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also there are reent posts that suggest that all's just going swimmingly in the Antarctic ... (where there has been massive loss of sea ice)
mind you people who care about the long term health /survival of whales, Emporer penguins, etc might read this ...
mind you people who care about the long term health /survival of whales, Emporer penguins, etc might read this ...
2004 : it was found that the northern tip of Antartica was growing grass – (hitherto sparse tussocks). Over the summer of 2004, great meadows of the stuff. – Hard to imagine anything more emblematic of transformations at the poles.
The subantarctic seas are rich in plankton and hence krill which grow despite low iron. The presence of sea ice compensates for this. The semi-frozen edge between salt water and floating ice promotes remarkable growth of microscopic plankton that is the base of the food chain. - and hence penguins seals and great whales. The seaice has a massive influence on plankton.
Dr Angus Atkinson et al of British Antarctic Survey examined records of krill … before 1939 it was “stable”, no overall trend. But since 1976, the krill have been in sharp decline, reducing at a rate of nearly 40% per decade. Atkinson sums up “These changes … have profound implications for the Southern Ocean food web. Penguins albatrosses seals and whales … are prone to krill shortages”.
Since 1980s there has been satellite coverage to show the extent of winter sea ice. Prior to that it is stil possible to study the ice and estimate extent. The research reveals the extent of sea ice was stable to 1950, but has decreased sharply since. The northern boundary has shifted southwards from 59.3S to 60.8S (which I believe is about 6 miles). This corresponds to a 20% decrease in sea ice extent.
To gain a sense of magnitude and rate of change involved, imagine what it would mean for the animals of the Serengeti if their grasslands grasslands had been reduced by 40% per decade since 1976. Already there are signs that some Antarctic fauna are already feeling the pinch. The emperor penguin is half what it was 30 years ago, while the number of Adelie penguins has declined by 70%.
Such studies suggest that in the near future a point will be reached where, one after another, krill-dependent species will be unable to feed. If so, the southern right whales that have only recently begun to return to Australia and NZ shores will no longer come. The humpback whales that traverse the world’s oceans likewise will no longer be able to fill their capacious bellies, nor will the innumerable seals and penguins that cavort in southern seas. Instead we’ll have an ocean full of (useless) jelly-like salps, the ultimate inheritors of a defrosted cryosphere.