THE DEFINITIVE BLOG FOR EVERYTHING YOU NEED TO KNOW ABOUT THE ENVIRONMENT YOU LIVE IN, WITH REFERENCE TO LIFE, EARTH AND COSMIC SPACE SCIENCES, PRESENTED BY ENVIRONMENTAL ENGINEER DORU INDREI, ENVIRONMENTAL QUALITY AND ENERGY SPACIALIST
"Life is not about what we know, but what we don't know, craving the unthinkable makes it so amazing, that is worth dying for."Doru Indrei
F-22 Raptor stealth fighters at Langley Air Force Base in Virginia have been grounded after a pilot experienced oxygen loss mid-flight. It’s the second stand-down this year for the U.S. military’s most sophisticated dogfighter, and a foreboding sign for the Pentagon as it struggles to modernize its aerial armada.
Problems with the on-board oxygen system have vexed the $150-million-a-copy F-22 for more than a year. On May 3, the Air Force locked down the entire Raptor fleet while it investigated reports of pilot blackouts and disorientation — problems that might have contributed to a fatal F-22 crash in Alaska in November.
Investigators suspected a design flaw in the Raptor’s oxygen generator that was allowing high levels of unbreathable nitrogen to leak into the pilot’s air supply.
But they could never pin down the precise flaw, and last month the Air Force brass ordered the 170 F-22s — accounting for nearly half of the Pentagon’s air-superiority force — back into the air.
“We now have enough insight from recent studies and investigations that a return to flight is prudent and appropriate,” said Gen. Norton Schwartz, the Air Force chief of staff.
As added insurance, Raptor squadrons installed an extra air filter on the radar-evading jets built by Lockheed Martin. But the filter appears not to have solved the problem, if the Virginia incident is any indication.
The Air Force is being cagey about the new grounding.
“Part of our protocol is to allow units to pause operations whenever they need to analyze information collected from flight operations to ensure safety,” the flying branch said in a statement. “That is what is happening at Langley at the moment, and we support that decision.”
Considering the Raptor’s ongoing safety woes and continuing delays, cost overruns, maintenance woes and production cuts in the F-35 stealth fighter program, the Pentagon’s next-generation air arsenal is looking more and more like history’s most expensive hangar decoration. With many of the latest fighters unflyable, old-school F-15s and F-16s dating from the 1980s could be forced to hold the line for years to come.
Researchers in Alaska have tracked a female polar bear swimming for 232 consecutive hours, during which time she covered 687 kilometers (427 miles) until she finally reached the sea ice of the Arctic Ocean. The finding underlines the enormous capacity of polar bears to survive in the water, but also demonstrates the immense cost to them of having to do so for long periods. By the end of the ordeal, the bear had lost 22 percent of her body mass, and her yearling cub had apparently died.
Writing in the journal Polar Biology, George Durner of the United States Geological Survey and colleagues describe capturing an adult female bear and her cub on Alaska's Beaufort Sea coast in late August 2008. Around the adult's neck, the researchers placed a radio collar with GPS unit, satellite uplink, and an accelerometer to monitor the bear's activity rate independent of the GPS measurements. (She was one of 13 bears so equipped by the researchers that month.)
The bear weighed 226 kg (498 lbs), and the yearling weighed 159 kg (350 lbs). When the scientists found the bear again, two months later, she weighed just 177 kg (390 lbs) and was not lactating; the yearling was nowhere to be seen.
By analyzing the recovered data and overlaying the bear's movements with ice charts, Durner and colleagues deduced that on 25 August (two days after capture and release) she entered the water off the Beaufort Sea coast and swam north for nine days, before finally reaching sea ice. She then spent three days on the ice, another day swimming, and a further 49 days on the sea ice before being found again.
The researchers write that although polar bears are marine mammals, in that they derive their nutrition from the ocean (i.e. they eat seals), they are not aquatic mammals. They can swim reasonably well and survive for long periods in the water, but they pay a high energetic cost for doing so. (Durner and colleagues were unable to determine whether this particular bear had recovered some of her weight by eating seals after hauling out on to the ice, or whether her condition had continued to deteriorate, perhaps as a consequence of patrolling an area of ice that was not rich in hunting opportunities.)
The question might reasonably be asked: Why did the bear keep swimming? Why didn't she at some point turn around? The answer seems to be that, simply, late August is the period when polar bears in northern Alaska head north on to the sea ice, and that is what she was doing. It is what polar bears are programmed to do, and there is nothing in their mental toolkit that would lead them to believe that ice wouldn't be just around the figurative corner, as long as they headed in the right direction.
Which, for the great majority of the time that polar bears have been polar bears, has been a reasonable assumption. But in 2008, Arctic sea ice extent was the second-lowest on record, with losses particularly acute in the Beaufort Sea. At the time this bear and her cub took their plunge, the ice was well over 500 km (320 miles) north of the Alaska coast.
As Arctic sea ice continues to decline, situations such as that confronted by this female bear could become more common, with even more severe consequences, an observation previously made in a 2006 paper in Polar Biology. In that paper, Charles Monnett and Jeffrey Gleason reported that, during aerial observations from 1987 to 2003, they saw 315 polar bears, of which just 12 were in open water. All 315 bears were alive. But in 2004, they saw 55 bears, of which 51 were alive. Ten of those 51 were found in open water, as were all four of the dead bears. And while it could not be proven that those four bears had drowned, it could reasonably be inferred that they had died in the water.
Monnett and Gleason speculated that "mortalities due to offshore swimming during late-ice (or mild ice) years may be an important and unaccounted source of natural mortality," and suggested that "drowning-related deaths of polar bears may increase in the future if the observed trend of regression of pack ice and/or longer open water periods continues."
Off Svalbard a male eats a young polar bear, a behavior that leaner times could accentuate
The Arctic is warming so fast that by 2050 it may be largely ice free in summer. Without their frozen hunting platform, how will polar bears survive?
In August 1881 the naturalist John Muir was sailing off Alaska aboard the steamer Thomas Corwin, searching for three vessels that had gone missing in the Arctic. Off Point Barrow he spotted three polar bears, "magnificent fellows, fat and hearty, rejoicing in their strength out here in the bosom of the icy wilderness."
Were Muir to sail off Point Barrow in August today, any polar bears he'd see would not be living in a wilderness of ice but swimming through open water, burning precious fat reserves. That's because the bears' sea-ice habitat is disappearing. And it's going fast.
Polar bears ply the Arctic niche where air, ice, and water intersect. Superbly adapted to this harsh environment, most spend their entire lives on the sea ice, hunting year-round, visiting land only to build maternal birthing dens.
They prey mainly on ringed and bearded seals (it's been said that they can smell a seal's breathing hole from more than a mile away) but sometimes catch walruses and even beluga whales.
Sea ice is the foundation of the Arctic marine environment. Vital organisms live underneath and within the ice itself, which is not solid but pierced with channels and tunnels large, small, and smaller. Trillions of diatoms, zooplankton, and crustaceans pepper the ice column. In spring, sunlight penetrates the ice, triggering algal blooms. The algae sink to the bottom, and in shallow continental shelf areas they sustain a food web that includes clams, sea stars, arctic cod, seals, walruses—and polar bears.
A polar bear rides a summer sea-ice raft off Norway's Svalbard archipelago. Sea ice provides crucial habitat for the Arctic's top predator, but warming temperatures are creating extended ice-free periods that tax bears.
Experts estimate the world's polar bear numbers at 20,000 to 25,000, in 19 subpopulations. Bears in Svalbard (the Norwegian archipelago where Florian Schulz made most of these photographs), the Beaufort Sea, and Hudson Bay have been studied the longest. It was in western Hudson Bay, where ice melts in the summer and freezes back to shore in the fall, that the creatures' predicament first came to light.
Ian Stirling, now retired from the Canadian Wildlife Service, has monitored polar bears there since the late 1970s. He found that they gorged on seals in the spring and early summer, before breakup, then retreated to land as the ice melted. In a good year, breakup found bears packing a thick layer of fat. Ashore, the bears entered a state known as walking hibernation, their metabolisms on idle to hoard their fat stores. "Until about the early 1990s at Hudson Bay," Stirling says, "bears were able to fast through the open-water season of summer and fall because hunting on the spring sea ice was so good."
During subsequent years of bear-watching, Stirling and a colleague, Andrew Derocher, began to see an alarming pattern. They observed that although the bears' population held steady, the animals were getting thinner. The western Hudson Bay bears were missing vital weeks of peak seal hunting, and the later winter freeze-up was extending their fast. By 1999 the biologists had correlated a steady decline in most measures of polar bear health with a decline in sea ice. Bears didn't grow as large, and some came ashore notably skinnier. Females gave birth less often and had fewer cubs. Fewer cubs survived.
Svalbard male (background) stalk a female with two cubs, alert to danger.
When that same year Stirling and his colleagues published their findings, it was still possible to doubt that warming in the Arctic had already affected polar bears. In a 1999 interview Steven Amstrup, chief scientist at Polar Bears International, who had studied bears in the Beaufort Sea since 1980 for the U.S. Geological Survey, said he hadn't yet seen the kind of changes Stirling had. Or had he? "My aha! moment," Amstrup recalls, "was when I realized the difficult time I'd been having getting out onto the ice to conduct my autumn fieldwork was not just an odd year or two but a prolonged and worsening trend. Shortly thereafter we began to see the same biological changes in our bears as well."
The world didn't know it yet, but during the summer in the Arctic Ocean, sea ice had been melting earlier and faster, and the winter freeze had been coming later. In the three decades since 1979 the extent of summer ice has declined by about 30 percent. The lengthening period of summer melt threatens to undermine the whole Arctic food web, atop of which stand polar bears.
Data have since bolstered the early warning signs. Since Muir set out in the Corwin, greenhouse gases have contributed to an average warming of the Earth of about one degree Fahrenheit. This may seem negligible, but even one degree of warming can noticeably disrupt an environment of ice and snow. It's as if a giant hand has trained a magnifying glass over the Pole.
The sea ice above the shallow continental shelves provides the richest sustenance for polar bears, but recently the ice has been retreating far from those areas, reducing the summer habitat bears need most to survive. Whether a polar bear lives in Hudson Bay or the Beaufort or Barents Seas, it faces the same problem. Sea ice on which to hunt is available for progressively shorter periods, forcing bears to fast for longer periods. And because thinner sea ice is more easily shifted by winds and currents, bears may be swept into strange territory, forcing them to make longer, more arduous swims in open water to find favorable sea ice or to get to land.
Polar bears are strong swimmers, but swimming long distances in open water is draining and can be fatal. In 2008 a radio-collared bear with a yearling cub swam an astounding 427 miles to reach the ice off the northern Alaska coast. The cub didn't make it. Researchers counting bowhead whales in September 2004 spotted four dead polar bears afloat after a storm in the Beaufort Sea. Scientists estimated that as many as 27 bears may have drowned in that one storm.
Impervious to a dive-bombing arctic tern, a hungry bear on the shore of Hudson Bay uses up energy prowling for tern eggs. Summers dry-dock bears around the bay, where biologist Ian Stirling has linked shrinking sea ice to skinnier bears and smaller litters.
Females face especially hard times. Malnourished males may kill and eat cubs—and even their mothers—behavior scientists believe may become more common as food diminishes. Increasingly, getting to ancestral denning places on land can be an ordeal. On one island in Svalbard, when the sea has frozen late in the year, scientists have seen few, if any, dens the following spring. That's when they'd normally see 20 or more, Jon Aars, of the Norwegian Polar Institute, says. Whether females find other sites or skip a year of breeding, Aars can't say.
From childhood we create a picture of our physical world: The sky is blue, the Arctic is white. But before this century ends—and perhaps much sooner—most of the Arctic is predicted to be blue water every summer.
Ashore on Svalbard, a male polar bear investigates a whale's backbone. Fat reserves from hunting ringed and bearded seals, and sometimes walruses, must carry bears through lean summers.
Can a blue Arctic support polar bears? Only in the short run, Amstrup and Stirling say.
Currents still cram drifting sea ice against the Canadian Arctic Islands and northern Greenland in summer, creating pockets that may retain enough ice to support polar bears through this century.
If we can reduce the warming of the atmosphere, Amstrup says, it will not be too late for polar bears, but "if the world keeps warming, ultimately even those last refuges will fail to sustain the icon of the Arctic."
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