Can you feel the world getting warmer? Maybe you can\u2019t, but ice across the planet\u2019s surface has certainly been feeling the heat, according to new reports. Indeed, the dramatic shrinkage of Arctic ice\u2014and at some spots, its seasonal near disappearance\u2014is one sure sign that our planet has developed a fever.<\/p>\n
Glaciers are also melting\u2014and 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.<\/p>\n
\u201cThe latest figures are part of what appears to be an accelerating trend with no apparent end in sight,\u201d said Wilfried Haeberli, who directs the glacier-monitoring group.
\nIn 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\u2019s 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.<\/p>\n
Scientists from the U.S. National Snow and Ice Data Center and the British Antarctic Survey put the blame for the Wilkins\u2019 massive melt-triggered event on a warmer world. \u201cWe believe the Wilkins [Shelf] has been in place for at least a few hundred years,\u201d said Ted Scambos, a lead scientist with the snow and ice data center. \u201cBut warm air and exposure to ocean waves are causing a break-up.\u201d<\/p>\n
With strong evidence that ice is melting globally atop mountains and at Earth\u2019s poles, scientists say that it\u2019s pretty clear our planet is warming. And that could spell big changes even in regions where the only ice you\u2019d normally encounter is in a beverage.<\/p>\n
arctic ice on the rocks<\/strong><\/p>\n Changes in the Arctic\u2019s sea ice offer more cause for concern. That\u2019s the March 18 conclusion of a team of federal scientists who performed a recent checkup on this cold region.<\/p>\n The Arctic is a normally ice-covered ocean surrounded by land. Sea ice grows and shrinks seasonally\u2014building throughout the cold, sunless winter and then melting somewhat during the sunny, warmer summer.<\/p>\n Satellite data has shown that a colder-than-average winter this year has actually increased the amount of the Arctic\u2019s new\u2014or seasonal\u2014ice. However, some ice in this region can last for up to 10 years. This older\u2014or perennial\u2014 sea ice has continued to decline.<\/p>\n \u201cPerennial ice can be very thick and very tough, but there\u2019s much less of it left,\u201d says Walt Meier of the National Snow and Ice Data Center. \u201cThere\u2019s much more seasonal ice, which is weaker and thinner.\u201d It\u2019s also especially vulnerable to the summer sun.<\/p>\n 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 \u201cis going to melt away,\u201d Meier warns. So any winter gains in ice cover \u201care going to be quickly lost.\u201d<\/p>\n 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. \u201cSince the mid 1980s, we\u2019ve lost about a million square miles of perennial ice,\u201d says Meier. \u201cThat\u2019s about one and half times [the size of] the state of Alaska.\u201d<\/p>\n The very old, tough ice that\u2019s 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.<\/p>\n Meier says that this is a record low for perennial ice in winter and a very sharp drop even from last winter. \u201cThere\u2019s this fear,\u201d he says, \u201cthat we\u2019re going over a cliff, in a sense, with this perennial ice.\u201d He says the planet could be heading towards a situation where there won\u2019t 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.<\/p>\n The decline of Arctic sea ice \u201cis an iconic signal of global warming,\u201d Meier says. It\u2019s something that really sticks out \u201cas being clear cut and definitely due to global warming.\u201d<\/p>\n real warming, real warning<\/strong><\/p>\n Most scientists believe people are largely responsible for the warming of Earth\u2019s atmosphere throughout the past century. Their burning of fossil fuels\u2014such as coal, oil, and gas\u2014releases greenhouse gases that trap the sun\u2019s heat.<\/p>\n Until fairly recently, scientists debated whether Earth\u2019s fever was likely to last only a few years or whether it could persist for decades\u2014maybe even longer.<\/p>\n Now the debate appears to be over.<\/p>\n 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 \u201cunequivocal,\u201d the Intergovernmental Panel on Climate Change (IPCC) stated last year in a convincing set of reports.<\/p>\n 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 \u201cunequivocal\u201d was important, she says. The data that the IPCC reviewed were so strong, she explains, that the words \u201cvery likely\u201d just wouldn\u2019t get the point across. There\u2019s a greater than 99 percent chance that our planet has warmed, she says. So there really \u201cjust isn\u2019t any doubt about it.\u201d<\/p>\n The IPCC reports describe possible dramatic and lasting impacts of global warming that may occur. But, cautions Solomon, the warming and impacts that we\u2019ll 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.<\/p>\n 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\u2019s surface temperatures climb, Solomon says. But if we don\u2019t, she warns, by the end of the century Earth\u2019s average temperature could climb somewhere between 2 and 6 degrees Celsius (3.6 to 10.8 degrees Fahrenheit).<\/p>\n \u201cAnd under those circumstances, a lot of things would change,\u201d Solomon says. \u201cWe\u2019d see more drought, more heat waves. We\u2019d also, ironically, see more heavy rainfall. We\u2019d see sea levels rise\u2014and though there\u2019s a lot of uncertainty in how much they\u2019d rise, numbers like half a meter [about 20 inches] wouldn\u2019t surprise me in 100 years.\u201d<\/p>\n Such projections about droughts and sea-level rise aren\u2019t certain. They are simply \u201cbest guesses,\u201d Meier observes. \u201cThey could be wrong,\u201c he says. In fact, he notes, \u201cMany skeptics focus on the fact that things might not be quite as bad as projected.\u201d On the other hand, he points out that the effects of Earth\u2019s fever could prove much worse than scientists have anticipated, \u201cwhich is what we\u2019re already seeing in terms of the rate of ice melt.\u201d<\/p>\n no summer sea ice\u2014soon?<\/strong><\/p>\n 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. \u201cAnd that\u2019s indeed what we\u2019re seeing with the decline of Arctic sea ice,\u201d says Meier.<\/p>\n 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\u2019re finding that changes are occurring \u201cmuch, much faster than the models have projected. The way things are going it\u2019s likely that we\u2019ll have an ice-free Arctic Ocean in the summer within a couple of decades. It could be even sooner.\u201d Indeed, some scientists have speculated summer sea ice could disappear by 2013\u2014only five years from now. \u201cThat\u2019s on the extreme pessimistic edge of the estimates,\u201d Meier says, \u201cbut it\u2019s not implausible any longer.\u201d<\/p>\n 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.<\/p>\n \u201cYou don\u2019t need just one cold summer or one cold winter to turn things around,\u201d he explains. \u201cIt 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\u2019s not very likely.\u201d That\u2019s especially true, he says, because people are still using fossil fuels\u2014and spewing greenhouse gases\u2014at high and growing rates.<\/p>\n Though it may be too late to save the Arctic Ocean from experiencing ice-free summers, \u201cit\u2019s not too late to prevent the worst of the impacts of global warming,\u201d Meier argues. \u201cThe sea ice is an early warning and we can heed that warning. There is hope and there are solutions.\u201d<\/p>\n Next week: Part 2: What\u2019s behind global warming, and what can we do?<\/strong><\/p>\n Can you feel the world getting warmer? Maybe you can\u2019t, but ice across the planet\u2019s surface has certainly been feeling the heat, according to new reports. Indeed, the dramatic shrinkage of Arctic ice\u2014and at some spots, its seasonal near disappearance\u2014is … Continue reading This article appeared in the April 23, 2008 issue of the online science magazine <\/em>Science News for Kids.<\/h6>\n","protected":false},"excerpt":{"rendered":"