Monday, September 29, 2014

Just Under 8 Inches an Hour

If you were looking at something moving at 8 inches an hour, you would notice that wouldn't you? 

20 cm or just about 8 inches per hour is the pace at which wildlife - fauna and flora - is migrating away from the equator due to climate change.  That's almost 5 metres a day.  That's roughly 1.8 kilometres a year or more than 70-kilometres since the migration is believed to have started 40-years ago.

Plant life tends to migrate slowly but animal life, that's another story altogether.  The denizen of the Sea of Cortez, the Humboldt squid, seemed to migrate from the waters of Baja to the beaches of Vancouver Island quite rapidly, possibly within a year.  Sardines from California also seem to have migrated to our waters very quickly with their predators, white-sided dolphins, and their predators, transient orcas, in hot pursuit.   Even the return of large numbers of Humpback whales to our waters may reflect the migration of the whales' prey.  Something must have seemed inviting.

Species have moved towards the poles (further north in the northern hemisphere, to locations where conditions are cooler) at three times the rate previously accepted in the scientific literature, and they have moved to cooler, higher altitudes at twice the rate previously realised.

Analysing data for over 2000 responses by animal and plant species, the research team estimated that, on average, species have moved to higher elevations at 12.2 metres per decade and, more dramatically, to higher latitudes at 17.6 kilometres per decade.

For Alpine species, plants and animals, this migration can be a death sentence.  While climate change may compel them to migrate ever higher, they can go only so far before they reach an altitude at which they can no longer survive.  When they reach that line, they die.

Simply moving to higher latitudes can also be difficult due to both natural and man-made obstacles to migration.  America's fortification of its border with Mexico can present an insurmountable blockage to anything that can't fly over the fence.  Some creatures can't cross waterways, others are unable to cross deserts. 

First author Dr I-Ching Chen, previously a PhD student at York and now a researcher at the Academia Sinica in Taiwan, said: “This research shows that it is global warming that is causing species to move towards the poles and to higher elevations. We have for the first time shown that the amount by which the distributions of species have changed is correlated with the amount the climate has changed in that region.”

Co-author Dr Ralf Ohlemüller, from Durham University, said: “We were able to calculate how far species might have been expected to move so that the temperatures they experience today are the same as the ones they used to experience, before global warming kicked in.  Remarkably, species have on average moved towards the poles as rapidly as expected.”

...previous studies suggest that climate change represents a serious extinction risk to at least 10 per cent of the world’s species. Professor Thomas says: “Realisation of how fast species are moving because of climate change indicates that many species may indeed be heading rapidly towards extinction, where climatic conditions are deteriorating."


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