Category Archives: Global Warming

Ocean Warming off Greenland near Petermann Glacier

Posted on September 14, 2011 by | 2 comments

Testifying before the Select Committee on Energy Independence and Global Warming last year, I fumbled one question asked by the Honorable Chairman Edward J. Markey (D-MA): “Is it warming in the Petermann Glacier area?” I was unsure how the regionally relevant ocean temperatures had changed and how it impacts the melting glacier. A year late, we got the answer.

Floating ice shelf of Petermann Glacier on July 22, 2010 (NASA).

I was thinking of my former student Ms. Zweng. Three years earlier she had published a thorough analysis of ocean temperatures in Baffin Bay, that showed statistically significant warming by 0.11 +/- 0.06 degrees centigrade per decade for the 1916 through 2003 period (Zweng and Muenchow, 2006). But Baffin Bay is more than 800 miles away and it is not clear if those waters actually can make it to Petermann Fjord. I was also thinking of data in hand from only 80 miles away in Nares Strait whose waters definitely make it into Petermann, but I had not yet done the analyzes and thus did not know what the data would tell me. Now I do, and the peer-reviewed results (Muenchow et al., 2011) were published last week in Oceanography.

Time series of temperature (bottom) salinity (top) from the bottom of the ocean in Nares Strait between northern Greenland and Canada (from Muenchow et al, 2011). Trends are indicated for the 2003-06 and 2007-09 periods.

The data come from thermometers taking readings for years every 15 minutes. We placed the instruments on the bottom of the 300 meter deep ocean in 2003, recovered them in 2006, threw them back into the ocean in 2007 and found them again in 2009. We got data from three such instruments in 2003-06 and five in 2007-09 that all pretty much show the same thing: Bottom temperature change little during the 2003-06 period and about 0.06 +/- 0.02 degrees centigrade per year during the 2007-09 period of oberservations. Putting this together, we find a warming of 0.023 +/- 0.015 degrees centigrade per year. Next question would be, does this observed ocean warming in Nares Strait matter with regard to Petermann Glacier?

My current answer is a strong no. First, there is so much ocean heat already inside Petermann Fjord to melt away the entire floating section of the glacier (Johnson et al., 2011), that the extra ocean warming in recent years makes little difference. Second, the trends are from very short data sets that are dominated by physics unrelated to warming or could relate to a sequence of a few strong events that could either relate to man-made global warming or natural fluctuation at longer decadal cycles. This detection of signals in noise is a common problem in both engineering and geophysics, it is a required class for all our graduate students.

Very closely related is a paper entitled “Separating Signal and Noise in Atmospheric Temperature Changes: The Importance of Timescale” by Santer et al. (2011). Elegantly and comprehensively the authors expose and quantify the challenges one faces trying to extract the man-made warming signal from globally averaged near surface air temperature records sensed both from satellites and simulated in a number of numerical models. For this variable, the authors conclude convincingly, one needs records between 15-20 years long to extract a statistically significant man-made global warming signal from the much larger noise of natural variability.

So, if I had done my homework better last year, this should have been my answer to the question if it is warming in the Petermann Glacier area: “Yes, both the ocean and the atmosphere are warming in the Petermann region, but this may have little or no impact on the changing Petermann Glacier. Today we do not even know why Petermann Glacier has a floating ice shelf. Since we do not yet understand the physics of ice-ocean interactions, we can neither know nor predict what changes it has in store for us.”

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Posted in Global Warming, Oceanography, Uncertainty

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Why Petermann Glacier and Fjord?

Posted on September 13, 2011 by | Leave a comment

The National Science Foundation (NSF) declined to fund a Physical-Ocean-Ice-Shelf-Experiment (POISE) at Petermann Fjord in northern Greenland this year. The reviews by three anonymous peers, a panel of eight scientists, and two sympathetic program managers were all very good, but not without criticism.

Floating ice shelf of Petermann Glacier in August 2009 as seen from a helicopter of the Canadian Coast Guard Ship Henry Larsen. View is to the south-east with the glacier to the left and the ocean to the right. Photo by David Riedel, British Columbia.

Our admittedly expensive 4-year proposal was rejected along with at least five competing proposals in the same general subject area, because we did not show why a study of ice-ocean interaction of glaciers and ice-sheets has to take place at Petermann Glacier, a remote location less than 800 miles from the North Pole. Claiming this glacier to be unique, we made a fatal mistake, because NSF cares little about each glacier, but cares much about the underlying physical problem, that is, how do tidewater glaciers with floating ice shelves interact with the ocean they float on.

There are several glaciers in Greenland that have extensive ice shelves. To the best of my knowledge, they are all in northern Greenland. Nioghalvfjerdsfjorden and Petermann Fjord contain the largest floating areas exposed to the oceans on the east and west coasts of Greenland, respectively. Both these glaciers have seen preliminary studies during the last 15 years including radar measurements that describe the geometry of the ice shelves, the bedrock below, as well as the ice streams to connect the glaciers to the inland ice. Smaller and less studied glaciers with past or present ice shelves are Steensby, Ryder, and C.F. Ostenfeldt in the north-west as well as Academy and Marie-Sophie glaciers in the north-east (Weidick, 1995).

The most extensive ice shelves are located around Antarctica, however, and one thus may wonder, what uniform physics can and should be studied in northern Greenland that also applies to the ice sheets in the south? I would need some scaling law or normalization scheme that connects many glaciers into an organizational scheme. In physical oceanography the near-balance of a density-driven (internal) pressure gradient and the effects of a rotating earth provides a dynamical scale that connects river discharges off Delaware, with ice patterns off Eastern Greenland, and algae bloom patters off northern Norway, among many other phenomena. What dynamical metric connects the ice sheets of Greenland to each other and to those off Antarctica?

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Global Weight Watch: Slimmer Greenland and Fatter Tropics

Posted on August 6, 2011 by | 3 comments

An ice island four times the size of Manhattan separated from Petermann Glacier, Greenland last year. Today one of these Manhattans reached the coast of Newfoundland. Never before has as large a piece of ice from Greenland reached this far south. Does this show a warming climate taping into Greenland’s 20 feet potential to raise global sea level?

Track of Petermann Ice Island from Aug.-2010 through Aug.-2011 traveling in shallow water from northern Greenland along Baffin Island and Labrador to Newfoundland.

Greenland’s glaciers always melt with pieces breaking off. This raises sea level if Greenland receives less snow atop than it loses ice at the bottom. For the last 10 years Greenland lost about 200 trillion pounds of mass, net, per year. [At 5 cents per pound, this pays off the federal debt within a year.] Distributing this mass over all oceans, we raise global sea level by one inch in 75 years. Nothing to worry about, but there is a twist: Weight watching satellites show that Greenland becomes thinner, while the Tropic grow fatter. Records of weight gain and loss are too short to draw firm conclusions, yet, but they are consistent across the globe and the trends of gain and loss are increasing, too.

We do not understand the physics, stability, and uncertainty of these increasing gains and losses well enough to make reliable predictions. If the climate over Greenland is stable, as it has been for the last 10,000 years, then this matters little. If the present equilibrium reaches a tipping point, where a small change will kick us into different stable state, then we can expect sea level to increase 10 times or more. We understand tipping points in theory, but not in practice. In practical terms, we do not know if our children must deal with two inches of sea level from Greenland by the end of this century or 80 inches or none at all. We know only too well, however, that low-lying places like Bangladesh, the Netherlands, and New Orléans struggle with the sea level we have now.

Greenland’s ice island off Newfoundland indicates a globally connected world. Burning stuff over Europe, America, and increasingly Asia creates heat that melts Greenland at a rate that is increasing. What happens in Greenland does not stay in Greenland, but it impacts Rome, Miami, and Shanghai. More ice and rising sea level will come. To play it safe, let’s think smartly what and how we burn. To play it loose and reckless: burn, baby, burn … or was it drill?

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Winners and Losers of Climate Change

Posted on August 2, 2011 by | Leave a comment

People with computers live long, prosperous lives, those without die early. Does this correlation mean that computers make us live longer? Of course not, but on average computer users live longer the same way that global temperatures increase as more people use computers. Does this now mean that warmer temperatures are good for you? Absolutely, if you have a computer …

Sum of undepleted CO2 emissions (top) 1950-200 and expected death by malaria, hunger, diarrhea, and flooding (bottom) as adapted from Patz et al. (2007)

I came across a report sponsored by the medical journal “The Lancet” and the University College of London entitled “ Managing the health effects of climate change.” There are pictures of glaciers, volcanos, floods, and many dazzling graphs. The most stunning is a distorted and bulging earth (Patz et al., 2007).

On top it shows the total undepleted CO2 put into the air from 1950-2000. The larger a region on the map, the more CO2 a region puts into the air. On the bottom, it shows how many people will likely die as a result of calamities that are larger in a warming climate for the 2000-2030 period. The larger the region on the map, the more people will be wiped out.

Enjoying a high standard of living fueled by burning coal, oil, and gas, we Europeans and North-Americans use energy to keep our computers, cars, and industries running. In the process we released about 10-30 pounds of CO2 per person per day averaged of the last 50 years. We are immune to malaria, a disease fostered by warmer climates; we got a strong economy to feed and cloth us so we do not starve; and except for the poor of New Orleans who drowned in hurricane Katrina, we rarely die of floods.

The situation is different in Africa and Asia. The average CO2 released is well below 2 pounds per person per day. There just are not as many computers, cars, and industries there. Instead, malaria is the main killer as it reproduces fast. Rising sea levels caused by a warming climate will cause more flooding of poorly protected areas where more poor people will drown.

No single flood, malaria, or drought will ever be caused by global warming alone. Global warming is an abstract and statistical concept that varies by region and over time. It is always present and poses an ethical dilemma: those with computers cause most of the global warming, but we do not pay the full price, while those without computers who contribute the least to the warming, they will pay more than full price. Hardly seems fair, but such is life … and we need our computers.

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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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