Pacific trade winds stall global surface warming … for now

The strongest trade winds have driven more of the heat from global warming into the oceans; but when those winds slow, that heat will rapidly return to the atmosphere causing an abrupt rise in global average temperatures.Heat stored in the western Pacific Ocean caused by an unprecedented strengthening of the equatorial trade winds appears to be largely responsible for the hiatus in surface warming observed over the past 13 years.New research published today in the journal Nature Climate Change indicates that the dramatic acceleration in winds has invigorated the circulation of the Pacific Ocean, causing more heat to be taken out of the atmosphere and transferred into the subsurface ocean, while bringing cooler waters to the surface.”Scientists have long suspected that extra ocean heat uptake has slowed the rise of global average temperatures, but the mechanism behind the hiatus remained unclear” said Professor Matthew England, lead author of the study and a Chief Investigator at the ARC Centre of Excellence for Climate System Science.”But the heat uptake is by no means permanent: when the trade wind strength returns to normal — as it inevitably will — our research suggests heat will quickly accumulate in the atmosphere. So global temperatures look set to rise rapidly out of the hiatus, returning to the levels projected within as little as a decade.”The strengthening of the Pacific trade winds began during the 1990s and continues today. Previously, no climate models have incorporated a trade wind strengthening of the magnitude observed, and these models failed to capture the hiatus in warming. Once the trade winds were added by the researchers, the global average temperatures very closely resembled the observations during the hiatus.”The winds lead to extra ocean heat uptake, which stalled warming of the atmosphere. Accounting for this wind intensification in model projections produces a hiatus in global warming that is in striking agreement with observations,” Prof England said.”Unfortunately, however, when the hiatus ends, global warming looks set to be rapid.”The impact of the trade winds on global average temperatures is caused by the winds forcing heat to accumulate below surface of the Western Pacific Ocean.”This pumping of heat into the ocean is not very deep, however, and once the winds abate, heat is returned rapidly to the atmosphere” England explains.”Climate scientists have long understood that global average temperatures don’t rise in a continual upward trajectory, instead warming in a series of abrupt steps in between periods with more-or-less steady temperatures. Our work helps explain how this occurs,” said Prof England.”We should be very clear: the current hiatus offers no comfort — we are just seeing another pause in warming before the next inevitable rise in global temperatures.”Story Source:The above story is based on materials provided by University of New South Wales. Note: Materials may be edited for content and length.

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Global warming could change strength of El Niño

Sep. 11, 2013 — Global warming could impact the El Niño Southern Oscillation (ENSO), altering the cycles of El Niño and La Niña events that bring extreme drought and flooding to Australia and many other Pacific-rim countries.New research published in Nature Geoscience using coral samples from Kiribati has revealed how the ENSO cycle has changed over the past 4300 years. This research suggests that external changes have an impact on the strength and timing of El Niño events.”Our research has showed that while the development of La Niña and El Niño events is chaotic and hard to predict, the strength of these events can change over long time spans due to changes in the global climate,” said one of the paper’s authors Dr Steven Phipps.”For instance, we found that the ENSO cycle was much weaker 4300 years ago than it is today. This weaker cycle persisted for almost two centuries.”The researchers determined that natural influences on Earth’s climate, such as those caused by variations in its orbit around the sun, could affect the strength of El Niño events.Although small, these natural influences altered seasonal trade winds across the Eastern Pacific and affected the development of El Niño events. Interestingly, the research also showed that El Niño events in the past started later in the year and were often less intense.”We found there was a small strengthening of the regular seasonal trade winds in the Eastern Pacific in response to natural warming cycles in the Earth’s orbit around the sun. Remarkably this acted in a big way to stop El Niño events from forming and growing,” said lead author Dr Helen McGregor from the University of Wollongong.”This shows us that external factors can influence the ENSO process and that it may have a sustained response to future greenhouse gas changes. Currently 20th Century observations are too short to confirm whether this is occurring now.”Importantly, these new observations can now be used in climate models to see if these past changes in ENSO processes can be reproduced.”Currently, climate models do not agree on how El Niño may change under future global warming scenarios,” said Dr Phipps”With these new observations we can determine which models reproduce the most accurate response to changes in the global climate. This will help us to more accurately forecast the response of ENSO under future global warming scenarios.”

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Breaking deep-sea waves, as high as a skyscraper, reveal mechanism for global ocean mixing

Sep. 9, 2013 — Waves breaking over sandy beaches are captured in countless tourist photos. But enormous waves breaking deep in the ocean are seldom seen, although they play a crucial role in long-term climate cycles.A University of Washington study for the first time recorded such a wave breaking in a key bottleneck for circulation in the world’s largest ocean. The study was published online this month in the journal Geophysical Research Letters.The deep ocean is thought of as dark, cold and still. While this is mostly true, huge waves form between layers of water of different density. These skyscraper-tall waves transport heat, energy, carbon and nutrients around the globe. Where and how they break is important for the planet’s climate.”Climate models are really sensitive not only to how much turbulence there is in the deep ocean, but to where it is,” said lead author Matthew Alford, an oceanographer in the UW Applied Physics Laboratory. He led the expedition to the Samoan Passage, a narrow channel in the South Pacific Ocean that funnels water flowing from Antarctica.”The primary importance of understanding deep-ocean turbulence is to get the climate models right on long timescales,” Alford said.Dense water in Antarctica sinks to the deep Pacific, where it eventually surges through a 25-mile gap in the submarine landscape northeast of Samoa.”Basically the entire South Pacific flow is blocked by this huge submarine ridge,” Alford said. “The amount of water that’s trying to get northward through this gap is just tremendous — 6 million cubic meters of water per second, or about 35 Amazon Rivers.”In the 1990s a major expedition measured these currents through the Samoan Passage. The scientists inferred that a lot of mixing must also happen there, but couldn’t measure it.In the summer of 2012 the UW team embarked on a seven-week cruise to track the 800-foot-high waves that form atop the flow, 3 miles below the ocean’s surface. …

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Certification of aquaculture: one of the strategies to sustainable seafood production

Sep. 5, 2013 — Certification of products from aquatic farming — aquaculture — is contributing to sustainable production, but it also has serious limits. Therefore it should be seen as one approach among many for steering aquaculture toward sustainability.This is argued by an international team of researchers in a paper published in Science on September 6th.Aquaculture is one of the fastest growing global food production systems, and now contributes around 13% of world animal-protein supply. It provides almost half of the world’s supply of seafood. The rapid expansion of the sector has come with a wide range of concerns about the environmental and social impact of aquaculture. In response, NGO-led certification schemes, such as the Dutch based Aquaculture Stewardship Council (ASC), have developed standards against which the environmental and social performance of aquaculture can be measured.Based on the work of an international network of researchers, the paper argues that aquaculture certification has limits as a means of governing sustainable production. Aquaculture certification is limited in the volume of global production it can certify, given market demand for certified seafood is currently limited to the US and EU while the majority of seafood consumption occurs in other markets. The impact of certification is also limited in reaching wider sustainability goals, it is focused on the farm-level instead of the cumulative impacts of multiple farms in one location on the surrounding environment or farming communities. Furthermore it is limited in its ability to include stakeholders, particularly smallholder producers, in the Global South where the vast majority of global production comes from.The implication of these limits is that certification needs to be seen as but one of a wider array of strategies for regulating sustainable production. Assumptions that countries in the Global South are unwilling or incapable to regulate aquaculture no longer holds true everywhere. …

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Uncontrolled hypertension is common, but untreated, worldwide

Sep. 3, 2013 — A global study has found that many patients don’t know they have hypertension and, even if they do, too few are receiving adequate drug therapy for their hypertension.This is true in high income countries, like Canada, as well as middle and low income countries, say an international team of researchers led by the Population Health Research Institute (PHRI) of McMaster University and Hamilton Health Sciences.The report, which was published today by JAMA, the journal of the American Medical Association, is part of the PURE (Prospective Urban Rural Epidemiological) study.”Our study indicates over half of people with hypertension are unaware of their condition and, amongst those identified, very few are taking enough treatment to control their blood pressure,” said Dr. Clara Chow, lead author, a member of PHRI and an associate professor of medicine of Sydney University and the George Institute for Global Health in Australia.Dr. Salim Yusuf, senior author and professor of medicine of McMaster University’s Michael G. DeGroote School of Medicine, added that drug treatments that work to control hypertension are well known, however this study found only about a third of patients who are aware of their condition were achieving target blood pressure control.”Blood pressure lowering drugs are generally inexpensive and commonly available treatments,” said Yusuf. “However only a third of patients commenced on treatment are on enough treatment to control their blood pressure. This is worst in low income countries, but significant in high and middle income countries too.”This is important because hypertension or high blood pressure is the leading cause of cardiovascular disease, which is associated with at least 7.6 million deaths per year worldwide.Participants in the PURE study included 154,000 adults between 35 and 70 years old, with and without a history of heart disease or stroke, from 17 high, middle and low-income countries.Each participant had their blood pressure measured and medication use recorded, along with information about their age, gender, education, and key risk factors, including whether they knew they had hypertension. The study found 46.5% of those with hypertension were aware of the diagnosis, while blood pressure was controlled among 32.5% of those being treated.The authors could only guess at potential solutions for the poor detection and inadequate treatment of hypertension.”The findings are disturbing and indicate a need for systematic efforts to better detect those with high blood pressure,” said Yusuf. “Early use of combination therapies, that is, two or more types of blood pressure-lowering treatments taken together, may be required.”Yusuf is the executive director of the PHRI which initiated the PURE study, the only multi-country study of its kind. The study was funded by more than 25 organizations including the Canadian Institutes for Health Research, the Heart and Stroke Foundation of Ontario, similar organizations in several countries and by unrestricted grants from several pharmaceutical companies.

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Prehistoric climate shift linked to cosmic impact

Sep. 2, 2013 — For the first time, a dramatic climate shift that has long fascinated scientists has been linked to the impact in Quebec of an asteroid or comet, Dartmouth researchers and their colleagues report in a new study funded by the National Science Foundation.The event took place about 12,900 years ago, at the beginning of the Younger Dryas period, and marks an abrupt global change to a colder, dryer climate, with far-reaching effects on both animals and humans, the scientists say. In North America the big animals, including mastodons, camels, giant ground sloths, and saber-toothed cats, all vanished. Their human hunters, known to archaeologists as the Clovis people, set aside their heavy-duty spears and turned to a hunter-gatherer subsistence diet of roots, berries, and smaller game.”The Younger Dryas cooling is a very intriguing event that impacted human history in a profound manner,” says Mukul Sharma, a professor in the Department of Earth Sciences and one of the authors of a new paper published in the Proceedings of the National Academy of Sciences (PNAS). “Environmental stresses may also have caused Natufians in the Near East to settle down for the first time and pursue agriculture.”That these powerful environmental changes occurred is not in dispute, but there has been controversy over why they happened. The new PNAS paper focuses on one cause: a comet or meteor striking Earth.The classical view of the Younger Dryas cooling interlude has been that a surge of meltwater from the North American ice sheet was behind it all. According to this theory, a large quantity of fresh water accumulated behind an ice dam. The dam suddenly ruptured and dumped all this water into the Atlantic Ocean. The sudden influx is thought to have shut down the ocean currents that move tropical water northward, resulting in the cold, dry climate of the Younger Dryas.However, Sharma and his colleagues from Dartmouth and other institutions have discovered conclusive evidence linking an extraterrestrial impact with this environmental transformation. The PNAS paper presents a scenario in which a meteor or a comet collided with Earth.The report focuses on spherules, droplets of solidified molten rock expelled by the impact. …

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Where can coral reefs relocate to escape the heat?

Aug. 29, 2013 — The best real estate for coral reefs over the coming decades will no longer be around the equator but in the sub-tropics, new research from the University of Bristol suggests.Fossil fuel emissions are impacting corals through high temperatures which can cause their deaths and ocean acidification which makes it difficult for them to produce their skeletons. In a study published today in Global Change Biology, Dr Elena Couce, Professor Andy Ridgwell and Dr Erica Hendy used computer models to predict future shifts in the global distribution of coral reef ecosystems under these two stressors.The researchers found that warming impacts were dominant, with a significant decline in suitability for corals near the equator.Dr Couce said: “Just as we have to take into account many factors when deciding where to live and juggle the trade-offs such as proximity to a city centre or the desire for a garden, whether a coral reef can establish or not depends on conflicting stressors. Global warming is stronger at the equator and drives corals away into higher latitudes, whereas acidification is stronger close to the poles and pushes coral habitat towards the equator.”Dr Hendy said: “We also found that some areas where conditions are currently borderline for corals, such as the eastern Pacific Ocean, could remain as they are or even become more suitable. This was unexpected and has important implications for coral management, as it suggests that these areas are not necessarily a ‘lost cause’.”Coral reefs are very sensitive to future changes. They are also very important to life in the oceans, with the highest biodiversity of all marine ecosystems.Dr Couce continued: “By 2070 we predict that the Western Pacific, including the area known as the ‘Coral Triangle’, the bridge between Asia and Australia, will become much less suitable for corals. This is concerning because the Coral Triangle is a biodiversity hotspot containing over 70 per cent of known coral species. Conditions in the Great Barrier Reef in Australia will also get worse, although less rapidly, since it is farther away from the equator.”Professor Ridgwell added: “Suitability for corals gets better at the limits of the current coral reef distribution. But a possible move into higher latitudes will also be difficult. Range expansion is constrained by availability of shallow water areas with adequate light penetration for coral larvae to settle and form new reefs.”

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Do herbicides alter ecosystems around the world? Scant research makes it hard to prove

Aug. 16, 2013 — The number of humans on the planet has almost doubled in the past 50 years ‒ and so has global food production. As a result, the use of pesticides and their effect on humans, animals and plants have become more important. Many laboratory studies have shown that pesticides can harm organisms which they were not meant to affect. Intensive farming is also linked to collapsing populations of wild animals and the endangerment of species such as amphibians. Can the biochemical effects of pesticides upset entire ecosystems?Share This:Professor Heinz Köhler and Professor Rita Triebskorn from the University of Tübingen’s Institute of Evolution and Ecology (EvE) have published a study on the link between pesticides and changing ecological systems in the latest edition of Science. The two ecotoxicologists cite deficits in the research which have prevented recognition of the consequences of biochemical pesticide effects on a species population or on the composition of biological communities. “Although there are many indications of animal populations and ecosystems changing because of pesticides, there are few studies proving the connection without a doubt,” Köhler and Triebskorn say. The researchers point to mathematical and experimental approaches which can be used to recognize links between the effects of pesticides in individuals and ecological changes in biological communities and ecosystems in regions where intensive farming is practiced.An important role is played by number of rare studies combining experimental fieldwork and research on sections of ecosystems, as well as a broad selection of chemical and biological analyses. An interdisciplinary approach can plausibly demonstrate connections between the effects of chemicals in humans and animals and the often indirect consequences on the population, community and ecosystem levels.Köhler and Triebskorn also postulate interdependent effects between pesticides and global warming. …

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Ozone hole might slightly warm planet, computer model suggests

Aug. 8, 2013 — A lot of people mix up the ozone hole and global warming, believing the hole is a major cause of the world’s increasing average temperature. Scientists, on the other hand, have long attributed a small cooling effect to the ozone shortage in the hole.Now a new computer-modeling study suggests that the ozone hole might actually have a slight warming influence, but because of its effect on winds, not temperatures. The new research suggests that shifting wind patterns caused by the ozone hole push clouds farther toward the South Pole, reducing the amount of radiation the clouds reflect and possibly causing a bit of warming rather than cooling.”We were surprised this effect happened just by shifting the jet stream and the clouds,” said lead author Kevin Grise, a climate scientist at Lamont-Doherty Earth Observatory of Columbia University in New York City.Grise notes this small warming effect may be important for climatologists trying to predict the future of Southern Hemisphere climate.The work is detailed in Geophysical Research Letters, a journal of the American Geophysical Union. Grise collaborated on the study with Lorenzo Polvani of Columbia University, George Tselioudis of NASA Goddard Institute for Space Studies, Yutian Wu of New York University, and Mark Zelinka of Lawrence Livermore National Laboratory.Hole in the skyEach ozone molecule consists of three oxygen atoms bound together. These ozone molecules gather in the lower portion of the stratosphere about 20 to 30 kilometers (12 to 19 miles) above the ground — about twice as high as commercial airliners fly.Thankfully for the living things below, this layer of ozone shields Earth from some of the hazardous ultraviolet radiation barraging the atmosphere. Unchecked, these ultraviolet rays can cause sunburns, eye damage and even skin cancer.In the 1980s, scientists discovered thinning of the ozone layer above Antarctica during the Southern Hemisphere’s spring months. The cause of this “hole” turned out to be chlorofluorocarbons, such as Freon, from cooling systems, aerosols cans and degreasing solvents, which break apart ozone molecules. Even though the1987 Montreal Protocol banned these chlorofluorocarbons worldwide, the ozone hole persists decades later.Many people falsely equate the ozone hole to global warming. In a 2010 Yale University poll, 61 percent of those surveyed believed the ozone hole significantly contributed to global warming. …

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Ozone-protection treaty had climate benefits, too

Aug. 5, 2013 — The global treaty that headed off destruction of earth’s protective ozone layer has also prevented major disruption of global rainfall patterns, even though that was not a motivation for the treaty, according to a new study in the Journal of Climate.The 1987 Montreal Protocol phased out the use of chloroflourocarbons, or CFCs, a class of chemicals that destroy ozone in the stratosphere, allowing more ultraviolet radiation to reach earth’s surface. Though the treaty aimed to reverse ozone losses, the new research shows that it also protected the hydroclimate. The study says the treaty prevented ozone loss from disrupting atmospheric circulation, and kept CFCs, which are greenhouse gases, from warming the atmosphere and also disrupting atmospheric circulation. Had these effects taken hold, they would have combined to shift rainfall patterns in ways beyond those that may already be happening due to rising carbon dioxide in the air.At the time the Montreal Protocol was drafted, the warming potential of CFCs was poorly understood, and the impact of ozone depletion on surface climate and the hydrological cycle was not recognized at all. “We dodged a bullet we did not know had been fired,” said study coauthor Richard Seager, a climate scientist at Columbia University’s Lamont-Doherty Earth Observatory.Today, rising carbon dioxide levels are already disturbing earth’s hydrological cycle, making dry areas drier and wet areas wetter. But in computer models simulating a world of continued CFC use, the researchers found that the hydrological changes in the decade ahead, 2020-2029, would have been twice as severe as they are now expected to be. Subtropical deserts, for example in North America and the Mediterranean region, would have grown even drier and wider, the study says, and wet regions in the tropics, and mid-to-high latitudes would have grown even wetter.The ozone layer protects life on earth by absorbing harmful ultraviolet radiation. As the layer thins, the upper atmosphere grows colder, causing winds in the stratosphere and in the troposphere below to shift, displacing jet streams and storm tracks. The researchers’ model shows that if ozone destruction had continued unabated, and increasing CFCs further heated the planet, the jet stream in the mid-latitudes would have shifted toward the poles, expanding the subtropical dry zones and shifting the mid-latitude rain belts poleward. …

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Rocks can restore our climate… after 300,000 years

July 26, 2013 — A study of a global warming event that happened 93 million years ago suggests that the Earth can recover from high carbon dioxide emissions faster than thought, but that this process takes around 300,000 years after emissions decline.Scientists from Oxford University studied rocks from locations including Beachy Head, near Eastbourne, and South Ferriby, North Lincolnshire, to investigate how chemical weathering of rocks ‘rebalanced’ the climate after vast amounts of carbon dioxide (CO2) were emitted during more than 10,000 years of volcanic eruptions.In chemical weathering CO2 from the atmosphere dissolved in rainwater reacts with rocks such as basalt or granite, dissolving them so that this atmospheric carbon then flows into the oceans, where a large proportion is ‘trapped’ in the bodies of marine organisms.The team tested the idea that, as CO2 warms the planet, the reactions involved in chemical weathering speed up, causing more CO2 to be ‘locked away’, until, if CO2 emissions decline, the climate begins to cool again. The Oxford team looked at evidence from the ‘Ocean Anoxic Event 2′ in the Late Cretaceous when volcanic activity spewed around 10 gigatonnes of CO2 into the atmosphere every year for over 10,000 years. The researchers found that during this period chemical weathering increased, locking away more CO2 as the world warmed and enabling the Earth to stabilise to a cooler climate within 300,000 years, up to four times faster than previously thought.A report of the research is published in Nature Geoscience.’Looking at this event is rather like imagining what the Earth would be like if humans disappeared tomorrow,’ said Dr Philip Pogge von Strandmann of Oxford University’s Department of Earth Sciences, who led the research. ‘Volcanic CO2 emissions in this period are similar to, if slightly slower than, current manmade emissions so that we can imagine a scenario in which, after human CO2 emissions ceased, the planet’s climate would start to recover and cool down. The bad news is that it’s likely this would take around 300,000 years.’Reconstructing a record of past chemical weathering is challenging because of how plants and animals take carbon out of the environment. To get around this the team used a recently-developed technique involving studying lithium isotopes in marine limestone (this lithium could only come from weathering and is not changed by biological organisms).The Ocean Anoxic Event 2 is believed to have been caused by a massive increase in volcanic activity in one of three regions: the Caribbean, Madagascar, or the Solomon Islands. The event saw the temperature of seawater around the equator warm by about 3 degrees Celsius. It is thought that this warming caused around 53% of marine species to go extinct. Animals like turtles, fish, and ammonites were amongst those severely affected.’Everyone remembers the mass extinction of land animals caused by the K-T meteorite impact 30 million years later, thought to be responsible for the demise of the dinosaurs, but in many ways this was just as devastating for marine life,’ said Dr Pogge von Strandmann. ‘Whilst nutrients from weathering caused a population boom of some species near the surface of the oceans, it also led to a loss of oxygen to the deeper ocean, killing off over half of all marine species and creating a ‘dead zone’ of decaying animals and plants. …

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Cost of Arctic methane release could be ‘size of global economy’, experts warn

July 24, 2013 — Researchers have warned of an “economic time-bomb” in the Arctic, following a ground-breaking analysis of the likely cost of methane emissions in the region.Economic modelling shows that the methane emissions caused by shrinking sea ice from just one area of the Arctic could come with a global price tag of 60 trillion dollars — the size of the world economy in 2012.Writing in a Comment piece in the journal, Nature, academics argue that a significant release of methane from thawing permafrost in the Arctic could have dire implications for the world’s economy. The researchers, from Cambridge and Rotterdam, have for the first time calculated the potential economic impact of a scenario some scientists consider increasingly likely — that methane from the East Siberian Sea will be emitted as a result of the thaw.This constitutes just a fraction of the vast reservoirs of methane in the Arctic, but scientists believe that the release of even a small proportion of these reserves could trigger possibly catastrophic climate change. According to the new assessment, the emission of methane below the East Siberian Sea alone would also have a mean global impact of 60 trillion dollars.The ground-breaking Comment piece was co-authored by Gail Whiteman, from Erasmus University; Chris Hope, Reader in Policy Modelling at Cambridge Judge Business School, University of Cambridge; and Peter Wadhams, Professor of Ocean physics at the University of Cambridge.”The global impact of a warming Arctic is an economic time-bomb,” Whiteman, who is Professor of sustainability, management and climate change at Rotterdam School of Management, Erasmus University (RSM), said.Wadhams added: “The imminent disappearance of the summer sea ice in the Arctic will have enormous implications for both the acceleration of climate change, and the release of methane from off-shore waters which are now able to warm up in the summer. This massive methane boost will have major implications for global economies and societies.”Most discussion about the economic implications of a warming Arctic focuses on benefits to the region, with increased oil-and-gas drilling and the opening up of new shipping routes that could attract investments of hundreds of billions of dollars. However, the effects of melting permafrost on the climate and oceans will be felt globally, the authors argue.Applying an updated version of the modelling method used in the UK government’s 2006 Stern Review on the Economics of Climate Change, and currently used by the US Environmental Protection Agency, the authors calculate the global consequences of the release of 50 gigatonnes of methane over a decade from thawing permafrost beneath the East Siberian Sea.”The methane release would bring forward the date at which the global mean temperature rise exceeds 2 degrees C by between 15 and 35 years,” said Chris Hope. “In the absence of climate-change mitigation measures, the PAGE09 model calculates that it would increase mean global climate impacts by $60 trillion.”If other impacts such as ocean acidification are factored in, the cost would be much higher. Some 80% of these costs will be borne by developing countries, as they experience more extreme weather, flooding, droughts and poorer health, as Arctic warming affects climate.The research also explored the impact of a number of later, longer-lasting or smaller pulses of methane, and the authors write that, in all these cases, the economic cost for physical changes to the Arctic is “steep.”The authors write that global economic institutions and world leaders should “kick-start investment in rigorous economic modelling” and consider the impacts of a changing Arctic landscape as far outweighing any “short-term gains from shipping and extraction.”They argue that economic discussions today are missing the big picture on Arctic change. “Arctic science is a strategic asset for human economies because the region drives critical effects in our biophysical, political and economic systems,” write the academics. Neither the World Economic Forum nor the International Monetary Fund currently recognise the economic danger of Arctic change.According to Whiteman, “Global leaders and the WEF and IMF need to pay much more attention to this invisible time-bomb. The mean impacts of just this one effect — $60 trillion — approaches the $70-trillion value of the world economy in 2012.”

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Bees ‘betray’ their flowers when pollinator species decline

July 22, 2013 — Remove even one bumblebee species from an ecosystem and the impact is swift and clear: Their floral “sweethearts” produce significantly fewer seeds, a new study finds.The study, to be published by the Proceedings of the National Academy of Sciences, focused on the interactions between bumblebees and larkspur wildflowers in Colorado’s Rocky Mountains. The results show how reduced competition among pollinators disrupts floral fidelity, or specialization, among the remaining bees in the system, leading to less successful plant reproduction.”We found that these wildflowers produce one-third fewer seeds in the absence of just one bumblebee species,” says Emory University ecologist Berry Brosi, who led the study. “That’s alarming, and suggests that global declines in pollinators could have a bigger impact on flowering plants and food crops than was previously realized.”The National Science Foundation (NSF) funded the study, co-authored by ecologist Heather Briggs of the University of California-Santa Cruz.About 90 percent of plants need animals, mostly insects, to transfer pollen between them so that they can fertilize and reproduce. Bees are by far the most important pollinators worldwide and have co-evolved with the floral resources they need for nutrition.During the past decade, however, scientists have reported dramatic declines in populations of some bee species, sparking research into the potential impact of such declines.Some studies have indicated that plants can tolerate losing most pollinator species in an ecosystem as long as other pollinators remain to take up the slack. Those studies, however, were based on theoretical computer modeling.Brosi and Briggs were curious whether this theoretical resilience would hold up in real-life scenarios. Their team conducted field experiments to learn how the removal of a single pollinator species would affect the plant-pollinator relationship.”Most pollinators visit several plant species over their lifetime, but often they will display what we call floral fidelity over shorter time periods,” Brosi explains. “They’ll tend to focus on one plant while it’s in bloom, then a few weeks later move on to the next species in bloom. You might think of them as serial monogamists.”Floral fidelity clearly benefits plants, because a pollinator visit will only lead to plant reproduction when the pollinator is carrying pollen from the same plant species. “When bees are promiscuous, visiting plants of more than one species during a single foraging session, they are much less effective as pollinators,” Briggs says.The researchers conducted their experiments at the Rocky Mountain Biological Laboratory near Crested Butte, Colorado. Located at 9,500 feet, the facility’s subalpine meadows are too high for honeybees, but they are buzzing during the summer months with bumblebees. …

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Ancient ice melt unearthed in Antarctic mud: 20 meter sea level rise, five million years ago

July 21, 2013 — Global warming five million years ago may have caused parts of Antarctica’s large ice sheets to melt and sea levels to rise by approximately 20 metres, scientists report today in the journal Nature Geoscience.The researchers, from Imperial College London, and their academic partners studied mud samples to learn about ancient melting of the East Antarctic ice sheet. They discovered that melting took place repeatedly between five and three million years ago, during a geological period called Pliocene Epoch, which may have caused sea levels to rise approximately ten metres.Scientists have previously known that the ice sheets of West Antarctica and Greenland partially melted around the same time. The team say that this may have caused sea levels to rise by a total of 20 metres.The academics say understanding this glacial melting during the Pliocene Epoch may give us insights into how sea levels could rise as a consequence of current global warming. This is because the Pliocene Epoch had carbon dioxide concentrations similar to now and global temperatures comparable to those predicted for the end of this century.Dr Tina Van De Flierdt, co-author from the Department of Earth Science and Engineering at Imperial College London, says: “The Pliocene Epoch had temperatures that were two or three degrees higher than today and similar atmospheric carbon dioxide levels to today. Our study underlines that these conditions have led to a large loss of ice and significant rises in global sea level in the past. Scientists predict that global temperatures of a similar level may be reached by the end of this century, so it is very important for us to understand what the possible consequences might be.”The East Antarctic ice sheet is the largest ice mass on Earth, roughly the size of Australia. The ice sheet has fluctuated in size since its formation 34 million years ago, but scientists have previously assumed that it had stabilised around 14 million years ago.The team in today’s study were able to determine that the ice sheet had partially melted during this “stable” period by analysing the chemical content of mud in sediments. These were drilled from depths of more than three kilometres below sea level off the coast of Antarctica.Analysing the mud revealed a chemical fingerprint that enabled the team to trace where it came from on the continent. They discovered that the mud originated from rocks that are currently hidden under the ice sheet. The only way that significant amounts of this mud could have been deposited as sediment in the sea would be if the ice sheet had retreated inland and eroded these rocks, say the team.The academics suggest that the melting of the ice sheet may have been caused in part by the fact that some of it rests in basins below sea level. …

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First global atlas of marine plankton reveals remarkable underwater world

July 19, 2013 — Under the microscope, they look like they could be from another planet, but these microscopic organisms inhabit the depths of our oceans in nearly infinite numbers.To begin to identify where, when, and how much oceanic plankton can be found around the globe, a group of international researchers have compiled the first ever global atlas cataloguing marine plankton ranging in size from bacteria to jellyfish. The atlas was published today in a special issue of the journal Earth System Science Data.The atlas, known as the Marine Ecosystem Biomass Data (MAREDAT), is the first step towards a comprehensive inventory of the marine biota based on counts of individual cells or organisms. It will help researchers better understand marine biodiversity for conservation and monitoring and is the result of collaborations between scientists at the Woods Hole Oceanographic Institution (WHOI), the University of East Anglia, ETH Zurich, University of Manchester, Université d’Angers and CNRS, the US National Oceanic and Atmospheric Administration (NOAA), together with many other scientific institutions around the world.”One of the more surprising findings from the study is that phytoplankton and zooplankton biomass are roughly the same size in the upper ocean. Compare that to more familiar land ecosystems where the biomass of plants greatly exceeds that of animals and it’s pretty illuminating,” says WHOI Senior Scientist and Marine Chemist Scott Doney, a collaborator on the project.The MAREDAT database is open-source and available through a public website.Thus far, it has catalogued about half a million measurements of plankton biomass, which are subdivided into 12 broad plankton groups. Each group has a separate database.”The data and documentation can be downloaded by any researcher so that they can explore their own scientific questions,” Doney says. “Over time we hope to grow the database by adding other historical and newly collected data for plankton groups already in the database as well as extend into different plankton groups.”One group of microorganisms Doney and his colleague Yawei Luo have focused on cataloguing in MAREDAT is marine nitrogen-fixing bacteria called “diazotrophs.” These unique microbes can literally make the nutrients they need for growth out of thin air, or at least from dissolved nitrogen gas. They play an essential role in subtropical ocean gyres providing a source of nitrogen in the otherwise nutrient-poor surface waters. The nitrogen fixation rates and diazotroph cell counts are being used to study the environmental conditions that determine nitrogen fixation and diazotroph community structure.Working with more than 45 other scientists from WHOI and around the world, Luo and Doney built the first-ever global dataset on nitrogen-fixers by collecting data from historical scientific literature and existing databases. The past decade has seen a virtual explosion in new ocean field data on marine nitrogen-fixers spanning a wide range of taxonomic groups including free-living cells and filamentous organisms as well as symbiotic organisms that live inside other plankton. Luo and Doney study ocean microbes as part of the Center for Microbial Oceanography, Research, and Education (C-MORE), a National Science Foundation Science and Technology Center based at the University of Hawaii.The first edition of the MAREDAT global plankton atlas took three years to compile and combines information from half a million data points. …

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Climate change: Disequilibrium will become the norm in the plant communities of the future

July 1, 2013 — The forest we are used to looking at is not at all in equilibrium. Since the Ice Age, a number of plants have been ‘missing’ in Northern Europe, i.e. species that have not yet arrived. The same applies in many other parts of the world. Similarly, there is evidence that — even today — it often takes a very long time before plants follow when glaciers retreat, or the climate changes. In future, such disequilibrium will become the norm in the plant communities on Earth.This has been demonstrated by a new synthesis carried out by two researchers at Aarhus University — Professor of Biology Jens-Christian Svenning and Assistant Professor Brody Sandel.Professor Svenning explains: “In the climate debate, even researchers have had a tendency to overlook the fact that ecological dynamics can be slow. However, our forests take an extremely long time to adapt. For example, we still have a small amount of small-leaved lime in Denmark, which has held on since the warm period during the Bronze Age, i.e. about 3000 years. Perhaps it will now get another chance to spread when the summers once more get warmer. …

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Global cooling as significant as global warming, study of marine ecosystems during Cretaceous period shows

June 16, 2013 — A “cold snap” 116 million years ago triggered a similar marine ecosystem crisis to the ones witnessed in the past as a result of global warming, according to research published in Nature Geoscience.The international study involving experts from the universities of Newcastle, UK, Cologne, Frankfurt and GEOMAR-Kiel, confirms the link between global cooling and a crash in the marine ecosystem during the mid-Cretaceous greenhouse period.It also quantifies for the first time the amplitude and duration of the temperature change. Analysing the geochemistry and micropaleontology of a marine sediment core taken from the North Atlantic Ocean, the team show that a global temperature drop of up to 5oC resulted in a major shift in the global carbon cycle over a period of 2.5 million years.Occurring during a time of high tectonic activity that drove the breaking up of the super-continent Pangaea, the research explains how the opening and widening of new ocean basins around Africa, South America and Europe created additional space where large amounts of atmospheric CO2 was fixed by photosynthetic organisms like marine algae. The dead organisms were then buried in the sediments on the sea bed, producing organic, carbon rich shale in these new basins, locking away the carbon that was previously in the atmosphere.The result of this massive carbon fixing mechanism was a drop in the levels of atmospheric CO2, reducing the greenhouse effect and lowering global temperature.This period of global cooling came to an end after about 2 million years following the onset of a period of intense local volcanic activity in the Indian Ocean. Producing huge volumes of volcanic gas, carbon that had been removed from the atmosphere when it was locked away in the shale was replaced with CO2 from Earth’s interior, re-instating a greenhouse effect which led to warmer climate and an end to the “cold snap.”The research team highlight in this study how global climate is intrinsically linked to processes taking place in Earth’s interior at million year time scales. These processes can modify ecospace for marine life, driving evolution.Current research efforts tend to concentrate on global warming and the impact that a rise of a few degrees might have on past and present day ecosystems. This study shows that if global temperatures swing the other way by a similar amount, the result can be just as severe, at least for marine life.However, the research team emphasise that the observed changes of the Earth system in the Cretaceous happened over millions of years, rather than decades or centennial, which cannot easily be related to our rapidly changing modern climate conditions.”As always it’s a question of fine balance and scale,” explains Thomas Wagner, Professor of Earth Systems Science at Newcastle University, and one of the leaders of this study.”All earth system processes are operating all the time and at different temporal and spatial scales; but when something upsets the balance — be it a large scale but long term natural phenomenon or a short and massive change to global greenhouse gases due to anthropogenic activity — there are multiple, potential knock-on effects on the whole system.”The trick is to identify and quantify the initial drivers and consequences, which remains an ongoing challenge in climate research.”

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Deep biosphere harbors active, growing communities of microorganisms

June 12, 2013 — The deep biosphere — the realm of sediments far below the seafloor — harbors a vast ecosystem of bacteria, archaea, and fungi that are actively metabolizing, proliferating, and moving, according a new study by scientists at Woods Hole Oceanographic Institution (WHOI) and the University of Delaware (UD).”This is the first molecular evidence for active cell division in the deep biosphere,” says WHOI postdoctoral investigator and lead author on the study Bill Orsi. Previous studies and models had suggested cells were alive, but whether the cells were actually dividing or not had remained elusive.The finding of so much activity in the deep biosphere has implications for our understanding of global biogeochemical cycles, say the study’s authors.”Cells are very abundant there, but they do not have high activity levels,” says WHOI microbial ecologist Virginia Edgcomb. “But it’s a huge biosphere, and when you do the math, you see we’re talking about a potentially significant contribution. Carbon is being turned over, and that has important implications for models of carbon and nitrogen cycling.”The researchers analyzed messenger RNA (mRNA) from different depths in a sediment core collected off the coast of Peru in 2002 during Leg 201 of the Ocean Drilling Program. Their work was published in Nature on June 12.This first glimpse into the workings of the heretofore hidden ecosystem was made possible by the first successful extraction of total mRNA, or the “metatranscriptome,” from the deep biosphere.Messenger RNA is highly sought-after by microbial ecologists because its presence indicates that the cells that made it are alive, and because it carries the instructions for the proteins the cells are making. That gives researchers valuable information about the biochemical mechanisms and processes the organisms are using to function.But because the metabolic rates in the deep biosphere are very low, and because mRNA is present in such small amounts — only 4 to 10 percent of the total RNA in most environmental samples — that extracting enough of it to analyze from deep sediments has been thought by many scientists to be impossible, says Edgcomb.”It’s not easy,” says William Orsi, who developed the extraction technique while a post-doctoral investigator in Edgcomb’s lab at WHOI. “There’s a certain amount of banging your head against the wall before it works.”Among the proteins they found coded for in the mRNA, many are involved in cell division, indicating that the cells that made them belong to growing, multiplying populations.The group found mRNAs related to cell division at all depths tested, from 5 to 159 meters below the seafloor. Such messages were most abundant in zones where cell numbers were the highest, says Orsi, which indicates that the larger cell populations there were likely due to dividing cells.The study also identified mRNAs for specific biochemical pathways that reveal much about the workings of the deep biosphere ecosystem and its significance to global cycles. The mRNAs came from bacteria and archaea, which have long been recognized as major players in the subseafloor ecosystem; and from fungi, which have recently been suggested to have an important ecological role there.”Until recently, the fungi in deep sediments have been ignored,” says Orsi. “The fact that fungi are metabolically active in deep sediments refines our understanding of the extent of the deep biosphere.”Messenger RNAs coding for enzymes involved in sulfate reduction and nitrate reduction, processes cells use to generate the energy-storing molecule ATP, were also found.”It’s been theorized that much of the energy that microbes get in this environment comes from sulfate reduction,” says Orsi. …

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Biotech crops vs. pests: Successes and failures from the first billion acres

June 10, 2013 — Since 1996, farmers worldwide have planted more than a billion acres (400 million hectares) of genetically modified corn and cotton that produce insecticidal proteins from the bacterium Bacillus thuringiensis, or Bt for short. Bt proteins, used for decades in sprays by organic farmers, kill some devastating pests but are considered environmentally friendly and harmless to people. However, some scientists feared that widespread use of these proteins in genetically modified crops would spur rapid evolution of resistance in pests.A team of experts at the University of Arizona has taken stock to address this concern and to figure out why pests became resistant quickly in some cases, but not others. Bruce Tabashnik and Yves Carrière in the department of entomology at the College of Agriculture and Life Sciences together with visiting scholar Thierry Brévault from the Center for Agricultural Research for Development (CIRAD) in France scrutinized the available field and laboratory data to test predictions about resistance. Their results are published in the journal Nature Biotechnology.”When Bt crops were first introduced, the main question was how quickly would pests adapt and evolve resistance,” said Tabashnik, head of the UA department of entomology who led the study. “And no one really knew, we were just guessing.””Now, with a billion acres of these crops planted over the past 16 years, and with the data accumulated over that period, we have a better scientific understanding of how fast the insects evolve resistance and why.”Analyzing data from 77 studies of 13 pest species in eight countries on five continents, the researchers found well-documented cases of field-evolved resistance to Bt crops in five major pests as of 2010, compared with only one such case in 2005. Three of the five cases are in the United States, where farmers have planted about half of the world’s Bt crop acreage. Their report indicates that in the worst cases, resistance evolved in 2 to 3 years; but in the best cases, effectiveness of Bt crops has been sustained more than 15 years.According to the paper, both the best and worst outcomes correspond with predictions from evolutionary principles.”The factors we found to favor sustained efficacy of Bt crops are in line with what we would expect based on evolutionary theory,” said Carrière, explaining that conditions are most favorable if resistance genes are initially rare in pest populations; inheritance of resistance is recessive — meaning insects survive on Bt plants only if have two copies of a resistance gene, one from each parent — and abundant refuges are present. Refuges consist of standard, non-Bt plants that pests can eat without ingesting Bt toxins.”Computer models showed that refuges should be especially good for delaying resistance when inheritance of resistance in the pest is recessive,” explained Carrière.Planting refuges near Bt crops reduces the chances that two resistant insects will mate with each other, making it more likely they will breed with a susceptible mate, yielding offspring that are killed by the Bt crop. The value of refuges has been controversial, and in recent years, the EPA has relaxed its requirements for planting refuges in the U.S.”Perhaps the most compelling evidence that refuges work comes from the pink bollworm, which evolved resistance rapidly to Bt cotton in India, but not in the U.S.,” Tabashnik said. …

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