Warming Threatens Global Food And Water Security
09 October, 2013
Over 80% of the world's ice-free land is at risk of profound ecosystem transformation by 2100 that could threaten food and water security  while the thawing of permafrost in Alaska damages roads, buildings, airport runways, and releases vast amounts of greenhouse gases .
"Essentially, we would be leaving the world as we know it," says Sebastian Ostberg of the Potsdam Institute for Climate Impact Research, Germany.
Ostberg and his colleagues studied the critical impacts of climate change on landscapes.
The study results have been published in Earth System Dynamics, an open access journal of the European Geosciences Union (EGU).
The researchers state in the article that "nearly no area of the world is free" from the risk of climate change transforming landscapes substantially, unless mitigation limits warming to around 2 degrees Celsius above preindustrial levels.
Ecosystem changes could include boreal forests being transformed into temperate savannas, trees growing in the freezing Arctic tundra or even a dieback of some of the world's rainforests. Such profound transformations of land ecosystems have the potential to affect food and water security, and hence impact human well-being just like sea level rise and direct damage from extreme weather events.
The study indicates that up to 86% of the remaining natural land ecosystems worldwide could be at risk of major change in a business-as-usual scenario . This assumes that the global mean temperature will be 4 to 5 degrees warmer at the end of this century than in pre-industrial times -- given many countries' reluctance to commit to binding emissions cuts, such warming is not out of the question by 2100.
"The research shows there is a large difference in the risk of major ecosystem change depending on whether humankind continues with business as usual or if we opt for effective climate change mitigation," Ostberg points out.
But even if the warming is limited to 2 degrees, some 20% of land ecosystems -- particularly those at high altitudes and high latitudes -- are at risk of moderate or major transformation, the team reveals.
The researchers studied over 150 climate scenarios, looking at ecosystem changes in nearly 20 different climate models for various degrees of global warming.
"Our study is the most comprehensive and internally consistent analysis of the risk of major ecosystem change from climate change at the global scale," says Wolfgang Lucht, also an author of the study and co-chair of the research domain Earth System Analysis at the Potsdam Institute for Climate Impact Research. Few previous studies have looked into the global impact of raising temperatures on ecosystems because of how complex and interlinked these systems are. "Comprehensive theories and computer models of such complex systems and their dynamics up to the global scale do not exist."
The team measured simultaneous changes in the biogeochemistry of terrestrial vegetation and the relative abundance of different vegetation species. "Any significant change in the underlying biogeochemistry presents an ecological adaptation challenge, fundamentally destabilizing our natural systems," explains Ostberg.
The researchers defined a parameter to measure how far apart a future ecosystem under climate change would be from the present state. The parameter encompasses changes in variables such as the vegetation structure (from trees to grass, for example), the carbon stored in the soils and vegetation, and freshwater availability.
"Our indicator of ecosystem change is able to measure the combined effect of changes in many ecosystem processes, instead of looking only at a single process," says Ostberg.
He hopes the new results can help inform the ongoing negotiations on climate mitigation targets, "as well as planning adaptation to unavoidable change."
Cathy Richard of North Pole, Alaska, shows her cracked sidewalk (Photo: Wendy Koch, USA TODAY)
A North Pole, Alaska datelined report in USA Today describes problems the residents in the area are facing:
Up the road from Santa Claus Lane, past the candy cane-striped streetlamps, Cathy Richard's backyard has a problem that not even elves — or the big guy in red — could fix.
The wood deck moves up and down, like a slow-motion sleigh. "You leave for work and when you come home, it can be 7 inches higher," says Richard, 36, a married bookkeeper and mom of three children.
She knows the Grinch involved. Her home in this Fairbanks suburb, built in 2007, sits on land that thaws and refreezes so the concrete pillars holding up her deck have crumbled. The front walkway and garage floor are also cracking, and the lumpy lawn has fissures.
The report said:
Warmer temperatures are thawing the surface layer of land that covers most of Alaska and is known as permafrost (frozen below for at least two years in a row.) This thawing not only damages roads, buildings and airport runways, but also releases vast amounts of GHG that further warm the atmosphere — not just over Richard's house but worldwide.
The nation's last frontier is — in many ways — its ground zero for climate change. Alaska's temperatures are rising twice as fast as those in the lower 48, prompting more sea ice to disappear in summer. While this may eventually open the Northwest Passage to sought-after tourism, oil exploration and trade, it also spells trouble as wildfires increase, roads buckle and tribal villages sink into the sea.
On Aug. 26, a worker with the Alaska Department of Transportation secures sheets of polystyrene insulation to a road in Fairbanks, Alaska, that was damaged by permafrost thawing and will be repaved on top of the insulation. The sheets will minimize thawing in the future.(Photo: Wendy Koch, USA TODAY)
The report added:
USA TODAY traveled to the Fairbanks area, where workers were busy insulating thaw-damaged roads this summer amid a record number of 80-degree (or hotter) days, as the eighth stop in a year-long series to explore how climate change is changing lives.
The pace of permafrost thawing is "accelerating," says Vladimir Romanovsky, who runs the University of Alaska's Permafrost Laboratory in Fairbanks. He expects widespread degradation will start in a decade or two. By mid-century, his models suggest, permafrost could thaw in at least a third of Alaska and by 2100, in two-thirds of the state.
"This rapid thawing is unprecedented" and is largely due to fossil-fuel emissions, says Kevin Schaefer of the National Snow and Ice Data Center in Boulder, Colo. He says it's already emitting its own heat-trapping carbon dioxide and methane, but the amount will skyrocket in the next 20 to 30 years. "Once the emissions start, they can't be turned off."
Telltale signs are common — from huge potholes in parking lots to collapsed hill slopes and leaning trees in what are called "drunken forests" in Denali National Park, home of the majestic Mount McKinley — North America's tallest peak.
"You can see and hear the ice melting," says Ted Schuur, a permafrost expert at the University of Florida who's doing field studies in central Alaska. He says permafrost contains soil and plant matter as well as chunks of ice as big as cars. When the ice melts, the ground sinks. He's seen it with his own cabin near Fairbanks, which was listing until he leveled one side with adjustable foundation piers.
Ruth Macchione's old home in Fairbanks, Alaska, shown here on Aug. 26, is sinking into the ground. Her late husband hand-built it with sturdy logs, but the house rests on permafrost -- the top layer of which freezes and thaws each year -- so it's now tilted.(Photo: Wendy Koch, USA TODAY)
The report cites Ruth Macchione, an 84-year-old grandmother in Fairbanks, who has also witnessed the damage.
Ruth and her late husband raised nine children in a home he built more than 50 years ago with logs that he sanded and polished. He lived there until his death in 1986 and she stayed until 2000, when she was forced to move to a small new house next door.
"Everything's tilted," she says, gazing at the old family home that is sinking into the ground. For years, she put furniture and other items on blocks to try to level them, but it got to the point where she could no longer open or close the doors.
"It's a shame," she says sadly of her partly submerged homestead. "It was well-built."
Permafrost thawing emits greenhouse gases
Permafrost has existed for eons. During the last Ice Age, it swept as far south as Missouri and Illinois. Today, most of it is located in Russia and Canada, but the United States accounts for 6% of the world's total — almost all of which exists in Alaska. It has a top "active" layer that thaws and refreezes each year and a deeper layer that remains frozen and stores organic carbon from decaying plants and animals — possibly twice as much carbon as in the atmosphere.
As air temperatures rise, the top layer thickens and more thawing occurs; its pace depends on local conditions. Some areas such as Fairbanks are particularly vulnerable, because the ground temperature now hovers near the thaw point so the permafrost is less stable and thaws less evenly.
The perils of permafrost have long been known. Back in the early 1970s, government scientists insisted that parts of the Trans-Alaska Pipeline be built above ground with refrigerated supports. The pipeline's oil is hot and, if buried underground in permafrost, could help thaw the top layer and cause potential spills.
Yet scientists have just begun in the past five to 10 years to figure out how much carbon is stored in the permafrost and what its accelerated thawing will mean for climate change — and vice versa.
"It's like burning fossil fuels," says Schaefer. He and other permafrost experts have varying estimates on how much carbon dioxide and methane will be released into the atmosphere from thawing. Yet they agree climate change is exacerbating the problem and creating a "feedback loop" or vicious circle in which thawing then exacerbates global warming.
"We're on the edge of a major transition point," Schuur says, pointing to a 2013 report he authored that found tundras worldwide may already be emitting more carbon than they absorb. He says global permafrost emissions will be significant — akin to those from current deforestation — but probably much less than those from power plants, cars and other burning of oil and gas.
These emissions weren't included in the global warming estimates developed by the Intergovernmental Panel on Climate Change (IPCC) and released in September as the first part of its Fifth Assessment Report. The report, which said with heightened certainty that humans are responsible for the planet's rising temperatures, serves as a basis for negotiating future climate treaties.
Many Alaskans are skeptical about the climate link. "Permafrost has been thawing since the last Ice Age," says Jeff Curley, an engineer for the Alaska Department of Transportation, saying its amount depends on naturally-occurring variability. He notes the state's temperatures have fluctuated every 30 or so years.
"When I'm in Alaska, I stop talking about climate change," Schuur says, adding the term has become politically charged. Still, he says Alaskans are deeply concerned about permafrost changes.
"In our region, roads affected by permafrost thawing are very common," Curley says. "There are places around Fairbanks where there's asphalt 10 feet thick, because they were filled in to keep leveling off the road on an annual basis."
Jack Hebert, president of the non-profit Cold Climate House Research Center in Fairbanks, shows on Aug. 27 the triple-paned windows and other materials his staff recommends in building homes that are resilient and energy-efficient.(Photo: Wendy Koch, USA TODAY)
Permafrost isn't Alaska's only climate problem. As its temperatures rise (up 3.4 degrees Fahrenheit year-round in the past 60 years and 6 degrees Fahrenheit in the winter), there's not enough rain to offset the higher amount of evaporation, so surface soils dry up — a drying amplified by thawing permafrost. The result? Increased risk of wildfires.
"All climate impacts are connected to each other," says Sarah Trainor, who directs the Alaska Center for Climate Assessment and Policy at the University of Alaska, noting the state has had more large wildfires in the past two decades than in the prior 40 years. Wildfires emit their own greenhouse gases that intensify global warming.
Declining sea ice creates another vicious circle. Most of the world's sea ice is in the Arctic, and since it reflects sunlight (seawater absorbs it), its loss will accelerate northern warming. And, in turn, higher temperature will melt more ice.
This has happened dramatically in the past 30 years, according to measurements in September, when the extent of sea ice reaches its annual low after a summer of heat. Arctic sea ice hit an all-time low in Sept. 2012 but recovered somewhat last month.
"We could be looking at summers with essentially no sea ice on the Arctic Ocean only a few decades from now," Mark Serreze, director of the University of Colorado-Boulder's National Snow and Ice Data Center, said in announcing its 2013 satellite measurements. Despite yearly ups and downs, he says the long-term trend is downward.
The loss of sea ice offers tantalizing trade opportunities, because it could make the Northwest Passage navigable more often in summer. This sea route across the Arctic Ocean hugs Alaska's coast and can now be crossed only about every seven summers. Sought by explorers for centuries as a short-cut between Europe and Asia, it could be about 50% fewer nautical miles than a trip via the Panama Canal.
Yet while the loss of sea ice could open coastal Alaska to more oil exploration, tourism and shipping, it's not likely to help native Alaskans, says Laurence Smith, a geography professor at the University of California-Los Angeles. He says melting ice may open up the sea but close off the land. Because much of Alaska is traversed in winter by ice — rather than paved — roads, he says its interior will become less accessible.
"We're more likely to see an abandonment of these northern landscapes," says Smith, author of The World in 2050: Four Forces Shaping Civilization's Northern Future.
Schuur sees sea ice loss as a huge problem but worries more about permafrost, because the latter is not as well monitored. "It's a sleeping giant that affects us all."
1. Story Source:
The story is based on materials provided by European Geosciences Union (EGU).
S. Ostberg, W. Lucht, S. Schaphoff, D. Gerten. Critical impacts of global warming on land ecosystems. Earth System Dynamics, 2013; 4 (2): 347 DOI: 10.5194/esd-4-347-2013
European Geosciences Union (EGU) (2013, October 8). Terrestrial ecosystems at risk of major shifts as temperatures increase. ScienceDaily. Retrieved October 9, 2013, from http://www.sciencedaily.com /releases/2013/10/131008091232.htm
2. USA Today, October 8, 2013, Wendy Koch, “Alaska sinks as climate change thaws permafrost”,
3. Even though 86% of land ecosystems are at risk if global temperature increases by 5 degrees Celsius by 2100, it is unlikely all these areas will be affected. This would mean that the worst case scenario from each climate model comes true.
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