Tag Archives: Petermann

Petermann Ice Island PII-A Breaks into Two

The 35 square kilometer sized ice island from Petermann Glacier PII-A has split into two pieces of about equal size over the last 4 days while moving almost 10 km per day to the south along the 150 meter contour of water depth.

Petermann Ice Island PII-A as seen by MODIS/Terra as one piece on Aug.-14, 2011 and as two pieces on Aug.-22, 2011 (click to enlarge).

It cleared the Grey Islands to its north and may now turn counter-clockwise around deeper water to the north of Horse Islands. The Canadian Ice Service continues to watch the many icebergs that PII-A has spawned all along the Great Northern Peninsula of Newfoundland with daily charts and RadarSat imagery. While the data from the NASA’s MODIS mission resides in the public domain serving a global community, the Canadian RadarSat is commercial product unaffordable serving only a select few.

The two new ice islands should perhaps be called PII-Aa and PII-Ab. While their size no longer compares well to that of all of Manhattan, each is about as big as 5 Central Parks of Manhattan, or about 10,000 times my garden which is a third of an acre.

Petermann Ice Island PII-A on the move again

Sitting stuck on the bottom at 80 meters depth for the past week off St. Anthony’s, PII-A is in the move again heading south by south-east (click on image to enhance). It is melting only at the surface, breaking off smaller icebergs, because the ocean water temperatures near the bottom are colder than the freezing point of fresh water. The ocean’s salinity ensures that the freezing point of sea water is close to -1.7 C while that of fresh water is 0.0 C. More details on how the waters off Labrador and Newfoundland looked like in 2009 within a climate context is Colbourne et al. (2010) (big file, slow link).

Petermann Ice Island PII-A on Aug.-7 and Aug.-14, 2011 off St. Anthony, Newfoundland over contours of bottom depth. Black dotted line is the track until Aug.-9, 2011 from a beacon on PI-A

Petermann Ice Island PII-A Within Three Miles off Newfoundland

The Petermann Ice Island PII-A is within 5 km (3 miles) from the shores off St. Anthony, Newfoundland. The MODIS Terra image of this morning shows PII-A sitting in water 100 meters (330 feet) deep. The island may be partially grounded, because its thickness is close to the water depth.

Petermann Ice Island PII-A 3 miles from shore.

Petermann Ice Island PII-A off Labrador and Newfoundland.

The dotted black line shows the track of PII-A until last week as determined from one of three beacons placed by the Canadian Coast Guard and Ice Service.

Global Weight Watch: Slimmer Greenland and Fatter Tropics

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?

Petermann Ice Island Seen from International Space Station

Ron Garan aboard the International Space Station just send this photograph of Petermann Ice Island PII-A down to earth as reported by Jason Major.

Petermann Ice Island PII-A on July-25/26, 2011 as seen by MODIS/Terra and the International Space Station

While the detailed photo indicates that the ice island was about as close to the coast as it is long, it has since moved offshore and to the south. The ice island is on its way to clear the similar sized island of Belle Isle in the middle of a channel that separates Labrador in the north from Newfoundland in the south. The distance from the coast is not all that relevant, but the water depth is. Classical physical oceanography says so and I urge you to watch this MIT movie.

In a nutshell: The rotating earth limits large-scale flows, such as those that propel the ice island, to move in ways that seem to make no sense. More specifically, if there is a tiny change of the bottom depth, then the flow at all depths, and this includes the surface, will want to go around this obstacle to stay with the depth it started at. It is very hard to move water from water 200 meters deep such as on continental shelves to water 2000 meters deep such as further offshore. There are exceptions to this rule, of course, but they involve other forces that usually, but not always, are small.

It is so much fun to watch and predict where this ice island will move next, especially if one can be proven wrong so easily. “The proof of the pudding is,” as Cervantes has Don Quixote say so wisely, “in the eating.”