The study, led by Natalie Mahowald, associate professor of earth and atmospheric sciences, used available data and computer modeling to estimate the amount of desert dust, or soil particles in the atmosphere, throughout the 20th century. It's the first study to trace the fluctuation of a natural (not human-caused) aerosol around the globe over the course of a century.
Mahowald presented the research at the fall meeting of the American Geophysical Union in San Francisco Dec. 13.
Desert dust and climate influence each other directly and indirectly through a host of intertwined systems. Dust limits the amount of solar radiation that reaches the Earth, for example, a factor that could mask the warming effects of increasing atmospheric carbon dioxide. It also can influence clouds and precipitation, leading to droughts; which, in turn, leads to desertification and more dust.
Ocean chemistry is also intricately involved. Dust is a major source of iron, which is vital for plankton and other organisms that draw carbon out of the atmosphere.
To measure fluctuations in desert dust over the century, the researchers gathered existing data from ice cores, lake sediment and coral, each of which contain information about past concentrations of desert dust in the region. They then linked each sample with its likely source region and calculated the rate of dust deposition over time. Applying components of a computer modeling system known as the Community Climate System Model, the researchers reconstructed the influence of desert dust on temperature, precipitation, ocean iron deposition and terrestrial carbon uptake over time.
Among their results, the researchers found that regional changes in temperature and precipitation caused a global reduction in terrestrial carbon uptake of 6 parts per million (ppm) over the 20th century. The model also showed that dust deposited in oceans increased carbon uptake from the atmosphere by 6 percent, or 4 ppm, over the same time period.
While the majority of research related to aerosol impacts on climate is focused on anthropogenic aerosols (those directly emitted by humans through combustion), Mahowald said, the study highlights the important role of natural aerosols as well.
"Now we finally have some information on how the desert dust is fluctuating. This has a really big impact for the understanding of climate sensitivity," she said.
It also underscores the importance of gathering more data and refining the estimates. "Some of what we're doing with this study is highlighting the best available data. We really need to look at this more carefully. And we really need more paleodata records," she said.
Meanwhile, the study is also notable for the variety of fields represented by its contributors, she said, which ranged from marine geochemistry to computational modeling. "It was a fun study to do because it was so interdisciplinary. We're pushing people to look at climate impacts in a more integrative fashion."

A report released by the British government warned the country’s National Health System to expect thousands more deaths and complications from heatwaves, malaria, and contaminated water as global warming effects progress in the next five years.
The report, “Health Effects of Climate Change in the UK”, was written by Professor Bob Maynard and colleagues with the Health Protection Agency. It is being issued as official government advice to hospitals, nursing homes, and other medical institutions run by the government’s nationalized health care system.
The biggest danger to health, and the most likely to occur, is a major heatwave. The report predicts a heatwave will occur by 2012, causing between 3,000 and 10,000 deaths. Scientists put the odds of a heatwave in the south-east of England by that time at around 1 in 40. The report says: "In terms of conventional thinking about risks to health, 1 in 40 is high.” A French heatwave in 2003 caused the deaths of an estimated 14,000 people, most of them elderly.

The government has told all national medical institutions to create a plan to deal with the health effects of global warming. For one, they are told to prepare for possible outbreaks of malaria. Even though the study claims that a widespread outbreak of the disease is unlikely, rising temperatures will contribute to greater levels of mosquito and tick-borne diseases. The hospitals may also have to deal with the fallout from larger outbreaks of malaria in continental Europe, such as English tourists who contract the disease while travelling.
In addition to heatwaves and potential malaria outbreaks, the report suggests that deaths and health complications related to air pollution will also rise as global warming affects the pollution levels in Britain. They estimate up to 1,500 more deaths and hospital admissions related to air pollution each year, mostly related to asthma attacks and other breathing problems. Skin cancer deaths are also predicted to rise with increased exposure to sunlight.
There are some other odd side effects of the warmer summers the report predicts will be one of the effects of global warming in the near future. Warmer summers also mean more cases of food poisoning. The report predicts an almost 15% increase in food poisoning cases, working out to about 14,000 extra food poisoning cases every year. Floods, which were a major problem in the UK last summer, are expected to become a more common issue. The researchers believe the floods will cause more bacterial and algae blooms in reservoir and cause issues with the safety of drinking water.
Professor Maynard weighed in on the report recently, saying: "Climate change is likely to be one of the major challenges that humanity faces this century. It is important that we assess the possible health impact and take any actions that could minimise the consequences."
While global warming skeptics will undoubtedly call the research fear-mongering, I take a more positive view of the report. If they’re wrong, nobody dies. If they’re right, hospitals are better prepared to deal with the resulting health issues and less people die. You may not think the effects of global warming will occur, or that human activity causes global warming. Even if you believe all that, however, I fail to see the problem in hospitals being better prepared to treat respiratory diseases, skin cancer, and heat stroke. These aren’t rarities in medicine anyway, so why not be ready for them?

The researcher suggests that atmospheric carbon dioxide -- often thought of as a key "greenhouse gas" -- is not the cause of global warming. The opposite is most likely to be true, according to Robert Essenhigh, E.G. Bailey Professor of Energy Conservation in Ohio State's Department of Mechanical Engineering. It is the rising global temperatures that are naturally increasing the levels of carbon dioxide, not the other way around, he says.

Essenhigh explains his position in a "viewpoint" article in the current issue of the journal Chemical Innovation, published by the American Chemical Society.Many people blame global warming on carbon dioxide sent into the atmosphere from burning fossil fuels in man-made devices such as automobiles and power plants. Essenhigh believes these people fail to account for the much greater amount of carbon dioxide that enters -- and leaves -- the atmosphere as part of the natural cycle of water exchange from, and back into, the sea and vegetation.

"Many scientists who have tried to mathematically determine the relationship between carbon dioxide and global temperature would appear to have vastly underestimated the significance of water in the atmosphere as a radiation-absorbing gas," Essenhigh argues. "If you ignore the water, you're going to get the wrong answer."
How could so many scientists miss out on this critical bit of information, as Essenhigh believes? He said a National Academy of Sciences report on carbon dioxide levels that was published in 1977 omitted information about water as a gas and identified it only as vapor, which means condensed water or cloud, which is at a much lower concentration in the atmosphere; and most subsequent investigations into this area evidently have built upon the pattern of that report.

For his hypothesis, Essenhigh examined data from various other sources, including measurements of ocean evaporation rates, man-made sources of carbon dioxide, and global temperature data for the last one million years.
He cites a 1995 report from the Intergovernmental Panel on Climate Change (IPCC), a panel formed by the World Meteorological Organization and the United Nations Environment Programme in 1988 to assess the risk of human-induced climate change. In the report, the IPCC wrote that some 90 billion tons of carbon as carbon dioxide annually circulate between the earth's ocean and the atmosphere, and another 60 billion tons exchange between the vegetation and the atmosphere.
Compared to man-made sources' emission of about 5 to 6 billion tons per year, the natural sources would then account for more than 95 percent of all atmospheric carbon dioxide, Essenhigh said.

"At 6 billion tons, humans are then responsible for a comparatively small amount - less than 5 percent - of atmospheric carbon dioxide," he said. "And if nature is the source of the rest of the carbon dioxide, then it is difficult to see that man-made carbon dioxide can be driving the rising temperatures. In fact, I don't believe it does."
Some scientists believe that the human contribution to carbon dioxide in the atmosphere, however small, is of a critical amount that could nonetheless upset Earth's environmental balance. But Essenhigh feels that, mathematically, that hypothesis hasn't been adequately substantiated.
Here's how Essenhigh sees the global temperature system working: As temperatures rise, the carbon dioxide equilibrium in the water changes, and this releases more carbon dioxide into the atmosphere. According to this scenario, atmospheric carbon dioxide is then an indicator of rising temperatures -- not the driving force behind it.
Essenhigh attributes the current reported rise in global temperatures to a natural cycle of warming and cooling.

As to why highs and lows follow a 100,000 year cycle, the explanation Essenhigh uses is that the Arctic Ocean acts as a giant temperature regulator, an idea known as the "Arctic Ocean Model." This model first appeared over 30 years ago and is well presented in the 1974 book Weather Machine: How our weather works and why it is changing, by Nigel Calder, a former editor of New Scientist magazine.
According to this model, when the Arctic Ocean is frozen over, as it is today, Essenhigh said, it prevents evaporation of water that would otherwise escape to the atmosphere and then return as snow. When there is less snow to replenish the Arctic ice cap, the cap may start to shrink. That could be the cause behind the retreat of the Arctic ice cap that scientists are documenting today, Essenhigh said.
As the ice cap melts, the earth warms, until the Arctic Ocean opens again. Once enough water is available by evaporation from the ocean into the atmosphere, snows can begin to replenish the ice cap. At that point, the Arctic ice begins to expand, the global temperature can then start to reverse, and the earth can start re-entry to a new ice age.

According to Essenhigh's estimations, Earth may reach a peak in the current temperature profile within the next 10 to 20 years, and then it could begin to cool into a new ice age.
Essenhigh knows that his scientific opinion is a minority one. As far as he knows, he's the only person who's linked global warming and carbon dioxide in this particular way. But he maintains his evaluations represent an improvement on those of the majority opinion, because they are logically rigorous and includes water vapor as a far more significant factor than in other studies.

More than 35% of the world’s mangroves are already gone. The figure is as high as 50% in countries such as India, the Philippines, and Vietnam, while in the Americas they are being cleared at a rate faster than tropical rainforests. 


Threats to mangrove forests and their habitats include:


  Clearing: Mangrove forests have often been seen as unproductive and smelly, and so cleared to make room for agricultural land, human settlements and infrastructure (such as harbours), and industrial areas. More recently, clearing for tourist developments, shrimp aquaculture, and salt farms has also taken place. This clearing is a major factor behind mangrove loss around the word.

 Overharvesting: Mangrove trees are used for firewood, construction wood, wood chip and pulp production, charcoal production, and animal fodder. While harvesting has taken place for centuries, in some parts of the world it is no longer sustainable, threatening the future of the forests.

 River changes: Dams and irrigation reduce the amount of water reaching mangrove forests, changing the salinity level of water in the forest. If salinity becomes too high, the mangroves cannot survive. Freshwater diversions can also lead to mangroves drying out. In addition, increased erosion due to land deforestation can massively increase the amount of sediment in rivers. This can overcome the mangrove forest’s filtering ability, leading to the forest being smothered.

 Overfishing: The global overfishing crisis facing the world’s oceans has effects far beyond the directly overfished population. The ecological balance of food chains and mangrove fish communities can also be altered.

 Destruction of coral reefs: Coral reefs provide the first barrier against currents and strong waves. When they are destroyed, the stronger-than-normal waves and currents reaching the coast can undermine the fine sediment in which the mangroves grow. This can prevent seedlings from taking root and wash away nutrients essential for mangrove ecosystems.

 Pollution: Fertilizers, pesticides, and other toxic man-made chemicals carried by river systems from sources upstream can kill animals living in mangrove forests, while oil pollution can smother mangrove roots and suffocate the trees.

 Climate change: Mangrove forests require stable sea levels for long-term survival. They are therefore extremely sensitive to current rising sea levels caused by global warming and climate change.

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