H.D. Pritchard, RJ. Arthern, D.G. Vaughan & L.A. Edwards, Nature 461 (2009): Extensive dynamic thinning on the margins of the Greenland and Antarctic ice sheets

Nature 461, 971-975 (15 October 2009); doi: 10.1038/nature08471

Extensive dynamic thinning on the margins of the Greenland and Antarctic ice sheets

Hamish D. Pritchard^*,1, Robert J. Arthern¹, David G. Vaughan¹ and Laura A. Edwards²

1. British Antarctic Survey, Natural Environment Research Council, Madingley Road, Cambridge CB3 0ET, U.K.
2. School of Geographical Sciences, University of Bristol, Bristol BS8 1SS, U.K.

(Received 23 October 2008; accepted 28 August 2009; published online 23 September 2009.)

Abstract

Many glaciers along the margins of the Greenland and Antarctic ice sheets are accelerating and, for this reason, contribute increasingly to global sea-level rise^{1, 2, 3, 4, 5, 6, 7}. Globally, ice losses contribute 1.8 mm yr^-1 (ref. 8), but this could increase if the retreat of ice shelves and tidewater glaciers further enhances the loss of grounded ice⁹ or initiates the large-scale collapse of vulnerable parts of the ice sheets¹⁰. Ice loss as a result of accelerated flow, known as dynamic thinning, is so poorly understood that its potential contribution to sea level over the twenty-first century remains unpredictable¹¹. Thinning on the ice-sheet scale has been monitored by using repeat satellite altimetry observations to track small changes in surface elevation, but previous sensors could not resolve most fast-flowing coastal glaciers¹². Here we report the use of high-resolution ICESat (Ice, Cloud and land Elevation Satellite) laser altimetry to map change along the entire grounded margins of the Greenland and Antarctic ice sheets. To isolate the dynamic signal, we compare rates of elevation change from both fast-flowing and slow-flowing ice with those expected from surface mass-balance fluctuations. We find that dynamic thinning of glaciers now reaches all latitudes in Greenland, has intensified on key Antarctic grounding lines, has endured for decades after ice-shelf collapse, penetrates far into the interior of each ice sheet and is spreading as ice shelves thin by ocean-driven melt. In Greenland, glaciers flowing faster than 100 m yr^-1 thinned at an average rate of 0.84 m yr^-1, and in the Amundsen Sea embayment of Antarctica, thinning exceeded 9.0 m yr^-1 for some glaciers. Our results show that the most profound changes in the ice sheets currently result from glacier dynamics at ocean margins.

*Correspondence and requests for materials, e-mail: hprit@bas.ac.uk

Link to abstract: http://www.nature.com/nature/journal/v461/n7266/abs/nature08471.html

Richard Van Noorden, Nature blog, The Great Beyond, "Ice-sheets fading faster"

Ice-sheets fading faster

by Richard Van Noorden, Nature blog, The Great Beyond, September 24, 2009

The edges of ice sheets in Greenland and the Antarctic are thinning faster than we’d thought, thanks to a surprisingly extensive network of fast-flowing and accelerating glaciers, new satellite measurements show (Nature, doi:10.1038/nature08471).

"We were surprised to see such a strong pattern of thinning glaciers across such large areas of coastline – it's widespread and in some cases thinning extends hundreds of kilometres inland. We think that warm ocean currents reaching the coast and melting the glacier front is the most likely cause of faster glacier flow. This kind of ice loss is so poorly understood that it remains the most unpredictable part of future sea level rise," said Hamish Pritchard, of the British Antarctic Survey [press release].

"This report provides a much more ominous picture than we have had, and a depressing prospect of the potential for sea level rise," Inez Fung, an atmospheric scientist at UC Berkeley, told the San Francisco Chronicle. "It's very much a cause for worry."

Pritchard and other researchers analysed some 50 million laser readings from Nasa’s ICESat (Ice, Cloud and land Elevation Satellite) between 2003 and 2007. 81 of 111 Greenland glaciers surveyed are thinning at an accelerating, self-feeding pace, AP highlights. While in parts of Antarctica, ice sheets have been losing 30 feet a year in thickness since 2003 (though there’s plenty of ice to get through – some of these areas are a mile thick). “To some extent, it’s a runaway effect. The question is, how far will it run?” Pritchard tells them.
That’s what everyone wants to know, and the scientists were careful to point out that it was “too early to determine whether the thinning was a sign that sea level rise would accelerate” (Reuters).

Image credit: British Antarctic Survey

Posted by Richard Van Noorden on September 24, 2009

Link:  http://blogs.nature.com/news/thegreatbeyond/2009/09/icesheets_fading_faster.html 

Hamish Pritchard, Nature study, Satellite lasers measure more thinning of Greenland and Antarctic ice sheets

Lasers from space show thinning of Greenland and Antarctic ice sheets

September 23rd, 2009 
 

The most comprehensive picture of the rapidly thinning glaciers along the coastline of both the Antarctic and Greenland ice sheets has been created using satellite lasers. The findings are an important step forward in the quest to make more accurate predictions for future sea level rise.

Reporting this week in the journal Nature researchers from British Antarctic Survey and the University of Bristol describe how analysis of millions of NASA satellite measurements* from both of these vast ice sheets shows that the most profound ice loss is a result of glaciers speeding up where they flow into the sea.
The authors conclude that this 'dynamic thinning' of glaciers now reaches all latitudes in Greenland, has intensified on key Antarctic coastlines, is penetrating far into the ice sheets' interior and is spreading as ice shelves thin by ocean-driven melt. Ice shelf collapse has triggered particularly strong thinning that has endured for decades.

Lead author Dr Hamish Pritchard from British Antarctic Survey (BAS) says, "We were surprised to see such a strong pattern of thinning glaciers across such large areas of coastline - it's widespread and in some cases thinning extends hundreds of kilometres inland. We think that warm ocean currents reaching the coast and melting the glacier front is the most likely cause of faster glacier flow. This kind of ice loss is so poorly understood that it remains the most unpredictable part of future sea level rise."

The scientists compared the rates of change in elevation of both fast-flowing and slow-flowing ice. In Greenland for example they studied 111 fast-moving glaciers and found 81 thinning at rates twice that of slow-flowing ice at the same altitude.They found that ice loss from many glaciers in both Antarctica and Greenland is greater than the rate of snowfall further inland.

In Antarctica some of the fastest thinning glaciers are in West Antarctica (Amundsen Sea Embayment) where Pine Island Glacier and neighbouring Smith and Thwaites Glacier are thinning by up to 9 metres per year.

More information: Extensive dynamic thinning on the margins of the Greenland and Antarctic ice sheets by Hamish D. Pritchard, Robert J. Arthern, David G. Vaughan & Laura A. Edwards is published online this week in the journal Nature (Advanced Online Publication).

Source: British Antarctic Survey (news : web)

Link:  http://www.physorg.com/news172931543.html

Hamish Pritchard, Nature study using lasers measures more glacial ice loss than previously thought

Thinner ice than expected in Greenland, Antarctica

September 23, 2009

Buzz up!

The thinning of ice sheets in Greenland and western Antarctica is far more extensive than was previously thought, according to new research published online today in the British journal Nature.

A new method of anaylzing the ice loss -- using laser measurements from a satellite -- was key to the discovery, and will likely lead to further research into this key component of climate change. The rate of glacial ice loss is important because it can cause sea levels to rise rapidly around the world.

Led by Hamish Pritchard of the British Antarctic Survey, the study found that the most profound ice loss from these two vast ice sheets is a result of glaciers speeding up where they flow into the sea.

The “thinning of Greenland and Antarctic ice-sheet ocean margins is more sensitive, pervasive, enduring and important than previously realized,” wrote the authors in the study.

In some parts of Antarctica, ice sheets have been losing 30 feet a year in thickness since 2003, according to the study.

"We were surprised to see such a strong pattern of thinning glaciers across such large areas of coastline – it's widespread and in some cases thinning extends hundreds of kilometres inland, said Pritchard.

“We think that warm ocean currents reaching the coast and melting the glacier front is the most likely cause of faster glacier flow. This kind of ice loss is so poorly understood that it remains the most unpredictable part of future sea level rise."

It’s so poorly understood that the Intergovernmental Panel on Climate Change, in its 2007 report, didn’t include glacial melt in their assessment of future global sea-level rise, which they predicted to be anywhere from seven to 23 inches by the end of the century.

“This could push it toward the high end of that range,” said Pritchard. “It’s a wake up call to look at the extent of this problem.”

The research team used 50 million laser readings from NASA's ICESat (Ice, Cloud and Land Elevation Satellite), which was launched in 2003 to study changes in the world's ice and land masses.

By Doyle Rice (The Associated Press contributed to this article.)

Photo: Image from ICEsat data shows the pattern of surface height change over the Antarctic and Greenland ice sheets for the 2003-2008 period (red shows lowering). Rapid lowering is concentrated on the ice streams and glaciers that drain West Antarctica and Greenland. (Pritchard)

Link:  http://blogs.usatoday.com/sciencefair/2009/09/thinner-ice-than-expected-in-greenland-antarctica.html

Crossing planetary boundaries (irreversible tipping points, or points of no return as James Hansen calls them), Nature study by Rockstrom et al.

23 Sep 2009: Analysis

Provocative New Study Warns of Crossing Planetary Boundaries

The Earth has nine biophysical thresholds beyond which it cannot be pushed without disastrous consequences, the authors of a new paper in the journal Nature report. Ominously, these scientists say, we have already moved past three of these tipping points.

by Carl Zimmer, environment360, September 23, 2009

Human civilization has had a stable childhood. Over the past 10,000 years, as our ancestors invented agriculture and built cities, the Earth remained relatively stable. The average global temperature fluttered slightly, never lurching towards a greenhouse climate or chilling enough to enter a new Ice Age. The pH of the oceans remained steady, providing the right chemical conditions for coral reefs to grow and invertebrates to build shells. Those species, in turn, helped support a stable food web that provided plenty of fish for us humans to catch. The overall stability of the past 10,000 years may have played a big part in humanity’s explosion.

Now, ironically, civilization has become so powerful that it can reshape the planet itself. “We have become a force to contend with at the global level,” as Johan Rockstrom of the Stockholm Resilience Center in Sweden, puts it. Humans have changed the chemistry of Earth’s oceans, turning them acidic. We are shifting the composition of the atmosphere, raising levels of carbon dioxide higher than they’ve been in at least the past 800,000 years."

A number of scientists have warned in recent years that if we keep pushing the planet this way, we will cause sudden, irreversible damage to the systems that made human civilization possible in the first place. Typically, they’ve just focused on one of these tipping points at a time. But in today’s issue of the journal Nature, Rockstrom and 27 of his fellow environmental scientists argue that we have to conceive of many tipping points at once. They propose that humans must keep the planet in what they call a “safe operating space,” inside of which we can thrive. If we push past the boundaries of that space — by wiping out biodiversity, for example, or diverting too much of the world’s freshwater — we risk catastrophe.

Unfortunately, the authors of the Nature paper maintain, we’ve already started pushing out beyond these boundaries without knowing where they actually are. “We’re sitting on top of a mesa right now, and we’re driving

Nature

CLICK TO ENLARGE: Overstepping the world’s “planetary boundaries”

around, but we don’t have our lights on and we don’t even have a map,” says Jonathan Foley, a co-author of the new study and the director of the University of Minnesota’s Institute on the Environment. “That’s a dangerous way to move around.”

In their new study, Foley and his colleagues put down stakes to mark where they believe seven of these boundaries lie. By their estimate, we have already pushed beyond three of these boundaries, and are moving quickly toward the other four. “We’re running out of time,” says Rockstrom.

The new paper has already drawn strong reactions from other scientists, some glowing, some harsh. “This kind of work is critically important,” says Christopher Field, the director of the Department of Global Ecology at the Carnegie Institution at Stanford University. “Overall, this is an impressive attempt to define a safety zone.”

But other scientists wonder whether a planetary safety zone is a concept worth bothering with. “I don’t think this is in any way a useful way of thinking about things,” says Stuart Pimm, a conservation biologist at Duke University.

Rockstrom and his colleagues developed the concept of planetary boundaries from earlier work on how natural systems change. Those changes are sometimes gradual, but they can also come in jolts. A lake, for example, can absorb a fair amount of phosphorus from fertilizer runoff

In five areas, the scientists found, the world has not yet reached the danger threshold.

without any sign of change. “You add a little, not much happens,” says Shahid Naeem of Columbia University, who was not involved in the Nature paper. “Add a little more, not much happens. Add a little... then, all of sudden, you add a little more and — boom! — phytoplankton bloom, oxygen depletion, fish die-off, smelliness. Remove the little phosphorus that caused the tipping of the system, and it does not reverse. In fact, you have to go back to much cleaner water than you would have imagined.”

In recent years, some scientists have argued that the entire planet behaves in a similar way. Adding extra greenhouse gases can raise the planet’s temperature in a steady, proportional rate. But there may come a point when the climate will get pushed into a drastically new state. Some climate scientists have argued, for example, that global warming may trigger the runaway collapse of ice sheets in Greenland and Antarctica. Even if we then immediately stopped emitting greenhouse gases, the ice sheets would keep collapsing into the sea. And then we couldn’t do anything to reverse the change. “We don’t know how to refreeze the Greenland ice sheet,” says Rockstrom.

Rockstrom helped organize a workshop in Stockholm in April 2008 where environmental scientists talked about the other possible thresholds that might exist on a global scale. They concluded that there was good evidence for nine kinds of thresholds: climate change, ocean acidity, the ozone layer, freshwater use, the movement of nitrogen and phosphorus, the amount of land used for crops, aerosols (haze and other particles), biodiversity, and chemical pollution.

The scientists then reviewed each of those factors to mark boundaries that the world should not push beyond. “The idea is to say, ‘Let’s put up some guard rails,’” says Robert Costanza of the University of New Hampshire. “Maybe the guard rails are for a slope we could have taken and survived, but maybe not. We owe it to human civilization to be more careful.”

Ultimately, the scientists felt confident in estimating seven boundaries, three of which we have already pushed past. For one thing, they argue, we’ve already put too much carbon dioxide in the atmosphere. James Hansen, a NASA climate scientist and co-author of the Nature paper, has argued that to avoid catastrophic melting of ice sheets, we should keep carbon dioxide levels no higher than 350 parts per million. Before the Industrial Revolution, the concentration was at about 280 parts per million, but today we’re up to 387. In other words, we’ve moved out of the safe operating space — and into risky territory.

The scientists also argue that as we spread fertilizer on farmland and burn coal, we are pumping far too much nitrogen into the environment. Human activity releases 121 million tons of nitrogen, much of which ends up polluting rivers, lakes and oceans and potentially pushing their ecosystems into irreversible changes. At most, the scientists argue, less than 35 million tons of nitrogen would be a safe boundary.

The rate at which species are becoming extinct is also far beyond a safe boundary, according to the scientists. During most of the history of life, species have become extinct at a slow, fairly regular pace. And as old

The concept of boundaries is provocative because it highlights how much scientists don’t yet understand.

species have become extinct, new ones have been evolving. There have been times when many species have become extinct at a much faster rate, and these pulses have sometimes ushered in a global collapse of ecosystems. The authors of the new Nature paper propose that to avoid collapse, the extinction rate cannot rise above 10 times the long-term background rate. Today, however, scientists estimate that the extinction rate is 100 to 1,000 times higher.

In five other areas, the scientists found, we have not yet crossed the boundary into the danger zone. As we release carbon dioxide, for example, some of it goes into the oceans and makes it more acidic. In acidic seawater, coral reefs have a harder time building skeletons, because the minerals they produce for their skeletons quickly dissolve. Invertebrates have the same trouble making shells. According to recent surveys, the ocean is now acidifying 100 times faster than at any time during the past 20 million years. Yet the Nature co-authors estimate that we have not yet reached the point where acidity may cause ecological collapse. But we are close.

While the paper makes for a sobering read, its authors think we should also find some cause for optimism in it. Humanity nearly crossed another threshold by destroying the ozone layer with chlorofluorocarbons. But we recognized the crisis in time and banned chlorofluorocarbons, allowing the ozone layer to slowly recover. If we had waited much longer we might have been too late to do anything. “We were able to avoid a global disaster,” says Rockstrom. He hopes we can do the same again, and keep human civilization from falling off the environmental mesa.

“The authors make a strong case for their selection of key boundaries,” says the Carnegie Institution’s Christopher Field, “and the proposed locations for the boundaries are conceptually reasonable.” Field said he would not be surprised if other researchers argue for shifting the boundaries based on further research. “But most would agree with the general theme that we are pushing very hard on the Earth system, so hard that we should not be surprised if key parts begin to break.”

More from Yale e360

As Climate Warms, Species May Need to Migrate or Perish
With global warming pushing some animals and plants to the brink of extinction, Carl Zimmer writes that conservation biologists are now saying that the only way to save some species may be to move them.

With Temperatures Rising,
Here Comes ‘Global Weirding’
They’re calling it “global weirding” — the way in which rising temperatures are causing species to change their ranges, the timing of their migrations, and the way they interact with other living things. And the implications of all this are only beginning to be understood.

Other researchers agree with the basic concept of the new paper, but question whether we should be trying to pin down planetary boundaries. Michael Mann, a climate scientist at Penn State University, agrees that there probably is a dangerous threshold for climate change, but he thinks that 350 ppm might be too strict a limit. And on a practical level, Mann points out that the policies being considered by the U.S. Congress probably won’t even be able to keep carbon dioxide levels down to 550 ppm in 2100. “I sometimes worry that there is the danger that if we dramatically move the goalposts and argue that 350 ppm must be the stabilization target, policymakers will just throw their hands up in futility,” says Mann, or reach instead for a quick-fix geoengineering scheme, “which frankly terrifies me.”

But some critics question the basic concept itself. “The notion of a single boundary is just devoid of serious content,” says Stuart Pimm. “In what way is an extinction rate 10 times the background rate acceptable?”

One reason that the concept of planetary boundaries is so provocative is that it highlights how much scientists don’t yet understand about the thresholds built into our planet. “I think this is interesting and I’m glad the paper is coming out,” says Naeem, “but it could lead to the false sense that we understand the biosphere better than we do.”

Link:  http://www.e360.yale.edu/content/feature.msp?id=2192

Primitive emotions lead us to give more weight to immediate risk rather than to future but greater risk

Our emotions can lead us astray when assessing risks, says new CU-Boulder study

by Science Blog, September 23, 2009

If you find yourself more concerned about highly publicized dangers that grab your immediate attention such as terrorist attacks, while forgetting about the more mundane threats such as global warming, you're not alone.
And you can't help it because it's human nature, according to a new study led by University of Colorado at Boulder psychology Professor Leaf Van Boven. That's because people tend to view their immediate emotions, such as their perceptions of threats or risks, as more intense and important than their previous emotions.

In one part of the study focusing on terrorist threats, using materials adapted from the U.S. Department of Homeland Security, Van Boven and his research colleagues presented two scenarios to people in a college laboratory depicting warnings about traveling abroad to two countries.

Participants were then asked to report which country seemed to have greater terrorist threats. Many of them reported that the country they last read about was more dangerous.

"What our study has shown is that when people learn about risks, even in very rapid succession where the information is presented to them in a very clear and vivid way, they still respond more strongly to what is right in front of them," Van Boven said.

With that in mind, Van Boven says one of the take-home messages from the study is that when communicating to the public, people must be mindful of how and when they publicize threats, which is a tall task in the around-the-clock news cycle of today.

"Whatever the threat of the season is can 'crowd out' concern about other threats even if those other threats are actually more dangerous," Van Boven said. "Because we are so emotionally influenced when it comes to assessing and reacting to threats, we may ignore very dangerous threats that happen not to be very emotionally arousing."

Human emotions stem from a very old system in the brain, Van Boven says. When it comes to reacting to threats, real or exaggerated, it goes against the grain of thousands of years of evolution to just turn off that emotional reaction. It's not something most people can do, he said.

"And that's a problem, because people's emotions are fundamental to their judgments and decisions in everyday life," Van Boven said. "When people are constantly being bombarded by new threats or things to be fearful of, they can forget about the genuinely big problems, like global warming, which really need to be dealt with on a large scale with public support."

In today's 24-hour society, talk radio, the Internet and extensive media coverage of the "threat of the day" only exacerbate the trait of focusing on our immediate emotions, he said.

"One of the things we know about how emotional reactions work is they are not very objective, so people can get outraged or become fearful of what might actually be a relatively minor threat," Van Boven said. "One worry is some people are aware of these kinds of effects and can use them to manipulate our actions in ways that we may prefer to avoid."

The study, which involved undergraduate students as subjects, was published in the August edition of the Journal of Experimental Psychology: General. Michaela Huber, a doctoral student of psychology and neuroscience at CU-Boulder, and Assistant Professor Katherine White of the University of Calgary co-authored the study.

Van Boven said the study would be of particular interest to policymakers.

"If you're interested in having an informed citizenry you tell people about all the relevant risks, but what our research shows is that is not sufficient because those things still happen in sequence and people will still respond immediately to whatever happens to be in front of them," he said. "In order to make good decisions and craft good policies we need to know how people are going to respond."

Link:  http://www.scienceblog.com/cms/our-emotions-can-lead-us-astray-when-assessing-risks-says-new-cu-boulder-study-25468.html

R. Curry, Woods Hole: We're heading off to a climate extreme and this is just going to snowball

Warming ocean melts Greenland glaciers, alters marine ecosystems

by Karl Ritter, Associated Press Writer, Sermilik Fjord, Greenland, ABC News, September 23, 2009 (AP)

With whale fins splashing in the distance, Ruth Curry hauls up her catch from the blustery deck of an icebreaker.

This Aug. 23, 2009, file photo shows University of Maine...

TO GO WITH CLIMA 09 GROENLANDIA-GLACIARES - This Aug. 23, 2009 file photo shows University of Maine glaciologist Gordon Hamilton, left, and graduate student Kristin Schild waiting for a helicopter after placing GPS receivers on Helheim Glacier in southeast Greenland. Like Greenland's other major glaciers, it accelerated earlier this decade, contributing to the melt of the ice sheet and sea level rise. (AP Photo/Karl Ritter, File)

An orange tube fixed to a metal frame breaks the surface as the motorized winch stops groaning. Inside: data on the water temperature deep down in this glacial fjord off southeast Greenland.

"If you were to dip your hand in it, it doesn't seem that warm," says Curry, an American climate scientist. "But it is. It's warm enough to melt ice. And that's the important thing here."

Curry and her colleagues from the Woods Hole Oceanographic Institution in Massachusetts zigzagged between majestic icebergs in the Sermilik fjord last month in search of proof that waters from warmer latitudes, or subtropical waters, are flushing through this remote and frigid region.

They found it — all the way up to the base of the outlet glaciers that spill into the ocean like tongues of ice from Greenland's massive ice sheet.

Coupled with similar findings off western Greenland, the discovery could help to explain why the glaciers have started flowing quicker in the past decade, a phenomenon that raised alarm because it contributes to rising sea levels.

"The measurements alone are not enough to conclude that the glacial melt is to a high degree driven by subtropical water. But I think the story is (starting) to come together," says research leader Fiamma Straneo.

The team found subtropical water with a temperature of about 39 °F (4 °C) deep inside the Sermilik fjord.

The findings confirm the outcome of an undersea battle below the dark surface of the North Atlantic: Arctic waters that usually dominate this region have yielded to an influx of subtropical water carried north by westward branches of the current commonly called the Gulf Stream.

Scientists say it's a natural process — in one period the cold waters will have the upper hand, and in the next it's the other way round. But the rapidly increasing temperatures of the subtropical oceans suggest that the balance could be tilted beyond natural variability, Curry says.

"We've actually measured the waters at their source and have seen their temperature going up, up, up in a way that can't be explained without taking into account human influences," she says.

TO GO WITH CLIMA 09 GROENLANDIA-GLACIARES - This Aug. 23, 2009 file photo shows University of Maine...

TO GO WITH CLIMA 09 GROENLANDIA-GLACIARES - This Aug. 23, 2009 file photo shows University of Maine glaciologist Gordon Hamilton and graduate student Kristin Schild working on a GPS receiver tracking the flow speed of Helheim Glacier in southeast Greenland. Like Greenland's other major glaciers, it accelerated earlier this decade, contributing to the melt of the ice sheet and sea level rise. (AP Photo/Karl Ritter, file)

The research underscores the complex interaction between the world's oceans and a warming atmosphere.
Oceans help to contain global warming by absorbing about half of the carbon dioxide released by humans into the atmosphere, but the water also expands as it warms, raising sea levels.

It could also have a big impact on climate through feedback mechanisms, such as the melting of seaside glaciers and changes to ocean currents that warm or cool different parts of the globe.

In the June-August period, the world's ocean surface temperature was the warmest on record since 1880, according to the U.S. National Oceanic and Atmospheric Administration. The surface temperature was 62.5 °F (17 °C), 1 °F (0.6 °C) above the 20th century average. Meteorologists say the reason was El Nino weather patterns combined with manmade global warming.

The North Atlantic has seen especially large changes in recent years.

The temperature of the water that flows into the Arctic has increased by as much as 3.5 °F (2 °C) since the 1990s, says Helge Drange, professor of oceanography at Norway's University of Bergen. "This can only be understood as a combined effect of natural variability and man-made warming," he says.

That has had a big impact on marine ecosystems, with fish traveling north into waters that were previously too cold for them. For example, more than 20 new species of fish have been found off Iceland, including blue sharks and flounders.

Meanwhile, cod has followed the warm water as it flows around Greenland's southern tip and up the giant island's west coast. "If you talk to local people they say it's fantastic because the Atlantic cod is coming," Drange says.

To many scientists, however, the shifts in ocean currents are no cause for celebration. Even if there's natural variability, there's concern that global warming may make the fluctuations more extreme.

And while some species thrive in warmer water, others that live on the edge of the Arctic, such as polar bears and seals, find their habitat melting away.

"We're heading off to a climate extreme and this is just going to snowball," says Curry, reflecting on the state of the global climate on the Greenpeace icebreaker hosting the Woods Hole research team.

"I think that we've done it, really kicked Earth's climate system. And that says a lot," she says. "It's a beast. It's huge. And to have moved it in as short a period of time as a 100 years, basically, to have done that is enormous."
 
Copyright 2009 The Associated Press. 

Link:  http://abcnews.go.com/Technology/JustOneThing/wireStory?id=8648158

by Scoop at Unique Post: Stunning views of glaciers from space

Stunning Views of Glaciers From Space

posted by Scoop, Unique Post, September 2009

To a geologist, glaciers are among the most exciting features on Earth. Though they seem to creep along at impossibly slow speeds, in geologic time glaciers are relatively fast, powerful landscape artists that can carve out valleys and fjords in just a few thousand years.

Glaciers also provide an environmental record by trapping air bubbles in ice that reveal atmospheric conditions in the past. And because they are very sensitive to climate, growing and advancing when its cold and shrinking and retreating when its warm, they can be used as proxies for regional temperatures.

Over geologic time, they have ebbed and flowed with natural climate cycles. Today, the world’s glaciers are in retreat, sped up by relatively rapid warming of the globe. In our own Glacier National Park in Montana, only 26 named glaciers remain out of the 150 known in 1850. They are predicted to be completely gone by 2030 if current warming continues at the same rate.

Here we have collected 13 stunning images of some of the world’s most impressive and beautiful glaciers, captured from space by astronauts and satellites.

Above: Bear Glacier, Alaska

This image taken in 2005 of Bear Glacier highlights the beautiful color of many glacial lakes. The hue is caused by the silt that is finely ground away from the valley walls by the glacier and deposited in the lake. The particles in this “glacial flour” can be very reflective, turning the water into a distinctive greenish blue. The lake, eight miles up from the terminus of the glacier, was held in place by the glacier, but in 2008 it broke through and drained into Resurrection Bay in Kenai Fjords National Park.

The grey stripe down the middle of the glacier is called a medial moraine. It is formed when two glaciers flow into each other and join on their way downhill. When glaciers come together, their lateral moraines, long ridges formed along their edges as the freeze-thaw cycle of the glacier breaks off chunks of rock from the surrounding walls, meet to form a rocky ridge along the center of the joined glaciers.

Heiltskuk Ice Field, British Columbia (above)

Covering nearly 1,400 square miles, the vast Heiltskuk Ice Field lies in the southern Coast Mountains of British Columbia. Taken by an astronaut on the International Space Station, this photo captures the snow-covered mountain slopes as well as several of the ice field’s valley glaciers, which are wide swaths of slowly flowing ice and debris. As these glaciers creep downhill, they carve out large U-shaped valleys that will remain long after the glacier melts. In fact, scientists use these characteristic valleys to identify regions that were once covered in ice but are now glacier-free.

The two largest valley glaciers shown here are the Silverthrone Glacier and the Klinaklini Glacier, which merge with each other at the top of the photo. The dark lines of rock and detritus of the lateral and medial moraines along the edges and middle of the glaciers are clearly visible.

Erebus Ice Tongue, Antarctica (above)

The saw-shaped projection jutting out from this glacier is known as the Erebus Ice Tongue, a long, narrow sheet of ice almost 7 miles long and 33 feet high. This peculiar structure is formed as the Erebus glacier in Antarctica flows rapidly down Mount Erebus and into the McMurdo Sound. During the summer, when the rest of the sea ice in McMurdo melts, the ice tongue floats on the water without thawing. As waves of sea water crash over the sides of the tongue, they carve elaborate shapes and sometimes create deep caves along the edges of the ice sheet. Occasionally, sections of the ice tongue calve off to form small icebergs.

Data for this false-color landscape was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite, and the image was created by combining data in various wavelengths.

Western Greenland Valley (above)

This natural-color image captured in August shows several small glaciers spilling into a mostly dry valley in western Greenland that itself was formed by a glacier in the past. Ground up rock from past glaciations has collected in the valley, giving the pools of water at the snouts of the current glaciers a turquoise color.

The photo was aqcuired by the Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite.

Grey Glacier, Chile (above)

Part of the Southern Patagonian Ice Field of Chile and Argentina, Grey Glacier covered 104 square miles when it was measured in 1996. By 2007, when this photograph was taken by astronauts from the International Space Station, the glacier had shrunk considerably, as seen in a comparative false-color image. Scientists think increased regional temperatures and changes in the amount of precipitation have led to more ice calving off as free-floating chunks, and less ice being replenished each year.

In the natural-color image above, Grey Glacier looks pale blue because ice absorbs red wavelengths of light and scatters blue. The rough surface of this part of the glacier is caused by vertical cracks in the surface called crevasses, which are formed near the ends of glaciers as the flow of ice at the bottom speeds up relative to the brittle ice on top.

Eugenie Glacier, Dobbin Bay in the Canadian Arctic (above)

This stunning shot of the Eugenie Glacier in the Canadian Arctic was taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite, which takes high-resolution images designed to detect even minute changes in the extent and features of the world’s glaciers.

This image highlights the fact that glaciers are flowing much like water but at a far slower pace. Smaller glaciers flow down valleys like river tributaries into larger glaciers. The bottom of Eugenie Glacier is floating on the surface of Dobbin Bay; a close-up of the tongue shows extensive surface cracks and calving of small icebergs into the bay.

Retreat of the Helheim Glacier, Greenland (above)

Glaciers stay intact as long as the ice thickness and water depth allow them to stay firmly attached to the ground. But when the ice becomes too thin or the water gets too deep, the tip of a glacier starts to float and rapidly cracks into icebergs, creating what’s called a “calving edge.” This photograph, captured by NASA’s Terra satellite in 2003, shows the calving edge of the Helheim Glacier in Greenland. Comparing similar images from 2001 and 2005 reveals that the solid portion of the glacier has been shrinking rapidly. Measurements from NASA reveal that in just four years, the glacier’s margin retreated 4.7 miles and its flow speed increased from 5 to 7.5 miles per year. Between 2001 and 2003, the thickness of the glacier also shrunk by about 131 feet.

Unfortunately, the entire Greenland Ice Sheet has been undergoing similar shrinkage, thinning by tens of yards in the past decade. While warmer temperatures have certainly caused some of the thinning, scientists also think that the retreat of the ice margin has played a role: With less grounded ice to slow the ice sheet down, it’s moving out to sea at a faster rate.

Ellesmere Island National Park Reserve (above)

This false-color composite image shows a tidewater glacier in the Greely Fjord that extends out over the sea water for a short distance and breaks off into icebergs, which can be seen floating away. The dark spots on the glaciers are likely melt ponds. The pond water is darker than the surface of the glacier and consequently absorbs more heat, which melts more ice and causes the ponds to grow. Sometimes, water from glacial melt ponds will flow through cracks in the glacier to the base, lubricating the surface and causing the glacier to flow more quickly.

Mt. Rainier, Washington (above)

At 14,411 feet, Mt. Rainier is the tallest volcano in the Cascade Range and has a 1,280 foot-wide summit crater. On its eastern slope, it hosts Emmons Glacier, the largest glacier in the lower 48 states. Rainier is an active volcano that is continuously monitored by the U.S. Geological Survey’s Cascade Volcano Observatory. And though it last erupted in 1840, it is considered the most hazardous volcano in the country, in part because of the risk of flooding from melting glaciers in the event of an eruption. This photo was captured on a rare clear day by astronauts on the International Space Station.

Upsala Glacier, Patagonian Argentina (above)

Upsala Glacier is the third largest glacier of the Southern Patagonian Ice Field at around 300 square miles and ends in Lake Argentino. Patagonian glaciers have been retreating rapidly in recent decades, some as much as 2.5 miles between the late 1960s and mid 1990s, making them a target for International Space Station crew observations. Upsala appears to still be retreating with visible changes between this photo taken in 2004 and another from 2000.

Byrd Glacier, Antarctica

The Byrd Glacier near McMurdo Station in Antarctica runs 100 miles through a steep 15-mile-wide valley in the Transatlantic Mountains. This fast-flowing glacier moves ice toward the Ross Ice Shelf at the rate of one half mile a year and adds more ice to the ice sheet than any other glacier. Images such as this one from the U.S. Geological Survey’s Landsat-7 satellite have been combined to form the Landsat Image Mosaic of Antarctica. The mosaic incorporates more than 1,000 images.

Pasterze Glacier, Austria (above)

European glaciers have been rapidly retreating in recent years, due to higher summer temperatures and lower winter precipitation. Pasterze Glacier has been shrinking since 1856. Satellite data such as this image is used by scientists to keep track of the movement of glaciers around the world.

Bering Glacier, Alaska (above)

Bering Glacier, combined with the ice field that feeds it, is the largest glacier in North America at 2,000 square miles, as well as the longest at 118 miles. This glacier has retreated around 7.5 miles and thinned by several hundred yards over the last century, though it is still around 2,500 feet thick in some places. Scientists think the shrinking of Alaskan glaciers such as Bering has reduced the pressure on the boundary between tectonic plates beneath them and consequently increased the number of earthquakes in the region.

Link: http://www.uniquescoop.com/2009/09/stunning-views-of-glaciers-from-space.html

M. H. England, A. S. Gupta, & A. J. Pitman, PNAS, Vol. 106 (2009): Constraining future greenhouse gas emissions by a cumulative target

Proceedings of the National Academy of Sciences, Vol. 106, No. 39, pp. 16539-16540 (September 29, 2009); doi: 10.1073.pnas.0908197106

Constraining future greenhouse gas emissions by a cumulative target

Matthew H. England*, Alexander Sen Gupta, and Andrew J. Pitman

Climate Change Research Centre, University of New South Wales, Sydney, New South Wales 2052, Australia

By 1994 all major industrialized nations, including the United States, had ratified the United Nations Framework Convention on Climate Change (UNFCCC), yet 15 years later policymakers still debate how best to formulate emissions legislation.

Article 2 of the UNFCCC calls for ‘‘stabilization of greenhouse gas concentrations . . . at a level that would prevent dangerous anthropogenic interference with the climate system.’’ Emissions targets are commonly quoted as a percentage reduction relative to a baseline year.

A different framework for emissions targets is presented in a recent issue of PNAS (1), wherein the targets are set as a cumulative emissions inventory, spelling out to policymakers the net emissions allowable to avoid the worst impacts of climate change.

Setting emissions targets around a net cumulative quota is a familiar paradigm for policymakers. It is analogous to planning for expenditure against a net income or setting a catch quota to maintain a sustainable fishery. In such cases, the available resource is fundamentally limited in a cumulative sense; harvest or spend too much and things become unsustainable.

For the global harvesting of fossil fuels the message becomes clear: burn beyond a cumulative cap and you commit the planet to a high risk of dangerous anthropogenic climate change.

The article by Zickfeld et al. (1) uses a coupled climate model to carefully diagnose, via inverse methods, the level of emissions allowable to track toward a given stabilization target for global
warming. Normally, the problem is addressed in reverse: namely, for a given future emission pathway (2), how will the climate system respond? Both approaches are valid, yet to make meaningful projections they each need to carefully incorporate coupled carbon feedbacks.

Carbon feedbacks occur when there are climate-induced changes in the net fluxes of carbon between the land/ocean and the atmosphere. The strength of the feedback depends on the scale of physical climate change and biophysical processes in the ocean and land systems. A simple example of an ocean carbon feedback is caused by the solubility of CO2, which varies inversely with temperature. Ocean warming reduces...

www.pnas.org/cgi/doi/10.1073/pnas.0908197106

More at this link: http://www.pnas.org/content/early/2009/09/21/0908197106.full.pdf

Charles J. Hanley: Climate trouble may be bubbling up in far north (methane hydrates in permafrost)

Climate trouble may be bubbling up in far north

by CHARLES J. HANLEY, AP Special Correspondent, August 31, 2009

MACKENZIE RIVER DELTA, Northwest Territories (AP) -- Only a squawk from a sandhill crane broke the Arctic silence - and a low gurgle of bubbles, a watery whisper of trouble repeated in countless spots around the polar world.

"On a calm day, you can see twenty or more 'seeps' out across this lake," said Canadian researcher Rob Bowen, sidling his small rubber boat up beside one of them. A tossed match would have set it ablaze.

"It's essentially pure methane."

Pure methane, gas bubbling up from underwater vents, escaping into northern skies, adds to the global-warming gases accumulating in the atmosphere. And pure methane escaping in the massive amounts known to be locked in the Arctic permafrost and seabed would spell a climate catastrophe.

Is such an unlocking under way?

Researchers say air temperatures here in northwest Canada, in Siberia and elsewhere in the Arctic have risen more than 2.5 °C (4.5 °F) since 1970 -- much faster than the global average. The summer thaw is reaching deeper into frozen soil, at a rate of 4 cm (1.5 inches) a year, and a further 7 °C (13 °F) temperature rise is possible this century, says the authoritative, U.N.-sponsored Intergovernmental Panel on Climate Change (IPCC).

In 2007, air monitors detected a rise in methane concentrations in the atmosphere, apparently from far northern sources. Russian researchers in Siberia expressed alarm, warning of a potential surge in the powerful greenhouse gas, additional warming of several degrees, and unpredictable consequences for Earth's climate.

Others say massive seeps of methane might take centuries. But the Russian scenario is disturbing enough to have led six U.S. national laboratories last year to launch a joint investigation of rapid methane release. And IPCC Chairman Rajendra Pachauri in July asked his scientific network to focus on "abrupt, irreversible climate change" from thawing permafrost.

The data will come from teams like one led by Scott Dallimore, who with Bowen and others pitched tents here on the remote, boggy fringe of North America, 2,200 kilometers (1,400 miles) from the North Pole, to learn more about seeps in the 25,000 lakes of this vast river delta.

A "puzzle," Dallimore calls it.

"Many factors are poorly studied, so we're really doing frontier science here," the Geological Survey of Canada scientist said. "There is a very large storehouse of greenhouse gases within the permafrost, and if that storehouse of greenhouse gases is fluxing to the surface, that's important to know. And it's important to know if that flux will change with time."

Permafrost, tundra soil frozen year-round and covering one-fifth of Earth's land surface, runs anywhere from 50-600 m (160-2,000 feet) deep in this region. Entombed in that freezer is carbon -- plant and animal matter accumulated through millennia.

As the soil thaws, these ancient deposits finally decompose, attacked by microbes, producing carbon dioxide and -- if in water -- methane. Both are greenhouse gases, but methane is many times more powerful in warming the atmosphere.

Researchers led by the University of Florida's Ted Schuur last year calculated that the top 3 meters (10 feet) of permafrost alone contain more carbon than is currently in the atmosphere.

"It's safe to say the surface permafrost, 3-5 meters, is at risk of thawing in the next 100 years," Schuur said by telephone from an Alaska research site. "It can't stay intact."

Methane also is present in another form, as hydrates -- ice-like formations deep underground and under the seabed in which methane molecules are trapped within crystals of frozen water. If warmed, the methane will escape.

Dallimore, who has long researched hydrates as energy sources, believes a breakdown of such huge undersea formations may have produced conical "hills" found offshore in the Beaufort Sea bed, some of them 40 m (more than 100 feet) high.

With underwater robots, he detected methane gas leaking from these seabed features, which resemble the strange hills ashore here that the Inuvialuit, or Eskimos, call "pingos." And because the coastal plain is subsiding and seas are rising from warming, more permafrost is being inundated, exposed to water warmer than the air.

The methane seeps that the Canadians were studying in the Mackenzie Delta, amid grassy islands, steel-gray lakes and summertime temperatures well above freezing, are saucer-like indentations just 10 m (30 feet) or so down on the lake bed.

The ultimate source of that gas -- hydrates, decomposition or older natural gas deposits -- is unclear, but Dallimore's immediate goal is quantifying the known emissions and finding the unknown.

With tent-like, instrument-laden enclosures they positioned over two seeps, each several meters (yards) wide, the researchers have determined they are emitting methane at a rate of up to 0.6 m³ (almost 1 cubic yard) per minute.

Dallimore's team is also monitoring the seeps with underwater listening devices, to assess whether seasonal change -- warming -- affects the emissions rate.

Even if the lake seeps are centuries old, Bowen said, the question is, "Will they be accelerated by recent changes?"

A second question: Are more seeps developing?

To begin answering that, Dallimore is working with German and Canadian specialists in aerial surveying, teams that will fly over swaths of Arctic terrain to detect methane "hot spots" via spectrometric imagery, instruments identifying chemicals by their signatures on the light spectrum.

Research crews are hard at work elsewhere, too, to get a handle on this possible planetary threat.

"I and others are trying to take field observations and get it scaled up to global models," said Alaska researcher Schuur. From some 400 boreholes drilled deep into the tundra worldwide, "we see historic warming of permafrost. Much of it is now around 2 below zero (28 °F)," Schuur said.

A Coast Guard C-130 aircraft is overflying Alaska this summer with instruments sampling the air for methane and carbon dioxide. In parts of Alaska, scientists believe the number of "thermokarst" lakes -- formed when terrain collapses over thawing permafrost and fills with meltwater -- may have doubled in the past three decades. Those lakes then expand, thawing more permafrost on their edges, exposing more carbon.

Off Norway's Arctic archipelago of Svalbard last September, British scientists reported finding 250 methane plumes rising from the shallow seabed. They're probably old, scientists said, but only further research can assess whether they're stable. In March, Norwegian officials did say methane levels had risen on Svalbard.

Afloat above the huge, shallow continental shelf north of Siberia, Russian researchers have detected seabed "methane chimneys" sending gas bubbling up to the surface, possibly from hydrates.

Reporting to the European Geophysical Union last year, the scientists, affiliated with the University of Alaska and the Russian Academy of Sciences, cited "extreme" saturation of methane in surface waters and in the air above. They said up to 10% of the undersea permafrost area had melted, and it was "highly possible" that this would open the way to abrupt release of an estimated 50 billion tons of methane.

Depending on how much dissolved in the sea, that might multiply methane in the atmosphere several-fold, boosting temperatures enough to cause "catastrophic greenhouse warming," as the Russians called it. It would be self-perpetuating, melting more permafrost, emitting more methane.

Some might label that alarmism. And Stockholm University researcher Orjan Gustafsson, a partner in the Russians' field work, acknowledged that "the scientific community is quite split on how fast the permafrost can thaw."

But there's no doubt the north contains enough potential methane and carbon dioxide to cause abrupt climate change, Gustafsson said by telephone from Sweden.

Canada's pre-eminent permafrost expert, Chris Burn, has trekked to lonely locations in these high latitudes for almost three decades, meticulously chronicling the changes in the tundra.

On a stopover at the Aurora Research Institute in the Mackenzie Delta town of Inuvik, the Carleton University scientist agreed: "We need many, many more field observations." But his teams have found the frozen ground warming down to about 80 meters, and he believes the world is courting disaster in failing to curb warming by curbing greenhouse emissions.

"If we lost just 1% of the carbon in permafrost today, we'd be close to a year's contributions from industrial sources," he said. "I don't think policymakers have woken up to this. It's not in their risk assessments."

How likely is a major release?

"I don't think it's a case of likelihood," he said. "I think we are playing with fire."

© 2009 The Associated Press. All rights reserved.

Link: http://hosted.ap.org/dynamic/stories/C/CN_CLIMATE_09_TROUBLING_BUBBLES

Dutch help California's Bay Area plan for sea level rise

Dutch help California's Bay Area plan for sea level rise

by Julia Scott, physorg.com, September 22nd, 2009

How to plan for sea level rise, a still-abstract concept for many Californians, drew serious consideration from engineers, designers and urban planners from Holland and the U.S. at a symposium held on Monday.

A group of government-sponsored Dutch experts presented a report with strategies to deal with sea level rise in the San Francisco Bay and the Sacramento-San Joaquin Delta based on a year's worth of research in partnership with the Francisco Bay Conservation and Development Commission.

With 50% of the Netherlands below sea level, the Dutch have been perfecting flood perfection for the last 600 years.

The inevitable effects of climate change in California, and how cities can adapt to them, are starting to get more attention from planners. While no one knows how exactly how sea level rise will play out 100 or 200 years from now, experts agree more severe and frequent floods are going to be a part of it.

Avoiding sea level rise is by now impossible. The Bay has already risen 8 inches since the start of the 20th century, and scientists in California and worldwide agree the Bay Area in particular can expect to experience sea level rise of up to 16 inches by midcentury and up to 55 inches by 2100.

Extreme storms will increase annual risk of flooding from 1% to 100% if no actions are taken to protect the Bay Area shoreline, potentially endangering 270,000 people, according to the Pacific Institute. Development along the shoreline is currently valued at $62 billion.

How to plan for a future in which some of that real estate is threatened by storm surges -- for a time beyond what today's urban planners will live to see -- is the crucial question, said Will Travis, executive director of the Bay Conservation and Development Commission.

"We're in the same position as the captain of the Titanic. By the time he looked up it was too late -- he was going to hit (the iceberg)," said Travis. "We need to stop trying to protect the Bay Area the way it is.

Instead, we need to design it for the way it will be in the future."

That future may involve dismantling development in some places and letting the tide take its course, according to the report. Local leaders may decide that some areas, such as the Port of Oakland and both regional airports, are too valuable to lose and must be protected at all costs. Other areas could be transformed to incorporate rising tides into the heart of a city.

The key is to begin asking those questions now, especially as several major developments at the edge of the Bay await approval, including Treasure Island and a Cargill saltworks site in Redwood City, Calif. Those areas were singled out in the report as "hot spots" for the Bay, meaning they represent the types of development most at risk from sea level rise.

"Just as in an emergency room, making these policy decisions will be difficult," said Travis. "It may be better to abandon some places then to allow the houses to be built and then try to protect them from flooding."

Frustratingly little is known about how well protected the Bay Area is from a serious flood even now, according to the report (cities on the Bay are expected to prepare for a once-in-a-century flood, but the shores of the Netherlands are armored with flood gates and other equipment strong enough to withstand a once-in-10,000-years onslaught from the North Sea).

While many of the Bay Area's most vulnerable and valuable areas are protected by federally certified levees, they were all built before planners became aware of how sea level rise would change the whole equation.

Simply building higher levees is not a silver bullet, however. The Dutch came to that conclusion in 1995 after major flooding though the country's interior estuaries made them rethink the policy of walling off every section of river. They invented a new concept called "living with water" designed to embrace sea level rise. They raised houses and let water flow underneath them. The government bought farmland along waterways and turned it into tidal wetlands, which naturally absorb water.

"People realize we can't just raise levees forever. If something goes wrong, you have an entire city that will be flooded in an instant. Water is a fact -- we need to do something about it," said David Van Raalten, project manager for the pilot project between the Netherlands and California and a principal in ARCADIS, an international engineering and consultancy firm.

Rather than propose a series of tailor-made design solutions for each Bay Area "hot spot" based on a Dutch blueprint, the report offers a new way of thinking about what types of development ought to exist in which area. Zones with high economic value might continue to fill the Bay and expand with the help of levees and sea walls. Another option, labeled "tidal embracing development," could involve urban tidal canals carved into the suburbs or parking lots that retain storm water underground.

The Dutch government has formed similar partnerships in most of the world's most vulnerable water regions, including Louisiana, Indonesia, the Yangzee Delta in China and the Mekong Delta in Vietnam, with the goal of sharing expertise and learning from each other.

The Dutch government spent 120,000 € ($176,000) on the Bay Area pilot project and is proposing to invest another 100,000 € for further research in California, provided the state can match the money.

(c) 2008, San Mateo County Times (San Mateo, Calif.). Visit the San Mateo County Times on the Web at http://www.insidebayarea.com/sanmateocountytimes/
Distributed by McClatchy-Tribune Information Services.

K. Zickfeld et al., PNAS, Vol. 106: Setting cumulative emissions targets to reduce the risk of dangerous climate change

Proceedings of the National Academy of Sciences, Vol. 106, No. 38, pp. 16129−16134 (September 22, 2009), published online before print August 17, 2009; doi: 10.1073/pnas.0805800106

Setting cumulative emissions targets to reduce the risk of dangerous climate change

Kirsten Zickfeld^a,¹,², , Michael Eby^a, H. Damon Matthews^b and Andrew J. Weaver^a

Edited by Hans Joachim Schellnhuber, Potsdam Institute for Climate Impact Research, Potsdam, Germany, and approved July 20, 2009 (received for review June 16, 2008)

Abstract

Avoiding “dangerous anthropogenic interference with the climate system” requires stabilization of atmospheric greenhouse gas concentrations and substantial reductions in anthropogenic emissions. Here, we present an inverse approach to coupled climate-carbon cycle modeling, which allows us to estimate the probability that any given level of carbon dioxide (CO₂) emissions will exceed specified long-term global mean temperature targets for “dangerous anthropogenic interference,” taking into consideration uncertainties in climate sensitivity and the carbon cycle response to climate change. We show that to stabilize global mean temperature increase at 2 °C above preindustrial levels with a probability of at least 0.66, cumulative CO₂ emissions from 2000 to 2500 must not exceed a median estimate of 590 petagrams of carbon (PgC) (range, 200 to 950 PgC). If the 2 °C temperature stabilization target is to be met with a probability of at least 0.9, median total allowable CO₂ emissions are 170 PgC (range, −220 to 700 PgC). Furthermore, these estimates of cumulative CO₂ emissions, compatible with a specified temperature stabilization target, are independent of the path taken to stabilization. Our analysis therefore supports an international policy framework aimed at avoiding dangerous anthropogenic interference formulated on the basis of total allowable greenhouse gas emissions.

Link to abstract: http://www.pnas.org/content/106/38/16129.abstract

Chinese hackers have hacked my blog code, disabling followers

UPDATE:  September 24, 2009

OK, maybe I over-reacted.  Well, make that:  yeah, I over-reacted.

But I did have Chinese characters from out of nowhere running up at the top of my browser.

I just tried to go to a certain innocuous seeming site called www dot chinajeweler dot com

Guess what?  Chrome strongly advised me not to go there!

Whoa!  I must be pretty isolated -- I have never been warned off a site before.  I guess I don't get out much.



September 23, 2009 UPDATE

Apparently, I am not the only blogger in the world who has lost their "followers." http://www.google.com/support/forum/p/blogger/thread?tid=0ec7484f9f4cee69&hl=en&fid=0ec7484f9f4cee6900047442a9bbda85

However, it was on the same day that Chinese characters appeared at the very top line of my Mozilla browser screen.

I expect blogger will get it fixed, sooner or later.

Thanks for sending comments and e-mails to let me know what you could see and not see -- I really appreciate it!

Tenney



Dear Readers,

Although this blog is primarily about climate change science, I have always believed that Chinese government policies are an equal danger to the environment and maintaining our freedoms.

They have already hacked into the U.S. military computer systems and the U.S. electrical grid.

They did this with complete impunity and with the full realization that their hacking would be recognized and they just didn't even care.

Nearly every time I post an article about China, I receive e-mails from Chinese people or I get a Chinese follower.

Well, sorry, but I do not respond to the e-mails and I delete Chinese followers. I know that this is painting all Chinese with the same brush, but yet I do this.

So, anyway, this past week, I posted about China spending over $70 billion to buy up fossil-fuel assets around the world, and what do I get? A Chinese follower.

I subsequently blocked said follower.

What happened next is interesting.

Chinese characters appeared at the top of my Mozilla browser.

My blog's followers have disappeared, and I can't see them.

If you can see the followers to this blog, please let me know at:

apaixonada.por.rio@gmail.com

Thanks!

Tenney

Cynthia McPherson said...

I'm not sure what you mean by "followers". I assume you're referring to posters who make comments following your essays. I didn't see any posts after what your wrote. (?!)

September 22, 2009 10:59 PM

Tenney Naumer said...

I personally dislike the term "followers," but it is the term for the gadget that permits readers to be informed when there are new posts -- there were 54 people connected to this blog, each with their own atavar. Now, where the atavars once were is a big blank space. I will try to contact google to see what can be done to restore them.

September 23, 2009 12:25 AM

owl905 said...

It says 54 bloggers, and there's a square of tiny pictures. Didjeridust is in the upper left corner with a beard.

September 23, 2009 4:24 AM

Anonymous said...

You may already know this - but it looks like your followers are back! Says 54 - is that about right?

September 23, 2009 5:11 AM

Tenney Naumer said...

Well, I am glad you guys can see the 54 "followers" because they are still invisible on my machine. I have a completely separate google account for another blog, and those 6 are also invisible, even though I use Chrome to look at it instead of Mozilla. Does it get any weirder than that? Other blog: gringa-gem-news.blogspot.com

September 23, 2009 8:25 AM

Rick said...

At first, I thought the followers info and icons had gone away after I reopened your site, but then I realized that they had just moved from the TOP of the left-hand column to the BOTTOM of the column. Maybe Google did some reformatting. BTW, thanks for this fantastic blog.

September 23, 2009 7:51 PM

Tenney Naumer said...

Dear Rick, Thanks for your comment. I really appreciate it. I myself moved the followers section to a different location because I still cannot see them. I am glad that others are able. I went to blogspot help and found a discussion where many people are complaining (beginning on the 22nd) that their followers have disappeared. Some say they have reappeared and then disappeared again. Anyway, we will just have to be patient and wait for google to solve the problem, whatever it is. Nevertheless, Chinese characters appeared at the top of my browser on the same day. Best regards, Tenney

September 24, 2009 9:38 AM

R. M. Clark & R. Thompson, Intl. J. Climatology, 2009, Predicting the impact of global warming on the timing of spring flowering

International Journal of Climatology, published online September 3, 2009; DOI: 10.1002/joc.2004

Predicting the impact of global warming on the timing of spring flowering

Robert Malcolm Clark1, *and Roy Thompson2

1School of Mathematical Sciences, Monash University, Clayton, PO Box No. 28M, Victoria 3800, Australia 2School of GeoSciences,The University of Edinburgh, Edinburgh EH9 3JW, U.K.

(Received 20 November 2007; accepted 20 November 2007.)

Abstract

Many plants flower in response to a change in the environment. Since one of the main goals for a plant is to complete a growth cycle in order to produce seed, flowering is a key stage in plant development. We have developed a statistical procedure for explaining the variations in flowering date, which is based on a well-accepted phenological model (growing degree-days). Our approach has several advantages over previous methods based around multiple-regression procedures, the main one being that we have a direct interpretation in terms of just two meaningful phenological parameters (thermal requirement and thermal threshold) per species. The model is used to classify 79 flowering plants. By using a statistical approach based on empirical p-values, we can decide which species can be regarded as sensitive to temperature. Our model, while a simplification of the real system, is easy to work with and enables the consequences of future temperature change to be predicted. By adopting a simple (linear), but realistic, approximation to the rise in temperature each spring, we derive a simple expression for the change in expected flowering dates under global warming. We use the expression to examine changes under three different climate change scenarios involving increasing warmth, oceanicity and continentality. Variations in flowering from species to species and year to year are explained in a straightforward manner by variations in our two parameters and the linear temperature functions, respectively. We find that the sensitivity of spring flowering dates to temperature is strongly governed by the continentality of the climate. We make predictions that will allow the assumptions used in constructing our model to be validated or repudiated. Our formulae can be used for any global warming scenario of the type we consider, whenever our basic assumptions hold. In particular, we predict the likely change in world-wide spring flowering dates under the likely climatic conditions in the 2080s as predicted under the Intergovernmental Panel on Climate Change scenario A1FI.

^*Correspondence to Robert Malcolm Clark, School of Mathematical Sciences, Monash University, Clayton, PO Box No. 28M, Victoria 3800, Australia. e-mail malcolm.clark@sci.monash.edu.au)

Link to abstract: http://www3.interscience.wiley.com/journal/122581311/abstract

Copyright © 2009 Royal Meteorological Society