Showing posts with label Global warming. Show all posts
Showing posts with label Global warming. Show all posts

2.18.2011

Rising seas threaten 180 U.S. cities by 2100


(Reuters) - Rising seas spurred by climate change could threaten 180 U.S. coastal cities by 2100, a new study says, with Miami, New Orleans and Virginia Beach among those most severely affected.

Previous studies have looked at where rising waters might go by the end of this century, assuming various levels of sea level rise, but this latest research focused on municipalities in the contiguous 48 states with population of 50,000 or more.

Cities along the southern Atlantic coast and the Gulf of Mexico will likely be hardest hit if global sea levels rise, as projected, by about 3 feet (1 meter) by 2100, researchers reported in the journal Climate Change Letters.

Sea level rise is expected to be one result of global warming as ice on land melts and flows toward the world's oceans.

Using data from the U.S. Geological Survey, the scientists were able to calculate in detail how much land could be lost as seas rise, said study author Jeremy Weiss of the University of Arizona.

Rising coastal waters threaten an average of nine percent of the land in the 180 coastal cities in the study.

Miami, New Orleans, Tampa, Florida, and Virginia Beach, Virginia could lose more than 10 percent of their land area by century's end, the study found.

New York City, Washington DC and the San Francisco Bay area could face lesser impacts, according to the study.

CLIMATE CHANGE

The effects of higher seas can range from erosion to permanent inundation, and the severity of the damage depends in great measure on where the cities are, Weiss said by telephone on Wednesday.

"In Miami, it's not just strictly along their coastal edge. They have to worry about the issue in all directions," because much of the area around Miami is relatively flat, making it more vulnerable to encroaching waters, Weiss said.

By contrast, he said, people in the New York metropolitan area can concentrate their efforts along the shorelines because the land rises quickly away from the coast.

Sea level rise is expected as a consequence of continuing climate change, which is spurred by human activities including the burning of fossil fuels.

The U.N. Intergovernmental Panel on Climate Change (IPCC) has estimated global average temperature will rise by 3.6 degrees F (2 degrees C) by 2100. However, Weiss and his colleagues put the warming at more like 8 degrees F (4.4 degrees C).

Weiss said the lesser degree of warming projected by the IPCC reflects a moderate scenario. The study's higher temperature estimate is based on the idea that greenhouse emissions will continue along the current trajectory through the century.

Source: http://in.reuters.com/article/2011/02/16/us-climate-usa-cities-idINTRE71F7HQ20110216


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12.24.2010

Overfishing and Global Warming Killing Billfish and Tuna


ScienceDaily — Billfish and tuna, important commercial and recreational fish species, may be more vulnerable to fishing pressure because of shrinking habitat, according to a new study published by scientists from NOAA, The Billfish Foundation, and University of Miami Rosenstiel School of Marine and Atmospheric Science.

An expanding zone of low oxygen, known as a hypoxic zone, in the Atlantic Ocean is encroaching upon these species' preferred oxygen-abundant habitat, forcing them into shallower waters where they are more likely to be caught.

During the study, published recently in the journal Fisheries Oceanography, scientists tagged 79 sailfish and blue marlin with satellite tracking devices in the western North Atlantic, off south Florida and the Caribbean; and eastern tropical Atlantic, off the coast of West Africa. The pop off archival satellite tags monitored horizontal and vertical movement patterns. Researchers confirmed that billfish prefer oxygen rich waters closer to the surface and will actively avoid waters low in oxygen.

While these hypoxic zones occur naturally in many areas of the world's tropical and equatorial oceans, scientists are concerned because these zones are expanding and occurring closer to the sea surface, and are expected to continue to grow as sea temperatures rise.

"The hypoxic zone off West Africa, which covers virtually all the equatorial waters in the Atlantic Ocean, is roughly the size of the continental United States, and it's growing," said Dr. Eric D. Prince, NOAA's Fisheries Service research fishery biologist. "With the current cycle of climate change and accelerated global warming, we expect the size of this zone to increase, further reducing the available habitat for these fish."

Less available habitat can lead to more fish being caught since the fish are concentrated near the surface. Higher catch rates from these areas may give the false appearance of more abundant fish stocks. The shrinking availability of habitat and resulting increases to catch rates are important factors for scientists to consider when doing population assessments.

Researchers forecast that climate change and its associated rise in ocean temperatures will further increase the expansion of hypoxic zones in the world's oceans. As water temperature increases, the amount of oxygen dissolved in water decreases, further squeezing billfish into dwindling available habitat and exposing them to even higher levels of exploitation.

Source: http://www.sciencedaily.com/releases/2010/12/101222162402.htm



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11.11.2010

South Florida water managers weigh costly consequences of sea level rise


For millions of South Floridians, life on a peninsula means melting icecaps in Greenland aren't just something for polar bears to worry about.

South Florida's coastal flood-control structures, counted on to protect low-lying communities from getting swamped, already are at risk from sea level rise due to climate change, according to scientists for the South Florida Water Management District.

In the coming months, the district's governing board will be asked to endorse more scientific studies and potentially costly flood-control construction projects aimed at preparing for the rising sea levels expected to come.

A district proposal outlined Tuesday calls for the agency over the next five years to buy more land for flood control, design improvements for 50-year-old drainage structures and start building pumps that could keep discharging stormwater out to the ocean even as sea levels continue to rise.

While politicians and world leaders debate the causes of climate change and how to respond, district scientists are adopting a "no-regrets strategy" to get ready, even if the worst-case scenarios don't come to pass.

"This is an issue of global importance that will have regional impacts," said Jayantha Obeysekera, who is leading the district's response to climate change and sea level rise. He briefed the district board Tuesday. "All aspects of water management would be impacted."

An increase in carbon dioxide and other greenhouse gases in the Earth's atmosphere are trapping more of the sun's heat, leading to climate change — blamed for higher temperatures that are projected to increase the rate of sea level rise.

Manmade pollution produces more of those heat-trapping greenhouse gases.

Sea ice, glaciers and snow cover around the world all are shrinking as temperatures rise, Obeysekera said.

The district is anticipating sea levels to climb 5 to 20 inches during the next 50 years.

High water levels at times already are creating problems for some of the floodgates, spillways and drainage canals that protect South Florida from flooding.

South Florida now has periods of extreme high tides, when water levels rise higher than the point where stormwater from coastal drainage canals normally gets dumped into the sea.

When that happens, floodgates stay closed, increasing the flood risk if those drainage canals overflow. That would worsen if sea levels rise.

Overwhelmed coastal drainage canals would have a "domino effect" on the rest of South Florida's drainage system, according to Carol Wehle, water district executive director.

If there's insufficient room for water in drainage canals, then there's not enough room for water coming in from community drainage systems. Those community systems help keep inland neighborhoods dry.

"The capacity … of the system is going to be negatively impacted by sea level rise," Wehle said.

The district has so far identified 28 flood-control structures along the southeast coast and six along the west coast most at risk to rising sea levels.

The first three are the S27, S28 and S29 facilities in northern Miami-Dade County.

New pumps are proposed to push stormwater into the ocean while keeping floodgates closed to hold back the elevated seas.

Cost remains a hurdle to getting that done. The current proposal would begin work by 2015. Each one cost "tens of millions of dollars," Obeysekera said.

Another threat from rising sea levels is more saltwater seeping in underground and contaminating drinking water supplies. South Florida has coastal well fields that through the years have had to shut down or reduce pumping due to saltwater intrusion.

Water utilities in Lake Worth, Hallandale Beach and Lantana have been among the most at risk of saltwater intrusion.

If that continues, it means increased costs to find new drinking water supplies or to switch to more costly water treatment processes — both of which would mean higher water bills for South Florida residents.

In addition, the Everglades can expect to suffer from an influx of saltwater.

Sea level rise is expected to affect the southern end of the Everglades by increasing coastal erosion, reducing mangrove forests, pushing migrating wading birds northward, increasing peat collapse and raising salinity levels in freshwater marshes that could result in fish kills and loss of wildlife habitat.

The state and federal government are in the midst of investing billions of dollars in Everglades restoration. Some contend that those restoration projects should be reconsidered due to the expected damage from sea level rise.

Others counter that restoring more of the stormwater flows that once naturally reached the Everglades will counterbalance the effects of climate change.

"It's critical to act fast enough," said Jane Graham of Audubon of Florida. "Fight water with water."

Computer modeling is being used to try to chart which areas are most at risk of flooding from sea level rise.

During the coming year, the district plans to further identify water-management projects affected by sea level rise; complete reports on trends in sea-level rise and climate change; and finish an analysis of the saltwater-intrusion monitoring system.

The sea level rise is not really in dispute, said district board member Jerry Montgomery, pointing to melting glaciers and ice sheets from Greenland to Antarctica. The question, Montgomery said, is the rate of rise and how much it will affect South Florida.

"It is clearly melting and it is clearly melting at a faster rate," Montgomery said.

Andy Reid can be reached at abreid@SunSentinel.com or 561-228-5504.

Source: http://www.sun-sentinel.com/news/palm-beach/fl-sea-level-rise-south-florida-20101109,0,5651053,full.story


About Oceanic Defense
We are an international non-profit organization with members in over 60 countries, spanning 6 continents with 1 mission; healthy aquatic ecosystems free from human abuse and neglect. Oceanic Defense teaches people to protect our oceans by acting responsibly as consumers and by making smart decisions in our daily lives. Whether we are buying groceries, commuting to work, planning a vacation or advocating within our own communities; each action we take or decision we make either helps or hurts our oceans. We empower people to be part of the solution rather than part of the problem and work together to protect our blue planet.

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1.28.2010

Lawsuit Filed To Protect 83 Coral Reefs


SAN FRANCISCO, California -- The Center for Biological Diversity has formally notified the National Marine Fisheries Service of its intent to sue the agency for its failure to respond to a petition seeking to protect 83 imperiled coral species under the Endangered Species Act. These corals, all of which occur in U.S. waters ranging from Florida and Hawaii to U.S. territories in the Caribbean and Pacific, face a growing threat of extinction due to rising ocean temperatures caused by global warming, and the related threat of ocean acidification. The Endangered Species Act requires that the National Marine Fisheries Service respond to the petition within 90 days, and this initial finding is delinquent.

“Within a few decades, global warming and ocean acidification threaten to completely destroy magnificent coral reefs that took millions of years to build,” said Miyoko Sakashita, oceans director at the Center for Biological Diversity. “Timing is of the essence to reverse the tragic decline of these vitally important reefs, and we can’t afford any delays in protecting corals under the Endangered Species Act.”

Scientists have warned that coral reefs are likely to be the first worldwide ecosystem to collapse due to global warming; all world’s reefs could be ruined by 2050. When corals are stressed by warm ocean temperatures, they are vulnerable to bleaching and death. Mass bleaching events have become much more frequent and severe as ocean temperatures have risen in recent decades. Scientists predict that most of the world’s corals will be subjected to mass bleaching events at deadly frequencies within 20 years on our current emissions path.

Further, ocean acidification, caused by the ocean’s absorption of carbon dioxide, impairs the ability of corals to grow and build their protective skeletons. Therefore, global warming and ocean acidification are an overriding threat to coral reefs that have already experienced population declines from threats such as destructive fishing, agriculture runoff, pollution, abrasion, predation, and disease.

Leading coral biologist Charlie Veron warned in a recent scientific paper that at current levels of CO2 in the atmosphere (387 ppm) most of the world’s coral reefs are committed to an irreversible decline. Other scientists have warned that CO2 concentrations must be reduced to levels below 350 ppm to protect corals and avoid runaway climate change.

“The coral conservation crisis is already so severe that preventing the extinction of coral reefs and the marine life that depends upon them is an enormous undertaking. The Endangered Species Act has an important role to play in that effort,” added Sakashita. “But without rapid CO2 reductions, the fate of the world’s coral reefs will be sealed.”

Protection under the Endangered Species Act would open the door to greater opportunities for coral reef conservation, as activities ranging from fishing, dumping, dredging, and offshore oil development, all of which hurt corals, would be subject to stricter regulatory scrutiny. Additionally, the Endangered Species Act would require federal agencies to ensure that that their actions do not harm the coral species, which could result in agencies approving projects with significant greenhouse gas emissions to consider and minimize such impacts on vulnerable corals.

Source: http://www.underwatertimes.com/news.php?article_id=81510930267



About Oceanic Defense
We are an international non-profit organization with members in over 60 countries, spanning 6 continents with 1 mission; healthy aquatic ecosystems free from human abuse and neglect. Oceanic Defense teaches people to protect our oceans by acting responsibly as consumers and by making smart decisions in our daily lives. Whether we are buying groceries, commuting to work, planning a vacation or advocating within our own communities; each action we take or decision we make either helps or hurts our oceans. We empower people to be part of the solution rather than part of the problem and work together to protect our blue planet.

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1.10.2010

Coral Can Recover from Climate Change Damage, New Research Suggests


ScienceDaily — A study by the University of Exeter provides the first evidence that coral reefs can recover from the devastating effects of climate change. Published Jan. 11, 2010 in the journal PLoS ONE, the research shows for the first time that coral reefs located in marine reserves can recover from the impacts of global warming.

Scientists and environmentalists have warned that coral reefs may not be able to recover from the damage caused by climate change and that these unique environments could soon be lost forever. Now, this research adds weight to the argument that reducing levels of fishing is a viable way of protecting the world's most delicate aquatic ecosystems.

Increases in ocean surface water temperatures subject coral reefs to stresses that lead quickly to mass bleaching. The problem is intensified by ocean acidification, which is also caused by increased CO2. This decreases the ability of corals to produce calcium carbonate (chalk), which is the material that reefs are made of.

Approximately 2% of the world's coral reefs are located within marine reserves, areas of the sea that are protected against potentially-damaging human activity, like dredging and fishing.
The researchers conducted surveys of ten sites inside and outside marine reserves of the Bahamas over 2.5 years. These reefs have been severely damaged by bleaching and then by hurricane Frances in the summer of 2004. At the beginning of the study, the reefs had an average of 7% coral cover. By the end of the project, coral cover in marine protected areas had increased by an average of 19%, while reefs in non-reserve sites showed no recovery.
Professor Peter Mumby of the University of Exeter said: "Coral reefs are the largest living structures on Earth and are home to the highest biodiversity on the planet. As a result of climate change, the environment that has enabled coral reefs to thrive for hundreds of thousands of years is changing too quickly for reefs to adapt.

"In order to protect reefs in the long-term we need radical action to reduce CO2 emissions. However, our research shows that local action to reduce the effects of fishing can contribute meaningfully to the fate of reefs. The reserve allowed the number of parrotfishes to increase and because parrotfish eat seaweeds, the corals could grow freely without being swamped by weeds. As a result, reefs inside the park were showing recovery whereas those with more seaweed were not. This sort of evidence may help persuade governments to reduce the fishing of key herbivores like parrotfishes and help reefs cope with the inevitable threats posed by climate change."

Professor Mumby's research was funded by National Environment Research Council (NERC) and the Khaled bin Sultan Living Oceans Foundation.

Reef facts
  • A coral reef is made up of thin layers of calcium carbonate (limestone) secreted over thousands of years by billions of tiny soft bodied animals called coral polyps.
  • Coral reefs are the world's most diverse marine ecosystems and are home to twenty-five percent of known marine species, including 4,000 species of fish, 700 species of coral and thousands of other plants and animals.
  • Coral reefs have been on the planet for over 400 million years.
  • The largest coral reef is the Great Barrier Reef, which stretches along the northeast coast of Australia, from the northern tip of Queensland, to just north of Bundaberg. At 2,300km long, it is the largest natural feature on Earth.
  • Coral reefs occupy less than one quarter of one percent of the Earth's marine environment, yet they are home to more than a quarter of all known fish species.
  • As well as supporting huge tourist industries, coral reefs protect shorelines from erosion and storm damage.
High quality reef videos by Professor Peter Mumby can be viewed at: www.reefvid.org
The main funding for the research came from Khaled bin Sultan Living Oceans Foundation and the Natural Environment Research Council.

Source: http://www.sciencedaily.com/releases/2010/01/100109002310.htm


About Oceanic Defense
We are an international non-profit organization with members in over 60 countries, spanning 6 continents with 1 mission; healthy aquatic ecosystems free from human abuse and neglect. Oceanic Defense teaches people to protect our oceans by acting responsibly as consumers and by making smart decisions in our daily lives. Whether we are buying groceries, commuting to work, planning a vacation or advocating within our own communities; each action we take or decision we make either helps or hurts our oceans. We empower people to be part of the solution rather than part of the problem and work together to protect our blue planet.

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12.11.2009

How Arctic Food Webs Affect Mercury in Polar Bears


ScienceDaily — With growing concerns about the effects of global warming on polar bears, it's increasingly important to understand how other environmental threats, such as mercury pollution, are affecting these magnificent Arctic animals.

New research led by biogeochemists Travis Horton of the University of Canterbury and Joel Blum of the University of Michigan lays the groundwork for assessing current and future effects of mercury deposition and climate change on polar bears.

The study appears in the December issue of the journal Polar Research.

Mercury is a naturally occurring element, but some 150 tons of it enter the environment each year from human-generated sources such as coal-burning power plants, incinerators and chlorine-producing plants. Deposited onto land or into water, mercury is picked up by microorganisms, which convert some of it to methylmercury, a highly toxic form that builds up in fish and the animals that eat them. As bigger animals eat smaller ones, the methylmercury is concentrated -- a process known as bioaccumulation. Sitting at the top of the food chain, polar bears amass high concentrations of the contaminant.

Although that much is known, the details of how mercury moves through different food webs -- particularly in the Arctic, where snow and ice contribute to mercury deposition -- are not well understood. To tease out that information, Horton, Blum and co-workers studied polar bear hair samples from museum specimens collected in the late 19th and early 20th centuries, before mercury emissions from human-generated sources began to escalate.

By looking at three chemical signatures -- nitrogen isotopes, carbon isotopes and mercury concentrations -- the researchers learned that polar bears get their nutrition (and mercury) from two main food webs. At the base of one web are microscopic plants that float on the surface of the ocean (known as phytoplankton). The foundation of the second web is algae that live on sea ice.

The study showed that polar bears that get most of their nutrition from phytoplankton-based food webs have greater mercury concentrations than those that participate primarily in ice algae-based webs.

While it's tempting to speculate that declining sea ice, due to global warming, may force polar bears to depend more on phytoplankton-based webs, thus increasing their mercury exposure, the study doesn't directly address that issue. It does, however, provide other useful information, said Blum, who is the John D. MacArthur Professor of Geological Sciences and a professor of ecology and evolutionary biology.

"If you want to understand the potential effects of changing ecosystems on polar bears, you need to be aware of the existence of these two food webs, which may possibly be affected by sea ice," Blum said. "This work provides background information that will be important in our in-depth understanding of mercury bioaccumulation in polar bears."

In addition to Horton and Blum, the paper's authors are Zhouqing Xie, who was at U-M when the research was done and now is at the University of Science and Technology of China; Michael Hren, who was at Yale University when the work was done and now is a postdoctoral fellow at U-M; and C. Page Chamberlain of Stanford University.

Source: http://www.sciencedaily.com/releases/2009/12/091208170915.htm

12.08.2009

Earth More Sensitive to Carbon Dioxide Than Previously Thought


The temperature response of the Earth (in degrees C) to an increase in atmospheric carbon dioxide from pre-industrial levels (280 parts per million by volume) to higher levels (400 parts per million by volume). (a) shows predicted global temperatures when processes that adjust on relatively short-term timescales (for example sea-ice, clouds, and water vapour) are included in the model (b) includes additional long-tem processes that adjust on relatively long timescales (vegetation and land-ice). (Credit: Image courtesy of University of Bristol)

ScienceDaily — In the long term, the Earth's temperature may be 30-50% more sensitive to atmospheric carbon dioxide than has previously been estimated, reports a new study published in Nature Geoscience.

The results show that components of the Earth's climate system that vary over long timescales -- such as land-ice and vegetation -- have an important effect on this temperature sensitivity, but these factors are often neglected in current climate models.

Dan Lunt, from the University of Bristol, and colleagues compared results from a global climate model to temperature reconstructions of the Earth's environment three million years ago when global temperatures and carbon dioxide concentrations were relatively high. The temperature reconstructions were derived using data from three million-year-old sediments on the ocean floor.

Lunt said, "We found that, given the concentrations of carbon dioxide prevailing three million years ago, the model originally predicted a significantly smaller temperature increase than that indicated by the reconstructions. This led us to review what was missing from the model."

The authors demonstrate that the increased temperatures indicated by the reconstructions can be explained if factors that vary over long timescales, such as land-ice and vegetation, are included in the model. This is primarily because changes in vegetation and ice lead to more sunlight being absorbed, which in turn increases warming.

Including these long-term processes in the model resulted in an increased temperature response of the Earth to carbon dioxide, indicating that the Earth's temperature is more sensitive to carbon dioxide than previously recognised. Climate models used by bodies such as the Intergovernmental Panel on Climate Change often do not fully include these long-term processes, thus these models do not entirely represent the sensitivity of the Earth's temperature to carbon dioxide.

Alan Haywood, a co-author on the study from the University of Leeds, said "If we want to avoid dangerous climate change, this high sensitivity of the Earth to carbon dioxide should be taken into account when defining targets for the long-term stabilisation of atmospheric greenhouse-gas concentrations."

Lunt added: "This study has shown that studying past climates can provide important insights into how the Earth might change in the future."

(a) shows predicted global temperatures when processes that adjust on relatively short-term timescales (for example sea-ice, clouds, and water vapour) are included in the model

(b) includes additional long-tem processes that adjust on relatively long timescales (vegetation and land-ice).

This research was funded by the Research Council UK and the British Antarctic Survey.

Souce: http://www.sciencedaily.com/releases/2009/12/091206162955.htm

12.05.2009

Sumo-sized jellyfish throwing Japan's fishing industry into chaos


Jellyfish in Japan the size of sumo wrestlers are wreaking havoc on thefisheries industry.

AN invasion of jellyfish the size of sumo wrestlers is throwing Japan's fishing industry into chaos, the UK's Sky News Online reports.

The vast stinging creatures have appeared on Japan's Pacific coast after floating from Chinese and Korean waters where they breed every year.

The Echizen jellyfish grow up to 2.2m in diameter and can weigh over 300kg.

Their size means they are capable of ruining fisherman's nets and poisoning and crushing catches.

One fishing boat was even capsized after a mammoth creature got caught in its net.

A local fisherman said: " I have never seen anything this big before."

Much about the jellyfish swarms remains a mystery but some scientists believe global warming and rising sea temperatures may be a factor.

Japan's Meteorological Agency says the waters of the Sea of Japan are warming at a speed three times faster than the global average.

Source: http://www.news.com.au/weird-true-freaky/sumo-sized-jellyfish-throwing-japans-fishing-industry-into-chaos/story-e6frflri-1225806901682

10.19.2009

Cabinet Ministers Illustrate Global Warming Issues



Maldivian President Mohammed Nasheed dos scuba gear as he signs a document in Girifushi, Maldives, on Saturday that calls on all countries to cut down their carbon dioxide emissions ahead of a U.N. climate change conference.

GIRIFUSHI, Maldives - Members of the Maldives' Cabinet donned scuba gear and used hand signals Saturday at an underwater meeting staged to highlight the threat of global warming to the lowest-lying nation on earth.

President Mohammed Nasheed and 13 other government officials submerged and took their seats at a table on the sea floor — 20 feet below the surface of a lagoon off Girifushi, an island usually used for military training.

With a backdrop of coral, the meeting was a bid to draw attention to fears that rising sea levels caused by the melting of polar ice caps could swamp this Indian Ocean archipelago within a century. Its islands average 7 feet above sea level.

"What we are trying to make people realize is that the Maldives is a frontline state. This is not merely an issue for the Maldives but for the world," Nasheed said.

As bubbles floated up from their face masks, the president, vice president, Cabinet secretary and 11 ministers signed a document calling on all countries to cut their carbon dioxide emissions.

Urgency
The issue has taken on urgency ahead of a major U.N. climate change conference scheduled for December in Copenhagen. At that meeting countries will negotiate a successor to the Kyoto Protocol with aims to cut the emission of greenhouse gases such as carbon dioxide that scientists blame for causing global warming by trapping heat in the atmosphere.

Wealthy nations want broad emissions cuts from all countries, while poorer ones say industrialized countries should carry most of the burden.

Dozens of Maldives soldiers guarded the event Saturday, but the only intruders were groupers and other fish.

Nasheed had already announced plans for a fund to buy a new homeland for his people if the 1,192 low-lying coral islands are submerged. He has promised to make the Maldives, with a population of 350,000, the world's first carbon-neutral nation within a decade.

"We have to get the message across by being more imaginative, more creative and so this is what we are doing," he said in an interview on a boat en route to the dive site.

Nasheed, who has emerged as a key, and colorful, voice on climate change, is a certified diver, but the others had to take diving lessons in recent weeks.

Three ministers missed the underwater meeting because two were not given medical permission and another was abroad.

Source: http://www.msnbc.msn.com/id/33354627/ns/world_news-weird_news/

7.05.2009

Sea Ice At Lowest Level In 800 Years Near Greenland



There has never been so little sea ice in the area between Svalbard and Greenland in the last 800 years. (Credit: NASA/GSFC)


ScienceDaily — New research, which reconstructs the extent of ice in the sea between Greenland and Svalbard from the 13th century to the present indicates that there has never been so little sea ice as there is now. The research results from the Niels Bohr Institute, among others, are published in the scientific journal, Climate Dynamics.

There are of course neither satellite images nor instrumental records of the climate all the way back to the 13th century, but nature has its own 'archive' of the climate in both ice cores and the annual growth rings of trees and we humans have made records of a great many things over the years - such as observations in the log books of ships and in harbour records. Piece all of the information together and you get a picture of how much sea ice there has been throughout time.

Modern research and historic records

"We have combined information about the climate found in ice cores from an ice cap on Svalbard and from the annual growth rings of trees in Finland and this gave us a curve of the past climate" explains Aslak Grinsted, geophysicist with the Centre for Ice and Climate at the Niels Bohr Institute at the University of Copenhagen.

In order to determine how much sea ice there has been, the researchers needed to turn to data from the logbooks of ships, which whalers and fisherman kept of their expeditions to the boundary of the sea ice. The ship logbooks are very precise and go all the way back to the 16th century. They relate at which geographical position the ice was found. Another source of information about the ice are records from harbours in Iceland, where the severity of the winters have been recorded since the end of the 18th century.

By combining the curve of the climate with the actual historical records of the distribution of the ice, researchers have been able to reconstruct the extent of the sea ice all the way back to the 13th century. Even though the 13th century was a warm period, the calculations show that there has never been so little sea ice as in the 20th century.

In the middle of the 17th century there was also a sharp decline in sea ice, but it lastet only a very brief period. The greatest cover of sea ice was in a period around 1700-1800, which is also called the 'Little Ice Age'.

"There was a sharp change in the ice cover at the start of the 20th century," explains Aslak Grinsted. He explains, that the ice shrank by 300.000 km2 in the space of ten years from 1910-1920. So you can see that there have been sudden changes throughout time, but here during the last few years we have had some record years with very little ice extent.

"We see that the sea ice is shrinking to a level which has not been seen in more than 800 years", concludes Aslak Grinsted.

Source: http://www.sciencedaily.com/releases/2009/07/090701102900.htm

Journal reference:
  1. Macias Fauria et al. Unprecedented low twentieth century winter sea ice extent in the Western Nordic Seas since A.D. 1200. Climate Dynamics, 2009; DOI: 10.1007/s00382-009-0610-z
Adapted from materials provided by University of Copenhagen.

7.04.2009

How the Oceans Once Ended Global Warming



Larry O'Hanlon, Discovery News - During a period of natural global warming 55 million years ago, ocean plant life kicked into high gear. All that productivity captured excessive carbon from the atmosphere and dropped it to the ocean floor, where it was buried -- or "sequestered." Scientists studying the remains of those plants are starting to understand how they helped cool the Earth.

Last time Earth suffered a carbon-induced fever, it was the oceans that helped saved the day, say marine scientists in California.

Massive ocean-bottom accumulations of the mineral barite show that the last severe global warming episode 55 million years ago was accompanied by several thousands of years of ocean plant life kicking into high gear. All that productivity captured excessive carbon from the atmosphere and dropped it to the ocean floor, where it was buried -- or "sequestered."

"Basically what we're trying to say is the increasing barite accumulation rate is really generally recording greater productivity and not just changes in ocean chemistry," said Adina Paytan, an oceanographer at the University of California at Santa Cruz.

She is the author of a report on barite in the deep sea which appears in the December issue of the journal Geology, published by the Geological Society of America.

Barite, also known as barium sulfate, is a good indicator of productivity, Paytan said, because all living things contain a lot of the element barium in their tissues. When organisms in the life-rich upper waters die, they sink to the sea floor, taking that barium with them. At great depths that barium reaches its saturation point in the water and combines with sulfur to create the mineral barite.

In other words, barite is a secondary product of boom times in the sunny surface waters of a warmer world.

The new research contrasts with previous work on the signs of changing ocean productivity 55 million years ago -- what's called the Paleocene-Eocene Thermal Maximum (PETM) -- by looking for direct products of living organisms, Paytan told Discovery News.

If the barite speaks the truth about what turned down the thermostat during the PETM, it also could be a clue to how Earth will eventually respond to current global warming.

"I think the main contribution here is that the PETM is our best example of a natural carbon cycle experiment," said PETM expert James Zachos, who also works at U.C. Santa Cruz, but was not involved in Paytan's research.

"This study is suggesting that the peaks in barite observed in the deep sea...are accurately reflecting changes in the accelerated, though temporary, sequestration of carbon by one process -- higher algal production," Zachos told Discovery News.

That doesn't mean Earth is likely to repair the damage done by current global warming in any timely way, however, he cautions.

"Unfortunately, this process is slow and thus lags the buildup of carbon in the atmosphere," said Zachos.

In fact, said Paytan, the barite accumulation went on for about 170,000 years. That suggests it takes a lot longer to cool off a hot Earth than to heat up a cool planet.

Source: http://dsc.discovery.com/news/2007/12/26/global-warming-ocean.html

6.05.2009

Wind Shifts May Stir Carbon Dioxide From Antarctic Depths, Amplifying Global Warming




ScienceDaily— Natural releases of carbon dioxide from the Southern Ocean due to shifting wind patterns could have amplified global warming at the end of the last ice age--and could be repeated as manmade warming proceeds, a new paper in the journal Science suggests.


Many scientists think that the end of the last ice age was triggered by a change in Earth's orbit that caused the northern part of the planet to warm. This partial climate shift was accompanied by rising levels of the greenhouse gas CO2, ice core records show, which could have intensified the warming around the globe. A team of scientists at Columbia University's Lamont-Doherty Earth Observatory now offers one explanation for the mysterious rise in CO2: the orbital shift triggered a southward displacement in westerly winds, which caused heavy mixing in the Southern Ocean around Antarctica, pumping dissolved carbon dioxide from the water into the air.

"The faster the ocean turns over, the more deep water rises to the surface to release CO2," said lead author Robert Anderson, a geochemist at Lamont-Doherty. "It's this rate of overturning that regulates CO2 in the atmosphere." In the last 40 years, the winds have shifted south much as they did 17,000 years ago, said Anderson. If they end up venting more CO2 into the air, manmade warming underway now could be intensified.

Scientists have been studying the oceans for more than 25 years to understand their influence on CO2 levels and the glacial cycles that have periodically heated and chilled the planet for more than 600,000 years. Ice cores show that the ends of other ice ages also were marked by rises in CO2.

Two years ago, J.R. Toggweiler, a scientist at the National Oceanic and Atmospheric Administration (NOAA), proposed that westerly winds in the Southern Ocean around Antarctica may have undergone a major shift at the end of the last ice age. This shift would have raised more CO2-rich deep water to the surface, and thus amplified warming already taking place due to the earth's new orbital position. Anderson and his colleagues are the first to test that theory by studying sediments from the bottom of the Southern Ocean to measure the rate of overturning.

The scientists say that changes in the westerlies may have been triggered by two competing events in the northern hemisphere about 17,000 years ago. The earth's orbit shifted, causing more sunlight to fall in the north, partially melting the ice sheets that then covered parts of the United States, Canada and Europe. Paradoxically, the melting may also have spurred sea-ice formation in the North Atlantic Ocean, creating a cooling effect there. Both events would have caused the westerly winds to shift south, toward the Southern Ocean. The winds simultaneously warmed Antarctica and stirred the waters around it. The resulting upwelling of CO2 would have caused the entire globe to heat.

Anderson and his colleagues measured the rate of upwelling by analyzing sediment cores from the Southern Ocean. When deep water is vented, it brings not only CO2 to the surface but nutrients. Phytoplankton consume the extra nutrients and multiply.

In the cores, Anderson and his colleagues say spikes in plankton growth between roughly 17,000 years ago and 10,000 years ago indicate added upwelling. By comparing those spikes with ice core records, the scientists realized the added upwelling coincided with hotter temperatures in Antarctica as well as rising CO2 levels.

In the same issue of Science, Toggweiler writes a column commenting on the work. "Now I think this really starts to lock up how the CO2 changed globally," he said in an interview. "Here's a mechanism that can explain the warming of Antarctica and the rise in CO2. It's being forced by the north, via this change in the winds."

At least one model supports the evidence. Richard Matear, a researcher at Australia's Commonwealth Scientific and Industrial Research Organisation, describes a scenario in which winds shift south and produce an increase in CO2 venting in the Southern Ocean. Plants, which incorporate CO2 during photosynthesis, are unable to absorb all the added nutrients, causing atmospheric CO2 to rise.

Some other climate models disagree. In those used by the Intergovernmental Panel on Climate Change, the westerly winds do not simply shift north-south. "It's more complicated than this," said Axel Timmermann, a climate modeler at the University of Hawaii. Even if the winds did shift south, Timmermann argues, upwelling in the Southern Ocean would not have raised CO2 levels in the air. Instead, he says, the intensification of the westerlies would have increased upwelling and plant growth in the Southeastern Pacific, and this would have absorbed enough atmospheric CO2 to compensate for the added upwelling in the Southern Ocean.

"Differences among model results illustrate a critical need for further research," said Anderson. These, include "measurements that document the ongoing physical and biogeochemical changes in the Southern Ocean, and improvements in the models used to simulate these processes and project their impact on atmospheric CO2 levels over the next century."

Anderson says that if his theory is correct, the impact of upwelling "will be dwarfed by the accelerating rate at which humans are burning fossil fuels." But, he said, "It could well be large enough to offset some of the mitigation strategies that are being proposed to counteract rising CO2, so it should not be neglected."

In addition to Anderson, the paper was coauthored by Simon Nielsen of Florida State University, and five Lamont-Doherty researchers: Shahla Ali, Louisa Bradtmiller, Martin Fleisher, Brenton Anderson and Lloyd Burckle. The study was funded by NOAA, the National Science Foundation, Norwegian Research Council and Norwegian Polar Institute.

Journal reference:

1. . Wind-Driven Upwelling in the Southern Ocean and the Deglacial Rise in Atmospheric CO2. Science, March 13, 2009

Adapted from materials provided by The Earth Institute at Columbia University.