Climate Feedback

Quirin Schiermeier

Rising temperatures cause melting and retreat of large ice sheets, sea ice, and mountain glaciers – that’s pretty much common knowledge by now, as are implications on sea level, ecosystems, water supply and natural hazard risk. But a couple of news stories this week may cause confusion.

That the Greenland ice sheet is losing ice, and that mass loss has further accelerated in recent years, comes as no particular surprise. Using ground observations and satellite gravity measurements, a team led by Michiel van den Broeke from Utrecht University in the Netherlands, estimates that some 1,500 gigatonnes – roughly 1,500 cubic kilometers – have been lost from 2000-2008, equivalent to about 0.46 millimeters of global sea level rise.

Melting rates have accelerated since 2006, with mass loss reaching 273 gigatons of mass per year, equivalent to 0.75 millimeters of sea level rise. Without the moderating effects of increased snowfall, post 1996 mass losses would have been 100% higher, the team writes in a paper in this week’s issue of Science [subscription].

But the cryosphere – those parts of the globe that are permanently or seasonally covered by ice – does have surprises in store. Or so it seems.

Here’s one: Himalayan glaciers (there are tens of thousands of them of) are not – or at least not yet - shrinking as a result of climate change, the world learned this week from an Indian geologist.

“Although shrinking in volume and constantly showing a retreating front, [Himalayan glaciers] have not in any way exhibited, especially in recent years, an abnormal annual retreat,” concludes retired glaciologist Vijay Kumar Raina, formerly of the Geological Survey of India, in a report to India's Ministry of Environment and Forests.

“It is premature to make a statement that glaciers in the Himalayas are retreating abnormally because of global warming,” he goes on.

Following the release of the study – based on observations of 25 glaciers – India’s environment minister Jairam Ramesh was quick to challenge the“conventional wisdom" about melting ice in the world’s tallest mountains.

Fellow Indian Rajendra Pachauri, the chairman of the Intergovernmental Panel on Climate Change (IPCC), was put out: "We have a very clear idea of what is happening. I don't know why the minister is supporting this unsubstantiated research. It is an extremely arrogant statement," he told the Guardian.

The IPCC had warned in its latest report, published in 2007, that Himalayan glaciers "are receding faster than in any other part of the world and, if the present rate continues, the likelihood of them disappearing by the year 2035 and perhaps sooner is very high if the Earth keeps warming at the current rate."

So what's going on? I asked Lonnie Thompson, a veteran glaciologist and leading paleoclimatologist at Ohio State University. Here’s what he said:

“First and foremost this is not a peer reviewed report and nothing scientific can be claimed based on 25 glaciers out of over 15,000 glaciers in the Himalayas and 46,300 in the Himalayas and Tibetan region.”

Continue reading "Greenland ice and Himalayan glaciers: What’s going on?" »

Posted by Olive Heffernan on November 13, 2009
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A new study in Geophysical Research Letters [subscription] adds to the evidence that glaciers in high mountain regions are under threat from climate change.

The research, by Ray Bradley at the University of Massachusetts in Amherst and colleagues, looks at changes in the altitude at which temperature reaches 0 degrees Celsius – known as the freezing level height – in the tropical Andes.

They find that, over the past three decades, freezing level height has increased over most of the region, which is a good indicator that high elevation glaciers are losing mass due to surface melting. Their finding is consistent with observed changes in surface temperature and upper air data in the region, which has experienced a 0.1 degree Celsius increase in temperature per decade over the past half century.

Strikingly, they find that the summit of the Quelccaya ice cap in Peru – the largest body of ice in the Tropics – frequently experiences daily maximum temperatures above freezing between October and May. At the ice cap margin at 5200m, temperatures rise well above freezing for much of the year.

Bradley and co-authors say this phenomenon is likely to be affecting other high elevation glaciers in Ecuador, Peru and Bolivia, with potentially serious implications for the region’s water supply.

Olive Heffernan

Posted by Olive Heffernan on September 10, 2009
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A new reservoir of fossil fuel could be ready to tap much sooner than previously thought. R&Ders have been talking up natural gas extraction from methane hydrates - a solid form of the greenhouse gas, found tucked away beneath the sea floor where low temperature and high pressure keep it stable.

Following an enthusiastic Congressional testimony, Ray Boswell of the US Department of Energy's National Energy Technology Laboratory (NETL) has a commentary in Science on hydrates’ potential as an energy source. But methane hydrates are also making headlines this week as a worrying harbinger of climate change. Some scientists have warned that ocean warming could destabilize hydrates and send methane gas bubbling into the ocean. Now a team led by Graham Westbrook of the University of Birmingham has spotted over 250 such gas plumes near Svalbard, Norway - echoing a similar observation from a group in Siberia earlier this year.

Much of the released gas dissolves in the water column, but any portion that reaches the air could amplify warming.
By drilling for hydrates, could we wake a sleeping giant? Boswell doesn’t tackle this question head on, but he offers some relevant points.

First off, hydrates in the Arctic - where gas plumes have been seen - are hard to get at. Before they go messing with the permafrost lid that protects the vast northern stores of methane, prospectors will find more enticing targets, says Boswell. Specifically, it’s hydrates found in sandy deposits in the Gulf of Mexico that are raising hopes at NETL.

Hydrate-bearing sands were first spotted off Japan in 1999. By recent estimates the Gulf of Mexico holds 190 trillion cubic meters of natural gas in such sands - over 300 times the amount of gas the US burns annually. An April expedition to probe the Gulf's deposits found promising pockets of highly saturated hydrates. There are technical and economic hurdles to extracting this gas, says Boswell, but many could be overcome with existing technology. That's a big difference from the hydrates known a decade ago, which were dispersed across muddy fields or packed into solid mounds.

Methane from sandy hydrates may also be easier to control. Boswell writes:

These resevoirs are commonly buried many hundreds of meters below the sea floor and enclosed in a matrix of impermeable sediments that help to prevent the escape of released methane. The most prospective gas hydrate deposits are also those that are most effectively buffered from environmental change.

Speaking of which, does the world need another fossil fuel reservoir? Not if you’re hoping our supplies will run out in time to save the climate. But with the world facing dwindling oil reserves and a sluggish start on renewables, Boswell implies the gas could fill an important gap: “hydrates may offer an important ‘bridging’ fuel that will help ease the transition to the sustainable energy supplies of the future.”

Anna Barnett

Image: Methane actively dissociating from a hydrate mound / National Energy Technology Lab

Posted by Anna Barnett on August 21, 2009
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I've always been fascinated with large-scale ecological manipulation experiments. This week, at the Ecological Society of America meeting in Albuquerque, I got perhaps more than I was looking for.

During a session on results from the recently-concluded International Polar Year, Walt Oechel and Donatella Zona of San Diego State University presented a pair of talks about their work at the Barrow Environmental Observatory. This is a 3,000-hectare reserve, set aside by the Ukpeagvik Inupiat, about 10 kilometers from the coastal town of Barrow, Alaska. The far north coastal town. You really just can't get any farther north in Alaska than Barrow.

Which all goes to show that Barrow is a convenient place for the US to measure changes in the Arctic, and atmospheric researchers have been working there for decades. In the latest work, Oechel and Zona took a lake, 1.2 kilometers long, and divided it into three parts. One part they left alone. One part they pumped water out of, into the third part.

The objective? To manipulate the water table and see what effect that had on greenhouse gas emissions from the tundra. As I report in a story over on Nature News, they found the higher the water table, the more carbon dioxide was given off. This observation relies on just a single year of data so far, but if it turns into a trend - as so many things in the Arctic are these days - it would be more grim news for Arctic carbon fluxes in a globally warmed world.

Posted by Alex Witze on August 06, 2009
Categories: Cryosphere | Permalink | Comments (0) | TrackBacks (0)

Some of scientists’ gravest concerns about future climate change are rooted in the past. Records studied by paleoclimatologists reveal that the more extreme possibilities for this century and beyond — temperatures soaring, ice sheets vanishing, fertile lands withering into deserts — were realized previously on Earth when atmospheric greenhouse gas levels surged. At this summer's AGU Chapman Conference on Abrupt Climate Change, researchers described this turbulent history through all manner of proxies - ice, tree rings, corals, marine and lake sediments, among others. But few talks went without a slide showing the wiggly line of a deep ice core.

Each proxy has its own merits, but ice cores offer records of climatic history whose detail and completeness are unmatched. Their data stretch back 800,000 years and are conveniently located in some of the world’s most climatically sensitive regions. Two new features on Nature Reports Climate Change pay homage to the work of scientists who, over the last few decades, have been tireless in their efforts to extract clues about the Earth’s past climate from air bubbles, isotopes and dust particles trapped in ice.

First, a timeline of deep polar cores documents in fine detail the discoveries of scientific pioneers, from the first efforts to read ice records through to today’s hunt for ice a million years old or more. Complementing this chronology of scientific discovery is an interactive map layer for Google Earth. This virtual tour takes you to the sites where polar researchers have holed up year after year, drilling thousands of metres of Greenland or Antarctic ice before hitting bedrock. In the window below, spin the globe to the pole of your choice, zoom in and click on the map points to see the drilling stations. For a full-size view and more navigation controls - plus a built-in web browser window where you can check out the timeline - download the map layer here and run it in Google Earth, which you can download here.

As I highlighted earlier on the blog, this month's issue of NRCC also features an exclusive interview with world-renowned glaciologist Lonnie Thompson. On his quest to understand how ice is changing atop the world’s mountains, Thompson has spent more spent more time above 20,000 feet than any other human being; he's currently with a team at the Quelccaya glacier in Peru, racing to bring back ice that is rapidly being lost to climate change. The American Museum of Natural History has put together a great video on his work.

Such endeavours come with scientific challenges as well as personal ones. As understanding abrupt climate change becomes increasingly crucial, ambitious plans for studying these icy environs will be ever more important.

Anna Barnett

Posted by Anna Barnett on August 03, 2009
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At the AGU Chapman Conference last month I met up with Lonnie Thompson, the alpine glaciologist who has spent more time above 20,000 feet than any other human. Despite being interrupted by last-minute demands from Peruvian customs officials - he was squeezing me in before taking off for a new expedition in the Andes - an unphased Thompson carefully laid out the past and present-day climate change that his work has uncovered. Here's an extract:

What information can you garner from glaciers?

Glaciers are like sentinels, and they're telling us that the system is changing. The first thing we look for in the ice is radioactivity from thermonuclear bomb tests in 1962–1963 and 1951–1952. Back in 2006, we drilled three cores in the southwestern Himalayas. At 6,050 metres, where those glaciers reach their highest elevation, we found that neither of these radioactive layers was preserved. The glaciers are being decapitated. Not only are they retreating up the mountain slopes, but they are thinning from the top down.

This same scenario is playing out on Mount Kilimanjaro in Africa. When we drilled there in 2000 we found the 1951 test preserved, but not the 1962 test. We've since continued to monitor those glaciers and we know that we've lost three metres of ice since 2000. If we had waited until this year to drill, we would not have found the 1951 bomb horizon, because that has now been lost.

What does that mean for climate science?

Once a glacier melts, the history it contained is gone forever, so there's an urgency in trying to collect the records before they are lost.

The loss of tropical glaciers is very telling because they're in such sensitive places. Half of the surface of the planet lies between 30° N and 30° S. That's where the heat that drives the climate system is received. It's also where 70 per cent of the 6.7 billion people on the planet live.

What's the effect on people as these glaciers disappear?

After this meeting, we're headed to Peru to drill new ice cores at two sites. That country contains 75 per cent of the world's glaciers. Eighty per cent of its population is in the desert on the west coast, and 76 per cent of the electricity comes from hydropower, from streams that are fed by glaciers in the Andes, all of which are retreating. Those changes are impacting the ability to produce hydropower, to irrigate crops in the desert and to provide municipal water supplies.

Read the full interview here.

Anna Barnett

Image: © Thomas Nash 2000. All rights reserved.

Posted by Anna Barnett on July 09, 2009
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Jane Qiu has an interesting interview on Nature News with aquatic ecologist Breck Bowden of the University of Vermont, who is heading up new research looking at what happens when thawing ground in the Arctic begins to fall apart. Here's an excerpt:

Last week marked the start of a US$5 million project to study the effects of thawing permafrost on ecosystems in the Arctic. Based at the Toolik Field Station in northern Alaska and sponsored by the US National Science Foundation, the project will look at the impact of thermokarsts — the scars and pits left behind as melt water from permanently frozen ground leaks away, and soil and rock collapses in its wake.

The project was inspired by a serendipitous discovery in 2003, says Bowden:

My colleagues and I were flying over the high Arctic in search of research sites. We noted that the Toolik River was brown and muddy, which was odd as it hadn't rained recently. As we went further upstream, we came to a tiny stream that was washing tons of thermokarst sediments into the river. We were astounded how this tiny feature was influencing the river 40 kilometres downstream. The volume that had been displaced was enough to smother the bottom of the entire river. The sediments would release a lot of nutrients normally locked up in permafrost into freshwater cycles. That's got to have a significant impact on the ecosystem.

Read the full interview here.

Anna Barnett

Posted by Anna Barnett on July 01, 2009
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Cross-posted from The Great Beyond

Following the collapse on April 4 of a narrow ice bridge that had connected the Wilkins ice shelf with a small island off the Antarctic Peninsula, the northern ice front of the ice sheet is beginning to disintegrate.

A high-resolution radar image taken on April 20 by the German TerraSAR-X satellite shows large icebergs being released from a rift zone near Latady Island. Scientists expect up to 3,400 square kilometretres of the Wilkins Ice Sheet to break into icebergs before a new stable ice front will form.

Quirin Schiermeier

Posted by Quirin Schiermeier on April 29, 2009
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Arctic sea ice continues to shrink, according to the latest satellite data. And in a scenario all too familiar to people of a certain age, the ice that is left has been replaced by a younger, thinner version of itself.

According to the US National Snow and Ice Data Center, the maximum extent of Arctic sea ice last winter was the fifth lowest on record. All sixth lowest maximums have occurred in the last six years (press release).

This year’s maximum was 15.16 million square kilometres, which is smaller than the 1979-2000 average by an area roughly the size of Texas (or France). Younger, thinner ice which melts every year is now 70% of Arctic sea ice, says the NSIDC, meaning melting is easier. In the 1980s and 90s this type of ice was between 40 and 50% of the total.

Read the rest of this post at Nature's The Great Beyond blog.

Posted by Olive Heffernan on April 07, 2009
Categories: Climate Science, Cryosphere, Daniel Cressey, Regional climate | Permalink | Comments (0) | TrackBacks (0)

The narrow strip of ice which connected the Wilkins ice shelf with a small island off the southwestern Antarctic Peninsula has finally collapsed, threatening to speed up the disintegration of the 11,000 square kilometres-large shelf.

Scientists had expected the break up. A partial collapse of the ice sheet last year had already thinned and twisted the natural ice bridge which connected the Wilkins ice shelf with Charcot Island, providing stability. On 1 April scientists monitoring satellite images of the region first noticed that rifts had occurred in the Manhattan-sized strip of ice. On 4 April it broke into pieces.

Satellite image: Terra SAR-X ScanSAR, 5 April 2009 © DLR, 2009
(Charcot Island is to the left. The island at the bottom right is Latady Island. Behind the broken ice bridge are icebergs from the June/July 2008 break up)

The collapse could accelerate erosion of the Wilkins ice sheet, which is located in one of the most rapidly warming regions of Antarctica. Its demise threatens to speed up the flow of continental glaciers to the coast, with implications for global sea level rise.

Quirin Schiermeier

Posted by Quirin Schiermeier on April 07, 2009
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Last week I blogged on new research into shrinking Arctic summer sea ice. But as just reported at Nature News, climate change is not only "making Arctic sea ice disappear — it's also changing the type of ice that forms".

Nicola Jones writes that a patchwork of 'pancake ice' is becoming more common as the Arctic Ocean opens up and grows choppier. Because pancake ice is thinner and patchier than the usual think multi-year sea ice found in the Arctic, more sunlight is now reflected from the sea surface in the region, causing concern that it could accelerate local warming. It could have other knock-on effects on ocean circulation, ice growth and air temperature. More details in the story here.

Anna Barnett

Image: Pancake ice / Glenn Grant, National Science Foundation

Posted by Anna Barnett on March 24, 2009
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The Arctic has been losing summer sea ice fast. At the end of the melt season in September 2008 the ice extent was barely above its record low of 2007, even after a much cooler summer. Most climate models did not anticipate the pace of this ice disappearance and still can’t replicate it. And as shown in the figure above, the futures projected by models are all over the map.

But researchers are reporting this week that there may be a way around the problems with modelling sea ice. With a new method for using observations to constrain climate projections, they find that the summertime ice is going, going, and set to be gone well before 2100.

The study was published in Nature Geoscience (subscription) by Julien Boé and his colleagues at UCLA. They calculate that the models showing the fastest future ice loss are also the most realistic about the recent past - something you could guess at by looking at the graph above, where the actual ice trend is shown as a black line. So rather than simply averaging across models, their technique teases out the most likely future sea ice evolution using the differences between the models that show the 1979-2007 ice extent most accurately and those that perform less well at reproducing past trends (if you’ve a yen for statistics it’s worth checking out the paper itself - the method is explained in a neat graphic). They project, based on a moderate emissions scenario, that September sea ice will most likely disappear between 2066 and 2085. That is sooner than even the most pessimistic models suggest on their own (see graph again).

Continue reading "Reconciling sea ice models with reality" »

Posted by Anna Barnett on March 19, 2009
Categories: Anna Barnett, Climate prediction, Cryosphere | Permalink | Comments (1) | TrackBacks (0)

Two papers in Nature today shed light on the possible future behaviour of the West Antarctic ice sheet (WAIS), complete loss of which would produce a worldwide rise in sea level of around 5 metres.

The two teams - one using a high-resolution ice sheet model, the other looking at glacial records contained in seafloor sediment – independently arrive at similar conclusions: The WAIS has intermittently melted during the past five million years or so, and its oscillations follow a 40,000 year cycle in the Earth’s axial tilt. Small variations in tilt – called the obliquity of the ecliptic – result in reduced or increased amounts of sunlight reaching the poles, thus pacing the succession of ice ages and warm periods.

During the warmest interglacial phases the WAIS has in the past episodically collapsed entirely, the studies suggest (Editor's Summary) Global temperatures around 3 degrees Celsius warmer than today seem to have sufficed to initiate the transition from grounded ice to open waters in the Ross Bay, reports the team led by Tim Naish of Victoria University in Wellington, New Zealand, who analysed a sediment core recovered from beneath the Ross ice shelf by the ANDRILL programme. Model simulations suggest the transition from full glacial to intermediate state (such as today’s) to nearly ice-free conditions can proceed rapidly. In the warmest ‘super-interglacials’, such as one around 1.07 million years ago, it took only around thousand years for the WAIS to collapse, report David Pollard and Robert DeConto of Pennsylvania State University in the second study.

Image: Punchstock

Continue reading "Antarctica: Memento melting " »

Posted by Quirin Schiermeier on March 19, 2009
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One noteworthy observation at December’s AGU conference – the latest and largest ever gathering of earth and space scientists – was the attention being given to a threat conceivably worse than carbon dioxide. In numerous talks, during poster sessions and over coffee, scientists were discussing methane – a greenhouse gas with a warming potential 25 times that of CO2.

Researchers have long speculated that climate change will unleash vast stores of the gas from where it lies frozen beneath the sea floor and locked up in the Arctic, triggering rapid warming.

Until recently, however, there has been little cause for concern. But that could all be changing, reports Amanda Leigh Mascarelli in a feature online today (no subscription required). Several observations made in 2007 to 2008 and reported at the AGU suggest that we could be in danger of waking a sleeping giant.

For one, a group of researchers working in the shallow waters of the Siberian Shelf noticed that their methane measurements were usually high compared with previous observations made in the same location. Added to that, they saw large rings of gas — sometimes as wide as 30 centimetres in diameter — trapped in ice, as well as plumes bubbling to the ocean surface over hundreds of square kilometres.

Then a separate group of scientists reported that global atmospheric concentrations of methane had spiked in the same year, following almost a decade of stability. While scientists can’t say whether either of these observations are anomalies or part of a long-term trend, they are certainly paying closer attention to the problem than ever before. “If there’s a ticking bomb in the room, you’d like to know the possibility of it going off,” says geochemist James White of the University of Colorado. “The fact that it’s there at all is unnerving.”

Mascarelli’s feature gives the low-down on the latest science – from the role of methane in past warming events to projections of what might occur in the future – and looks at what experts are doing to avert the problem. Some intriguing approaches abound, from parts of re-wilding Siberia with large animals that literally stomp the permafrost to keep it intact to using natural methane leaks as a power source for remote villages.

But if understanding the methane problem sounds like all work and no play, think again. Katey Walter of the University of Alaska, whose work is featured by Mascarelli, has produced some amazing videos while studying methane bubbling up from lake bottoms in the Arctic. Here her team drills through lake ice, then lights the escaping methane.

Anna Barnett and Olive Heffernan

Image: The average atmospheric concentration of methane shot up suddenly in 2007, having remained stable for a decade. Data shown are from the Advanced Global Atmospheric Gases Experiment and the Australian Commonwealth Scientific and Industrial Research Organisation, courtesy of Matt Rigby.

Posted by Anna Barnett on March 05, 2009
Categories: Anna Barnett, Cryosphere, GHG emissions, Olive Heffernan | Permalink | Comments (0) | TrackBacks (0)

Researchers have discovered new hot spots for emissions of the greenhouse gas nitrous oxide: barren patches of peat dotted across northern tundra. And warming in the Arctic - just as it threatens to multiply emissions of carbon dioxide and methane from thawing permafrost and drying bogs - could accelerate the output of this lesser-known climate change culprit, according to a study in Nature Geoscience this week (subscription).

Nitrous oxide is the other other greenhouse gas. In the new paper, Pertii Martikainen of the University of Kuopio in Finland and colleagues call it third most important behind carbon dioxide and methane, noting that it contributes a reported 6% to global warming. It’s not been considered a player at all in the Arctic, where the few scientists who’ve looked for the gas have found negligible emissions. But that’s because they’ve been looking in the wrong places, say Martikainen’s team.

Continue reading "New Arctic feedback: vicious peat circles" »

Posted by Anna Barnett on February 17, 2009
Categories: Anna Barnett, Biosphere feedbacks, Cryosphere, GHG emissions | Permalink | Comments (0) | TrackBacks (0)

The research below, which I blogged from the AGU conference in December, is published today in Nature [subscription].

New research presented at the AGU today suggests that the entire Antarctic continent may have warmed significantly over the past 50 years. The study, led by Eric Steig of the University of Washington in Seattle and soon to be published in Nature, calls into question existing lines of evidence that show the region has mostly cooled over the past half-century. [Update: To be more specific here, incomplete records previously suggested that the interior was cooling].

Steig and colleagues combined satellite thermal infra-red collected over 25 years with weather station data for the region. Although the satellite data span a shorter time period and are accurate only for blue sky days i.e. when there is no cloud cover, they provide high spatial coverage of the region, which cannot be obtained from discrete ground measurements. In contrast, the weather station data provide complete temporal resolution over the past half-century.

Using an iterative process to analyse the data, they found warming over the entire Antarctic continent for the period 1957-2006. Restricting their analysis to 1969 to 2000, a period for which other studies have found a net cooling trend, Steig’s study found slight cooling in east Antarctica, but net warming over west Antarctica.

As well as uncovering evidence of warming over a wider region than previous studies have shown, the researchers found that warming occurred throughout all of the year and was greatest in winter and spring. In contrast, cooling over east Antarctica was restricted to autumn.

Continue reading "AGU 2008: Evidence that Antarctica has warmed significantly over past 50 years [updated]" »

Posted by Olive Heffernan on January 21, 2009
Categories: AGU, Cryosphere, Olive Heffernan | Permalink | Comments (19) | TrackBacks (1)

Monday was George W. Bush's last press conference as president, and the administration seized the day to release new security directives on US interests in the Arctic - where disappearing sea ice has the five bordering countries on edge about who will get their hands on assets set to be freed up.

Reuters reports that the new US policy contradicts Russian claims to seabed rich in oil and gas. Canadian press like the National Post are focused on the Northwest Passage: the US has asserted its right to sail the newly navigable waterway, which the White House calls an international strait but Canada says it owns.

The directives even look toward opportunities for terrorism in a warmer Arctic, says a press release reprinted at Dot Earth (alongside links and details on the new docs). The release is clear about the new reality up north:

Fourteen years have passed since the last review of federal Arctic policy. Our understanding of climate change in the Arctic has caused all Arctic nations to reassess their policies in the Arctic. In addition, with the increase in summer melting of Arctic sea ice, human activity is increasing. This raises new questions about the potential expansion of fisheries, pollution, energy exploration and development, and the nature of sustainable economic development in the region.

"When it comes to energy, the notion isn't a race to the Arctic to put our flags down," a National Security Council spokesman told Reuters - in a seeming jibe at Russia's flag-planting expedition at the underwater North Pole. "Our approach is going to be dealing with our fellow Arctic nations in finding ways to access and develop, when it comes to energy specifically, that takes into account conservation and the environment."

Continue reading "US stakes claims in melting Arctic" »

Posted by Anna Barnett on January 15, 2009
Categories: Anna Barnett, Cryosphere, In the News, Politics | Permalink | Comments (1) | TrackBacks (0)

The loss of ice from Greenland ranks as one of the most troubling, and poorly understood, aspects of climate change. Melting of the colossal ice sheet, which is already undoubtedly underway, has the capacity to raise global sea levels by an astounding 7 meters.

Not only is Greenland losing mass from direct surface melting, its outlet glaciers (those that terminate in the sea) are spewing large icebergs directly into the ocean at an increasingly alarming speed as they retreat. Many have worried that these changes are a sign of what’s in store. But a new study published this week in Nature Geoscience [subscription] suggests that the recent rapid retreat of many of Greenland’s outlet glaciers will be short-lived.

A team led by Andreas Vieli at Durham University, UK, used a computer model to reconstruct the recent behaviour of the Helheim Glacier, one of Greenland’s largest outlet glaciers. Helheim retreated some 7 kilometers between 2002 and 2005, during which time it discharged considerable volumes of ice into the ocean.

View image

Vieli’s team looked at whether the recent changes observed in the Helheim Glacier could be explained by one of two hypotheses; the first was that increased surface meltwater reaching the base of the glacier was speeding its slide toward the sea. The second potential explanation was that changing conditions in the area where the glacier meets the sea would trigger a domino effect on the glacier itself, leading to even faster ice flow and thinning upstream.

Their model showed that only the second hypothesis could explain past changes in the Helheim Glacier. Though they only analysed changes in this one outlet glacier, the authors say it is representative of many outlet glaciers south of 70°N that have recently thinned and rapidly released ice to the ocean.

Continue reading "Rapid retreat of Greenland's outlet glaciers may be temporary " »

Posted by Olive Heffernan on January 13, 2009
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A Chinese expedition is expected to start work this week on a new Antarctic base that will faciliate novel research in climate science as well as in other fields, reports Jane Qiu over on Nature News [subscription].

The Kunlun base will be located at Dome Argus, or 'Dome A', some 4,093 metres above sea level. It will be China's third Antarctic research facility and is being built as a legacy of International Polar Year, a major two-year scientific programme that comes to an end in March.

According to radar studies of the region, Dome A sits atop ice over 3,000 metres thick. Scientists hope that extracting ice cores of that depth at this particular site could extend the record of past climate changes back to 1.5 million years. Qiu writes:

A key focus of research is finding sites where ice cores stretching back further in time than any others could be drilled. A core obtained at a site known as Dome C — about 1,000 kilometres from Dome A (see map) — reached 3,200 metres deep and helped to reconstruct past climate going back 800,000 years. Many believe that Dome A promises older ice because it is higher and has less snow, meaning that researchers can get more years of climate records in a given thickness of ice.

Work on the station is expected to be completed by January 28, before temperatures drop tobelow –50 °C. At that stage it will have room for 25 people, with 11 sleeping units. I'm guessing they use that rotational bed-sharing system scientists sometimes use at sea?

Olive Heffernan

Image:P. Huybrechts, Vrije Universiteit Brussel

Posted by Olive Heffernan on January 07, 2009
Categories: Cryosphere, Features, In the News, Olive Heffernan, Palaeoclimate, Research | Permalink | Comments (0) | TrackBacks (0)

The Arctic tundra is letting loose a large and unexpected burst of methane in the autumn, finds a new study out in Nature today. Unlike the oceanic methane bubbles that made headlines a few months ago, this isn’t suggested to be an effect of climate change – it’s the formerly overlooked (or rather, never-looked-for) tail of a natural seasonal cycle. But it’s important for understanding natural methane-emitting processes that may be affected by future warming. I’ve got the full story over on Nature News.

The newly discovered surge of greenhouse gas is brought to you by International Polar Year. Thanks to that research push, a team led by biogeochemist Torben Christensen of Lund University, Sweden, got a two-month extension on the usual field season at a monitoring station in northeast Greenland. Scientists have been measuring methane emissions from far-northern tundra during the growing season for decades, but it had been assumed that once methane levels taper off in late summer, they stay at next to nil over the freezing fall and winter.

Far from it. Emissions actually spike as the ground starts to frost over, the researchers found, and cumulative emissions during the freeze-in are about equal to those in summer. If all wet meadow tundras release a similar methane burst, they calculate, about 4 million tonnes may be emitted each winter. That’s not enough to affect estimates of the total annual methane emissions from tundra (30 to 100 million tonnes), but it’s just right to account for an observed autumn surge in atmospheric methane over the frozen north that had previously gone unexplained.

Continue reading "Frozen tundra bursting with gas" »

Posted by Anna Barnett on December 03, 2008
Categories: Anna Barnett, Cryosphere, GHG emissions, In the News | Permalink | Comments (0) | TrackBacks (0)

Scientists have reported the first direct evidence of a link between flooding underneath the Antarctic ice sheet and the rate at which glaciers are discharged into the sea. The study, which was published online on Nature Geoscience yesterday [subscription], has important implications for understanding how ice released into the ocean from the Greenland and Antarctic land masses could raise sea level.

Led by Leigh Stearns of the Climate Change Institute at the University of Maine, the trio of researchers found that ice on the Byrd Glacier in East Antarctica accelerated just as there was a massive release of water from lakes beneath the ice.

Over the past 20 years, researchers have discovered more than 150 lakes beneath the Antarctic ice pack, the largest of which (Lake Vostok) is equal in size to Lake Ontario in Canada.

And more than a year ago, researchers reported that these subglacial lakes could actually lubricate the flow of ice off the continent and into the ocean, as I reported over on Nature News at the time.

Continue reading "Under-ice floods speed glaciers towards the sea " »

Posted by Olive Heffernan on November 17, 2008
Categories: Climate Science, Cryosphere, Features, Journal Club, Olive Heffernan | Permalink | Comments (0) | TrackBacks (0)

Humans are at fault for warming at both the Earth’s poles: so say unique findings published in Nature Geoscience today.

With stories of dwindling sea ice and collapsing ice shelves already saturating the media, this at first may hardly sound like news. But in fact, researchers had never formally pinned the Arctic’s rapid warming on humans, because limited data were swamped by great natural variability. Down south, where warming on the Antarctic Peninsula contrasts with cooling in some other regions of the continent, the IPCC’s 2007 assessment report concluded: “Anthropogenic influence has been detected in every continent except Antarctica (which has insufficient observational coverage to make an assessment)”.

In the new study, Nathan Gillett of the University of East Anglia and colleagues found a way to squeeze clear results from those sparse data. Their method was based on state-of-the-art models of the polar climates that either incorporated anthropogenic as well as natural influences on variability, or included natural factors only. (Human influences include greenhouse gases that cause warming and a cooling effect from depletion of stratospheric ozone; natural ones are solar variation and volcanic eruptions.) This type of study, pioneered by Peter Stott and co-authors in 2000, has greatly boosted the IPCC’s confidence that humans are causing climate change globally. The new Gillett et al. study - co-authored by Stott - gave the technique an important tweak, say Andrew Monaghan and David Bromwich in an accompanying News and Views article, by focusing on model results for only those places with observational temperature records:

By this restriction, the group is able to perform an ‘apples with apples’ comparison of model simulations and polar near-surface temperature records during the twentieth century. Their analysis implies that the models can simulate trends better than previous studies had suggested.

In the records since 1900 put together by Gillett et al., the average temperature across monitoring stations has risen at both poles. And the models match these trends only when they factor in all influences, including human hands (producing the line labelled ALL in the above figure).

“We detected the human fingerprint in both the Arctic and Antarctic regions,” says Gillett. The familiar litany of impacts - balding Arctic summer sea ice, ecological and human displacements, sea level rise - are likely down to us too, the authors say. Stott adds that the results make the poles’ future all the bleaker, since “the human component isn’t going to let up anytime soon.”

Continue reading "Human prints on the poles" »

Posted by Anna Barnett on October 30, 2008
Categories: Anna Barnett, Attribution, Climate Science, Cryosphere | Permalink | Comments (6) | TrackBacks (0)

For the long view on the 2008 Arctic sea ice melt, see today’s commentary on Nature Reports Climate Change by two National Snow and Ice Data Center researchers. Mark Serreze and Julienne Stroeve recap the results:

The seasonal minimum for 2008, occurring on 14 September, entered the books as the second-lowest of the satellite era, probably the second-lowest of at least a century, and just behind the standing record set in 2007.

Barely second-lowest still came as a shock, given the cooler weather this year. Said Stroeve in an NISDC press release, “I find it incredible that we came so close to beating the 2007 record — without the especially warm and clear conditions we saw last summer. I hate to think what 2008 might have looked like if weather patterns had set up in a more extreme way. ”

August 2008 saw the fastest melt ever recorded, according to NASA. And ice volume, a bellwether for the future, probably was at its lowest this year - an observation that hasn’t reached the broadsheets (but see Climate Progress and Stoat).

NSIDC scientist Walt Meier explains, “Warm ocean waters helped contribute to ice losses this year, pushing the already thin ice pack over the edge. In fact, preliminary data indicates that 2008 probably represents the lowest volume of Arctic sea ice on record, partly because less multiyear ice is surviving now, and the remaining ice is so thin.”

Continue reading "Has Arctic summer sea ice tipped?" »

Posted by Anna Barnett on October 09, 2008
Categories: Anna Barnett, Climate Science, Cryosphere | Permalink | Comments (4) | TrackBacks (0)

Arctic permafrost has been the subject of much global warming worry, but not so much detailed research. A new survey of North American Arctic permafrost published in Nature Geoscience this week (subscription required) breaks new ground, literally.

News accounts have focused on the paper’s bottom-line estimate: there is 60% more carbon frozen up there than previously thought. That’s a total of 98.2 billion tonnes of carbon, one-sixth of the amount currently circulating through the atmosphere.

Existing estimates already show more permafrost carbon around the globe than atmospheric carbon. If warming - which is happening faster in the Arctic than anywhere else - releases even a small portion of that store into the atmosphere as carbon dioxide and methane, the results won’t be pretty, especially if the amount frozen in the Asian north is also more than expected. Permafrost has been called a “slow-motion time bomb”, and the effects of its melting are not included in most global climate models.

The new research is by Chien-Lu Ping of the University of Alaska Fairbanks and colleagues. How did they do it?

Continue reading "Permafrost study breaks ground" »

Posted by Anna Barnett on August 29, 2008
Categories: Anna Barnett, Climate Science, Cryosphere, In the News | Permalink | Comments (3) | TrackBacks (0)

The predicted effects of climate change can be counted on to shake up international relations, even far from the impoverished, politically wobbly regions where the most obvious conflicts loom. A case in point is the tranquil Arctic seabed, believed to hold a substantial fraction* of the world's undeveloped oil reserves - which, as the summer sea ice extent decreases year by year, is suddenly set to become accessible for extraction.

As such, the Arctic Ocean is a new source of friction among the five countries that claim portions of it as their sovereign territory: the US, Canada, Norway, Denmark, and Russia, the latter of which elicited clucking from some of the others in August when it sent a submersible to the sea bottom and planted a titanium national flag at the underwater North Pole. And more than the pole is up for grabs. In a great piece on the politics of Arctic climate change in Vanity Fair, Alex Shoumatoff writes:

Last summer, Canada’s Northwest Passage was nearly free of ice and completely navigable for a few weeks—for the first time since records have been kept. This fabled route to the Orient, which eluded Henry Hudson, Sir Francis Drake, and Martin Frobisher, and was finally navigated by the Norwegian Roald Amundsen in 1905, would reshape global trade, being thousands of miles shorter than most currently used shipping routes, though it won’t be clear long enough to be commercially viable for at least another 15 to 20 years. Canada has claimed the passage as its internal waterway since the early 1970s, but the U.S. maintains that it is an international strait, through which any vessel, including submerged submarines gathering intelligence, has the right of “transit passage.”

On Wednesday, the five Arctic-bordering nations met in the tiny town of Ilulissat, Greenland, with the intention of staving off inconvenient squabbles over the newly unfrozen oil and gas sources. The high-level delegates sent to handle the promise of a new oil rush agreed to proceed in an orderly fashion and allow the UN to decide who owns what (Reuters, New York Times, FT).

When the UN rules on territorial rights, it will be ruling on geoscience. At issue is how far the continental shelf under each nation extends into the ocean - the criterion for sovereignty under the 1982 UN Law of the Sea Convention (still not ratified by the US Senate, which will apparently have to overcome past reluctance in order to achieve the country's Arctic aims). Wednesday's declaration gives the claimants time to gather scientific evidence to present to a commission on continental shelves.

The agreement also avoids aiming for a treaty like the one concocted to settle wrangling over Antarctica in the 1950s. A 1991 addition to the Antarctic treaty forbids exploitation of mineral resources until 2048, which may be why the delegates in Ilulissat hastened to hand their disagreements over to the UN and emphasize that no special laws would be necessary up north. Environmental groups, excluded from the meeting, would naturally prefer a treaty that could offer strong protection for Arctic ecosystems already stressed by warming.

Anna Barnett

Photo: North Pole sign set up by the crew and scientists of the German research vessel Polarstern; Hannes Grobe

*Often said to be 25% - erroneously, according to Shoumatoff.

Posted by Anna Barnett on May 30, 2008
Categories: Anna Barnett, Cryosphere, Energy, In the News, Politics | Permalink | Comments (3) | TrackBacks (0)

The current issue of Nature has a feature about the state of the Greenland ice sheet (See also the related editorial dealing with the state of polar research funding).

I got started on this story at the American Geophysical Union meeting last December, in which session after session presented new data about the extent of summer melt in Greenland. Information from the GRACE satellites shows that the overall mass balance of the ice sheet is dropping steadily, and although surface melt varies quite a bit from summer to summer, two of the last three years have seen record levels of melt.

“2007 was a shocking year,” Scott Luthcke, who works with GRACE at NASA’s Goddard Space Flight Center in Maryland, told me later.

One record melt season does not spell the end of Greenland, of course, and journalists must always be wary about sounding too alarmist based on short-term records. But overall, the outlook for Greenland is simply not good: Changes in speeds of the island’s outlet glaciers show that, no matter whether they are advancing or retreating, they are far faster at changing their behavior than anyone had thought before.

As the article was going to press, we learned that another pair of key Greenland papers would appear the next day online in Science. Such is the peril of scheduling features far in advance while knowing your competitor journal has interesting papers under review.

The basic point of the two new papers -- that vast quantities of meltwater can form and then drain away atop the ice sheet each summer – made it into my feature anyway. But if you want more details, check out the original papers at the Science Express website. One paper, with lead author Sarah Das of the Woods Hole Oceanographic Institution, reports on a 4-kilometre-long melt lake that vanished into the ice sheet within the space of two hours. The other, with lead author Ian Joughin of the University of Washington’s Applied Physics Laboratory, describes seasonal speed-up in ice flow along Greenland’s western flank – though not so much in the outlet glaciers. Together, the papers confirm how meltwater likely helps lubricate the slippage of the ice sheet towards the ocean.

If you’re still looking for more things Greenland, check out the recent posting on RealClimate that again suggests the details of how Greenland melts are more complicated than we thought.

And if you just need a fix of gorgeous Greenland pictures, click on over to the Extreme Ice Survey project of photographer James Balog and others. We used only one of Balog’s iceberg images in my Nature feature, but his time-lapse work of melting glaciers is stunning.

Alexandra Witze

Image credit: NASA/GSFC VISUALISATION STUDIO; SOURCE: S. LUTHCKE

Posted by Olive Heffernan on April 22, 2008
Categories: Alex Witze, Climate Science, Cryosphere, Features, In the News | Permalink | Comments (4) | TrackBacks (0)

The Guardian was far from alone in reporting this week that "A vast hunk of floating ice has broken away from the Antarctic peninsula, threatening the collapse of a much larger ice shelf behind it, in a development that has shocked climate scientists." On The Great Beyond, Quirin Schiermeier points out that the the most noteworthy thing about this delicately poised hunk of the Wilkins ice shelf may be its media visibility: the loss of a 400-square-kilometre piece of the same shelf earlier this year received no such fanfare.

Still, that visibility is pretty spectacular. Check out this mashup of the Twin Otter plane's flyover footage with the satellite images that tipped off British Antarctic Survey scientists:

"The ice shelf is hanging by a thread," said David Vaughan of the British Antarctic Survey. "We'll know in the next few days or weeks what its fate will be."

Anna Barnett

Posted by Anna Barnett on March 28, 2008
Categories: Anna Barnett, Climate Science, Cryosphere, In the News | Permalink | Comments (3) | TrackBacks (0)