A Planet Weak as a Baby

Posted on October 29, 2012

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Our Human-Stressed Planet Is Vulnerable to Climate Change

It has been clear for some time that climate change will bring about a passel of ecological changes, and that some elements of some systems will not survive the change.  Organisms will die.  In extreme cases, whole ecosystems will collapse.  And when ecosystems begin to collapse, some or many species will go extinct.

Nobody but the most Pollyanna of climate change deniers expected we were going to get out of climate change scot-free.  The questions really were: how bad was it going to get, how many species were going to die, and how were we to know?

Now, courtesy of a new scientific paper published in the Proceedings of the National Academy of Sciences, we have some sobering answers to these questions deriving from a close examination of another disaster and another mass extinction.

On first blush, the extinction event that wiped out the dinosaurs 65 million years ago at the Cretaceous–Paleogene boundary doesn’t seem to resemble climate change much.  A meteorite the size of a mountain slams into the Yucatan, and bye-bye T-Rex and friends.  But the event was a lot more complex and less direct than a simple meteorite crater and a loud thump.  The meteorite affected world-wide food webs by blocking out the Sun.  It sent particles into the atmosphere, inhibiting photosynthesis, killing the most vulnerable plants, which caused a die-off of the creatures who fed on those plants and of the predators who fed on the plant-eaters, and so on down the line.  According to the new study, not all ecosystems were equally affected.

“Our study suggests that the severity of the mass extinction in North America was greater because of the ecological structure of communities at the time,” said study lead author Jonathan Mitchell of the University of Chicago.

What determined severity?

“Our analyses show that more species became extinct for a given plant die-off in the youngest communities,” said Mitchell.

Oops!  All of human agricultural civilization technically fits within the good doctor’s technical definition of “youngest communities.”  People who deal in millions of years operate on a different time scale from the rest of us.  And according to the doctor, any system that has undergone recent change also qualifies as young.  Is there any ecosystem on the planet that humans have not interfered with?  I don’t imagine so.  Does that mean we have left the planet Earth a weak baby unable to fight off disaster?  Maybe.

Probably.

If so, then, unlike the time of the dinosaurs, the entire planet is vulnerable in a way that it has never been vulnerable.  Thus the disaster brought on by extreme climate change might be much worse than anybody is yet imagining.  That should worry us.

There have been some pretty stark imaginings already which I’d bring up except the children aren’t in bed yet.  Don’t want to spook the faint of heart.

Of course, if we want to avoid that mess, if we don’t want to endure mass extinctions and whatever those extinctions will mean to our civilization, to our lives, to our souls, then our only human choice is to avoid extreme climate change.

A good plan anyway.

And the only way to avoid extreme climate change (we’ve already got the other kind already) is to act, and to force our governments to act.

Beginning now.

The dinosaurs are warning us.

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See Mass Extinction Study Provides Lessons for Modern World – ScienceDaily

and Late Cretaceous restructuring of terrestrial communities facilitated the end-Cretaceous mass extinction in North America – PNAS abstract