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Tag Archives: flotation

Try this: Put some ice into a glass. Now fill the glass to the brim and watch what happens. The ice floats with some of it showing above the water level. As the ice melts, the water will overflow. Right? No, absolutely wrong! Melting ice will not raise the water level because, “Any floating object displaces its own weight of fluid.” — Archimedes of Syracuse.*

Yep, Archimedes. It’s as basic as that. Of course anyone who puts ice in their drink knows about this and anyone who has done Junior Cert. Science knows why.

Now, listen to this podcast of Newstalk Radio’s science programme, Futureproof, broadcast on Sat, 15 July 2017: http://www.newstalk.com/podcasts/Futureproof/Futureproof_with_Jonathan_McCrea/199154/Animals_adapt_to_Urban_environments_and_Reverse_Ageing

Not too far from the beginning there’s a discussion of the effects of global warming on the Arctic. Attention moves to an ice shelf the size of a county which has broken free in the Antarctic. Listen as a university scientist says that the melting of this huge iceberg will cause sea levels to rise. Notice that neither her colleague nor the presenter reacts, never mind corrects.**

The problem is not expert knowledge. The problem is a lack of basic knowledge which if widespread, makes citizen participation in debates about climate change impossible.

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* https://en.wikipedia.org/wiki/Archimedes%27_principle

** There is debate around the extent to which the more dense seawater will indeed rise when the floating freshwater melts. It will rise by a relatively small amount but even this is complicated by the intrusion of energy and temperature considerations. See here: https://www.skepticalscience.com/Sea-level-rise-due-to-floating-ice.html

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