2010 Diary week 34
Global warming, climate change and weather extremes
Book Review
Part II of With Speed and Violence: Why Scientists Fear Tipping Points in Climate Change by Fred Pearce is posted below. These are some snippets: “Welcome to the Anthropocene, a new geological era. A single species is in charge of the planet, altering its features almost at will.” “The big new discovery is that planet Earth does not generally engage in gradual change. Abrupt change seems to be the norm, not the exception.” “We have been lured into a false sense of security by the relatively quiet climatic era during which our modern complex civilizations have grown and flourished. It may have left us unexpectedly vulnerable as we stumble into a new era of abrupt change.” “A 2002 report from the U.S. National Academy of Sciences sounded a warning: ‘Recent scientific evidence shows that major and widespread climate changes have occurred with startling speed. The new paradigm of an abruptly changing climate system has been well established by research over the last decade, but this new thinking is little known and scarcely appreciated in the wider community of natural and social scientists and policy makers.’”
WITH SPEED AND VIOLENCE
WHY SCIENTISTS FEAR TIPPING POINTS IN CLIMATE CHANGE
FRED PEARCE
BEACON PRESS 2007
PART II
Chapter 4: The Anthropocene: A new name for a geological era
· Welcome to the Anthropocene, a new geological era. A single species is in charge of the planet, altering its features almost at will.
· The big new discovery is that planet Earth does not generally engage in gradual change. Abrupt change seems to be the norm, not the exception.
· We have been lured into a false sense of security by the relatively quiet climatic era during which our modern complex civilizations have grown and flourished. It may have left us unexpectedly vulnerable as we stumble into a new era of abrupt change.
· A 2002 report from the U.S. National Academy of Sciences sounded a warning: “Recent scientific evidence shows that major and widespread climate changes have occurred with startling speed. The new paradigm of an abruptly changing climate system has been well established by research over the last decade, but this new thinking is little known and scarcely appreciated in the wider community of natural and social scientists and policy makers.”
· Twenty years ago a hole suddenly opened in the ozone layer over Antarctica, stripping away the continent’s protective shield against ultraviolet radiation. We were lucky that it happened over Antarctica, and lucky that we spotted it before it spread too far.
· Many of the scientists who unravelled the cause of the ozone hole have analysed ice cores from both Greenland and Antarctica to map the patterns of past natural climate change. The results have been chilling.
· 12.000 years ago, as the last ice age waned and ice sheets were in full retreat across Europe and North America, the warming abruptly went into reverse.
· For a thousand years the world returned to the depths of the ice age, only to emerge again with such speed that, “roughly half of the entire warming between the ice ages and the postglacial world took place in only a decade.”
· The world warmed by at least 9 degrees – the IPCC’s prediction for the next century or so – within ten years.
· Similar switchback temperature changes occurred regularly through the last glaciation, and there were a number of other “flickers” as the planet staggered toward a new postglacial world.
· Heaven knows how modern human society would respond to such a change, whereby London would have a North African climate, Mexican temperatures would be visited on new England, and India’s billion-plus population would be deprived of the monsoon rains that feed them.
· It seems that the 100,000-year cycles of ice ages and interglacials that have persisted for around a million years have coincided with a minor wobble in Earth’s orbit.
· Somehow Earth’s systems amplify its impact, turning a minor cooling into an abrupt freeze or an equally minor warming into a sudden defrost.
· The amplification certainly involves greenhouse gases. The extraordinary way in which temperatures and carbon dioxide levels have moved in lockstep permits no other interpretation.
· It also probably involves changes to ocean currents and the temperature feedbacks from growing and melting ice.
· The planet seems primed to leap into and out of glaciation and, perhaps, other states too.
· The glacial state seems to have been anchored at carbon dioxide levels of around 190 ppm, while the interglacial state, which the modern world occupied until the Industrial Revolution, was anchored at about 280 ppm.
· The rapid flip between the two states must have involved a reallocation of about 220 billion tons of carbon between the oceans, land, and the atmosphere. Carbon was buried in the oceans during the glaciations and reappeared afterward.
· In the past two centuries, humanity has injected about another 220 billion tons of carbon into the atmosphere, pushing carbon dioxide levels up by a third, from the stable interglacial level of 280 ppm to the present 380 ppm, rising by about 20 ppm per decade.
· The past 10,000 years, since the end of the last ice age, have not been without climate change. The Asian monsoon has switched on and off; deserts have come and gone; Europe and North America have flipped from medieval warm period to the little ice age.
· None of these events has been as dramatic as the waxing and waning of the ice ages themselves. But most were equally abrupt, and civilizations have come and gone in their wake.
· In the Anthropocene, the rules of the game have changed. Humanity is today pushing planetary life-support systems toward their limits. The stakes are higher, because what is happening is global.
· We don’t have an exit option. We don’t have another planet.
Chapter 5: The Watchtower: Keeping climate vigil on an Arctic island
· I had come to Ny-Alesund, an international community of scientists on the Arctic watchtower on the northwest shores of Spitzbergen, the largest island of a cluster of Arctic islands called Svalbard, where our comfy, climatically benign world might begin to end. Where nature may start to take its revenge.
· Says Jack Kohler, of the Norwegian Polar Institute, down south in Tromso: “If you want to see the world’s climate system flip, you’d probably best come here to see it first.”
· Spitzbergen is already one of the epicentres of climate change. For a few days in July 2005, the scientists put aside their instruments, donned T-shirts and shorts, and sipped lager by the glaciers in temperatures that hit a record 68°F – just 600 miles from the North Pole.
· In the summer of 2005, British glaciologists discovered that the nearby Midtre Lovenbreen glacier had lost 12 inches of height in a single week as it melted in the sun. The Kronebreen glacier may be dumping close to 200,000 acre-feet of ice into the fjord every year.
· Jack Kohler reckons that 20 million acre-feet melts and runs off into the ocean each year now. Another 3 million acre-feet is lost from icebergs slumping into the sea from 620 miles of ice cliffs. At most, half of this loss is being replaced with new snow.
· That is an annual net loss of around 11 million acre-feet – a staggering volume for a small cluster of islands, and probably second in the Arctic only to the loss from the huge ice sheet covering Greenland.
· And there is more to come, Kohler says. Many of Svalbards’s glaciers and ice caps are close to the freezing point and “very sensitive to quite small changes” in temperature.
· Boreholes drilled into the permafrost show a staggering 0.7°F warming in the past decade. A few more tenths of a degree could be catastrophic, he says.
· Svalbard has long been recognized as extremely sensitive to climate variations. In the 20th century, during a period of modest warming in much of the Northern Hemisphere, temperatures rose here by as much as 9°F – a figure probably not exceeded anywhere on the planet.
· Ny-Alesund is a place where climate feedbacks like melting sea ice and changes in winds and ocean currents work with special force. Only about 100 miles out to sea, Wadham’s last chimney may be living out its final days.
· Svalbard is a place to watch like a hawk, and not just for changing climate. The ozone layer is on a hair trigger here, too. Many researchers expect a giant ozone hole to form over the Arctic one day soon, just as it did in the Antarctic 25 years ago.
· Sometimes it rains mercury here, as industrial pollution cruises north and suddenly, within a matter of minutes, precipitates onto the snow.
· Pesticides, too, have arrived in prodigious quantities, apparently from the fields of Asia.
· The summit of Mount Zeppelin, 1,600 feet above the settlement, is the top of the top of the world – the ultimate watchtower for the world’s climate. Carbon dioxide levels in the air have increased more sharply than at other monitoring stations around the world. Some days he measures levels approaching 390 ppm – fully 10 ppm above the global average.
· Carl Peter Niesen says that it seems as if fast-rising emission from the power plants and cars in China and India are travelling north on the winds with the mercury and the pesticides and the acid haze.
· Not for the first time, he has caught a whiff of the future here at the top of the world.
PART II. FAULT LINES IN THE ICE
Chapter 6: Ninety Degrees North: Why melting knows no bounds in the far North
· Sailing north from Svalbard in August 2000 on one of the world’s most powerful icebreakers, the researchers were amazed to find not pack ice but a mile-wide expanse of clear blue water. The whole Arctic was remarkably ice-free that summer.
· NASA satellites, which had been photographing the ice for a quarter century, offered the most incontrovertible evidence. Analyst-in-chief Ted Scambos reports annually on how the retreat of ice is turning into a rout.
· In 2005, just 2 million square miles of ice were left in mid-September, the usual date of minimum ice cover. That was 20% less than in 1978.
· Feedbacks in the system are starting to take hold. The winter refreeze is less complete every year; the spring melt is starting ever earlier – 17 days earlier than usual in 2005.
· With all that dark, open water, you start to see an increase in Arctic ocean heat storage.
· Most glaciologists agree with Scambos that the root cause of the great melt is Arctic air temperatures that have risen by about 3°F to 5°F in the past 30 years – several times the global average.
· Warmer air above the ice is being accompanied by warmer waters beneath. In February 2004, a thermostat strapped to a buoy recorded a jump in water temperature of half a degree within a few hours. The warm water stayed, the rise proved permanent, and the Laptev Sea rapidly became ice free.
· “The Arctic Ocean is in transition toward a new, warmer state,” says Polyakov. And most glaciologists working in the Arctic agree.
· Without the reflective shield of ice, the whole world would warm several more degrees. Ocean and air currents driven by temperature differences between the poles and the tropics would falter; on land, methane and other gases would break out of the melting permafrost, raising temperatures further; and as the ice caps on land melted, sea levels would rise so high that much of the world’s population would have to move or drown.
· If the Arctic is especially sensitive to climate change, the whole planet is especially sensitive to changes in the Arctic.
Chapter 7: On the Slippery Slope
· The world’s three great ice sheets – one over Greenland and the other two over Antarctica – contain vast amounts of ice. Leftovers from the last ice age, they are piles of compressed snow almost 2 miles high.
· For many centuries these great ice sheets have been in balance, with ice loss at the edges matched by accumulation in the centers.
· If the ice sheets all melted, or slumped into the ocean, they would make a big splash. They contain enough ice to raise sea levels worldwide by 230 feet.
· Small lakes have always formed on the surface of Greenland ice in the summer sun, sometimes emptying down flaws in the ice known as moulins.
· Waterfalls as high as 2 miles are taking surface water to the very base of the ice, where it meets the bedrock.
· Every year Jason Box visits Swiss Camp, set up in 1990 on the equilibrium line where the summer ice melt exactly matches the accumulation of new snow in winter.
· The equilibrium line has moved many miles north, as ever-larger chunks of Greenland find themselves in the zone of predominant melting.
· “Some of these lakes are three or four miles across and have lasted for a decade or more now. These lakes keep growing and growing until they find a crevasse into which they drain. Down there are extensive river systems between the ice and hard rock that eventually emerge at the glacier snout.. There may be great lakes, too.”
· Jay Zwally, one of Hansen’s colleagues at NASA, discovered that during warm years the half-mile thick ice lifts off the bedrock and floats on the water – rising half a yard or more at times. And it floats towards the ocean. Swiss Camp is already more than a mile west of where it started.
· In summer acceleration starts a few days after the melting begins at the surface and stops when melting ceases in the autumn.
· “We used to think that it would take 10,000 years for melting at the surface to penetrate down to the bottom of the ice sheet. But if you make a lake on the surface and a crack opens and the water goes down the crack, it doesn’t take 10,000 years, it takes ten seconds. That huge lag time is completely eliminated.”
· Greenland melting seems to have set in around 1979, and has been accelerating ever since. In 2006 NASA reported the results of a detailed satellite radar study showing a loss of 180-million acre-feet of ice every year.
· Swiss Camp is in the upper catchment of a glacier known as Jakobshavn Isbrae. It is now the world’s fastest moving glacier, at better than 7 miles a year.
· “What is most surprising is how quickly this massive volume of ice can respond to warming,” says Box.
· Jakobshavn, he estimates, could be shedding more than 40 million acre-feet a year, an amount of water close to the flow of the world’s longest river, the Nile. Half that volume is water flowing out to sea from beneath the glacier, and half is calving glaciers.
· The Kangerdlugssuaq glacier, which drains 4% of the ice sheet, was flowing into the sea three times faster in the summer of 2005 than when last measured in 1988. At an inch a minute, its movement was visible to the naked eye. Its snout has retreated by three miles in four years.
· The picture then is of great flows of ice draining out of Greenland, lubricated by growing volumes of meltwater draining from the surface to the base of the ice sheet and uncorked by melting ice shelves at the coast.
· “The whole Greenland hydrological system has become more vigorous, more hyperactive,” says Box. “It is a very non-linear response to global warming, with exponential increases in the loss of ice. I’ve seen it with my own eyes. Even five years ago we didn’t know about this.”
· “Building an ice sheet takes a long time – many thousands of years,” says Hansen. “It is a slow, dry process inherently limited by the snowfall rate. But destroying it, we now realize, is a wet process, spurred by positive feedbacks, and once under way it can be explosively rapid.”