Crisis in a northern sea: can marine animals survive warming waters? Science World Editor Patricia Janes sails with researchers to find out.

Tiny snowflakes pelt my face as a cold wind blasts my body. I zip my heavy coat up to my chin. Still, it's not enough to escape the chill. Like a turtle ducking into its shell for safety, I lift up my shoulders and tuck my head down. Just moments ago, the sky was clear. But the weather in Dutch Harbor--a port in Alaska's Aleutian Island--can change in a flash.

Dutch Harbor's landscape is as dramatic as its weather. The region's islands--filled with snow-capped mountain--jut up dramatically from the Bering Sea, the body of water between mainland Alaska and Siberia, Russia (see map, above). This remote area may be best known for its harrowing wintertime waves. Viewers of the Deadliest Catch, a TV series about the region's king-crab fishermen, have seen these waves toss boats around like toys.

But today, the seas are relatively calm. I stand on the dock and watch as a mammoth red and white ship pulls into port. The U.S. Coast Guard cutter Healy is the most technologically advanced icebreaker in its polar fleet. Members of the Coast Guard affectionately call the Healy "420 feet of ice-breaking steel." But for the next 30 days, I will call this ship--which is longer than a football field--home.

The Healy is designed to slice through sea ice up to 2.5 meters (8 feet) thick. That makes it the ideal floating laboratory for researchers investigating Earth's polar regions. Jackie Grebmeier and Lee Cooper, both oceanographers from the University of Tennessee, have invited me to join them onboard the cutter and assist their team of scientists as they study the changes that are taking place in the Bering Sea.

SEA CHANGE

"The northern Bering Sea is warming," says Cooper over dinner. The Healy has just set sail, and I am sitting with Cooper at a metal table lined with a long rubber mat. Its sticky grip keeps the cafeteria-style trays in place as the ship rolls with each unsettling wave.

For 20 years now, Cooper and Grebmeier have sailed the Bering Sea for weeks at a time to study its environment. Their years of collected data show that the region's air and water temperatures are rising. These changes are even evident to the naked eye. People native to the region, whose ancestors have lived there for thousands of years, are seeing signs of a diminishing amount of seasonal sea ice. The ice also melts earlier than it used to.

But the Bering Sea isn't alone in its hot spell. As people around the world burn oil and other fossil fuels, heat-trapping greenhouse gases like carbon dioxide get released into the atmosphere. As these gases build up, the entire planet warms. In response to global warming, or an increase in Earth's average temperature, animals and plants all over the planet are on the move (see Nuts & Bolts, p. 17).

"Crabs and fish from the southern Bering Sea are moving northward into the warming waters," says Jim Lovvorn, an ecologist from the University of Wyoming who is also aboard the Healy. The newcomers are slowly settling into waters that were once too cold for their taste. For the area's native animals, such as walruses, these new neighbors mean increased competition for food and habitat.

DIGGING FOR DATA

Cooper tells me that one of my onboard duties is to help the team study the region's animals. So the next morning I head to the Healy's rear deck, where most of the scientific research takes place. Every person working on the deck must wear a survival suit. The suit has built-in flotation and insulation that would help me survive if I were to fall overboard. I suit up and get to work.

Twenty-four hours a day, seven days a week, the deck buzzes with experiments. The ship sails to various sampling stations that Cooper and Grebmeier have visited in past years. They revisit these locations to collect data and take stock of the plant and animal species that live in each spot.

This long-term data set will help them learn more about the sea's changing conditions over time.

At each site we lower a huge metal scooper to the seafloor and grab a chunk of mud. The scientists collect a portion of the mud to take back to their universities for further study. We sift the rest through a screen to catch the small creatures living inside the mud.

During the final activity at each station, the scientists lower a large net to the seafloor. They signal the ship's crew members to sail the Healy slowly--about the speed that a person rims--for 20 minutes. As the ship moves, the net trawls along the seafloor, gathering bottom-dwelling animals such as clams, crabs, sea stars, and fish.

TRAWLING FOR ANSWERS

Once the net is up, everyone works to sort the catch by species. "We'll look at our catches to learn about the diets, densities, growth rates, and food requirements of the various animals," says Lovvorn. "This will help us understand the food web in the northern Bering Sea."

The crabs and fish that are moving up from the south are bottom feeders--they eat things like clams that live on the seafloor. But bearded seals and other animals that are adapted to ice eat similar foods. The scientists want to find out how many relocated crabs and fish are now competing with the ice-adapted species for food. As competition for food in the Bering Sea increases, the current ice-adapted populations could suffer and decline in numbers, explains Grebmeier.

During a break, I peer through binoculars to survey my surroundings. Two black and white birds flap into view--they're spectacled eiders. These rare sea ducks can dive roughly 70 meters (230 feet) to the shallow seafloor to reach their favorite meal: clams. The northern Bering Sea is this bird's sole wintering site. If this species loses its food source, it could become extinct, or die out. With that thought, I watch the birds disappear from view. It's time to get back to work.

web extra

While on the Healy, Science World Editor Patricia Janes (above) wrote journals describing the science taking place. Check out at: www.scholastic.com/globalwarming

cool tips

You can fight global warming by reducing your use of fossil fuels. Get started with these three tips.

1. Don't just turn off your TV or stereo--unplug it. Any appliance that has a remote control or permanent display uses energy, even when it's switched off.

2. Set your computer and printer's sleep function to go on after five minutes of inactivity.

3. It takes energy to heat water, so take shorter showers.

nuts & bolts

In response to a warming world, animals and plants are relocating to cooler areas. Below are some species in North America that are trekking northward or to higher elevations in search of relief from the heat.

1 Invertebrate species like snails and sea stars are moving northward, likely due to a rise in water and air temperatures.

2 Sub-alpine forests are invading alpine meadows, partly in response to warming temperatures.

3 The distribution of the Edith's checker-spot butterfly, which extends from the west coast of southern Canada through northern Mexico, is shrinking.

4 Robins are migrating from low to high elevations, where temperatures are cooler. The birds now breed two weeks earlier than they did in the late 1970s.

5 The distribution of the American alligator, which ranges from the Carolinas south to Florida and west to Texas, seems to be shifting northward in some areas.

STAY TUNED for the December 12 installment of Science World's global warming series from the Healy. Until then, check out the tips on page 16 for ways in which you can reduce your energy consumption--and help to curb global warming.

EARTH: Climate Change

Crisis in a Northern Sea

PRE-READING PROMPTS

Jump-start your lesson with these pre-reading questions:

* In 2003, the scientific journal Nature published an article that stated that global warming is causing many animals to shift their habitat ranges. A study of more than 1,700 plant and animal species showed that, on average, species are moving toward Earth's poles at a rate of 6.1 kilometers (3.8 miles) per decade in search of cooler climates. Can you name one animal in California that has moved northward?

CRITICAL THINKING

* Many national and state parks have been established ill the United States to protect precious landscapes and properties from development. Many animals rely on these protected parks for survival. What might happen to them if they have to shift their range north of the parks due to global warning?

CROSS-CURRICULAR CONNECTIONS

MATH: According to the Nebraska Public Power District, electricity usage in your home can be broken down as follows: water heating, 14 percent; cooling, 7 percent; space heating, 48 percent; appliances and lighting, 31 percent. Create a pie chart using the data above. How much more electricity does your house use to power appliances and lights than for heating water? Answer: 17 percent.

RESOURCES

* To learn more about global warming, be sure to check out Science World's special Web site on the topic: www.scholastic.com/globalwarming

* Every U.S. state has a state bird. As a result of global warming, many of the birds are moving north of their usual ranges to find cooler habitats. How is your state bird faring? Find out at: www.nwf.org/birdsandglobalwarming/statebirds.cfm

PAGE (14) Crisis in a Northern Sea

DIRECTIONS: Answer the following questions in complete sentences.

1. Where is the Bering Sea located?

2. What are four signs that the northern Bering Sea is warming?

3. How does human activity contribute to global warming?

4. Why are crabs and fish from the southern Bering Sea moving northward into the northern Bering Sea?

5. How might the crabs and fish that are moving up from the south disturb the food web in the northern Bering Sea?

Crisis in a Northern Sea

1. The Bering Sea is the body of water between mainland Alaska and Siberia, Russia.

2. Scientists' years of collected data show that the Bering Sea region's air and water temperatures are rising. People native to the region, whose ancestors have lived there for thousands of years, are seeing signs of a diminishing of amount of seasonal sea ice. The ice also melts earlier than it used to.

3. As people around the world burn oil and other fossil fuels, heat-trapping greenhouse gases like carbon dioxide get released into the atmosphere. As these gases build up, the entire planet warms.

4. In response to global warming, crabs and fish from the southern Bering Sea are moving northward. They are slowly settling into waters that were once too cold for their taste.

5. The crabs and fish that are moving up from the south are bottom feeders. They eat things like claims that live on the seafloor. But ice-adapted animals like bearded seals also eat similar foods. As competition for food in the Bering Sea increases, the current ice-adapted populations could suffer and decline in numbers.