Does the Antarctic ice sheet have a gravitational effect on sea level?

Interesting writing about West Antarctica. I’m interested also about West A and PIG. I read somewhere that Greenland icemass has gravitational effect drawing  water 20-30 cm higher than normally. So , if all that ice would melt, sea water would not rise in northern areas but in southern areas more. Is that true and does Antarcica ice mass has such effect also?

Asked by Jarno

hi Jarno,

I deferred to my colleague Dr Pippa Whitehouse to answer this question. This is what she said:

Yup, good question. Jarno is absolutely right in saying that the sea level would fall in regions close to a melting ice sheet – this is due to the decrease in the mass of ice and hence the decrease in the gravitational attraction between the ice sheet and the ocean. Jarno is also correcting in deducing that there would be a greater-than-average rise in sea level at locations furthest from the melting ice sheet.

The effect is the same for both Greenland and Antarctica, i.e. if Greenland melts then sea-level rise will be greatest in the southern hemisphere, and if Antarctica melts then sea-level rise will be greatest in the northern hemisphere. In both cases, sea level would fall slightly within a few hundred kilometres of the melting ice sheet.

If Jarno has access to Nature Geoscience then this is covered very nicely in ‘Identifying the causes of sea-level change’ by Milne et al. (2009)(doi: 10.1038/ngeo544); this paper includes lotsof useful references for further reading. If they don’t have access to Nature Geoscience, then the concept is also covered in the Sea Level chapter of the IPCC 5th Assessment Report (chapter 13) where it is referred to as ‘sea-level fingerprinting’. In particular, see FAQ13.1 Figure 2 of the Report for a good diagram showing the predicted pattern of sea-level rise if Greenland and West Antarctica both melt at a rate of 0.5 mm/yr.

Hope that helps,

Pippa

 

About

I am a Senior Lecturer at Newcastle Univeristy, specialising in glaciology and glacial geology. I wrote and developed the AntarcticGlaciers.org website as part of an ongoing commitment to outreach, education and research impact. Read more about me at www.antarcticglaciers.org/bethan-davies.

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