The horizontal WAF of PWs 1 and 2 generally shows a
poleward propagation in the high latitudes near the tropopause (Figures 7(a1)-7(a5)), which is the main channel for PWs entering the stratosphere (Figures 5(a1)-5(a5)).
It may mean that the thermodynamically favourable conditions for these storms are migrating
poleward.'
Under current global warming, land animals and plants are migrating
polewards at a rate of about 6 kilometers a decade -- but sea creatures may have to move several times faster to keep in touch with the water temperature and conditions that best suit them.