Showing posts with label Sea level rise. Show all posts

Written by fatih al-farahat in , ,


Peter Gleick: It's too late. Past the point of no return -- unavoidable climate change

It's too late. Past the point of no return -- unavoidable climate change

by Peter H. Gleick (co-founder & president, Pacific Institute, Huffington Post, November 20, 2010

It's too late. The world has missed the opportunity to avoid serious, damaging human-induced climate change. For a variety of reasons ranging from ignorance to political ideology to commercial self-interest to inertia to intentional misrepresentations and misdirections on the part of a small number of committed climate deniers, the United States and the rest of the world have waited too long to act to cut the emissions of damaging greenhouse gas pollutants. We are now committed to irreversible long-term and inevitably damaging consequences ranging from rapidly rising sea levels, far greater heat stress and damages, disappearing glaciers and snowpack, more flooding and droughts, and far, far more.

For over two decades, there have only been a few people and groups that have argued against climate change, and very few of these have done so in good faith (though there is no denying that they've been effective). Sometimes they have tried to hide behind scientific "uncertainty" to mask their anti-climate-change arguments. But the fundamental science has long been irrefutable, and so recently, we've seen all pretense of caring about science thrown out the door by elected officials such as Congressman John Shimkus (vice chairman of the Republican Party's Congressional campaign committee and vying to become chair of the influential House Energy and Commerce Committee), who rejects climate change by turning to the Bible to refute the science or as justification to ignore it.


"The earth will end only when God declares it's time to be over. Man will not destroy this earth," Shimkus said. "I believe that's the infallible word of God, and that's the way it's going to be for his creation."

Here, in a nutshell, is the best argument against global climate change:

There isn't one.

No scientific body of national or international standing rejects the findings that humans are changing the climate. Indeed, every single legitimate scientific organization and society that works on atmospheric, climatological, meteorological, geological, hydrological, ecological, physical, chemical, and biological sciences supports the scientific findings of human-induced climate change. All of them. Here are a few examples.

For reasons well described by Naomi Oreskes and Erik Conway in their book Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming, the media has also failed to distinguish between correct and incorrect, because it is far easier simply to describe this as a debate between equals. Like the argument about the health consequences of tobacco, it is inevitable that reality will ultimately win over fantasy and that the truth about the seriousness of climate change will become widely accepted. But as I argue above, that inevitability will come too late, leading to another inevitability: unavoidable, severe climate impacts to all of us (or to coming generations).

Worse, the misrepresentations continue. At Wednesday's Congressional climate hearing of the House Committee on Science and Technology, some of the nation's top climate scientists once again (as they have over and over for decades) explained to a few congressmen about the nature of climate change, while climate-confusers such as Patrick Michaels (a perennial fixture in the decades-long effort of the fossil fuel industry and conservative "think tanks" to confuse Congress and the public about the science of climate change), came up with novel (but alas, scientifically discredited) arguments about why humans are not largely responsible for changing the climate. As a journal article noted a few years ago, in a funny, albeit dry academic style: "...the observations upon which PM [Patrick Michaels] draws his case are not good enough to bear the weight of the argument he wishes to make."

The new Congress will almost certainly see more science pushed out by ideology and hearings characterized by cherry-picking of witnesses and selective use of climate deniers rather than mainstream scientists.

As a result, in twenty more years, the Earth will be even hotter, sea levels will be higher and rising faster, water and food resources will be increasingly stressed, extinction rates will accelerate, and our forced expenditures for climate adaptation will be far, far greater than they would otherwise have been.

For example, at the request of three separate California state agencies, the Pacific Institute recently completed a comprehensive assessment of the vulnerabilities of the California coast to accelerating sea-level rise (using scenarios of sea-level rise that may turn out to be far too low). There is already over $100 billion in infrastructure (housing, airports, wastewater treatment plants, schools, hospitals, roads, power plants) and a population of nearly 500,000 people at risk of increased coastal flooding, and we estimated that adaptation costs just to protect existing infrastructure will run around $15 billion, plus high annual costs to maintain these protections. Other major areas and populations simply cannot be realistically protected and will have to be abandoned, with people forced to move over time. And this is just one small piece of the coming threats for one small part of the country. How bad it ultimately gets depends on how much longer we fail to act and how much longer Congress and others hide behind ignorance, political ideology, and religion to deny the reality of climate change.

Link:  http://www.huffingtonpost.com/peter-h-gleick/unavoidable-climate-chang_b_786158.html

Written by fatih al-farahat in , , ,


NYT: Restless Ice -- Greenland's glaciers accelerating

Dear Readers,

Please go to this link at the New York Times while it is still free to access their articles:


Sorry about formatting problems -- they began a couple of days ago. This is just an ordinary blogspot blog, nothing fancy, so I have no idea how to fix them.


Published: November 12, 2010

Restless Ice



Researchers studying Greenland note that its massive ice sheet appears to have become less stable. The movement of some glaciers has doubled or tripled in speed recently, possibly because of human-induced climate change. If the trend worsens, melting ice and icebergs falling into the ocean could raise global sea levels substantially.

Circles show quakes through 2005
Kangerdlugssuaq and Helheim Glaciers have had more glacial earthquakes since 1993 than any other glaciers in Greenland.
Dotted lines highlight the boundaries between Greenland’s major ice drainage basins. Snow falling inside a boundary will flow to the sea within the same boundary.

Helheim Glacier

This large glacier in southeastern Greenland had a recent increase in speed, which was paired with a thinning of its ice front.
Helheim Glacier empties into Sermilik Fjord, where temperature measurements reveal deep layers of warm water, which may be melting the glacier from below and increasing iceberg calving.
By JONATHAN CORUM and XAQUÍN G.V. / THE NEW YORK TIMES
Sources: Ian Joughin, University of Washington (speed imagery); Göran Ekström and Meredith Nettles, Columbia University (quake data); Fiammetta Straneo, Woods Hole Oceanographic Institution (water temp.); Journal of Glaciology; Nature; Science

Written by fatih al-farahat in , , ,


Water flowing through Greenland's ice sheet accelerates ice warming and could speed up ice flow, new study finds

Water flowing through ice sheets accelerates ice warming and could speed up ice flow, new study finds

environmentalresearchweb.org, November 17, 2010
Meltwater flowing through ice sheets can carry warmth to the interior via crevasses, fractures, and large drains called moulins. A new modeling study shows that such warming can greatly accelerate the thermal response of an ice sheet to climate change: An ice sheet can respond on the order of decades, rather than the centuries projected by conventional thermal models. Ice flows more readily as it warms, so a warming climate can increase ice flows much faster than previously thought.
"We are finding that once such water flow is initiated through a new section of ice sheet, it can warm rather significantly and quickly, sometimes in just 10 years, " said lead author Thomas Phillips, a research scientist with the University of Colorado at Boulder and NOAA's Cooperative Institute for Research in Environmental Sciences (CIRES). "We've termed this process cryo-hydrologic warming."
Phillips, University of Colorado engineering professor Harihar Rajaram, and CIRES Director Konrad Steffen described their model results in a paper published online this week in Geophysical Research Letters.
Conventional thermal models of ice sheets do not consider the presence of water as a warming agent within the ice sheet – those models primarily consider heating by warmer air on the ice sheet surface.  In water's absence, ice warms slowly in response to the increased surface temperatures from climate change, often requiring centuries to millennia to happen. "This would be correct if water only flowed on the ice surface without the opportunity to go into it," said Phillips.
However, the Greenland ice sheet is not one solid, smooth mass of ice. As the ice flows towards the coast, grating against bedrock, crevasses and new fractures form in the upper 100 feet of the ice sheet. Meltwater flowing through these openings can grow "ice caves" and networks of pipes that can carry water through the ice, spreading warmth.
To quantify the influence of that meltwater, the scientists modeled what would happen to the ice sheet temperature if water flowed through it for just eight weeks every summer, about the length of the active melt season.
"The key difference between our model and previous models is that we include heat exchange between water flowing through the ice sheet and the ice," said Rajaram.
The result was a significantly faster-than-expected increase in ice sheet warming, the research team reported. The warming could take place on the order of years to decades, depending on the spacing of crevasses and other "pipes" bringing warmer water into the ice sheet in summer. Several factors contributed to the warming and resultant acceleration of ice flow:
  1. Slower cooling: Some of the water that flows into the ice sheet can stay liquid even through the winter, slowing seasonal cooldown.
  2. Basal lubrication: A warmer ice sheet is more susceptible to increases in flow by long-understood mechanisms, such as basal lubrication of the ice.
  3. A downward spiral of damage: Water cascading into ice can warm the surrounding ice and also re-freeze, creating further cracks in the more vulnerable, warm ice.
Taken together, these interactions between water, temperature, and ice velocity spell even more rapid changes to ice sheets in a changing climate than currently anticipated, the authors concluded.
In fact, the authors compared observed temperature profiles from Greenland with  model results. Unless the cryo-hydrologic warming was accounted for, they could not explain observations.
"The fact that the ice temperatures warm rather quickly is really the key piece that's been overlooked in models currently being used to determine how Greenland responds to climate warming," Steffen said. "However, this process is not the 'death knell' for the ice sheet. It'll still take thousands of years, if not a multiple thereof, for the ice sheet to disappear."
Collaborators on this project include the Aerospace Engineering and Sciences, Geography, and Civil, Environmental, and Architectural Engineering departments at the University of Colorado at Boulder. This study was supported by NASA Cryosphere Science Program grants and is published online in the journal Geophysical Research Letters. Download a copy of the paper here.

Written by fatih al-farahat in , , ,


Joe Romm: Coastal studies experts: “For coastal management purposes, a [sea level] rise of 7 feet (2 meters) should be utilized for planning major infrastructure.” Front-page New York Times piece on sea level rise gets it mostly right


Coastal studies experts: “For coastal management purposes, a [sea level] rise of 7 feet (2 meters) should be utilized for planning major infrastructure”

Front-page NY Times piece on sea level rise gets it mostly right


by Joseph Romm, Climate Progress, November 14, 2010

The New York Times has a splashy front-page story on some of the latest research on sea level rise today.  The graphics above make clear the paper gets a big part of the story right — the latest science says we are facing 3-6 feet of sea level rise this century.

Kudos to the NYT for featuring such an important story.  Given that serious federal climate action is unlikely for years if not a decade or more, it is more incumbent on the media than ever to explain to the public what’s coming.

The story has its flaws, though.  For some reason the media — and many scientists — seem constitutionally incapable of explaining that inaction makes things much worse, that inaction greatly increases the chances of the worst impacts.  The NYT has usefully cited the work of Rahmstorf, but somewhat simplified and hence sanitized his graph:

SLR PNAS pic
Our current do-nothing or do-little path currently matches the A1F1 scenario (see “U.S. media largely ignores latest warning from climate scientists: “Recent observations confirm … the worst-case IPCC scenario trajectories (or even worse) are being realised” — 1000 ppm“), where the midpoint SLR projection is nearly 5 feet.  That’s no surprise since the unrestricted emissions scenario can leads to a staggering warming where the ice is located (see M.I.T. doubles its 2095 warming projection to 10 °F — with 866 ppm and Arctic warming of 20 °F).

So it is a tad frustrating that the NYT buries this crucial point in the final two paragraphs of this long article:
Climate scientists note that while the science of studying ice may be progressing slowly, the world’s emissions of heat-trapping gases are not. They worry that the way things are going, extensive melting of land ice may become inevitable before political leaders find a way to limit the gases, and before scientists even realize such a point of no return has been passed. 
“The past clearly shows that sea-level rise is getting faster and faster the warmer it gets,” Dr. Rahmstorf said. “Why should that process stop? If it gets warmer, ice will melt faster.”
The key point is that we are woefully prepared for what is likely to come:
“I think we need immediately to begin thinking about our coastal cities — how are we going to protect them?” said John A. Church, an Australian scientist who is a leading expert on sea level. “We can’t afford to protect everything. We will have to abandon some areas.”
Duh.  Triage.  It’s coming.

This NYT article give the answer to the question I posed Friday – AGU Climate Q&A Service won’t answer this Q: “Is current U.S. infrastructure adequate for sea level rise?” Is that prudent — or lame?

Key West and Galveston and probably New Orleans appear unsavable on our current emissions path, but what about Miami and Houston?  I’ll do a post on that subject later.

What should people plan for?  Obviously, it makes no sense to plan for the best case.  Most people are highly risk averse and spend a considerable amount of money planning for worst-case scenarios — that’s why they buy fire insurance and catastrophic health insurance.  Military and epidemiological planners routinely focus vast amounts of time and money around the worst-case scenarios.

Even if seas only rise, say 4 feet by 2100, then sea levels are likely to be rising 6 inches a decade or more at that point, probably for centuries, so again it makes little sense to plan for, say 2-3 feet of SLR, particularly when making big investments like, say, a new sewage treatment plant (or a major upgrade to an old one), which is going to last a very long time and not going to be easy to move.

As an aside, a 2009 study in Geophysical Research Letters found that “If Greenland’s ice melts at moderate to high rates, ocean circulation by 2100 may shift and cause sea levels off the northeast coast of North America to rise by about 12-20 inches (about 30-50 cm) more than in other coastal areas” (see here).
The NYT article notes:
One of the deans of American coastal studies, Orrin H. Pilkey of Duke University, is advising coastal communities to plan for a rise of at least five feet by 2100.
Since the NYT didn’t include a direct link to that claim or a direct quote, I went looking on Google, which turned up this op-ed piece from last November by Pilkey, “Rising sea levels: a strategy for N.C.“:
DURHAM — Western Carolina University’s Rob Young and I have argued that seas will rise at least 3 feet in this century and that, for coastal management purposes, a rise of 7 feet (2 meters) should be utilized for planning major infrastructure.
I have emailed Pilkey to find out the source of that discrepancy, but for now, I’m going with this as the headline quote.

I have three more issues with the article.  First, while the gratuitous quotes from the anti-science disinformers were kept to a minimum, the NYT should at least try to quote disinformers with relevant expertise:
Global warming skeptics, on the other hand, contend that any changes occurring in the ice sheets are probably due to natural climate variability, not to greenhouse gases released by humans… 
John R. Christy, a climatologist at the University of Alabama in Huntsville who is often critical of mainstream climate science, said he suspected that the changes in Greenland were linked to this natural variability, and added that he doubted that the pace would accelerate as much as his colleagues feared. 
For high predictions of sea-level rise to be correct, “some big chunks of the Greenland ice sheet are going to have to melt, and they’re just not melting that way right now,” Dr. Christy said.
As the link the NYT provides makes clear, Christy has no publications in this area.  His ‘expertise’  is in temperature trends and satellite measurements, but even there, how many times one has to be wrong before the media stops quoting you? (see “Should you believe anything John Christy and Roy Spencer say?“).

Second, the NYT asserts:
Certain measurements are so spotty for Antarctica that scientists have not been able to figure out whether the continent is losing or gaining ice.
In fact, while all such measurements have uncertainty, the literature is pretty clear that Antarctica has been losing mass in the past decade — at an accelerating rate, as Skeptical Science explains:
Figure 2 shows the ice mass changes in Antarctica for the period April 2002 to February 2009 (Velicogna 2009) . The blue line/crosses show the unfiltered, monthly values. The red crosses have seasonal variability removed. The green line is the best fitting trend.


Figure 2. Ice mass changes for the Antarctic ice sheet from April 2002 to February 2009. Unfiltered data are blue crosses. Data filtered for the seasonal dependence are red crosses. The best-fitting quadratic trend is shown as the green line (Velicogna 2009). 
With the longer time series, a statistically significant trend now emerges. Not only is Antarctica losing land ice, the ice loss is accelerating at a rate of 26 Gigatonnes/yr2 (in other words, every year, the rate of ice loss is increasing by 26 Gigatonnes per year). It turns out that since 2006, East Antarctica has no longer been in mass balance but is in fact, losing ice mass (Chen 2009). This is a surprising result as East Antarctica has been considered stable because the region is so cold. This indicates the East Antarctic ice sheet is more dynamic than previously thought. 
This is significant because East Antarctica contains much more ice than West Antarctica. East Antarctica contains enough ice to raise global sea levels by 50-60 metres while West Antarctica would contribute around 6-7 metres. The Antarctic ice sheet plays an important role in the total contribution to sea level. That contribution is continuously and rapidly growing.
I wrote about the Chen paper here (see Satellite data stunner: “Our data suggest that EAST Antarctica is losing mass…. Antarctica may soon be contributing significantly more to global sea-level rise”).  The study begins, “Accurate quantification of Antarctic ice-sheet mass balance and its contribution to global sea-level rise remains challenging, because in situ measurements over both space and time are sparse,” and it concludes:
Our results suggest that over the WAIS [West Antarctic ice sheet] (especially the ASE [Amundsen Sea Embayment]) there is accelerated ice loss since around 2005 and/or 2006, with the EAIS showing correlated changes of the same sign in this period, attributed to increased ice loss over EAIS coastal regions in recent years. Using a simple linear projection for the period 2006–2009, Antarctic ice loss rate can be as large as -220plusminus89 Gt yr-1. These new GRACE estimates, on average, are consistent with recent InSAR fluxes but, in contrast to previous estimates, they indicate that as a whole, Antarctica may soon be contributing significantly more to global sea-level rise.
Yes, a recent paper has questioned the full magnitude of some of the GRACE ice losses, but many leading experts have in turn questioned that work.  I suppose I will have to do a post on that.

Notwithstanding the NYT, the best science says that Antarctica is losing ice, and the ice loss is accelerating.

Third, one of the most puzzling statements in the entire piece is this:
The information problems are even more severe in Antarctica. Much of that continent is colder than Greenland, and its ice sheet is believed to be more stable, over all. But in recent years, parts of the ice sheet have started to flow rapidly, raising the possibility that it will destabilize in the same way that much of the world’s other ice has.
Notwithstanding the phrase “over all,” the WAIS has long been known it to be unstable, as the West Antarctic Ice Sheet Initiative explains at length here. As I wrote in the “high water” part of my book:
Perhaps the most important, and worrisome, fact about the WAIS is that it is fundamentally far less stable than the Greenland ice sheet because most of it is grounded far below sea level. The WAIS rests on bedrock as deep as two kilometers underwater. One 2004 NASA-led study found that most of the glaciers they were studying “flow into floating ice shelves over bedrock up to hundreds of meters deeper than previous estimates, providing exit routes for ice from further inland if ice-sheet collapse is under way.” A 2002 study in Science examined the underwater grounding lines–the points where the ice starts floating. Using satellites, the researchers determined that “bottom melt rates experienced by large outlet glaciers near their grounding lines are far higher than generally assumed.” And that melt rate is positively correlated with ocean temperature. 
The warmer it gets, the more unstable WAIS outlet glaciers will become. Since so much of the ice sheet is grounded underwater, rising sea levels may have the effect of lifting the sheets, allowing more-and increasingly warmer-water underneath it, leading to further bottom melting, more ice shelf disintegration, accelerated glacial flow, and further sea level rise, and so on and on, another vicious cycle. The combination of global warming and accelerating sea level rise from Greenland could be the trigger for catastrophic collapse in the WAIS.
And the WAIS Initiative notes:
A final, disturbing extension of West Antarctic collapse is that a substantial portion of the much-larger East Antarctic ice sheet would likely drain through the gap in the Transantarctic Mountains now occupied by the West Antarctic ice sheet. This would only increase the eventual magnitude of the change in sea level, further exacerbating the calamity.
So we have a cascading effect from Greenland to WAIS to EAIS.

For the record, a 2009 study in Science found that sea level rise from a collapse of the WAIS would likely be 25% higher for North America than previously estimated:
The catastrophic increase in sea level, already projected to average between 16 and 17 feet around the world, would be almost 21 feet in such places as Washington, D.C., scientists say, putting it largely underwater. Many coastal areas would be devastated. Much of Southern Florida would disappear.
And the WAIS is already in danger now:
So, yes, we can all hope that humanity somehow quickly becomes smart enough to stay at or below 450 ppm, and then returns to 350 ppm as quickly as possible, keeping overall sea level rise to below 3 feet this century.  But prudent planners should plan on 5-7 feet of SLR over the next 100 years.

Written by fatih al-farahat in , ,


New York Times publishes finest article (oops! see critique by Joe Romm) on climate science in years! "As Glaciers Melt, Science Seeks Data on Rising Seas" by Justin Gillis

As Glaciers Melt, Science Seeks Data on Rising Seas


Tony Cenicola/The New York Times
From a helicopter hovering over Greenland, the oceanographer Fiammetta Straneo took measurements to determine how fast the water is melting the nearby Helheim Glacier. More Photos »


UPDATE:  Dear Readers, Please go to Joe Romm's critique of this article -- it does contain some not so minor errors, particularly concerning the lack of stability of the ice sheets on Antarctica -- they are inherently unstable due to being situated below sea level:

http://climateprogress.org/2010/11/14/sea-level-rise-planning-coastal-infrastructure/

by JUSTIN GILLIS, The New York Times, November 13, 2010


TASIILAQ, Greenland — With a tense pilot gripping the stick, the helicopter hovered above the water, a red speck of machinery lost in a wilderness of rock and ice.

Temperature Rising

Articles in this series will focus on the central arguments in the climate debate and examine the evidence for global warming and its consequences.
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Restless Ice
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Rising Seas and Vulnerable Areas
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To the right, a great fjord stretched toward the sea, choked with icebergs. To the left loomed one of the immense glaciers that bring ice from the top of the Greenland ice sheet and dump it into the ocean.
Hanging out the sides of the craft, two scientists sent a measuring device plunging into the water, between ice floes. Near the bottom, it reported a temperature of 40 degrees. It was the latest in a string of troubling measurements showing that the water was warm enough to melt glaciers rapidly from below.
“That’s the highest we’ve seen this far up the fjord,” said one of the scientists, Fiammetta Straneo.
The temperature reading was a new scrap of information in the effort to answer one of the most urgent — and most widely debated — questions facing humanity: How fast is the world’s ice going to melt?
Scientists long believed that the collapse of the gigantic ice sheets in Greenland and Antarctica would take thousands of years, with sea level possibly rising as little as seven inches in this century, about the same amount as in the 20th century.
But researchers have recently been startled to see big changes unfold in both Greenland and Antarctica.
As a result of recent calculations that take the changes into account, many scientists now say that sea level is likely to rise perhaps three feet by 2100 — an increase that, should it come to pass, would pose a threat to coastal regions the world over.
And the calculations suggest that the rise could conceivably exceed six feet, which would put thousands of square miles of the American coastline under water and would probably displace tens of millions of people in Asia.
The scientists say that a rise of even three feet would inundate low-lying lands in many countries, rendering some areas uninhabitable. It would cause coastal flooding of the sort that now happens once or twice a century to occur every few years. It would cause much faster erosion of beaches, barrier islands and marshes. It would contaminate fresh water supplies with salt.
In the United States, parts of the East Coast and Gulf Coast would be hit hard. In New York, coastal flooding could become routine, with large parts of Queens and Brooklyn especially vulnerable. About 15 percent of the urbanized land in the Miami region could be inundated. The ocean could encroach more than a mile inland in parts of North Carolina.
Abroad, some of the world’s great cities — London, Cairo, Bangkok, Venice and Shanghai among them — would be critically endangered by a three-foot rise in the sea.
Climate scientists readily admit that the three-foot estimate could be wrong. Their understanding of the changes going on in the world’s land ice is still primitive. But, they say, it could just as easily be an underestimate as an overestimate. One of the deans of American coastal studies, Orrin H. Pilkey of Duke University, is advising coastal communities to plan for a rise of at least five feet by 2100.
“I think we need immediately to begin thinking about our coastal cities — how are we going to protect them?” said John A. Church, an Australian scientist who is a leading expert on sea level. “We can’t afford to protect everything. We will have to abandon some areas.”
Sea-level rise has been a particularly contentious element in the debate over global warming. One published estimate suggested the threat was so dire that sea level could rise as much as 15 feet in this century. Some of the recent work that produced the three-foot projection was carried out specifically to counter more extreme calculations.
Global warming skeptics, on the other hand, contend that any changes occurring in the ice sheets are probably due to natural climate variability, not to greenhouse gases released by humans.
Such doubts have been a major factor in the American political debate over global warming, stalling efforts by Democrats and the Obama administration to pass legislation that would curb emissions of heat-trapping gases. Similar legislative efforts are likely to receive even less support in the new Congress, with many newly elected legislators openly skeptical about climate change.
A large majority of climate scientists argue that heat-trapping gases are almost certainly playing a role in what is happening to the world’s land ice. They add that the lack of policies to limit emissions is raising the risk that the ice will go into an irreversible decline before this century is out, a development that would eventually make a three-foot rise in the sea look trivial.
Melting ice is by no means the only sign that the earth is warming. Thermometers on land, in the sea and aboard satellites show warming. Heat waves, flash floods and other extreme weather events are increasing. Plants are blooming earlier, coral reefs are dying and many other changes are afoot that most climate scientists attribute to global warming.
Yet the rise of the sea could turn out to be the single most serious effect. While the United States is among the countries at greatest risk, neither it nor any other wealthy country has made tracking and understanding the changes in the ice a strategic national priority.
The consequence is that researchers lack elementary information. They have been unable even to measure the water temperature near some of the most important ice on the planet, much less to figure out if that water is warming over time. Vital satellites have not been replaced in a timely way, so that American scientists are losing some of their capability to watch the ice from space.
The missing information makes it impossible for scientists to be sure how serious the situation is.
“As a scientist, you have to stick to what you know and what the evidence suggests,” said Gordon Hamilton, one of the researchers in the helicopter. “But the things I’ve seen in Greenland in the last five years are alarming. We see these ice sheets changing literally overnight.”
Dodging Icebergs
In the brilliant sunshine of a late summer day in southeastern Greenland, the pilot at the controls of the red helicopter, Morgan Goransson, dropped low toward the water. He used the downdraft from his rotor to clear ice from the surface of Sermilik Fjord.
The frigid waters were only 30 feet below, so any mechanical problem would have sent the chopper plunging into the sea. “It is so dangerous,” Mr. Goransson said later that night, over a fish dinner.
Taking the temperature of waters near the ice sheet is essential if scientists are to make sense of what is happening in Greenland. But it is a complex and risky business.
The two scientists — Dr. Straneo, of the Woods Hole Oceanographic Institution in Massachusetts, and Dr. Hamilton, of the University of Maine — are part of a larger team that has been traveling here every summer with financing from the National Science Foundation, the federal agency that sponsors much of the nation’s most important research. Not only do they remove the doors of helicopters and lean over icy fjords to get their readings, but they dodge huge icebergs in tiny boats and traipse over glaciers scarred by crevasses that could swallow large buildings.
The reading that the scientists obtained a few weeks ago, of 40 degrees near the bottom of the fjord, fit a broader pattern that researchers have been detecting in the past few years.
Water that originated far to the south, in warmer parts of the Atlantic Ocean, is flushing into Greenland’s fjords at a brisk pace. Scientists suspect that as it melts the ice from beneath, the warm water is loosening the connection of the glaciers to the ground and to nearby rock.
The effect has been something like popping a Champagne cork, allowing the glaciers to move faster and dump more ice into the ocean. Within the past decade, the flow rate of many of Greenland’s biggest glaciers has doubled or tripled. Some of them have eventually slowed back down, but rarely have they returned to their speed of the 1990s.
Two seismologists, Meredith Nettles and Göran Ekström of Columbia University, discovered a few years ago that unusual earthquakes were emanating from the Greenland glaciers as they dumped the extra ice into the sea. “It’s remarkable that an iceberg can do this, but when that loss of ice occurs, it does generate a signal that sets up a vibration that you can record all across the globe,” Dr. Nettles said in an interview in Greenland.
Analyzing past records, they discovered that these quakes had increased severalfold from the level of the early 1990s, a sign of how fast the ice is changing.
Satellite and other measurements suggest that through the 1990s, Greenland was gaining about as much ice through snowfall as it lost to the sea every year. But since then, the warmer water has invaded the fjords, and air temperatures in Greenland have increased markedly. The overall loss of ice seems to be accelerating, an ominous sign given that the island contains enough ice to raise global sea levels by more than 20 feet.
Strictly speaking, scientists have not proved that human-induced global warming is the cause of the changes. They are mindful that the climate in the Arctic undergoes big natural variations. In the 1920s and ’30s, for instance, a warm spell caused many glaciers to retreat.
John R. Christy, a climatologist at the University of Alabama in Huntsville who is often critical of mainstream climate science, said he suspected that the changes in Greenland were linked to this natural variability, and added that he doubted that the pace would accelerate as much as his colleagues feared.
For high predictions of sea-level rise to be correct, “some big chunks of the Greenland ice sheet are going to have to melt, and they’re just not melting that way right now,” Dr. Christy said.
Yet other scientists say that the recent changes in Greenland appear more pervasive than those of the early 20th century, and that they are occurring at the same time that air and ocean temperatures are warming, and ice melt is accelerating, throughout much of the world.
Helheim Glacier, which terminates in Sermilik Fjord, is one of a group of glaciers in southeastern Greenland that have shown especially big changes.
On a recent day, the red helicopter landed on a rocky outcrop above the glacier, a flowing river of ice about 25 miles long and nearly four miles wide. On the side of the canyon, Dr. Hamilton pointed toward a band of light-colored rock.
It was, in essence, a bathtub ring.
Something caused the glacier, one of Greenland’s largest, to speed up sharply in the middle of the last decade, and it spit so much ice into the ocean that it thinned by some 300 feet in a few years. A part of the canyon that was once shielded from the sun by ice was thus left exposed.
The glacier has behaved erratically ever since, and with variations, that pattern is being repeated all over Greenland. “All these changes are happening at a far faster pace than we would have ever predicted from our conventional theories,” Dr. Hamilton said.
A few days after the helicopter trip, an old Greenlandic freighter nudged its way gingerly up Sermilik Fjord, which was so choked with ice that the boat had to stop well short of its goal. “You have to be flexible to work out here,” said the leader of the team that day, Dr. Straneo of Woods Hole.
Soon she was barking orders, and her team swung into motion. A cold, Arctic drizzle fell on the boat and the people. Off the port side in a rickety skiff, David Sutherland, a young scientist at the University of Washington, tossed a floating buoy, carrying a string of instruments, into the water, and an anchor snatched it below the surface. Over the next year, it will measure temperature, currents and other factors in the fjord.
Dr. Sutherland climbed back aboard the freighter with cold, wet feet. As the boat headed back to port, it passed icebergs the size of city blocks, chunks of the Greenland ice sheet bound for the open sea.
An Ocean in Flux
The strongest reason to think that the level of the sea could undergo big changes in the future is that it has done so in the past.
With the waxing and waning of ice ages, driven by wobbles in the earth’s orbit, sea level has varied by hundreds of feet, with shorelines moving many miles in either direction. “We’re used to the shoreline being fixed, and it’s not,” said Robin E. Bell, a scientist at theLamont-Doherty Earth Observatory of Columbia University.
But at all times in the past, when the shoreline migrated, humans either had not evolved yet or consisted of primitive bands of hunter-gatherers who could readily move. By the middle of this century, a projected nine billion people will inhabit the planet, with many millions of them living within a few feet of sea level.
To a majority of climate scientists, the question is not whether the earth’s land ice will melt in response to the greenhouse gases those people are generating, but whether it will happen too fast for society to adjust.
Recent research suggests that the volume of the ocean may have been stable for thousands of years as human civilization has developed. But it began to rise in the 19th century, around the same time that advanced countries began to burn large amounts of coal and oil.
The sea has risen about eight inches since then, on average. That sounds small, but on a gently sloping shoreline, such an increase is enough to cause substantial erosion unless people intervene. Governments have spent billions in recent decades pumping sand onto disappearing beaches and trying to stave off the loss of coastal wetlands.
Scientists have been struggling for years to figure out if a similar pace of sea-level rise is likely to continue in this century — or whether it will accelerate. In its last big report, in 2007, the United Nations group that assesses climate science, the Intergovernmental Panel on Climate Change, said that sea level would rise at least seven more inches, and might rise as much as two feet, in the 21st century.
But the group warned that these estimates did not fully incorporate “ice dynamics,” the possibility that the world’s big ice sheets, as well as its thousands of smaller glaciers and ice caps, would start spitting ice into the ocean at a much faster rate than it could melt on land. Scientific understanding of this prospect was so poor, the climate panel said, that no meaningful upper limit could be put on the potential rise of sea level.
That report prompted fresh attempts by scientists to calculate the effect of ice dynamics, leading to the recent, revised projections of sea-level rise.
Satellite evidence suggests that the rise of the sea accelerated late in the 20th century, so that the level is now increasing a little over an inch per decade, on average — about a foot per century. Increased melting of land ice appears to be a major factor. Another is that most of the extra heat being trapped by human greenhouse emissions is going not to warm the atmosphere but to warm the ocean, and as it warms, the water expands.
With the study of the world’s land ice still in its early stages, scientists have lately been trying crude methods to figure out how much the pace might accelerate in coming decades.
One approach, pioneered by a German climate researcher named Stefan Rahmstorf, entails looking at the past relationship between the temperature of the earth and sea level, then making projections. Another, developed by a University of Colorado glaciologist named Tad Pfeffer, involves calculations about how fast the glaciers, if they keep speeding up, might be able to dump ice into the sea.
Those two methods yield approximately the same answer: that sea level could rise by 2 1/2 to 6 1/2 feet between now and 2100. A developing consensus among climate scientists holds that the best estimate is a little over three feet.
Calculations about the effect of a three-foot increase suggest that it would cause shoreline erosion to accelerate markedly. In places that once flooded only in a large hurricane, the higher sea would mean that a routine storm could do the trick. In the United States, an estimated 5,000 square miles of dry land and 15,000 square miles of wetlands would be at risk of permanent inundation, though the actual effect would depend on how much money was spent protecting the shoreline.
The worst effects, however, would probably occur in areas where land is sinking even as the sea rises. Some of the world’s major cities, especially those built on soft sediments at the mouths of great rivers, are in that situation. In North America, New Orleans is the premier example, with large parts of the city already sitting several feet below sea level.
Defenses can be built to keep out the sea, of course, like the levees of the New Orleans region and the famed dikes of the Netherlands. But the expense is likely to soar as the ocean rises, and such defenses are not foolproof, as Hurricane Katrina proved.
Storm surges battering the world’s coastlines every few years would almost certainly force people to flee inland. But it is hard to see where the displaced would go, especially in Asia, where huge cities — and even entire countries, notably Bangladesh — are at risk.
Moreover, scientists point out that if their projections prove accurate, the sea will not stop rising in 2100. By that point, the ice sheets could be undergoing extensive melting.
“Beyond a hundred years out, it starts to look really challenging,” said Richard B. Alley, a climate scientist at Pennsylvania State University. “You start thinking about every coastal city on the planet hiding behind a wall, with storms coming.”
A Shortage of Satellites
One Saturday morning a few months back, a University of Colorado student named Scott Potter, sitting in a control room on the Boulder campus, typed a word into a computer.
“GO.”
Over the next 40 seconds, indicators in the control room turned red. Alarms rang. Pagers buzzed. High above the earth, a satellite called ICESat, reacting to Mr. Potter’s order, prepared itself to die.
The commotion was expected. Mr. Potter, one of several Colorado students who hold part-time jobs as satellite controllers under professional supervision, was doing the bidding ofNASA. His command that day formally ended the ICESat mission, which had produced crucial information about the world’s ice sheets for seven years.
At the end of August, two weeks after Mr. Potter sent his order, the remains of ICESat plunged into the Barents Sea, off the Russian coast. Its demise was seen by many climate researchers as a depressing symbol.
After a decade of budget cuts and shifting space priorities in Washington, several satellites vital to monitoring the ice sheets and other aspects of the environment are on their last legs, with no replacements at hand. A replacement for ICESat will not be launched until 2015 at the earliest.
“We are slowly going blind in space,” said Robert Bindschadler, a polar researcher at the University of Maryland, Baltimore County, who spent 30 years with NASA studying ice.
Several federal agencies and two presidential administrations, Democratic and Republican, have made decisions that contributed to the problems.
For instance, an attempt by the Clinton and Bush administrations to combine certain military and civilian satellites ate up $5 billion before it was labeled a “horrendous and costly failure” by a Congressional committee.
A plan by President George W. Bush to return to the moon without allocating substantial new money squeezed budgets at NASA.
Now, the Obama administration is seeking to chart a new course, abandoning the goal of returning to the moon and seeking a substantial increase in financing for earth sciences. It is also promising an overall strategy for improving the country’s environmental observations.
Major elements of the administration’s program won support from both parties on Capitol Hill and were signed into law recently, but amid a larger budget impasse, Congress has not allocated the money President Obama requested.
In the meantime, NASA is spending about $15 million a year to fly airplanes over ice sheets and glaciers to gather some information it can no longer get by satellite, and projects are under way in various agencies to plug some of the other information gaps. NASA has begun planning new satellites to replace the ones that are aging.
“The missions that are being designed right now are fantastic,” said Tom Wagner, who runs NASA’s ice programs.
The satellite difficulties are one symptom of a broader problem: because no scientifically advanced country has made a strategic priority of studying land ice, scientists lack elementary information that they need to make sense of what is happening.
They do not know the lay of the land beneath most of the world’s glaciers, including many in Greenland, in sufficient detail to calculate how fast the ice might retreat. They have only haphazard readings of the depth and temperature of the ocean near Greenland, needed to figure out why so much warm water seems to be attacking the ice sheet.
The information problems are even more severe in Antarctica. Much of that continent is colder than Greenland, and its ice sheet is believed to be more stable, over all. But in recent years, parts of the ice sheet have started to flow rapidly, raising the possibility that it will destabilize in the same way that much of the world’s other ice has.
Certain measurements are so spotty for Antarctica that scientists have not been able to figure out whether the continent is losing or gaining ice. Scientists do not have good measurements of the water temperature beneath the massive, floating ice shelves that are helping to buttress certain parts of the ice sheet in West Antarctica. Since the base of the ice sheet sits below sea level in that region, it has long been thought especially vulnerable to a warming ocean.
But the cavities beneath ice shelves and floating glaciers are difficult to reach, and scientists said that too little money had been spent to develop technologies that could provide continuing measurements.
Figuring out whether Antarctica is losing ice over all is essential, because that ice sheet contains enough water to raise global sea level by nearly 200 feet. The parts that appear to be destabilizing contain water sufficient to raise it perhaps 10 feet.
Daniel Schrag, a Harvard geochemist and head of that university’s Center for the Environment, praised the scientists who do difficult work studying ice, but he added, “The scale of what they can do, given the resources available, is just completely out of whack with what is required.”
Climate scientists note that while the science of studying ice may be progressing slowly, the world’s emissions of heat-trapping gases are not. They worry that the way things are going, extensive melting of land ice may become inevitable before political leaders find a way to limit the gases, and before scientists even realize such a point of no return has been passed.
“The past clearly shows that sea-level rise is getting faster and faster the warmer it gets,” Dr. Rahmstorf said. “Why should that process stop? If it gets warmer, ice will melt faster.”