Tag Archives: climate

Nares Strait Ice Bridge and Arctic Ice Thickness Change

Posted on June 19, 2012 by | 9 comments

The ice of the Arctic Ocean is rapidly disappearing. This happens every summer, but for the last 30 years there is a little less ice left at the end of each summer than there was the year before. The areas covered by ice are not only shrinking, the ice is also getting thinner, or so many do believe.

To check out such claims, we placed sound systems on the ocean floor of Nares Strait from which to find out how much the thickness of the ice above has changed. We started this in 2003, were told to stop it in 2009, but privately parked our instruments where they would collect data. We must get to check our sound systems and retrieve the private recordings, because otherwise Poseidon will claim our possessions for parking violations. The Canadian Coast Guard Ship Henry Larsen, we hope, will help us to negotiate water and ice to get us deep into Nares Strait as she and her crew did so well in 2006, 2007, and last in 2009.

CCGS Henry Larsen in thick and multi-year ice of Nares Strait in August 2009. View is to the south with Greenland in the background. [Photo Credit: Dr. Helen Johnson]

The ice profiling sonar sounds system before its first deployment in Nares Strait in August 2003 from aboard the USCGC Healy. It measure ice thickness many times each seconds for up to 3 years. View is to the north-west with Ellesmere Island, Canada in the background. Listening in are Jay Simpkins (left), Helen Johnson, and Peter Gamble.

Nares Strait to the west of northern Greenland is one of two major gates for the thickest, the hardest, and the oldest ice to leave the Arctic for the Atlantic Ocean [Fram Strait to the east of Greenland is the other.] This gate is closed at the moment by an arching ice bridge that locks all ice in place. No ice can leave the Arctic via Nares Strait as long as these arches hold. The ice arch acts as a dam that holds back the flood of ice that will come streaming south hard once the dam breaks. And break it will, usually between the end of June and July.

Ice arch in southern Nares Strait as seen by MODIS Terra on June-18, 2012. Greenland is on the right, Canada on the left. The dark blue colors in the bottom-left are open water, yellow are the ice caps of Greenland and Ellesmere Island and lighter shades of blue are warm ice or land. Humboldt Glacier is the on the right-center where Nares Strait is at its widest with Kane Basin at about 80 N latitude.

Nares Strait Jun.-10, 2012 image showing land-fast ice between northern Greenland and Canada as well as the ice arch in the south (bottom left) separating sea ice from open water (North Water). The coastline is indicated as the black line.

The sooner it breaks, the more old ice the Arctic will lose and the better it is for us to get an icebreaker to where must be to recover our instruments and data. The data will tell us if the ice has changed the last 9 years.

I processed and archived maps of Nares Strait satellite images to guide 2003-2012 analyses of how air, water, and ice change from day to day. Ice arches formed as expected during the 2003/04, 2004/05, and 2005/06 winters lasting for about 180-230 days each year. In 2006/07 no ice arch formed, ice streamed freely southward all year, and this certainly contributed to the 2007 record low ice cover. In 2007/08 the arch was in place for only 65 days. In 2009/10, 2010/11, and now 2011/12 ice cover appear normal as the arches formed in December and lasted until July.

We live in exciting times of dramatic change, some to the better and some to the worse. Some of the change is caused by global warming while most is probably not. We do not know for sure, but most of the evidence points towards us people as a major driver of the change we observe in the Arctic and elsewhere. Nevertheless, climate and its change is one grand puzzle that no single scientist, no single discipline, no single country, and no single continent can solve. There are many pieces that all contribute to how and why the Arctic ice changes the way it does. And this includes the ice arches of Nares Strait. There are many mysteries and unresolved physics in what makes these ice arches tick and what makes them blow to bits, but blow they will … watch it, it’s fun, and perfectly natural.

EDIT: This movie shows just how stable the ice arch is at the moment.

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Pine Island Glacier on the Move

Posted on January 12, 2012 by | 1 comment

Pine Island Glacier, Antarctica, is the focus of a large observational effort to better understand how glaciers and floating ice shelves interact with the ocean.

Pine Island Glacier (view is to the north, ocean in the top left) with crevasses and large crack extending from the east (right) to the west (left) as seen from aboard NASA's DC-8 research aircraft in October 2011. Credit: Michael Studinger/NASA

Scientists, pilots, technicians, and students working with NASA’s IceBridge and NSF’s Antarctic programmes tried hard for several years now to reach this glacier, set up a base, and drill through the 400-600 m thick ice shelf to reach the ocean. The data from these gargantuan efforts will reveal physics of ice-ocean interactions. This process is poorly represented in the climate models that are used to project past and present climates into the future. Harsh and hostile conditions cut these efforts short today, again, as reported by OurAmazingPlanet.

The expedition leader, NASA’s Dr. Bindschadler wrote today, that

A decision had been made by NSF the day we left McMurdo that if the helos were not able to be flown to PIG by Saturday, January 7, this year’s field work would be cancelled … We worked through our cargo—some had not been seen for two years when we tested our equipment at Windless Bight—preparing for either helos or the Twin Otter to start moving us onto the ice shelf. Neither came. Weather worsened.

Despite this dramatic turn of events, skies were clear over Pine Island Glacier today as they on New Year Jan.1, 2012. Two MODIS images show detailed features at 250-m resolution. I here show the near infra-“red” signals that the satellite receives (865 nm). The dark ocean reflects little of red (low reflectance) as it is all absorbed while the bright snow and ice reflects lots of red (high reflectance). Recall that the color “white” looks white, because it reflects all colors into our eyes including red, while “black” absorbs all colors, so none are left to reach our eyes.

Pine Island Glacier and Bay, Antarctica on Jan.-1, 2012 as seen by MODIS Terra, notice the whitish crack near the center of the image.

I show lots of the near infra-“red” as, well, red, and I color little red as blue. I chose the colors of the “crayons” to do the coloring. The technical term for this is contouring. Formally, I am depicting a function f=f(x,y) where f is the amount of red and x and y are locations east and north, respectively.

Pine Island Glacier and Bay, Antarctica on Jan.-12, 2012 as seen by MODIS Terra, notice the whitish crack near the center of the image.

They almost look the same, don’t they? If they were identical, then the difference would get zero. Except, glaciers move, especially this one. It is also about to spawn a large ice island. A crack was first reported in Oct.-2011 by scientists aboard a DC-8 of a NASA Icebridge flight. This crack is also widening as, I speculate, the front moves faster seaward of the crack than it does landward. My question is if I can see movements in these easily accessible public MODIS images. And my first answer, to be refined later, is 80 meters per day plus or minus 50%:

Difference of reflectance by subtracting Jan.-1 reflectances from those on Jan.-12, 2012. Very dark red colors show large positive numbers, meaning that the ice occupies a place on Jan.-12 that was water on Jan.1.

I am neither a glaciologist nor a remote sensing person, so I may be running a few red lights differencing two images and assign meaning to it. For example, I estimate the speed at which the front of the glacier moves by dividing the width of the very dark thick red line (about 1 km wide) by 12 days to get 80 meters per day or 3.5 meters per hour. The error here is at least 2 pixels (500-m), about half the estimated speed. My assumption here is that the high reflectance on Jan.-12 at a location with a low reflectance on Jan.1 means that the “bright” glacier has moved to a place that was “dark” ocean before. There is more to this, but I have to start somewhere.

Incidentally, Dr. Bindschadler, the leader of the current Pine Island field project who had to leave the base camp near Pine Island Glacier today, is the very person who wrote a wonderful peer-reviewed paper in 2010 with the title “Ice Sheet Change Detection by Satellite Image Differencing.” I will need to study it more closely … along with the vagarities of field work in polar regions.

It is difficult to get data from the field as opposed to data from remote sensing or modeling. This is especially true for remote and hostile locations the ice and the oceans interact. It is frustrating to be sent home early because of inclement weather and the very narrow window of opportunity when the few available helicopters and planes can fly or the ships can sail near Antarctica and Greenland.

EDIT Jan.-13: The National Snow and Ice Center estimated speeds of Pine Island Glacier as determined from two LandSat images from 1986 and 1988:

Contours of glacier speeds in meter per year of Pine Island Glacier from 1986 and 1988 LandSat Imagery, National Snow and Ice Center

These speeds are very different, 2-3 km per year versus 1 km in 12 days. The former estimate is made from 2 carefully geolocated images 2 years apart without a crack across the floating glacier, while my estimate yesterday is more noisy, but it is for a segment of the glacier that is barely connected to it. Perhaps we should consider the segment seaward fo the crack a separate ice island that is moving with the ocean rather than the glacier?

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Global Warming, Signal to Noise, and the History of Doubt

Posted on September 15, 2011 by | 1 comment

A smart graduate student in our Physical Ocean Science and Engineering program (lets call him/her XXXX) sent me an e-mail yesterday night

Hi Andreas,

I stumbled upon this article tonight and thought you might find it interesting: http://www.climatedepot.com/a/12797/Exclusive-Nobel-PrizeWinning-Physicist-Who-Endorsed-Obama-Dissents-Resigns-from-American-Physical-Society-Over-Groups-Promotion-of-ManMade-Global-Warming

XXXX

I have been reading a lot on this very subject the last weeks and find that the intersection of science, policy, communication, politics, and history a fascinating area of new learning. My response to XXX was thus

XXXX:

This is sad, but neither news nor particular interesting. Dr. Giaever received his Nobel prize in physics for work he did on semi-conductors over 50 years ago. Based on his statements on religion, I am pretty sure, that he has not kept up with the modern peer-reviewed literature on statistics, climate dynamics, or any geophysical field.

He may have missed (or willfully ignored?) work such as Santer et al. (2011): “Separating Signal and Noise in Atmospheric Temperature Changes: The Importance of Timescale” to appear in JGR later this year. I placed a copy of the paper (in press) at

http://muenchow.cms.udel.edu/classes/MAST811/Santer2011.pdf

as it is hard to find right now, even though it is causing a storm in the blogosphere.

If you want to follow critical, skeptical, and credible discussions on climate and its variability (and perhaps the above paper) of actually active atmospheric scientists that fall neither into an “alarmist” nor a “denying” camp, then you may find Dr. Judith Curry’s (University of Georgia)

http://judithcurry.com/2011/09/12/santer-on-timescales-of-temperature-trends/

or Dr. Roger Pielke, Sr. (Colorado State University)

http://pielkeclimatesci.wordpress.com/2011/09/07/comments-on-the-new-paper-separating-signal-and-noise-in-atmospheric-temperature-changes-the-importance-of-timescale-by-santer-et-al-2011/

If you are interested in the historical and political content of this pseudo-debate, you may find Oreskes and Conway (2010) book entitled “Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming” at

http://www.amazon.com/Merchants-Doubt-Handful-Scientists-Obscured/dp/1596916109

I read the book over the weekend and could not put it down. Dr. Santer is an atmospheric scientist working at Los Alamos National Laboratory and has been a lead-author of the IPCC since 1995 while Dr. Oreskes is a science historian working and teaching at UCSD/Scripps.

andreas

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Uncertainty in the Physics and Philosophy of Climate Change

Posted on July 25, 2011 by | 2 comments

I wrote this post last year for the National Journal, but it also relates to the way I think about Petermann Glacier’s ice islands. There are now at least 4 larger ice islands that formed from last year’s single calving: one is the tourist attraction off Labrador and Newfoundland, a second has left Petermann Fjord last week, a third was grounded off Ellesmere Island for much of the year and is now where #1 was Nov.-2010, while the fourth … I do not know. Last I heart, it was grounded off central Baffin Island. With this much variation of where pieces of the ice island went, how can we possibly claim any skill in predicting anything?


Neither climate nor weather is linear, but this neither makes them unpredictable nor chaotic. The simple harmonic pendulum is the essence of a linear system with clear cause and effect relations. Oscillations are predictable as long as the initial forcing is small. Furthermore, a linear trend will show the pendulum to slow down due to friction. Corrections are straightforward.

Unfortunately, climate is not a simple, harmonic, or linear system. While this does not make it unpredictable or chaotic, it means that our “common sense” and loose talk of “totality of events” can easily fool us. We know that CO2 emissions for the last 150 years changed global temperatures. We also know that our current climate system has been very stable over the last 10,000 years. What we do not yet know is how small or how large a perturbations the last 150 years have been. If the pendulum is forced too much, if the spring is stretched too far, the system will find another stable state by breaking. Climate dynamics can find an adjustment less tuned to the areas where people presently live. This is what “tipping points” are about. Only numerical experimentation with the best physics and models will suggest how close to a different stable climate state we are. The IPCC process is one way to do so.

Ice cores from Greenland contain air bubbles 100,000 years old, which clearly demonstrate that our present climate state is the “anomaly of quiet” in terms of temperature fluctuations. The absence of large fluctuations for about 10,000 years made agriculture and advanced civilizations possible. The ice cores show that abrupt climate change has happened and may happen again, not this election cycle, but it is one possibility perhaps as likely as the possibility that climate change is mundane, linear, and follows trends that we can easily correct or mitigate later. Both are excellent hypotheses.

For scientists, these are exciting times as we conduct a massive, global experiment to see how much CO2 we can add to the atmosphere to perhaps find a different climate state. Dr. Terry Joyce, Senior Scientist at Woods Hole Oceanographic Institution once said: “I’m in the dark as to how close to an edge or transition to a new ocean and climate regime we might be. But I know which way we are walking. We are walking toward the cliff.” I agree with this sentiment, but add that we do not know if this cliff is a 1000 feet fall or a 2 feet step. Can we affort to wait until we know for sure? As a scientist I do not care. As a citizen, however, I think the time to act responsibly is now.

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Is Climate Change Causing Wild Weather?

Posted on July 23, 2011 by | 4 comments

Almost a year ago, Amy Calder of the National Journal asked:

Are extreme weather events, when considered collectively, evidence that climate change is occurring? If not, what are the missing links scientists still need to study in order to make a more conclusive find? Could these weather events revive congressional efforts to pass comprehensive climate legislation?

My answer is still the same, even though I grapple with what my resonsibilities and moral obligations are as a scientist learning, a tenured professor teaching, and a citizen voting. Here it is:

No, climate does not cause weather, the balances of forces, masses, and energies in the atmosphere do. Furthermore, the atmosphere interacts with oceans, ice sheets, lands, and livings things. Ask an equally ill-posed question “Is climate change contributing to wild weather?” and my answer becomes yes, but with the caveat that butterflies flapping their wings in Tokyo contribute as well. There is more to the question than meets the eye.

Globally averaged air temperatures have increased by about 0.6 degrees Celsius per decade over the last 50 years. This warming is not uniform as it varies in both space and time. Some places cool, some places warm, some places cool or warm more than expected. Floods, droughts, mudslides, and calving glaciers always have and always will occur. Some weather events separated in space and time are physically linked via large-scale tele-connections such as Rossby waves in the atmospheric jet stream or the El Nino-Southern Oscillations.

So, how much of the currently observed extreme weather events are due to globally increasing air temperatures that also coincide with globally increasing ocean temperatures? Does global warming increase, say, the intensity of hurricane by 1% or 10% or 50%? These much tougher questions are at the forefront of both observational and computational work on environmental physics. The IPCC numerical models and new understanding of key physical processes, I feel, are the only way to attribute global warming effects on extreme weather events. Ice-ocean interactions around Greenland are one such physical process poorly incorporated in IPCC models. Another such process is the way that hurricanes may dominate the ocean heat flux towards Greenland.

Three weeks before Katrina hit New Orleans in 2005 MIT professor Dr. Kerry Emanuel published that the power dissipation by hurricanes has increased by about 60% over the last 30 years and that this increase correlates with increasing sea surface temperatures in the tropical North Atlantic. Nevertheless, Dr. Emanuel himself stressed that nothing could be more absurd than stating that Katrina was caused by global warming. Furthermore, refining his methodology in 2008, he finds that “… global warming should reduce the global frequency of hurricanes, though their intensity may increase in some locations.” [Emanuel et al., 2008: Hurricanes and global warming, Bull. Amer. Meteor. Soc. 89, 347-367.]

Just because a pattern of extreme weather events feels like evidence of global warming, it does not make it so. This scientific uncertainty, however, should not distract from the potential costs that a potentially man-made climate change will cause. Climate zones may shift, sea level may rise, volatile weather events may become more volatile, etc. All of this may cause additional political instabilities in marginally stable nation states ill-equipped to deal with either natural or man-made disasters.

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