Computer Models Show How Skyborne Seawater Particles Change Cloud Brightness, Temperature, Rain Patterns

Ships blowing off steam are helping researchers understand how human-made particles might be useful against global warming. New results from modeling clouds like those seen in shipping lanes reveal the complex interplay between aerosols, the prevailing weather and even the time of day the aerosol particles hit the air, according to research presented at the American Association for the Advancement of Science's annual meeting in San Diego.

"We've seen ship tracks affect the reflectivity of clouds," said Phil Rasch, chief climate scientist at the Department of Energy's Pacific Northwest National Laboratory in Richland, Wash. "We want to know if we can do the same thing when we want to, on purpose, and how that might be helpful in countering some of the effects of global warming."We decided to see how the reflectivity of clouds is influenced by particles in a very detailed model that treats clouds much more realistically than we are able to do in a typical climate model."Reflecting sunlight back into space prevents that energy from hitting Earth's surface. So brighter clouds could have an overall cooling effect compared to darker ones.A handful of research groups in the US are exploring geoengineering, or the intentional modification of Earth's climate, in hopes of developing tools that might be used to lower global temperatures if atmospheric greenhouse gases reach levels that might produce disastrous climate change.Previous work analyzing clouds in shipping lanes showed that large ships spewing tiny particles into the sky change the characteristics of clouds. More aerosol particles -- tiny natural or human-made bits of dirt, water and gas, such as from pollution -- increase the number of droplets in clouds and make each droplet smaller. This reflects more sunlight from the surface, and the clouds appear brighter.But the previous work revealed that some parts of the clouds above shipping lanes became brighter and other parts darker, suggesting that using aerosols to increase cloud reflectivity will be more complex than simply adding more."Do the brighter and darker parts cancel each other out?" asked Rasch.To find out, the group performed some exploratory computer simulations to determine the net effect of increased aerosols. His team simulated three ships chugging along in a 93-mile by 37-mile block of the Pacific Ocean a few hundred miles southwest of Los Angeles.The team showed that introducing additional particles into the model near the surface -- as proposed for geoengineering -- would make the clouds significantly more reflective than they would otherwise be, in certain situations. They found that if the clouds were already drizzling then the new particles would not brighten them very effectively.Rasch will discuss other cloud, weather and climate characteristics affected by aerosols, such as how long the brighter clouds last, whether they burn off when the sun comes up, and what happens when they finally rain. The team is also using the simulations to test when the best time to spray seawater using the simulations is -- in the morning, late afternoon or perhaps all night long.Although ship tracks are helping researchers explore geoengineering methods, the real plans won't use polluting aerosols from ships. Instead, Rasch and others suggest that ocean vessels could spray seawater aerosols into the sky to brighten clouds. But many questions remain about how effective, predictable and safe such methods might be.Rasch will also discuss results from a Community Climate System Model study. He and colleagues simulated what happens to the global climate as aerosol concentrations rise. The work, published December 2009 in Environmental Research Letters, showed increasing aerosols in the ocean air can either increase the amount of sea ice to previous levels, restore precipitation, or reduce temperatures, but not all at the same time.

Clean Fuels Could Reduce Deaths From Ship Smokestacks By 40,000 Annually

Rising levels of smokestack emissions from oceangoing ships will cause an estimated 87,000 deaths worldwide each year by 2012 — almost one-third higher than previously believed, according to the second major study on that topic. The study says that government action to reduce sulfur emissions from shipping fuel (the source of air pollution linked to an increased risk of illness and death) could reduce that toll.

James Winebrake and colleagues note that most oceangoing ships burn fuels with a high sulfur content that averages 2.4 percent. Their smokestacks emit sulfur-containing particles linked to increased risks of lung and heart disease. A 2007 study by the researchers estimated that about 60,000 people died prematurely around the world due to shipping-related emissions in 2002. The new study estimates that the toll could rise to 87,000 by 2012, assuming that the global shipping industry rebounds from the current economic slump and no new regulation occurs.
Policymakers now are considering limiting ships emissions by either restricting sulfur content in fuel or designating air pollution control areas to reduce air pollution near highly populated coastal areas. Requiring ships to use marine fuel with 0.5 percent sulfur within 200 nautical miles of shore would reduce premature deaths by about 41,200, the study concludes. Lower sulfur reductions could reduce deaths even further, they say, adding that designated emission control areas will also have a positive impact.
Journal reference:
Winebrake et al. Mitigating the Health Impacts of Pollution from Oceangoing Shipping: An Assessment of Low-Sulfur Fuel Mandates. Environmental Science & Technology, 2009; 43 (13): 4776 DOI: 10.1021/es803224q
Adapted from materials provided by American Chemical Society, via EurekAlert!, a service of AAAS.

'Ocean glider' home after two-month voyage

Scientists are celebrating the first successful deployment and retrieval in Australia of a remotely controlled, deep ocean-going robotic submarine destined to play a central role in measuring changes in two of Australia's most influential ocean currents. Under the joint CSIRO Wealth from Oceans National Research Flagship and Integrated Marine Observation System (IMOS) project, the underwater ocean glider was launched in February on a two-month, 1,500 kilometre voyage. The ocean glider was supplied through IMOS's Australian National Facility for Ocean Gliders facility located at The University of Western Australia. The Integrated Marine Observing System has been developed as part of the Australian Government's National Collaborative Research Infrastructure Strategy. With its porpoising motion and an ability to descend to a depth of nearly 1,000 metres, the $200,000 robotic glider is being trialled in the Tasman Sea and the Indian Ocean as the latest tool in Australia's $94 million marine observing network. The glider's sensors measure temperature and salinity, as well a range of biological parameters including oxygen and turbidity. Senior CSIRO Wealth from Oceans Flagship researcher Ken Ridgway, says the Tasman Sea trial has generated new confidence among scientists broadening the array of instruments available to them to better understand the East Australian Current and Leeuwin Currents. "Ocean currents around Australia are critical to so many aspects of nature and human activity," Mr Ridgway says. "With the East Australian and Leeuwin Currents, we need to understand how they change from season to season and year to year, and the extent of their influence on local coastal conditions, as this affects climate, weather, fisheries, shipping and more. "Increasingly, these autonomous gliders are being used by northern hemisphere marine research groups. Australia is just beginning to use these deep-ocean systems, although shallow water gliders have been deployed off Western Australia, South Australia and New South Wales in recent months. The Tasman Sea deployment was the first deployment of a deep-ocean glider in the southern hemisphere." Together with data from research vessels, satellites and moored, drifting and expendable instruments, the glider will add a new dimension to profiling the oceans around Australia. But there are still challenges to be overcome. "In a lot of ways this first deployment is as much learning how to pilot the glider and guide it through and around the eddies of the East Australian Current as it is getting about the data we want," Mr Ridgway says. A recent innovation in oceanography, the winged gliders are programmable and guided by Global Positioning Systems. They glide during depth changes, driven by an inflated oil filled chamber. However, because the ocean currents can be faster than the glider's speed, ensuring they are not swept away has been a difficult process. "The appeal of these instruments is that they are out working while the scientist can be assessing what is near-real time information about ocean conditions," Mr Ridgway says. CSIRO initiated the National Research Flagships to provide science-based solutions in response to Australia's major research challenges and opportunities. The nine Flagships form multidisciplinary teams with industry and the research community to deliver impact and benefits for Australia.

Acoustic Phenomena Explain Why Boats And Animals Collide

Researchers at Florida Atlantic University have laid the groundwork for a sensory explanation for why manatees and other animals are hit repeatedly by boats. Last year, 73 manatees were killed by boats in Florida’s bays and inland waterways. Marine authorities have responded to deaths from boat collisions by imposing low speed limits on boats.

In spite of manatee protection policies that have been in effect for nearly two decades to slow down boats passing through manatee-protection habitats, the number of injuries and deaths associated with collisions has increased and reached record highs.
In an effort to reduce manatee deaths and injuries from boats, Dr. Edmund Gerstein, director of marine mammal research and behavior in FAU’s Charles E. Schmidt College of Science, set out in 1991 to investigate what might be the underlying cause for these collisions. Gerstein disagreed with the unsubstantiated assumptions, which wildlife officials had relied upon, that manatees could hear boats, but they were just too slow and could not learn to avoid boats.
“Manatees have the cognitive prowess to learn and remember as well as dolphins and killer whales,” said Gerstein. “Furthermore, when startled or frightened, manatees explode with a burst of power and can reach swimming speeds of up to 6.4 meters per second in an instant.”
Given that manatees have the cognitive ability to recognize danger and the physical prowess to evade boats, Gerstein sought to explore the answers to some simple questions. “After a manatee has been hit more than once (some have been hit up to 50 different times) why doesn't the animal learn to get out of the way?” “Is it possible that manatees are not aware or cannot hear the sounds of an approaching boat?"
Gerstein and his colleagues conducted rigorous, controlled underwater psychoacoustic (audiometric) studies to understand what sounds manatees can hear in their environment. After a comprehensive series of hearing studies, his research revealed that manatees cannot hear the dominant low frequency sounds of boats and that those sounds do not transmit well in shallow water. Furthermore, ambient noise in manatee habitats can conceivably mask the perception of many kinds of signals. Unlike dolphins, which can use active sonar to navigate and detect objects in the environment, manatees are passive listeners restricted to listening to their auditory landscape.
"It is ironic that slow speed zones result in quieter and lower frequency sounds which manatees can’t hear or locate in Florida’s murky waters,” said Gerstein. “Slow speed zones make sense in clear water where the boater and the manatee can see each other and therefore actively avoid encounters. However, in turbid waters where there is no visibility, slow speeds actually exacerbate the risks of collisions by making these boats inaudible to manatees and increasing the time it takes for a boat to now travel through manatee habitats thereby increasing the risk and opportunities for collisions to occur.”
With these issues in mind, Gerstein and his colleagues developed an acoustic alerting device specifically tailored to exploit the manatees’ hearing ability. The environmentally friendly device is narrowly focused in front of the boat so that only manatees in its direct path are alerted.
“The alarm emits a high-frequency signal which isn’t loud, doesn’t scare or harm manatees and doesn’t disturb the marine environment,” said Gerstein.
Gerstein has been testing this alarm in a NASA wildlife refuge where controlled studies are possible. He has reported that 100 percent of the controlled approaches toward manatees by a boat with the alarm have resulted in the manatees avoiding the boat up to 30 yards away. Without this alarm, only three percent of the manatees approached by the same boat moved to avoid the boat.
Manatees aren’t the only animals that collide with boats. Other passive-listening marine mammals, including great whales, are vulnerable to collisions when near the surface, where the risk of collisions with ships and boats is greatest or in shallow water. Gerstein and his colleagues are using the findings from their studies to help understand and reduce collisions in the open seas where great whales are regularly injured and often killed by large ships.
Adapted from materials provided by Florida Atlantic University.

Indian Ship Project Killing Whales Say Activists

NEW DELHI - At least six whales have died since July as a result of digging
under the sea to create a shipping route off India's southern coast, proving
that the controversial plan hurts the environment, activists said.

The digging or dredging is part of the US$560-million Sethusamudram Ship
Canal Project which will carve a channel in the narrow strip of sea between
southeastern India and western Sri Lanka, reducing distances and cutting
costs.
But environmentalists, who have opposed the project claiming it will badly
affect marine life, said the death of the whales proved their concerns were
valid.

"Since July, at least six whales have died after getting stranded on beaches
or have been washed ashore already dead," said Ossie Fernandez of Coastal
Action Network, an alliance of over 45 social and environmental groups.

"But local fishermen have seen more dead whales so it could be as high as
10," he said, adding that most of the dead whales were found off the coast
of Rameswaram -- a southeastern Hindu holy town in Tamil Nadu state.

Full story at