Monday, March 08, 2010

Missing 'Ice Arches' Contributed to 2007 Arctic Ice Loss

PASADENA, Calif. – In 2007, the Arctic lost a massive amount of thick, multiyear sea ice, contributing to that year's record-low extent of Arctic sea ice. A new NASA-led study has found that the record loss that year was due in part to the absence of "ice arches," naturally-forming, curved ice structures that span the openings between two land points. These arches block sea ice from being pushed by winds or currents through narrow passages and out of the Arctic basin.

Beginning each fall, sea ice spreads across the surface of the Arctic Ocean until it becomes confined by surrounding continents. Only a few passages -- including the Fram Strait and Nares Strait -- allow sea ice to escape.

"There are a couple of ways to lose Arctic ice: when it flows out and when it melts," said lead study researcher Ron Kwok of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We are trying to quantify how much we're losing by outflow versus melt."

Kwok and colleagues found that ice arches were missing in 2007 from the Nares Strait, a relatively narrow 30- to 40-kilometer-wide (19- to 25-mile-wide) passage west of Greenland. Without the arches, ice exited freely from the Arctic. The Fram Strait, east of Greenland, is about 400 kilometers (249 miles) wide and is the passage through which most sea ice usually exits the Arctic.

Despite Nares' narrow width, the team reports that in 2007, ice loss through Nares equaled more than 10 percent of the amount emptied on average each year through the wider Fram Strait.

"Until recently, we didn't think the small straits were important for ice loss," Kwok said. The findings were published this month in Geophysical Research Letters.

"One of our most important goals is developing predictive models of Arctic sea ice cover," said Tom Wagner, cryosphere program manager at NASA Headquarters in Washington. "Such models are important not only to understanding changes in the Arctic, but also changes in global and North American climate. Figuring out how ice is lost through the Fram and Nares straits is critical to developing those models."

To find out more about the ice motion in Nares Strait, the scientists examined a 13-year record of high-resolution radar images from the Canadian RADARSAT and European Envisat satellites. They found that 2007 was a unique year – the only one on record when arches failed to form, allowing ice to flow unobstructed through winter and spring.

The arches usually form at southern and northern points within Nares Strait when big blocks of sea ice try to flow through the strait's restricted confines, become stuck and are compressed by other ice. This grinds the flow of sea ice to a halt.

"We don't completely understand the conditions conducive to the formation of these arches," Kwok said. "We do know that they are temperature-dependent because they only form in winter. So there's concern that if climate warms, the arches could stop forming."

To quantify the impact of ice arches on Arctic Ocean ice cover, the team tracked ice motion evident in the 13-year span of satellite radar images. They calculated the area of ice passing through an imaginary line, or "gate," at the entrance to Nares Strait. Then they incorporated ice thickness data from NASA's ICESat to estimate the volume lost through Nares.

They found that in 2007, Nares Strait drained the Arctic Ocean of 88,060 square kilometers (34,000 square miles) of sea ice, or a volume of 60 cubic miles. The amount was more than twice the average amount lost through Nares each year between 1997 and 2009.

The ice lost through Nares Strait was some of the thickest and oldest in the Arctic Ocean.

"If indeed these arches are less likely to form in the future, we have to account for the annual ice loss through this narrow passage. Potentially, this could lead to an even more rapid decline in the summer ice extent of the Arctic Ocean," Kwok said.

For more information about NASA and agency programs, visit: .

JPL is managed for NASA by the California Institute of Technology in Pasadena.



Alan Buis
Jet Propulsion Laboratory, Pasadena, Calif.

Kathryn Hansen
NASA Goddard Space Flight Center, Greenbelt, Md.

This text derived from:

ICESat's Notable Moments in Science

Over the last decade, NASA has launched a series of satellites to monitor the health of our planet. One such satellite -- the Ice, Cloud and land Elevation Satellite (ICESat) -- has provided a sustained, big-picture look at ice thickness at Earth's polar regions.

Now, after seven years in orbit and 15 laser-operation campaigns, ICESat has stopped collecting science data. The last of three lasers on the satellite's Geoscience Laser Altimeter System (GLAS) ceased emitting light on Oct. 11, 2009. Attempts to restart the lasers have ended, and NASA is pursing options for satellite decommissioning.

"ICESat's loss is disappointing and it comes at a critical time," said Tom Wagner, cryosphere program manager at NASA Headquarters in Washington. "But we can't lose sight of the fact that ICESat and its team of talented scientists and engineers helped us see the Earth's polar ice caps in a new way. Those observations are feeding a new generation of models to help us figure out where the planet is headed.‪‪"

As the world's first laser-altimeter satellite, ICESat has measured Earth's surface and atmosphere in "unprecedented 3-D detail," said Jay Zwally, ICESat's project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "ICESat has been an outstanding success, despite disappointing limitations in the laser lifetimes. Scientific advances have been made in measuring changes in the mass of the Greenland and Antarctic ice sheets, polar sea ice thickness, vegetation-canopy heights, and the heights of clouds and aerosols."

In the Arctic, for example, scientists used ICESat to map Greenland's dramatic surface elevation, rising to 4,000 meters above sea level. They watched as thin, seasonal sea ice replaced thick, older sea ice as the dominant type in the Arctic Ocean. In Antarctica, scientists achieved a comprehensive inventory of lakes that actively drain or fill under the ice. At both poles, they have tracked glaciers along the coast of the Greenland and Antarctic ice sheets as they empty into the sea.

Learn more about the satellite's early days and subsequent discoveries in this Flickr image gallery.

Despite the end of ICESat's mission, NASA's observations of Earth's polar regions continue. Operation Ice Bridge began in 2009, becoming the largest airborne survey of Earth's polar ice ever flown. For the next five years, instruments on NASA aircraft will target areas of rapid change to yield an unprecedented 3-D view of Arctic and Antarctic ice sheets, ice shelves, and sea ice. The mission will bridge the gap in satellite data until the launch of ICESat-2, planned for 2015.

"Operation Ice Bridge is allowing us to get much higher resolution data over smaller, targeted regions," said Lora Koenig of NASA Goddard, and acting project scientist for the Ice Bridge mission.

Targeted information from aircraft combined with the broad and consistent coverage from satellites contribute to a more complete understanding of Earth's response to climate change, helping scientists make better predictions of what the future might hold.

Wednesday, October 28, 2009

What happens when global warming continues?

Human Health
Climate change may affect people's health both directly and indirectly. For example, heat stress and other heat related health problems are caused directly by very warm temperatures and high humidity. Untreated, heat stress can be a very serious medical problem. Scientists suspect that, in many places, climate change will increase the number of very hot days that occur during the year. More hot days increases the possibility of heat related health problems. Indirectly, ecological disturbances, air pollution, changes in food and water supplies, and coastal flooding are all examples of possible impacts that might affect human health. How people and nature adapt to climate change will determine how seriously it impacts human health. Some people and places are likely to be affected more than others. Generally, poor people and poor countries are less likely to have the money and resources they need to cope with preventing and treating health problems. Very young children and the elderly adults will run the highest risks.

Ecological Systems
Climate change may alter the world's habitats and ecosystems – all living things are included in and rely on these places. Many of these places depend on a delicate balance of rainfall, temperature, and soil type. A rapid change in climate could upset this balance and seriously endanger many living things. Most past climate changes occurred slowly, allowing plants and animals to adapt to the new environment or move somewhere else. However, if future climate changes occur as rapidly as some scientists predict, plants and animals may not be able to react quickly enough to survive. The ocean's ecosystems also could be affected for the same reasons.

Sea Level Rise
Global warming make the sea level become higher. Why? Well, warmer weather makes glaciers melt. A glacier is a large sheet of ice that moves very, very slowly. Some melting glaciers add more water to the ocean. Warmer temperatures also make water expand. When water expands in the ocean, it takes up more space and the level of the sea rises.
Sea level may rise between several inches and as much as 3 feet during the next century. This will affect both natural systems and manmade structures along coastlines. Coastal flooding could cause saltwater to flow into areas where salt is harmful, threatening plants and animals in those areas. For example, an increase in the salt content of the Delaware and Chesapeake bays is thought to have decreased the number of oysters able to live in those waters. Oceanfront property would be affected by flooding, and beach erosion could leave structures even more vulnerable to storm waves. Whether we move back from the water or build barricades in the face of a rising sea, it could cost billions of dollars to adapt to such change. Coastal flooding also may reduce the quality of drinking water in coastal areas.

Crops and Food Supply
Global warming may make the Earth warmer in cold places. People living in these places may have a chance to grow crops in new areas. But climate change also might bring droughts to other places where we grow crops. In some parts of the world, people may not have enough to eat because they cannot grow the food that they need.

Tuesday, October 06, 2009

Ultraviolet rays & Skin cancer

Skin cancer is the most common form of cancer in the United States. The two most common types of skin cancer—basal cell and squamous cell carcinomas—are highly curable. However, melanoma, the third most common skin cancer, is more dangerous, especially among young people. About 65%–90% of melanomas are caused by exposure to ultraviolet (UV) light.

Ultraviolet (UV) Light
Ultraviolet (UV) rays are an invisible kind of radiation that comes from the sun, tanning beds, and sunlamps. UV rays can penetrate and change skin cells.
The three types of UV rays are ultraviolet A (UVA), ultraviolet B (UVB), and ultraviolet C (UVC)—
• UVA is the most common kind of sunlight at the earth's surface, and reaches beyond the top layer of human skin. Scientists believe that UVA rays can damage connective tissue and increase a person's risk of skin cancer.
• Most UVB rays are absorbed by the ozone layer, so they are less common at the earth's surface than UVA rays. UVB rays don't reach as far into the skin as UVA rays, but they can still be damaging.
• UVC rays are very dangerous, but they are absorbed by the ozone layer and do not reach the ground.
Too much exposure to UV rays can change skin texture and cause the skin to age prematurely, leading to skin cancer. UV rays also have been linked to eye conditions such as cataracts.

Tuesday, September 15, 2009

10 best tips for a healthy life

• Start your day with breakfast.
Breakfast fills your "empty tank" to get you going after a long night without food. And it can help you do better in school. Easy to prepare breakfasts include cold cereal with fruit and low-fat milk, whole-wheat toast with peanut butter, yogurt with fruit, whole-grain waffles or even last night's pizza!
• Get Moving!
It's easy to fit physical activities into your daily routine. Walk, bike or jog to see friends. Take a 10-minute activity break every hour while you read, do homework or watch TV. Climb stairs instead of taking an escalator or elevator. Try to do these things for a total of 30 minutes every day.
• Snack smart.
Snacks are a great way to refuel. Choose snacks from different food groups - a glass of low-fat milk and a few graham crackers, an apple or celery sticks with peanut butter and raisins, or some dry cereal. If you eat smart at other meals, cookies, chips and candy are OK for occasional snacking.
• Work up a sweat.
Vigorous work-outs - when you're breathing hard and sweating - help your heart pump better, give you more energy and help you look and feel best. Start with a warm-up that stretches your muscles. Include 20 minutes of aerobic activity, such as running, jogging, or dancing. Follow-up with activities that help make you stronger such as push-ups or lifting weights. Then cool-down with more stretching and deep breathing.
• Balance your food choices - don't eat too much of any one thing.
You don't have to give up foods like hamburgers, french fries and ice cream to eat healthy. You just have to be smart about how often and how much of them you eat. Your body needs nutrients like protein, carbohydrates, fat and many different vitamins and minerals such as vitamins C and A, iron and calcium from a variety of foods. Balancing food choices from the Food Guide Pyramid and checking out the Nutrition Facts Panel on food labels will help you get all these nutrients.
• Get fit with friends or family.
Being active is much more fun with friends or family. Encourage others to join you and plan one special physical activity event, like a bike ride or hiking, with a group each week.
• Eat more grains, fruits and vegetables.
These foods give you carbohydrates for energy, plus vitamins, minerals and fiber. Besides, they taste good! Try breads such as whole-wheat, bagels and pita. Spaghetti and oatmeal are also in the grain group.
Bananas, strawberries and melons are some great tasting fruits. Try vegetables raw, on a sandwich or salad.
• Join in physical activities at school.
Whether you take a physical education class or do other physical activities at school, such as intramural sports, structures activities are a sure way to feel good, look good and stay physically fit.
• Foods aren't good or bad.
A healthy eating style is like a puzzle with many parts. Each part -- or food -- is different. Some foods may have more fat, sugar or salt while others may have more vitamins or fiber. There is a place for all these foods. What makes a diet good or bad is how foods fit together. Balancing your choices is important. Fit in a higher-fat food, like pepperoni pizza, at dinner by choosing lower-fat foods at other meals. And don't forget about moderation. If two pieces of pizza fill you up, you don't need a third.
• Make healthy eating and physical activities fun!
Take advantage of physical activities you and your friends enjoy doing together and eat the foods you like. Be adventurous - try new sports, games and other activities as well as new foods. You'll grow stronger, play longer, and look and feel better! Set realistic goals - don't try changing too much at once.

Wednesday, September 02, 2009

Wine may protect skin from harmful radiation

Studies say that wine can lower skin disease in women. Cancer patients before they undergo a radiation treatment are offered red wine. The red wine helps in minimizing the toxic effects of radiation therapy. Wine is mostly offered to breast cancer patients.

Some components like polyphenols and tannins that are present in wine protect against the harmful effects of radiation.

The researchers found that skin effects caused by radiation is
38.4 % in non-drinkers
31.8 % in women drinking only half a glass of wine per day
13.6 % in those drinking one glass of wine per day
35 % in those drinking two glass of wine per day
Women who take only a glass of wine daily had a much lower risk of suffering skin effects from harmful radiation.

Friday, August 28, 2009

The Apple Mac operating system OS X is on sale

The Apple Mac operating system OS X software - accessible only as a DVD, not a download - was at first due to hit shops in September however Apple promoted at the last minute. The system will go head-to-head with Microsoft's latest operating system, Windows 7 that will be release in October.

Both will compete with Google’s OS, called Chrome OS, set for release in the later half of 2010.
The Apple has announced the cost as £25 in UK and $29 in US for Mac users who run OS X 10.4.
Its disadvantage is that, it makes easier for third-party developers to take gain of the Mac hardware.

One the other hand, it is the first operating system to come up with inbuilt support for Microsoft Exchange Server, popular email and calendar services used by many companies.

The systems will also works with a new version of the Quicktime player that will allow users to record and turn up their own movies.

Tuesday, August 11, 2009

Symptoms of Swine Flu

In children, emergency warning signs that need urgent medical attention include:

• Fast breathing or trouble breathing
• Bluish or gray skin color
• Not drinking enough fluids
• Severe or persistent vomiting
• Not waking up or not interacting
• Being so irritable that the child does not want to be held
• Flu-like symptoms improve but then return with fever and worse cough

In adults, emergency warning signs that need urgent medical attention include:

• Difficulty breathing or shortness of breath
• Pain or pressure in the chest or abdomen
• Sudden dizziness
• Confusion
• Severe or persistent vomiting
• Flu-like symptoms improve but then return with fever and worse cough