Tag Archives: Greenland

New Calving of the Zachariae Isstrom Glacier

The Zachariæ Isstrøm glacier in North East Greenland is in the news at the moment. Here’s a recent article from The Guardian for example, which states that:

A major glacier in Greenland that holds enough water to raise global sea levels by half a metre has begun to crumble into the North Atlantic Ocean, scientists say. The calving of the glacier into chunks of floating ice will set in train a rise in sea levels that will continue for decades to come, the US team warns.

“Even if we have some really cool years ahead, we think the glacier is now unstable,” said Jeremie Mouginot at the University of California, Irvine. “Now this has started, it will continue until it retreats to a ridge about 30km back which could stabilise it and perhaps slow that retreat down.”

Mouginot and his colleagues drew on 40 years of satellite data and aerial surveys to show that the enormous Zachariae Isstrom glacier began to recede three times faster from 2012, with its retreat speeding up by 125 metres per year every year until the most recent measurements in 2015.

The same records revealed that from 2002 to 2014 the area of the glacier’s floating shelf shrank by a massive 95%, according to a report in the journal Science. The glacier has now become detached from a stabilising sill and is losing ice at a rate of 4.5bn tonnes a year.

Eric Rignot, professor of Earth system science at the University of California, Irvine, said that the glacier was “being hit from above and below”, with rising air temperatures driving melting at the top of the glacier, and its underside being eroded away by ocean currents that are warmer now than in the past.

“The glacier is now breaking into bits and pieces and retreating into deeper ground,” he said. The rapid retreat is expected to continue for 20 to 30 more years, until the glacier reaches another natural ledge that slows it down.

The Guardian article includes a picture of Zachariæ Isstrøm, along with much of the rest of North East Greenland. Here it is again, together with a helpful annotation revealing the location of the calving face of Zachariæ Isstrøm in amongst all the snow and ice:

zach-guardian

That’s still not really much help when it comes to visualising the “retreat speeding up by 125 metres per year”, so here’s a closer look at Zachariae Isstrom using an image prepared by Espen Olsen for the Arctic Sea Ice Forum, which is based on a Landsat 8 satellite image from September 2014:

Retreat of the calving face of the Zachariae Isstrøm glacier between 2009 and 2015
Retreat of the calving face of the Zachariae Isstrøm glacier between 2009 and 2015

North East Greenland is in the dark at the moment, but if you want to take a closer look at recent changes to Zachariæ Isstrøm for yourself you can do so with the aid of NASA’s EOSDIS Worldview web site, which allows you to scroll through images from both the Aqua and Terra satellites. Here’s one from August 26th 2015:

NASA Worldview “true-color” image of the Zachariae Isstrøm glacier on August 26th 2015, derived from the MODIS sensor on the Aqua satellite
NASA Worldview “true-color” image of the Zachariae Isstrøm glacier on August 26th 2015, derived from the MODIS sensor on the Aqua satellite

Our headline for today announces that yet another large chunk of ice has just detached itself from Zachariæ Isstrøm. You may wonder how we can be so sure of that when it’s dark in North East Greenland? That’s because yet another satellite can “see” in the dark, using synthetic aperture radar. Here’s an animation prepared earlier today by “Wipneus” using data from the European Space Agency’s Sentinel 1A satellite, once again for the Arctic Sea Ice Forum:

Animated comparison of Sentinel 1A visualisations of the Zachariae Isstrøm calving face on 4th and 16th November 2015
Animated comparison of Sentinel 1A visualisations of the Zachariae Isstrøm calving face on 4th and 16th November 2015

Can you spot “The new iceberg [that] seems to lie on its side”?

The conclusion to all this frantic activity, according to Mouginot, Rignot et al. at least, is that:

The Zachariæ Isstrøm / Nioghalvfjerdsfjorden sector is one of three major marine-based basins in Greenland along with the Jakobshavn Isbræ and Petermann–Humboldt glaciers, each holding a 0.6-m sea-level equivalent. Jakobshavn Isbræ started a rapid retreat (18 km in 2001-2015) following the collapse of its ice shelf and has undergone massive calving events since 2010. The central channel of the Petermann ice shelf lost 250 m of ice in 2002-2010, and the ice front retreated 33 km in 2010-2012. The Nioghalvfjerdsfjorden ice shelf will become vulnerable to break up in the near future if thinning continues. These observations combined suggest that all three major marine-based basins are undergoing significant changes at present. Jakobshavn Isbræ and Zachariæ Isstrøm have already transitioned to tidewater glacier regime, with increased calf-ice production and ice melting by the ocean. The retreat of these marine-based sectors is likely to increase sea-level rise from Greenland for decades to come.

Is Time Running Out for Arctic Sea Ice?

One eminent sea ice researcher certainly seems to think that time is indeed running out for the sea ice in the Arctic. First let’s take a look at the results of the first call for contributions of the 2015 melting season from the Sea Ice Prediction Network:

The Sea Ice Prediction Network  June 2015 Sea Ice Outlook results

Note that in the bottom left hand corner of that graph there is a prediction of 0.98 million square kilometers labelled “Wadhams (SIPOG)”. The acronym refers to the Sea Ice and Polar Oceanography Group in the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge, of which Prof. Peter Wadhams is the head. Before we get on to his explanation for what the SIPN refers to as “an extreme outlier” amongst all the other predictions, here’s a TEDx presentation given by Dr. David Barber, who is currently Associate Dean (Research) in the CHR Faculty of Environment, Earth and Resources at the University of Manitoba in Canada:

Here are what Dr. Barber refers to as the “seven surprising impacts” of declining Arctic sea ice:

  1. Increasing coverage of young ice significantly changes atmospheric chemistry

  2. More snow both preserves and destroys ice

  3. Polar bear habitat can actually improve in some areas while deteriorating in others

  4. Match-mismatch timing in the marine ecosystem increases vulnerability

  5. Uncertainty as to whether the Arctic ocean will increase or decrease in overall productivity is a key unknown

  6. Evidence that ice hazards are actually increasing while the world marshals to increase development of Arctic resources

  7. Evidence that our recent cold winters are actually linked to our warming Arctic.

However those bullet points from David’s closing summary don’t actually mention the part of his presentation that most interested me. Listen carefully at 7:40 when he says that:

In 2009 we had our icebreaker down here and we went up this line that you see right here in this figure.

Here’s a version of the map Dr. Barber is referring that comes from a 2009 paper of his entitled “Perennial pack ice in the southern Beaufort Sea was not as it appeared in the summer of 2009“:

Barber-2009-Map

Here’s the relevant passage from the paper rather than the TEDx video:

We departed from station L1 heading north towards station L1.5, expecting to enter MY sea ice cover at about 71°20′N, 139°00′W based on remotely sensed information (Orange polygon in the figure). The Canadian Ice Service (CIS) ice chart (which relies extensively on Radarsat-1 data) for 4 September 2009 indicated the ship track would range from 7 to 9 tenths coverage and this ice would consist of partial concentrations of 5 tenths to 7 tenths old ice and from 2 to 3 tenths thick first year ice.

In situ observations of the sea ice conditions however showed that the ice we were traversing was not MY or thick FY, nor was it 7 to 9 tenths concentration, but rather it was a mixture of a few small MY ice floes (1 tenth coverage) interspersed in a cover dominated by small (10–100 m) rounded floes of heavily decayed first year sea ice (4 tenths). These floes were overlain by a thin layer of new ice (7 tenth) where freeboard was negative and thin ice growing between remnant pieces when the ice had a positive freeboard. Likewise, some new ice covered open water areas between floes.

This is the “rotten sea ice” David refers to in the video, about which he says:

It was so rotten in fact that the ship that we had does 13.5 knots in open water, and we were able to traverse that ice at 13 knots, yet the satellites all thought that this was very thick multi-year sea ice, because that’s what it had always traditionally been.

This information is obviously very interesting of course, but even more interesting (to me at least) is a subsequent paper by Dr. Barber about the same voyage of the Canadian Research Icebreaker Amundsen, published in 2012 and entitled “Fracture of summer perennial sea ice by ocean swell as a result of Arctic storms“. Here’s a pertinent extract:

We progressed through the heavily decayed ice region into a transitional region containing a mix of decayed old and FY sea ice floes, and finally into thick late summer MY pack ice. Using the onboard helicopter to survey the area, we identified a vast MY floe (10 km diameter), to which we intended to moor the ship, and conduct our typical science operations. The ice in this area was much thicker than the heavily decayed FY ice we that we had encountered the previous day to the west. Our helicopter EMI system recorded overall thicknesses of sea ice around station MYI (e.g., mean = 2.0 m, max = 10 m).

As ice teams initially prepared to deploy to the ice, we noticed the appearance of a swell from the ships helicopter deck. Laser data collected during the helicopter EMI survey at station MYI indicated a swell period of 13.5 s, and a wavelength ranging from 200–300 m. Laser data were collected while the helicopter hovered over a large MY ice floe. These data were augmented with three-dimensional dynamic ship positioning data, which revealed approximate ship heave amplitude of 0.4 m, also with a period of 13.5 s. The swell caused the vast MY ice floe nearest the Amundsen to ride up one side of the swell and fracture as it crested the wave peak, creating smaller ice floes of width approximately one half of the wavelength of the swell. In a matter of minutes from the initial onset of swell propagation, all large MY ice floes in the region were fractured in this manner, yielding a new distribution of smaller MY ice floes ranging from 100–150 m in diameter. A helicopter-borne video system recorded this event in still photographs along its flight track which were later combined to create a series of photo mosaics.

On 09 September 2009, we conducted a longitudinal helicopter EMI survey at 72.5 N, and determined the limit of the swell penetration into the pack ice at 72.526 N 134.51 W, a penetration of 350 km. Furthermore, the rotted FY ice margin was heavily fractured, with small floe sizes ranging from 20–50 m in diameter.

Moving on from Manitoba to Cambridge, Peter Wadhams has recently recorded an interview for The University of Earth, which describes itself as “an entertaining educational reality television series”. Here it is:

So what is “the reality” of the situation in the Arctic? Prof. Wadhams doesn’t explain his “extreme outlier” 2015 prediction in detail in the interview, but he does identify three potentially significant problems:

  1. The “minor thing, in a way” of several feet of global sea level rise this century due to melting of the Greenland ice sheet
  2. A sudden increase in the rate of “global warming” due to Arctic albedo feedback, which leads to
  3. The exposure of the methane hydrate bearing continental shelves off Siberia to increasing water temperatures as the sea ice above them melts. “It’s a massive risk, if you do a risk analysis”

Peter also highlights the same concerns as Barber et al. 2012, often referred to in the literature as “waves-in-ice“. I highly recommend watching both videos from cover to cover. However if you’re in a rush then at least skip to 28:30 minutes where he points out that on his cruise around the Arctic this coming September:

We’re looking at one particular thing, which may not be the most important thing, but the retreat of the sea ice in summer is going much faster than computer models predict, and we think that one factor there is the fact that as the sea ice retreats it opens up this huge area of open water in the Arctic Ocean which then becomes like an ocean, with lots of waves and storms and swell, and the waves themselves break the remaining ice up and cause it to retreat faster so that there’s a kind of collaborative effect there that the remaining ice is vanishing faster because of so much open water producing wave action.

Getting back to the current situation in the 2015 melting season, here’s what the University of Hamburg’s AMSR2 sea ice concentration map currently reveals:

Arc_20150703_res3.125

and here’s what the Slater Probabilistic Ice Extent methodology is predicting will happen over the next 50 days:

Slater_fcst_20150703

Both suggest to me that although the rate of decline in the area of Arctic sea ice is not currently abnormal for post 2007 years, it may well become so in another month or so, when the extent curve “normally” starts to flatten out. Possibly even sooner than that, because here is the current GFS 2 metre temperature map for the Arctic:

CCI-T2-20150703+3

and temperatures, particularly on the Pacific side of the Arctic, are forecast to get warmer still over the next few days.

Watch this space and we’ll keep you posted, but in the meantime here’s a final thought from Peter Wadhams:

Our children have a future only if we take action now.

[Edit – July 6th 2015]

In a personal communication Prof. Wadhams informs me that:

This year I’m going out in September in the “Sikuliaq” (University of Alaska) to do some more specific wave-ice interaction experiments [in the Beaufort Sea Marginal Ice Zone], assuming there is any ice to experiment on.

[/Edit]

The House of Lords Responds to a Changing Arctic

The United Kingdom’s House of Lords are an unlikely bunch to be bundled under the banner of “alarmist” or even “warmist”. Nevertheless their Select Committee on the Arctic has just published a report entitled “Responding to a Changing Arctic“, and in this video the chairman of that committee, Lord Teverson, briefly outlines their findings:
 


 

Note that he starts by saying that:

Absolutely the obvious thing first of all is that with the temperatures going up [in the Arctic] at twice the rate of the rest of the world the thing that everybody is seeing is reduction in sea ice which has reduced quite substantially over recent years, and of course a lot of the Arctic is land and we have the melting ice on Greenland particularly, which is causing sea level rises in the rest of the world.

In order to get that message across the committee has also produced the following infographic:

LordsInfographic
 
which shows how the temperature over land has been increasing whilst the sea ice extent in the Arctic has been declining.  The committee have also made all the learned evidence they received whilst producing their report publicly available. Professor Andy Shepherd from the University of Leeds told the committee that:

The majority of sea ice changes witnessed in “the past 50 or 60 years” could be attributed to greenhouse gas emissions and their effect on temperatures in the Arctic region.

and:

Suggested that the length of the solar melt season had increased by around five days per decade, causing additional melting and retreat of the ice.

How strange then, that David Rose made no mention of any of this when reporting Prof. Shepherd’s views in his “Myth of Arctic meltdown” article of August 31st 2014?

How strange also, that Christopher Booker maintained in his “The fiddling with temperature data is the biggest science scandal ever” article of February 8th 2015 that:

The ice-melt is not caused by rising global temperatures at all.