Bjorkum repeats mistakes and is more misleading about the melting ice in Antarctica

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This is a discussion post. The post was written by an external contributor, and quality assured by Aftenbladet’s debate department. Opinions and analyzes are the author’s own.

Bjorkum reiterates the claim that Antarctica has not lost ice in the past 40 years. From his counter position on 8 November to my documented observation on 5 November that this is wrong – he clearly confuses the surface mass balance with the overall mass balance of the landlocked ice sheet in West and East Antarctica.
In repeated reference to 2022 edition of the American Meteorological Society (AMS) Climate Reports, Bjorkum only refers to a subsection on “ice sheet surface mass balance.” In glaciology, this term covers the difference between precipitation and various forms of surface melting and evaporation in summer.

It’s true that the data summarized there on surface mass balance show little change since 1980. But that’s only half the equation. The rest is missing from Purecom. A later subchapter in the Antarctic section of the AMS report titled “Ice Sheet Mass Balance” includes mass loss due to increased calving and further melting of glaciers moving faster seaward.

We have to see the big picture

This currently occurs mainly in West Antarctica, especially where it has increased
Sea temperatures cut off floating ice shelves that block the glacier’s outlets. When these conditions are taken into account, the multi-decade trend has been a net increase in land ice mass loss from the continent as a whole, with the exception of 2022. The AMS report confirms this on page 341.

“I claim that Antarctica has lost 2,670 gigatons of ice since the beginning of the 2000s,” Bjorkum writes. It is explained that this number is taken from UN Climate Panel (Sixth Major Report, Physical Science Basis, p. 1263) Among other things, it relies on terrain and gravity measurements based on satellites of NASA and the European Space Agency’s European partner, which, contrary to what Bjorkum suggests, are quite accurate. AMS also uses these measurements in the data that Björkum himself refers to.

both of them NASA And European Space Agency Earlier this year I published updated and animated figures on mass loss in both Antarctica and Greenland. (link) For reference, Bjorkum looked at the database of people collected
Consolidated observations of changes in glacier masses, glacier volumes, and glacier extents from around the world. He picks an eight-year-old update and writes that “Global Glacier Monitoring Service It states that the total loss of ground ice on Earth between 1961 and 2015 is 9,000 gigatons.

An imaginary mass of ice could cover the area of ​​Germany at an altitude of 30 metres. But Bjorkum’s use of the number is misleading. They include individual coastal and fjord glaciers also in Greenland and in West Antarctica. But it does not include the loss of ice, by the same order of magnitude, from the ice sheets themselves
Greenland and Antarctica. This was not mentioned.

We cannot put a lid on the discussion

For your information: Of the rapid rise in global sea level that currently averages 4 mm (link) per year, the world’s terrestrial glaciers outside the ice caps contribute about 1 mm, according to NASA, the European Space Agency and other professional groups. It is followed by the Greenland ice sheet at 0.8 mm, and Antarctica at 0.4 mm, while expansion in seawater volume due to rising sea temperatures accounts for the rest.

Bjorkum’s view that journalism in its dissemination of scientific research has an uncritical side makes it “a microphone stand for researchers who have scared themselves off, or are looking for attention or money,” reminiscent of a conspiracy theory. There is certainly room for improvement among some researchers and journalists. But the belief that media houses “should consider whether they should stop publishing” research material like Bjørkum’s based on their own views
What he doesn’t like – which he claims can “run wild” with the public – is the same call for an end to input into public debate and the need for society to commit to public and political action, for example in the fight to transform an increasingly dangerous climate and nature crisis.