Goodbye to Cold Nights
Farm in Candelario, Spain (G.Chris Clark)
Given the impact of climatic extremes on agriculture and health in Spain, researchers at the University of Salamanca (USAL) have analysed the two factors most representative of these thermal extremes between 1950 and 2006 – warm days and cold nights. The results for mainland Spain show an increase in the number of warm days greater than that for the rest of the planet and a reduction in the number of cold nights.
Few studies to date have focused on climatic extremes and the changes occurring in maximum and minimum temperatures and in warm day and cold night variables. Until now, most research studies had analysed average temperature changes on a global scale. These results indicated an increase “most probably” caused by human factors.
The new study, published in the journal Climatic Change, has made it possible to analyse the causes of the variations in climatic extremes from a physical point of view, in other words “which changes are taking place in the air masses reaching the Iberian Peninsula, as well as sea temperature”, as Concepción Rodríguez, lead author of the study and a researcher at the General and Atmospheric Physics Department at the USAL, tells SINC. (more…)
Climate Change Implicated in Decline of Horseshoe Crabs
Horseshoe crabs congregate annually at Delaware Bay. (Greg Breese, , U.S. Fish and Wildlife Service )
A distinct decline in horseshoe crab numbers has occurred that parallels climate change associated with the end of the last Ice Age, according to a study that used genomics to assess historical trends in population sizes.
The new research also indicates that horseshoe crabs numbers may continue to decline in the future because of predicted climate change, said Tim King, a scientist with the U.S. Geological Survey and a lead author on the new study published in Molecular Ecology.
While the current decline in horseshoe crabs is attributed in great part to overharvest for fishing bait and for the pharmaceutical industry, the new research indicates that climate change also appears to have historically played a role in altering the numbers of successfully reproducing horseshoe crabs. More importantly, said King, predicted future climate change, with its accompanying sea-level rise and water temperature fluctuations, may well limit horseshoe crab distribution and interbreeding, resulting in distributional changes and localized and regional population declines, such as happened after the last Ice Age. (more…)
Geo-Engineering and Sea-Level Rise Over the 21st Century
Scientific findings by international research group of scientists from England, China and Denmark just published suggest that sea level will likely be 30-70 centimetres higher by 2100 than at the start of the century even if all but the most aggressive geo-engineering schemes are undertaken to mitigate the effects of global warming and greenhouse gas emissions are stringently controlled.
“Rising sea levels caused by global warming are likely to affect around 150 million people living in low-lying coastal areas, including some of the world’s largest cities,” explained Dr Svetlana Jevrejeva of the National Oceanography Centre.
Most scientists agree that anthropogenic carbon dioxide emissions contribute greatly to global warming, and that these emissions need to be controlled if damaging future impacts such as sea-level rise are to be averted. But if we fail to do so, is there a ‘Plan B’?
Scientists have proposed ways of ‘geo-engineering’ the Earth system to tackle global warming, thereby reducing its impact on both the main contributors of sea level rise: thermal expansion of ocean water and melting of glaciers and ice sheets. Jevrejeva and her colleagues have modelled sea level over the 21st century under various geo-engineering schemes and carbon dioxide emission scenarios.
“We used 300 years of tide gauge measurements to reconstruct how sea level responded historically to changes in the amount of heat reaching the Earth from the Sun, the cooling effects of volcanic eruptions, and past human activities,” said Jevrejeva. “We then used this information to simulate sea level under geo-engineering schemes over the next 100 years.” (more…)
Limiting Ocean Acidification Under Global Change
Coral reefs are vulnerable to ocean acidification (Copyright (c) 2004 Richard Ling)
Emissions of carbon dioxide are causing ocean acidification as well as global warming. Scientists have previously used computer simulations to quantify how curbing of carbon dioxide emissions would mitigate climate impacts. New computer simulations have now examined the likely effects of mitigation scenarios on ocean acidification trends. They show that both the peak year of emissions and post-peak reduction rates influence how much ocean acidity increases by 2100. Changes in ocean pH over subsequent centuries will depend on how much the rate of carbon dioxide emissions can be reduced in the longer term.
Largely as a result of human activities such as the burning of fossil fuels for energy and land-use changes such deforestation, the concentration of carbon dioxide in the atmosphere is now higher that it has been at any time over the last 800,000 years. Most scientists believe this increase in atmospheric carbon dioxide to be an important cause of global warming.
“The oceans absorb around a third of carbon dioxide emissions, which helps limit global warming, but uptake of carbon dioxide by the oceans also increases their acidity, with potentially harmful effects on calcifying organisms such as corals and the ecosystems that they support,” explained Dr Toby Tyrrell of the University of Southampton’s School of Ocean and Earth Science (SOES) based at the National Oceanography Centre, Southampton. (more…)
Impacts of Climate Change on Mussels
Climate change is causing higher air and water temperatures along the east coast of the United States. These changes have shrunk the geographic region where blue mussels are able to survive, according to findings by University of South Carolina researchers published in the Journal of Biogeography.
Mytilus edulis, or blue mussels, a popular seafood, used to live along the East Coast as far south as Cape Hatteras, North Carolina, but now exist only as far south as Lewes, Delaware, according to Sierra Jones, a PhD student in the Department of Biological Sciences at USC.
Most plants and animals have geographic ranges defined by northern and southern limits. In many cases, ranges are thought to be controlled by temperature, and if it becomes too hot, the limits will shift. However, linking changes in geographic range to changes in climate is difficult unless long-term records in distribution are compared to equally long-term records of weather.
Spanning over 300 miles of coastline, Jones and colleagues explored how survival of mussels changed across latitudes and decades with respect to temperature. As recently as sixty years ago, these mussels thrived as far south as North Carolina. Due to air and water temperature increases over the past sixty years, they no longer survive throughout the year south of Lewes, Delaware, and populations to the north now experience higher rates of mortality than in the past. (more…)
Ocean’s Color Affects Hurricane Paths
Ocean chlorophyll as seen by NASA's SeaWiFS satellite, with dark shades of blue denoting lower chlorophyll concentrations. (Credit: NASA)
A change in the color of ocean waters could have a drastic effect on the prevalence of hurricanes, new research indicates. In a simulation of such a change in one region of the North Pacific, the study finds that hurricane formation decreases by 70 percent. That would be a big drop for a region that accounts for more than half the world’s reported hurricane-force winds.
It turns out that the formation of typhoons — as hurricanes are known in the region — is heavily mediatedby the presenceof chlorophyll, a green pigment that helps the tiny single-celled organisms known as phytoplankton convert sunlight into food for the rest of the marine ecosystem. Chlorophyll contributes to the ocean’s color.
“We think of the oceans as blue, but the oceans aren’t really blue, they’re actually a sort of greenish color,” said Anand Gnanadesikan, a researcher with the National Oceanic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory in Princeton, New Jersey. “The fact that [the oceans] are not blue has a [direct] impacton the distribution of tropical cyclones.”
In the study, to be published in an upcoming issue of Geophysical Research Letters, a journal of the American Geophysical Union, Gnanadesikan’s team describes how a drop in chlorophyll concentration, and the corresponding reduction in ocean color, could cause a decrease in the formation of hurricanes in the color-depleted zone. Although the study looks at the effects of a simulated drop in the phytoplankton population (and therefore in the ocean’s green tint), recently-published research argued that global phytoplankton populations have been steadily declining over the last century. (more…)
Greenland Glacier Calves Huge Ice Island
Satellite image from Aug. 5, 2010, shows the huge ice island calved from Greenland's Petermann Glacier. (Courtesy of Prof. Andreas Muenchow, University of Delaware)
A University of Delaware researcher reports that an “ice island” four times the size of Manhattan has calved from Greenland’s Petermann Glacier. The last time the Arctic lost such a large chunk of ice was in 1962.
“In the early morning hours of August 5, 2010, an ice island four times the size of Manhattan was born in northern Greenland,” said Andreas Muenchow, associate professor of physical ocean science and engineering at the University of Delaware’s College of Earth, Ocean, and Environment. Muenchow’s research in Nares Strait, between Greenland and Canada, is supported by the National Science Foundation (NSF).
Satellite imagery of this remote area at 81 degrees N latitude and 61 degrees W longitude, about 620 miles [1,000 km] south of the North Pole, reveals that Petermann Glacier lost about one-quarter of its 43-mile long [70 km] floating ice-shelf.
Trudy Wohlleben of the Canadian Ice Service discovered the ice island within hours after NASA’s MODIS-Aqua satellite took the data on Aug. 5, at 8:40 UTC (4:40 EDT), Muenchow said. These raw data were downloaded, processed, and analyzed at the University of Delaware in near real-time as part of Muenchow’s NSF research. (more…)
Coastal Creatures May Have Reduced Ability to Fight Off Infections in Acidified Oceans
Photo of blue crab being monitored for metabolism using a respirometer, courtesy of Louis and Karen Burnett.
Human impact is causing lower oxygen and higher carbon dioxide levels in coastal water bodies. Increased levels of carbon dioxide cause the water to become more acidic, having dramatic effects on the lifestyles of the wildlife that call these regions home. The problems are expected to worsen if steps aren’t taken to reduce greenhouse emissions and minimize nutrient-rich run-off from developed areas along our coastlines.
The ocean is filled with a soup of bacteria and viruses. The animals living in these environments are constantly under assault by pathogens and need to be able to mount an immune response to protect themselves from infection, especially if they have an injury or wound that is openly exposed to the water.
Louis Burnett, professor of biology and director of the Grice Marine Laboratory of the College of Charleston, and Karen Burnett, research associate professor at Grice Marine Laboratory of the College of Charleston, study the effects of low oxygen and high carbon dioxide on organisms’ immune systems. They have found that organisms in these conditions can’t fight off infections as well as animals living in oxygen rich, low carbon dioxide environments.
Decreased Ability to Fight Infection
The researchers examined fish, oysters, crabs and shrimp, and showed that all these animals have a decreased ability to fight off infection of Vibrio bacteria when subjected to low oxygen, high carbon dioxide conditions. It takes about half as much bacteria to administer a lethal dose to a creature in a low oxygen, high carbon dioxide environment. (more…)
Findings Overturn Old Theory of Phytoplankton Growth: New Concerns From Global Warming
A north Atlantic Ocean view of the spring phytoplankton bloom, as seen from a satellite image. (Image courtesy of Oregon State University)
A new study concludes that an old, fundamental and widely accepted theory of how and why phytoplankton bloom in the oceans is incorrect.
The findings challenge more than 50 years of conventional wisdom about the growth of phytoplankton, which are the ultimate basis for almost all ocean life and major fisheries. And they also raise concerns that global warming, rather than stimulating ocean productivity, may actually curtail it in some places.
This analysis was published in the journal Ecology by Michael Behrenfeld, a professor of botany at Oregon State University, and one of the world’s leading experts in the use of remote sensing technology to examine ocean productivity. The study was supported by NASA.
The new research concludes that a theory first developed in 1953 called the “critical depth hypothesis” offers an incomplete and inaccurate explanation for summer phytoplankton blooms that have been observed since the 1800s in the North Atlantic Ocean. These blooms provide the basis for one of the world’s most productive fisheries. (more…)
The North Pacific, a Global Backup Generator for Past Climate Change
The left panel shows the glacial conveyor belt flow 21,000 years ago. The right panel shows a reorganized conveyor belt flow 17,500-15,000 years ago with deep-water sinking in the North Pacific. (IPRC/SOEST)
Toward the end of the last ice age, a major reorganization took place in the current system of the North Pacific with far-reaching implications for climate, according to a new study published in the July 9, 2010, issue of Science by an international team of scientists from Japan, Hawaii, and Belgium.
Earth’s climate is regulated largely by the world ocean’s density-driven circulation, which brings warm surface water to the polar regions and transports cold water away from there at depth. As poleward flowing salty waters cool in the North Atlantic, they become so heavy that they sink. This sinking acts as a pump for the ocean’s conveyor belt circulation.
A well-established fact by now is that there have been times in the past when the North Atlantic branch of the conveyor belt circulation was shut down by melting ice sheets, which released so much fresh glacial meltwater that the sinking of cold water in the Nordic Seas stopped and the Northern Hemisphere was plunged into a deep freeze. The last time such a collapse took place was toward the end of the last ice age, from around 17,500 to 15,000 years ago, the first stage of what scientists call the Mystery Interval. (more…)
Carbon Emissions Threaten Fish Populations
Humanity’s rising CO2 emissions could have a significant impact on the world’s fish populations according to groundbreaking new research carried out in Australia.
Baby fish may become easy meat for predators as the world’s oceans become more acidic due to CO2 fallout from human activity, an international team of researchers has discovered.
In a series of experiments reported in the latest issue of the Proceedings of the National Academy of Science (PNAS), the team found that as carbon levels rise and ocean water acidifies, the behaviour of baby fish changes dramatically – in ways that decrease their chances of survival by 50 to 80 per cent.
“As CO2 increases in the atmosphere and dissolves into the oceans, the water becomes slightly more acidic. Eventually this reaches a point where it significantly changes the sense of smell and behaviour of larval fish,” says team leader Professor Philip Munday of the Australian Research Council’s Centre of Excellence for Coral Reef Studies (CoECRS) at James Cook University. (more…)
Why Mercury Is More Dangerous in Oceans
Heileen Hsu-Kim is a researcher at Duke University. (Credit: Duke University Photography)
Even though freshwater concentrations of mercury are far greater than those found in seawater, it’s the saltwater fish like tuna, mackerel and shark that end up posing a more serious health threat to humans who eat them.
The answer, according to Duke University researchers, is in the seawater itself.
The potentially harmful version of mercury – known as methylmercury — latches onto dissolved organic matter in freshwater, while it tends to latch onto chloride — the salt — in seawater, according to new a study by Heileen Hsu-Kim, assistant professor of civil and environmental engineering at Duke’s Pratt School of Engineering.
“The most common ways nature turns methylmercury into a less toxic form is through sunlight,” Hsu-Kim said. “When it is attached to dissolved organic matter, like decayed plants or animal matter, sunlight more readily breaks down the methylmercury. However, in seawater, the methlymercury remains tightly bonded to the chloride, where sunlight does not degrade it as easily. In this form, methylmercury can then be ingested by marine animals.” (more…)
Retooling the Ocean Conveyor Belt
Long-time collaborators Amy Bower (left) of WHOI and Susan Lozier (right) of Duke University aboard the research vessel Oceanus in July 2003 during a cruise to deploy the sound beacons and launch the first set of floats for their study on the North Atlantic circulation. (Woods Hole Oceanographic Institution)
For decades, oceanographers have embraced the idea that Earth’s ocean currents operate like a giant conveyor belt, overturning to continuously transport deep, cold polar waters toward the equator and warm equatorial surface waters back toward the poles along narrow boundary currents. The model held that the conveyor belt was driven by changes in the temperature and salinity of the surface waters at high latitudes.
In a paper in the June 18 issue of Science, a Duke University oceanographer reviews the growing body of evidence that suggests it’s time to rethink the conveyor belt model.
“The old model is no longer valid for the ocean’s overturning, not because it’s a gross simplification, but because it ignores crucial elements such as eddies and the wind field. The concept of a conveyor belt for the overturning was developed decades ago, before oceanographers had measured the eddy field of the ocean and before they understood how energy from the wind impacts the overturning,” says Susan Lozier, professor of physical oceanography and chair of the Division of Earth and Ocean Sciences at Duke University’s Nicholas School of the Environment.
“It is important to understand that there is clear and convincing evidence that the ocean waters overturn and that this overturning impact’s the Earth’s climate,” she says. “Recent studies, however, have cast doubt on our ability to describe this overturning as a conveyor belt. From these studies we now understand that the overturning waters are not restricted to narrow boundary currents, that the overturning may vary from one ocean basin to the next and that the winds may create variability in the amount of water that overturns and in the pathways for the upper and lower limbs of the overturning.” (more…)
Human Impacts Significantly Altering Ocean Chemistry
WHOI chemist Scott Doney.(Tom Kleindinst, Woods Hole Oceanographic Institution)
Numerous studies are documenting the growing effects of climate change, carbon dioxide, pollution and other human-related phenomena on the world’s oceans. But most of those have studied single, isolated sources of pollution and other influences.
Now, a marine geochemist at the Woods Hole Oceanographic Institution (WHOI) has published a report in the latest issue of the journal Science that evaluates the total impact of such factors on the ocean and considers what the future might hold.
“What we do on land—agriculture, fossil fuel combustion and pollution—can have a profound impact on the chemistry of the sea,” says Scott C. Doney, a senior scientist at WHOI and author of the Science report. “A whole range of these factors have been studied in isolation but have not been put in a single venue.”
Doney’s paper represents a meticulous compilation of the work of others as well as his own research in this area, which includes ocean acidification, climate change, and the global carbon cycle.
He concludes that climate change, rising atmospheric carbon dioxide, excess nutrient inputs, and the many forms of pollution are “altering fundamentally the…ocean, often on a global scale and, in some cases, at rates greatly exceeding those in the historical and recent geological record.” (more…)
Scientists Call for a New Strategy for Polar Ocean Observation
A Rutgers/Webb SLOCUM glider is deployed from a Zodiac near Palmer Station Antarctica. Automated glider robots can measure ocean characteristics continuously for weeks at a time. (Credit: Jason Orfanon)
In a report published in this week’s issue of Science, a team of oceanographers, including MBL (Marine Biological Laboratory) Ecosystems Center director Hugh Ducklow, outline a polar ocean observation strategy they say will revolutionize scientists’ understanding of marine ecosystem response to climate change. The approach, which calls for the use of a suite of automated technologies that complement traditional data collection, could serve as a model for marine ecosystems worldwide and help form the foundation for a comprehensive polar ocean observation system.
The complexity of marine food webs and the “chronic under-sampling” of the world’s oceans present major constraints to predicting the future of and optimally managing and protecting marine resources. “We know more about Venus than we do about the Earth’s oceans,” says Ducklow. “We need an ocean observation system analogous to meteorological monitoring for weather forecasting, but it’s harder to do in the ocean.” (more…)
The End of the Last Ice Age Offers Insights on CO2 in Oceans
Scientists have found the possible source of a huge carbon dioxide ‘burp’ that happened some 18,000 years ago and which helped to end the last ice age.
The results provide the first concrete evidence that carbon dioxide (CO2) was more efficiently locked away in the deep ocean during the last ice age, turning the deep sea into a more ’stagnant’ carbon repository – something scientists have long suspected but lacked data to support.
Working on a marine sediment core recovered from the Southern Ocean floor between Antarctica and South Africa, the international team led by Dr Luke Skinner of the University of Cambridge radiocarbon dated shells left behind by tiny marine creatures called foraminifera (forams for short).
By measuring how much carbon-14 (14C) was in the bottom-dwelling forams’ shells, and comparing this with the amount of 14C in the atmosphere at the time, they were able to work out how long the CO2 had been locked in the ocean.
By linking their marine core to the Antarctic ice-cores using the temperature signal recorded in both archives, the team were also able compare their results directly with the ice-core record of past atmospheric CO2 variability. (more…)
Melting Icebergs Also Causing Sea Level Rise
Scientists have discovered that changes in the amount of ice floating in the polar oceans are causing sea levels to rise.
The research, published this week in Geophysical Research Letters, is the first assessment of how quickly floating ice is being lost today.
According to Archimedes’ principle, any floating object displaces its own weight of fluid. For example, an ice cube in a glass of water does not cause the glass to overflow as it melts.
But because sea water is warmer and more salty than floating ice, changes in the amount of this ice are having an effect on global sea levels.
The loss of floating ice is equivalent to 1.5 million Titanic-sized icebergs each year. However, the study shows that spread across the global oceans, recent losses of floating ice amount to a sea level rise of just 49 micrometers per year – about a hair’s breadth. (more…)
‘Black Box’ Plankton Found to Have Huge Role in Ocean Carbon Fixation
Phytoplankton - the foundation of the oceanic food chain.
Carbon fixation by phytoplankton in the open ocean plays a key role in the global carbon cycle but is not fully understood. Until now researchers believed that cyanobacteria overwhelmingly accounted for phytoplankton’s role in carbon fixation in the open ocean. But now scientists at the University of Warwick and the National Oceanography Centre in Southampton have opened ‘the black box’ of eukaryotic phytoplankton and discovered that they actually account for almost half the ocean’s carbon fixation by phytoplankton.
Blue-green algae, or cyanobacteria, grow in vast numbers in the sunlit surface waters of the oceans, the photic zone. They use sunlight to ‘fix’ carbon by converting carbon dioxide into sugars and other organic compounds through photosynthesis.
Cyanobacteria belong to the ‘picophytoplankton’, the tiniest phytoplankton. Until now they have been thought to dominate carbon fixation in the open ocean, with species belonging to the genera Prochlorococcus and Synechococcus being particularly abundant. (more…)
“Evil Twin” Threatens World’s Oceans, Scientists Warn
The rise in human emissions of carbon dioxide is driving fundamental and dangerous changes in the chemistry and ecosystems of the world’s oceans, international marine scientists warned today.
“Ocean conditions are already more extreme than those experienced by marine organisms and ecosystems for millions of years,” the researchers say in the latest issue of the journal Trends in Ecology and Evolution (TREE).
“This emphasises the urgent need to adopt policies that drastically reduce CO2 emissions.”
Ocean acidification, which the researchers call the ‘evil twin of global warming’, is caused when the CO2 emitted by human activity, mainly burning fossil fuels, dissolves into the oceans. It is happening independently of, but in combination with, global warming.
“Evidence gathered by scientists around the world over the last few years suggests that ocean acidification could represent an equal – or perhaps even greater threat – to the biology of our planet than global warming,” co-author Professor Ove Hoegh-Guldberg of the ARC Centre of Excellence for Coral Reef Studies and The University of Queensland says.
More than 30% of the CO2 released from burning fossil fuels, cement production, deforestation and other human activities goes straight into the oceans, turning them gradually more acidic. (more…)
New Estimate of Glacier Melt Less Than Previously Thought
NAU geographer Erik Schiefer in British Columbia studying glacier melt. (Photo by Karl Schiefer)
The melting of glaciers is well documented, but when looking at the rate at which they have been retreating, a team of international researchers steps back and says not so fast.
Previous studies have largely overestimated mass loss from Alaskan glaciers over the past 40-plus years, according to Erik Schiefer, a Northern Arizona University geographer who coauthored a paper in the February issue of Nature Geoscience that recalculates glacier melt in Alaska.
The research team, led by Étienne Berthier of the Laboratory for Space Studies in Geophysics and Oceanography at the Université de Toulouse in France, says that glacier melt in Alaska between 1962 and 2006 contributed about one-third less to sea-level rise than previously estimated.
Schiefer said melting glaciers in Alaska originally were thought to contribute about .0067 inches to sea-level rise per year. The team’s new calculations put that number closer to .0047 inches per year. The numbers sound small, but as Schiefer said, “It adds up over the decades.” (more…)
Researchers Measure Impacts of Changing Climate on Ocean Biology
A bongo net, used to capture plankton, is recovered aboard the Delaware II. (Credit: Jerry Prezioso, NOAA)
A three-year field program now underway is measuring carbon distributions and primary productivity in the Northwest Atlantic Ocean to help scientists worldwide determine the impacts of a changing climate on ocean biology and biogeochemistry. The study, Climate Variability on the East Coast (CliVEC), will also help validate ocean color satellite measurements and refine biogeochemistry models of ocean processes.
Researchers from NOAA, NASA and Old Dominion University are collaborating through an existing NOAA Fisheries Service field program, the Ecosystem Monitoring or EcoMon program. The EcoMon surveys are conducted six times each year by the Northeast Fisheries Science Center (NEFSC) at 120 randomly selected stations throughout the continental shelf and slope of the northeastern U.S., from Cape Hatteras, N.C., into Canadian waters to cover all of Georges Bank and the Gulf of Maine. This area is known as the Northeast U.S. continental shelf Large Marine Ecosystem.
The climate study team will participate in three annual EcoMon cruises aboard the 155-foot NOAA Fisheries Survey Vessel Delaware II, based at the NEFSC’s laboratory in Woods Hole, Mass. The most recent cruise returned to Woods Hole on February 18.
Findings from the climate impact project, funded by NASA, will help scientists better understand how annual and decadal-scale climate variability affects the growth of phytoplankton, which is the basis of the oceanic food chain. The project will also examine organic carbon distributions along the continental margin of the East Coast and collect data for ocean acidification studies. (more…)
Ocean Geoengineering Scheme No Easy Fix for Global Warming
This map displays simulated additional surface warming (in Celsius) for the year 2100 caused by the temporary use of artificial upwelling in the green areas for the time period 2011-2060. (IFM-GEOMAR)
Pumping nutrient-rich water up from the deep ocean to boost algal growth in sunlit surface waters and draw carbon dioxide down from the atmosphere has been touted as a way of ameliorating global warming. However, a new study led by Professor Andreas Oschlies of the Leibniz Institute of Marine Sciences (IFM-GEOMAR) in Kiel, Germany, pours cold water on the idea.
“Computer simulations show that climatic benefits of the proposed geo-engineering scheme would be modest, with the potential to exacerbate global warming should it fail,” said study co-author Dr Andrew Yool of the National Oceanography Centre, Southampton (NOCS).
If international governmental policies fail to reduce emissions of carbon dioxide to levels needed to keep the impacts of human-induced climate change within acceptable limits it may necessary to move to ‘Plan B’. This could involve the implementation of one or more large-scale geo-engineering schemes proposed for reducing the carbon dioxide increase in the atmosphere. (more…)
Research Challenges Models of Sea Level Change During Ice-Age Cycles
by Gary Galluzzo
Theories about the rates of ice accumulation and melting during the Quaternary Period — the time interval ranging from 2.6 million years ago to the present — may need to be revised, thanks to research findings published by a University of Iowa researcher and his colleagues in the Feb. 12 issue of the journal Science.
Jeffrey Dorale, assistant professor of geoscience in the UI College of Liberal Arts and Sciences, writes that global sea level and Earth’s climate are closely linked. Data he and colleagues collected on speleothem encrustations (see photo right), a type of mineral deposit, in coastal caves on the Mediterranean island of Mallorca indicate that sea level was about one meter above present-day levels around 81,000 years ago. The finding challenges other data that indicate sea level was as low as 30 meters — the ice equivalent of four Greenland ice sheets — below present-day levels.
He said the sea level high stand of 81,000 years ago was preceded by rapid ice melting, on the order of 20 meters of sea level change per thousand years and the sea level drop following the high water mark, accompanied by ice formation, was equally rapid.
“Twenty meters per thousand years equates to one meter of sea level change in a 50-year period,” Dorale said. “Today, over one-third of the world’s population lives within 60 miles of the coastline. Many of these areas are low-lying and would be significantly altered — devastated — by a meter of sea level rise. Our findings demonstrate that changes of this magnitude can happen naturally on the timescale of a human lifetime. Sea level change is a very big deal.” (more…)
Oceans Reveal Further Impacts of Climate Change
Antarctic marine biologist Jim McClintock.
The increasing acidity of the world’s oceans - and that acidity’s growing threat to marine species - are definitive proof that the atmospheric carbon dioxide that is causing climate change is also negatively affecting the marine environment, says world-renowned Antarctic marine biologist Jim McClintock, Ph.D., professor in the University of Alabama at Birmingham (UAB) Department of Biology.
“The oceans are a sink for the carbon dioxide that is released into the atmosphere,” says McClintock, who has spent more than two decades researching the marine species off the coast of Antarctica. Carbon dioxide is absorbed by oceans, and through a chemical process hydrogen ions are released to make seawater more acidic.
“Existing data points to consistently increasing oceanic acidity, and that is a direct result of increasing carbon dioxide levels in the atmosphere; it is incontrovertible,” McClintock says. “The ramifications for many of the organisms that call the water home are profound.”
A substance’s level of acidity is measured by its pH value; the lower the pH value, the more acidic is the substance. McClintock says data collected since the pre-industrial age indicates the mean surface pH of the oceans has declined from 8.2 to 8.1 units with another 0.4 unit decline possible by century’s end. A single whole pH unit drop would make ocean waters 10 times more acidic, which could rob many marine organisms of their ability to produce protective shells - and tip the balance of marine food chains.
“There is no existing data that I am aware of that can be used to debate the trend of increasing ocean acidification,” he says. (more…)
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