agnieszka biskup — writer & editor

The debate about global warming appears to be pretty much over. A majority of climate scientists now agree that it’s occurring and there seems no end to the accumulating evidence that rising temperatures are causing changes all over the planet.

The yellow jacket population in Alaska, for example, has undergone a significant increase during the past decade. One effect of the insect’s growing numbers is that in 2006, Fairbanks experienced its first two sting-related deaths. “We think warmer temperatures are allowing the insects to thrive,” says Jeffrey Demain, director of an allergy immunology center in Anchorage. Demain presented his findings in March in Philadelphia at the annual meeting of the American Academy of Allergy, Asthma and Immunology.

Another symptom comes from plants: Leaves are emerging earlier in Eurasia’s northern forests in the spring. Researchers in France, the United Kingdom, Japan and Russia reported the finding in the March Global Change Biology. When leaves pop out depends largely on temperature in the northern hemisphere.

And some marine mammals may need special government protection because the icy environment they depend on is melting away. For instance, on March 26, the National Oceanic and Atmospheric Administration announced it was considering whether to list four types of seals as species threatened or endangered with extinction. At issue: Arctic sea ice is melting rapidly and could disappear entirely during polar summers fairly soon. Ribbon, bearded, spotted and ringed seals-the species in question-rely on sea ice for spots on which to rest, to mate and to have pups.

A second federal agency, the U.S. Fish & Wildlife Service, is evaluating whether polar bears should be listed as a threatened species for similar reasons. These bears are completely dependent upon Arctic sea ice for their hunting grounds.

But the warming is affecting more than seals and polar bears. “There’s going to be a widespread impact on the whole ecosystem of the Arctic, and the whole world,” says Walt Meier, a research scientist who studies Arctic ice at the National Snow and Ice Data Center in Boulder, Colo.

Why is our planet running a fever? That’s what scientists are investigating, and some of their findings are disturbing. But there are things that the public can do to potentially bring down that fever. Even kids.

understanding earth’s fever

At its simplest, global warming is the rise in the average temperature of Earth’s atmosphere. Since the 1950s, the planet has been experiencing a warming trend.
In a convincing set of reports issued last year by the Intergovernmental Panel on Climate Change (IPCC), scientists argued that it’s very likely that this warming trend has been caused by an increase of carbon dioxide and other greenhouses gases in the atmosphere. (See below: “Global Warming and the Greenhouse Effect.”)

The reports also blamed people and their actions for much of the increase in levels of these gases in the atmosphere. For instance, the IPCC linked increasing amounts of carbon dioxide-the most important of the greenhouse gases-primarily to humans’ use of fossil fuels, such as coal, oil, and natural gas.

The IPCC reports show that all but one of the years between 1995 and 2006 rank among the 12 warmest since 1850. That’s when scientists first began measuring surface temperatures across the globe. During the past century, the planet’s average temperature has risen about 0.74° Celsius (or 1.33° Fahrenheit). Satellite data since 1978 show that annual average Arctic sea ice has shrunk by 2.7 percent per decade. In addition, mountain glaciers and snow cover have declined all over the world. These decreases are all consistent with global warming.

Shrinking Arctic sea ice and retreating glaciers are both key and quick-responding indicators of global warming, says Meier. Long ago, coal miners brought caged canaries into their mines as a type of early-warning signal. If the birds died, it meant that toxic gases were building up in the mine, and that the workers were in trouble. Some scientists now view what’s happening to glaciers and Arctic ice as the climate equivalent of canaries in the coal mine. Once sea ice and glaciers begin to undergo serious melting, Meier says, “You know you’re having some kind of climate change.”

changes to the planet

The IPCC reports predict that by 2100, Earth’s average global temperature will have climbed by anywhere from 1.1 to 6.4° C (2 to 11.5° F). But global warming is about more than just temperature, says Susan Solomon. She’s a senior scientist at NOAA in Boulder, Colo., and led one of the IPCC working groups.

“We’ll also see changes in drought and rainfall, which will affect our ability to grow food,” Solomon says. “[Global warming] is about extremes of temperature and rainfall, and there are a lot of open questions about, for example, whether hurricanes become more intense as you have a warmer world.” What there’s no question about, she says, is that when climate changes, people will be affected.

Heavy rainfalls, warm spells and heat waves will all very likely become more common than they are today, the IPCC reports say. Heat waves can be deadly, especially for the very young or very old. The heat wave that struck Europe in 2003, for example, killed thousands of people.

Global warming also affects sea levels. As temperatures climb, glaciers and portions of the polar ice sheets start to melt. The glaciers’ melting will swell the size of Earth’s oceans, increasing their depth. Moreover, as ocean water warms, it expands, which makes it take up even more space.

Melting ice and expanding seawater are already making sea levels climb about 3 millimeters (one-eighth of an inch) each year, according to the IPCC reports. If sea levels continue to rise, coastal cities and small island nations will be in trouble. Some areas could become submerged. Remaining low-lying regions could be at risk of flooding during storms or a scouring away by waves along the coasts.

The environment could also suffer dramatically. Plants, insects, birds and other animals could lose their homes or sources of food. And, Solomon says, “There’s evidence that changes in temperature and other climate variables can cause extinction.”

The loss of Arctic sea ice will affect more than wildlife, says Meier. “The climate system is all interconnected,” he notes, “so you’re going to see changes in ocean currents, in winds and in weather patterns.” People throughout the world, but especially in the Northern Hemisphere, should expect to experience some impacts, he warns.

Disappearing sea ice will also add to the warming trend, Meier says. Because snow and ice are white, the Arctic acts like a big mirror-it reflects a lot of the sun’s rays. When you remove the ice through melting, you expose more ocean. Because the water’s very dark, almost black, it reflects less of the sun’s energy, and absorbs more of it. This leads to still more warming, which leads to still more ice melting, and so on.

So once this process gets underway, “you have the potential for the loss of sea ice to accelerate and for this to contribute even more to global warming,” Meier says. A warmer ocean can transfer its heat, he adds, further warming the atmosphere.

what to do

Global warming is a serious issue affecting the entire planet. But people working together can find answers to environmental problems. The IPCC reports offer recommendations for government leaders on ways to reduce fossil-fuel use, thereby reducing carbon-dioxide emissions. One way: begin substituting alternative energy sources, such as solar, wind, tidal and wave power for the burning of oil, gas and coal.

Solomon says that it’s important “to get involved in the issue, understand the issue and express your opinions, and get your family to express their opinions to [government leaders]” in Washington D.C. and elsewhere.

Even kids can have an impact, prompting changes within their families. Transportation-cars, trucks and airplanes-contribute a large share of carbon dioxide into the air, Solomon says. So one way to limit those emissions would be to encourage your family to walk or ride a bike for simple trips. You might also encourage your parents to buy a car that sips gasoline, not a vehicle that guzzles it. And remind your family that running several errands at one time will result in fewer car trips and less greenhouse-gas pollution.

Anything kids can do to conserve energy and avoid releasing extra carbon dioxide helps, Meier adds. This includes everything from installing energy-efficient compact-fluorescent light bulbs to turning down the thermostat (put on an extra sweater to stay warm). “If you get enough people working together, then you definitely start making a difference,” he says.

Keep in mind, Solomon points out, that what people do today could “affect the lives of their children and of their children’s children and the children of their children’s children.”
Overall, Solomon concludes, if countries around the world don’t reduce emissions of carbon dioxide, “the world will get a lot warmer in the next hundred or even maybe several hundred years. We have to decide whether we want to live in that world.”

global warming and the greenhouse effect

Earth’s atmosphere works something like a giant glass greenhouse. As the sun’s rays enter our atmosphere, most continue right down to the planet’s surface. As they hit the soil and surface waters, those rays release much of their energy as heat. Some of the heat then radiates back out into space.

However, certain gases in our atmosphere, such as carbon dioxide, methane and water vapor, work like a blanket to retain much of that heat. This helps to warm our atmosphere. The gases do this by absorbing the heat and radiating it back to Earth’s surface. These gases are nicknamed “greenhouse gases” because of their heat-trapping effect. Without the “greenhouse effect,” Earth would be too cold to support most forms of life.

But you can have too much of a good thing. Carbon dioxide is released when we use fossil fuels, such as coal, oil and natural gas. We burn these fuels, made from the ancient remains of plants and animals, to run electricity-generating plants that power factories, homes and schools. Products of these fossil fuels, such as gasoline and diesel fuel, power most of the engines that drive cars, airplanes and ships.

By examining air bubbles in ice cores taken from Antarctica, scientists can go back and calculate what the concentrations of carbon dioxide in the atmosphere have been throughout the last 650,000 years. The amount of carbon dioxide in the atmosphere has been climbing to where today it is 30 percent greater than 650,000 years ago. That rise in carbon dioxide “is essentially entirely due to the burning of fuels,” Susan Solomon says. She’s a senior scientist with the National Oceanic and Atmospheric Administration, in Boulder, Colo., and studies factors that affect climate.

Humans have further increased the levels of greenhouse gases in the air by changing the landscape. Plants take up carbon dioxide to make food in a process called photosynthesis. Once cut down, they can no longer take in carbon dioxide, and this gas begins building up in the air instead of fueling the growth of plants. So by cutting down trees and forests for farmland and other human uses, more carbon dioxide is also added into the atmosphere.

“We’ve always had some greenhouse gases in the atmosphere,” Solomon says. “But because we’ve burned a lot of fossil fuels and deforested parts of the planet, we’ve increased the amount of greenhouse gases, and as a result have changed the temperature of the planet.”

This article appeared in the May 5, 2008 issue of the online science magazine Science News for Kids.

Can you feel the world getting warmer? Maybe you can’t, but ice across the planet’s surface has certainly been feeling the heat, according to new reports. Indeed, the dramatic shrinkage of Arctic ice—and at some spots, its seasonal near disappearance—is one sure sign that our planet has developed a fever.

Glaciers are also melting—and not only at the poles. Around the world these massive moving fields of ice have been posting record losses. The World Glacier Monitoring Service, based at the University of Zurich in Switzerland, looked at nearly 30 reference glaciers in nine different mountain ranges across the globe. In March, its scientists reported disturbing news. The average melting and thinning rate of those glaciers has more than doubled between the years 2004 and 2006.

“The latest figures are part of what appears to be an accelerating trend with no apparent end in sight,” said Wilfried Haeberli, who directs the glacier-monitoring group.
In Antarctica, a large chunk of the Wilkins Ice Shelf recently collapsed into the sea. Satellite images show the Wilkins Shelf began falling apart in late February, when a large iceberg 41 kilometers by 2.5 kilometers (25.5 miles by 1.5 miles) broke away from the shelf. This triggered a runaway disintegration of an additional 405 square kilometers (160 square miles) of the shelf. The total loss was 8.5 times the area covered by New York’s Manhattan island. As of March 23, only a 6 km (3.7 mile) wide strip of intact ice was protecting the shelf from further collapse.

Scientists from the U.S. National Snow and Ice Data Center and the British Antarctic Survey put the blame for the Wilkins’ massive melt-triggered event on a warmer world. “We believe the Wilkins [Shelf] has been in place for at least a few hundred years,” said Ted Scambos, a lead scientist with the snow and ice data center. “But warm air and exposure to ocean waves are causing a break-up.”

With strong evidence that ice is melting globally atop mountains and at Earth’s poles, scientists say that it’s pretty clear our planet is warming. And that could spell big changes even in regions where the only ice you’d normally encounter is in a beverage.

arctic ice on the rocks

Changes in the Arctic’s sea ice offer more cause for concern. That’s the March 18 conclusion of a team of federal scientists who performed a recent checkup on this cold region.

The Arctic is a normally ice-covered ocean surrounded by land. Sea ice grows and shrinks seasonally—building throughout the cold, sunless winter and then melting somewhat during the sunny, warmer summer.

Satellite data has shown that a colder-than-average winter this year has actually increased the amount of the Arctic’s new—or seasonal—ice. However, some ice in this region can last for up to 10 years. This older—or perennial— sea ice has continued to decline.

“Perennial ice can be very thick and very tough, but there’s much less of it left,” says Walt Meier of the National Snow and Ice Data Center. “There’s much more seasonal ice, which is weaker and thinner.” It’s also especially vulnerable to the summer sun.

The Arctic remains dark for all or part of each day throughout much of the winter. When the sun returns in the spring and a warming begins, the seasonal ice “is going to melt away,” Meier warns. So any winter gains in ice cover “are going to be quickly lost.”

Perennial ice used to cover 50 to 60 percent of the Arctic, according to data collected by the National Aeronautics and Space Administration. This year it covers less than 30 percent. “Since the mid 1980s, we’ve lost about a million square miles of perennial ice,” says Meier. “That’s about one and half times [the size of] the state of Alaska.”

The very old, tough ice that’s been around for six years or more also has declined. Once making up more than 20 percent of the Arctic area in the mid- to late 1980s, it now covers just six percent of the region.

Meier says that this is a record low for perennial ice in winter and a very sharp drop even from last winter. “There’s this fear,” he says, “that we’re going over a cliff, in a sense, with this perennial ice.” He says the planet could be heading towards a situation where there won’t be any perennial ice left in the near future. Only seasonal ice would exist, which means that the Arctic Ocean would be ice-free during the summer.

The decline of Arctic sea ice “is an iconic signal of global warming,” Meier says. It’s something that really sticks out “as being clear cut and definitely due to global warming.”

real warming, real warning

Most scientists believe people are largely responsible for the warming of Earth’s atmosphere throughout the past century. Their burning of fossil fuels—such as coal, oil, and gas—releases greenhouse gases that trap the sun’s heat.

Until fairly recently, scientists debated whether Earth’s fever was likely to last only a few years or whether it could persist for decades—maybe even longer.

Now the debate appears to be over.

There is a scientific consensus, which means an agreement among the vast majority of researchers in the field, that global warming is not a temporary blip. The pattern of worldwide warming appears to signal a true and potentially very long-term change in climate. Indeed, global warming is “unequivocal,” the Intergovernmental Panel on Climate Change (IPCC) stated last year in a convincing set of reports.

Susan Solomon is a senior scientist at the National Oceanic and Atmospheric Administration in Boulder, Colo., who led one of the IPCC working groups. Using the word “unequivocal” was important, she says. The data that the IPCC reviewed were so strong, she explains, that the words “very likely” just wouldn’t get the point across. There’s a greater than 99 percent chance that our planet has warmed, she says. So there really “just isn’t any doubt about it.”

The IPCC reports describe possible dramatic and lasting impacts of global warming that may occur. But, cautions Solomon, the warming and impacts that we’ll see in the next century depend a lot on how much carbon dioxide we emit. Carbon dioxide, a pollutant emitted as fossil fuels burn, is a major greenhouse gas.

How severely the climate changes and precisely when and where those changes occur remain uncertain. If humanity drastically reduced its emissions of greenhouse gases, such as carbon-dioxide emissions, we could reduce how high Earth’s surface temperatures climb, Solomon says. But if we don’t, she warns, by the end of the century Earth’s average temperature could climb somewhere between 2 and 6 degrees Celsius (3.6 to 10.8 degrees Fahrenheit).

“And under those circumstances, a lot of things would change,” Solomon says. “We’d see more drought, more heat waves. We’d also, ironically, see more heavy rainfall. We’d see sea levels rise—and though there’s a lot of uncertainty in how much they’d rise, numbers like half a meter [about 20 inches] wouldn’t surprise me in 100 years.”

Such projections about droughts and sea-level rise aren’t certain. They are simply “best guesses,” Meier observes. “They could be wrong,“ he says. In fact, he notes, “Many skeptics focus on the fact that things might not be quite as bad as projected.” On the other hand, he points out that the effects of Earth’s fever could prove much worse than scientists have anticipated, “which is what we’re already seeing in terms of the rate of ice melt.”

no summer sea ice—soon?

The Arctic has shown the most rapid rates of warming in recent years. Surface air temperatures there have warmed at roughly twice the global rate, according to the IPCC reports. Science has predicted that the first signs of global warming would show up first and most dramatically in the Arctic. “And that’s indeed what we’re seeing with the decline of Arctic sea ice,” says Meier.

The IPCC reports have concluded that the Arctic Ocean could lose its summer sea ice by the latter part of the century. Meier cautions, however, that such estimates are based on computer models. Those models are not up to date. In fact, he says, we’re finding that changes are occurring “much, much faster than the models have projected. The way things are going it’s likely that we’ll have an ice-free Arctic Ocean in the summer within a couple of decades. It could be even sooner.” Indeed, some scientists have speculated summer sea ice could disappear by 2013—only five years from now. “That’s on the extreme pessimistic edge of the estimates,” Meier says, “but it’s not implausible any longer.”

He thinks the complete disappearance of summer sea ice in the Arctic is probably unavoidable. The warming trend is just too strong and seems to be accelerating.

“You don’t need just one cold summer or one cold winter to turn things around,” he explains. “It would take many, many cold years in a row to reverse things and get things back to the way they were in the 1980s. And that’s not very likely.” That’s especially true, he says, because people are still using fossil fuels—and spewing greenhouse gases—at high and growing rates.

Though it may be too late to save the Arctic Ocean from experiencing ice-free summers, “it’s not too late to prevent the worst of the impacts of global warming,” Meier argues. “The sea ice is an early warning and we can heed that warning. There is hope and there are solutions.”

Next week: Part 2: What’s behind global warming, and what can we do?

This article appeared in the April 23, 2008 issue of the online science magazine Science News for Kids.

You add like a monkey. No, really. Recent experiments with rhesus macaques suggest that monkeys do high-speed addition in much the same way as people do.

Duke University researchers Elizabeth Brannon and Jessica Cantlon tested college students’ ability to add numbers as quickly as possible without counting. The researchers compared the students’ performance with that of rhesus macaques taking the same test. Both the monkeys and the students typically answered in about a second. And their test scores weren’t all that different.

The scientists say that their findings support the idea that some forms of mathematical thinking use an ancient skill, one that people share with their nonhuman ancestors.

“These data are very good for telling us where our sophisticated human minds came from,” says Cantlon.

The research is an “important milestone,” says animal-math researcher Charles Gallistel of Rutgers University in Piscataway, N.J., because it sheds light on how the ability to do math developed.

Monkeys aren’t the only nonhuman animals with math skills. Previous experiments have shown that rats, pigeons, and other creatures also have some kinds of abilities to do rough calculations, says Gallistel. In fact, his research suggests that pigeons can even do a form of subtraction.

Brannon says she wanted to come up with a math test that would work for both adult humans and monkeys. Previous experiments were good at testing monkeys, but they didn’t work as well for people.

In one such experiment, for example, Harvard University researchers put some lemons behind a screen as a monkey watched. Then, as the monkey continued to observe, they put a second group of lemons behind the screen. When the researchers lifted the screen, monkeys saw either the correct sum of the two groups of lemons or an incorrect sum. (To reveal incorrect sums, the researchers added lemons when the monkeys weren’t looking.)

When the sum was incorrect, the monkeys seemed surprised: They stared longer at the lemons, suggesting they were expecting a different answer. An experiment such as this is a good way to test toddlers’ math skills, but not the most effective way to measure such skills in adults.

So Brannon and Cantlon developed a computer-based addition test, which both people and monkeys (after some training) could do. First, one set of dots flashed on a computer screen for a half-second. A second set of dots appeared after a short delay. Finally the screen showed two boxed sets of dots, one representing the correct sum of the previous sets of dots and the other displaying an incorrect sum.

To respond to the test, subjects, which included 2 female rhesus macaque monkeys and 14 college students, had to tap a box on the screen. The researchers recorded how often the monkeys and students tapped the box with the correct sum. The students were told to tap as quickly as possible, so that they wouldn’t have the advantage of counting out an answer. (Students were also told not to count the dots.)

In the end, the students beat the monkeys–but not by much. The humans were right about 94 percent of the time; the macaques averaged 76 percent. Both the monkeys and the students made more mistakes when the two sets of answers differed by only a few dots.

The study only measured the ability to approximate sums, and people are still better than animals at complicated math problems. In other words, it probably wouldn’t be a good idea to hire a monkey as a math tutor!

This article appeared in the January 9, 2008 issue of the online science magazine Science News for Kids.