Letters, published online 24 April 2013.

Contact: Joanne Fryer
joanne.fryer@bristol.ac.uk
44-011-733-17276
University of Bristol

Toxic waste sites cause healthy years of life lost

Mount Sinai researcher presents novel findings in environmental health at the Pediatric Academic Societies

Toxic waste sites with elevated levels of lead and chromium cause a high number of "healthy years of life lost" in individuals living near 373 sites located in India, Philippines and Indonesia, according to a study by a Mount Sinai researcher published online today in Environmental Health Perspectives.

The study leader, Kevin Chatham-Stephens, MD, Pediatric Environmental Health Fellow at the Icahn School of Medicine at Mount Sinai, presented the findings today at the Pediatric Academic Societies (PAS) annual meeting in Washington, DC. "Lead and hexavalent chromium proved to be the most toxic chemicals and caused the majority of disease, disability and mortality among the individuals living near the sites," said Dr. Chatham-Stephens, first author.

The study titled, "The Burden of Disease from Toxic Waste Sites in India, Indonesia, and the Philippines in 2010," was a joint research partnership between Mount Sinai and the Blacksmith Institute. Eight chemicals were sampled and collected at the toxic waste sites in 2010. The samples were then measured for pollutant levels in the soil and water and then compared with the 8,629,750 individuals who were at risk of exposure around these sites in order to calculate the loss of years of equivalent full health.

Researchers calculated healthy years of life lost due to ill-health, disability or early death, in disability-adjusted life years (DALY), a measure of overall disease burden used by the World Health Organization. One DALY represents the loss of one year of equivalent full health. In this study, the total number of lost years of full health or DALYs was 828,722. In comparison, malaria in the same countries caused 725,000 lost years of full health, and outdoor air pollution caused 1.4 million lost years of full health in 2008, according to Dr. Chatham-Stephens.

"The number of DALYs estimated in our study potentially places toxic waste sites on par with other major public health issues such as malaria and outdoor air pollution which are also causing a high number of healthy years of life lost," said Dr. Chatham-Stephens.

"This study highlights a major and previously under-recognized global health problem in lower and middle income countries," said Philip Landrigan, MD, MSc, Dean for Global Health at the Icahn School of Medicine at Mount Sinai and one of the authors of the study. "The next step is targeting interventions such as cleaning up the sites and minimizing the exposure of humans in each of these countries where toxic chemicals are greatly present."

Additionally, children and women of child-bearing age made up two-thirds of the population in the study. "If a woman is pregnant, the fetus may be exposed to these toxic chemicals," said Dr. Chatham-Stephens. "This data is relevant because the prenatal to early childhood period is the time when individuals are very vulnerable to some toxic exposures, such as lead's impact on the developing nervous system."

Previous studies have shown that lead can cause neurological, gastrointestinal and cardiovascular damage, while those also exposed to high levels of chromium have a greater chance of developing lung cancer. "Our research shows that chemical pollutants from toxic waste sites are insufficiently studied in lower and middle income countries and that disease and death caused by these chemicals can contribute to loss of life," said Dr. Chatham-Stephens.

Mount Sinai's Department of Preventive Medicine is internationally renowned for excellence in preventive medicine, occupational and environmental medicine, community health, and environmental pediatrics. The department is among the largest medical school departments of preventive medicine in the United States. Its mission is to prevent disease, protect the environment, and promote health in all the communities Mount Sinai serves. It consists of 57 full-time faculty, 137 adjunct and voluntary faculty, and 265 staff. The department's academic programs train medical students for residency programs in general preventive medicine and in occupational and environmental medicine. It also offer's a fellowship program in environmental pediatrics and the medical school's master's in public health (MPH) program.

Contact: Renatt Brodsky
Renatt.Brodsky@mountsinai.org
212-241-9200
The Mount Sinai Hospital / Mount Sinai School of Medicine

Toxic Waste Sites could also be present in the EU