East Antarctica Glacial Melting through the filter of BBC reporting

An indication of how little solid evidence there is for catastrophic anthropogenic global warming comes from a BBC story story carried during the COP24 Katowice conference in December. It carried the headline “East Antarctica’s glaciers are stirring” and began

Nasa says it has detected the first signs of significant melting in a swathe of glaciers in East Antarctica.

The region has long been considered stable and unaffected by some of the more dramatic changes occurring elsewhere on the continent.

But satellites have now shown that ice streams running into the ocean along one-eighth of the eastern coastline have thinned and sped up.

If this trend continues, it has consequences for future sea levels.

There is enough ice in the drainage basins in this sector of Antarctica to raise the height of the global oceans by 28m – if it were all to melt out.

Reading this excerpt one could draw a conclusion that the drainage basins on “one-eighth of the eastern coastline” have sufficient ice to raise sea levels by 28m. But that is not the case, at the melting of all of Antarctica would only raise sea levels by 60m. The map reproduced from NASA’s own website is copied below.

The study area is no where near a third or more of Antarctica. Further, although it might be one eighth of the eastern coastline, it is far less than the coastline of East Antarctica, which is two-thirds or more of the total area.

NASA does not mention the 28m of potential sea level rise in its article, only 3 metres from the disappearance of the Totten Glacier. So how large is this catchment area? From a Washington Post article in 2015 there is a map.

The upper reaches of the catchment area may include Vostok Station, known for being the location of the lowest reliably measured natural temperature on Earth of −89.2 °C (−128.6 °F). The highest temperature recorded in over 60 years is −14.0 °C. In other words, what is being suggested is that a slight increase in ocean current temperatures will cause, through gravity, the slippage of a glaciers hundreds of miles long into the ocean covering ten times the Totten Glacier catchment.

The Guardian article of 11th December also does not mention the potential 28m of sea level rise. This looks to be an insertion by the BBC making the significance of the NASA research appear orders of magnitude more important than the reality.

The BBC’s audio interview with Dr Catherine Walker gives some clarification of the magnitude of the detected changes. At 2.30 there is a question on the scale of the changes.

Physically the fastest changing one is Vincennes Bay which is why we were looking at that one. And, for instance, in 2017 they changed average about .5 meters a year. So that is pretty small.

Losing 0.5 metres out of hundreds of thousands of length is not very significant. It just shows the accuracy of the measurements. Dr Walker than goes on to relate this to Fleming Glacier in West Antarctica, which is losing about 8 meters a year. The interview continues:-

Q. But the point is that compared to 2008 there is definitely an acceleration here.
A. Yes. We have shown that looking at 2008 and today they have increased their rate of mass loss by 5 times.
Q. So it is not actually a large signal is it? How do we describe this then. Is this East Antarctica waking up? Is it going to become a West Antarctica here in a few decades time or something?
A. I think its hard, but East Antarctica given how cold it is, and it still does have that layer insulating it from warm Antarctic circumpolar current … that really eats away at West Antarctica. We’ve seen it get up under Totten, so of you know, but it is not continuous you know. Every so often it comes up and (…….) a little bit.

There is acceleration detected over a decade, but for the disappearance of the glacier would take tens or hundreds of thousands of years. 

Walker goes into say that for the small changes to further increase

you would have to change the Antarctic circumpolar current significantly. But the fact that you are seeing these subtle changes I guess you could say Antartica is waking up.
We are seeing these smaller glaciers – which couldn’t be seen before – see them also respond to the oceans. So the oceans are warming enough now to make a real difference in these small glaciers.

This last carry-away point – about glaciers smaller than Totten – is not related to the earlier comments. It is not ocean warming but movements in the warm Antarctic circumpolar current that seem to impact on West Antarctica and this small section of the East Antarctica coast. That implies a heat transfer from elsewhere could be the cause as much as additional heat.

This account misses out on another possible cause of the much higher rates of glacier movement in West Antarctica. It might be just a spooky coincidence, but the areas of most rapid melt seem to have a volcanoes beneath them.

Yet even these small movements in glaciers should be looked at in the context of net change in ice mass. Is the mass loss from moving glaciers offset by snow accumulation?
In June 2018 Jay Zwally claimed his 2015 paper showing net mass gain in Antarctica is confirmed in a forthcoming study. It is contentious (as is anything that contradicts the consensus. But the mainstream estimate of 7.6 mm of sea-level rise over 25 years is just 0.30mm a year. It is in Eastern Antarctica that the difference lies. 

From the Daily Caller

Zwally’s 2015 study said an isostatic adjustment of 1.6 millimeters was needed to bring satellite “gravimetry and altimetry” measurements into agreement with one another.

Shepherd’s paper cites Zwally’s 2015 study several times, but only estimates eastern Antarctic mass gains to be 5 gigatons a year — yet this estimate comes with a margin of error of 46 gigatons.

Zwally, on the other hand, claims ice sheet growth is anywhere from 50 gigatons to 200 gigatons a year.

In perspective the Shepard study has a central estimate of 2,720 billion tonnes of ice loss in 25 years leaving about 26,500,000 billion tonnes. That is a 0.01% reduction. 

As a beancounter I prefer any study that attempts to reconcile and understanding differing data sets. It is looking at differences (whether of different data sets; different time periods; hypothesis or forecast and empirical reality, word definitions etc.) that one can greater understanding of a subject, or at least start to map out the limits of one’s understanding. 

On the measure of reconciliation, I should tend towards the Zwally estimates with isostatic adjustment. But the differences are so small in relation to the data issues that one can only say that there is more than reasonable doubt about against the claim Antarctica lost mass in the last 25 years. The data issues are most clearly shown by figure 6 Zwally et al 2015, reproduced below.

Each colour band is for 25mm per annum whereas the isostatic adjustment is 1.6mm pa. In the later period the vast majority of Antarctica is shown as gaining ice, nearly all at 0-50mm pa. The greatest ice loss from 1992 to 2008 is from West Antarctica and around the Totten Glacier in East Antarctica. This contradicts the BBC headline “East Antarctica’s glaciers are stirring“, but not the detail of the article nor the NASA headline “More glaciers in East Antarctica are waking up“.

Concluding Comments

There are a number of concluding statements that can be made about the BBC article, along with the context of the NASA study.

  1. The implied suggestion by the BBC that recent glacier loss over a decade in part of East Antarctica could be a portent to 28m of sea level rise is gross alarmism. 
  2. The BBC’s headline “East Antarctica’s glaciers are stirring” implies the melt is new in area, but the article makes clear this is not the case. 
  3. There is no evidence put forward in the BBC, or elsewhere, to demonstrate that glacier melt in Antarctica is due to increased global ocean heat content or due to average surface temperature increase. Most, or all, could be down to shifts in ocean currents and volcanic activity. 
  4. Most, or all of any ice loss from glaciers to the oceans will be offset by ice gain elsewhere.  There are likely more areas gaining ice than losing it and overall in Antarctica there could be a net gain if ice.
  5. Although satellites can perform measures with increasing accuracy, especially glacier retreat and movement, the fine changes in ice mass are so small that adjustment and modelling assumptions for East Antarctica can make the difference between net gain or loss.

The NASA study of some of East Antarctica’s glaciers has to be understood in the context of when it was published. It was during the COP24 conference to control global emissions, with the supposed aim of saving the world from potential dangerous human-caused climate change. The BBC dressed it up the study make it appear that the study was a signal of this danger, when it was a trivial, localized (and likely) example of natural climate variation. The prominence given to such a study indicates the lack of strong evidence for a big problem that could justify costly emissions reduction policies. 

Kevin Marshall

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