Extinction is a
normal part of the evolution of life on our planet. You and I and all
individual organisms eventually die. That is the way of things. Entropy
happens. Entropy is a word from the third law of thermodynamics that basically
means: things fall apart. The natural tendency is for things to become less
orderly as time goes on: things break down, things erode, things rust, things wear
out. Entropy is a measurement of how fast that is happening in any given system.
Individual death is a natural outcome of entropy. But an extinction is where all the
members of a species are no longer living. Millions of species have gone
extinct over the lifetime of our planet. There are natural background
extinctions that happen continually. But sometimes there are events that
trigger mass extinctions, where vast masses of species go extinct all at once (all
at once in geologic terms, which might mean over the course of hundreds of years).
There have been
5 mass extinctions over the geological history of the earth. The most
well-known one was at the end of the Cretaceous period (that is the one that
wiped out the dinosaurs). What most of the five mass extinctions have in common
is climate change. Some event (meteor, volcanic activity, etc.) caused the
climate to warm or cool, killing off organisms who could not adapt to the
change, or whose food supply could not adapt and so they starved. Mass
extinction is a domino effect.
Many of the species
that go extinct during a mass event, might have gone extinct eventually anyway
over time, but it would have been a much more gradual thing, taking millions of
years allowing other species that rely on them time to adapt to other food.
Some are
wondering if we are witnessing the next mass extinction event. Since 1900, extinctions
have occurred at 1000 times the background rate. In our world today we are seeing
examples of organisms that are finding life more difficult than usual. For example, polar bears are finding it
difficult to thrive. The sea ice is melting. The bears have to swim more,
expending more energy, while their food supply is dwindling. There has been a
50% decline in the polar bear population since 1990, with some predicting that
by the end of the century the wild population of polar bears will be gone. If
the only members of a species are all in zoos, I would say that makes the
species functionally extinct. There is some evidence that in certain areas the
bears are evolving to meet the new conditions. Whether this will work or not
remains to be seen. Evolution is a process that typically happens over tens of
thousands of years, not over a hundred.
I like to think
that all creatures and plants are here for a reason. Just looking at an
individual, it is hard to see the trend. Individuals die. That is something we
understand. Entropy happens. An entire
species dying in our lifetime, that is a bit more difficult to wrap our heads
around.
Arctic whiteness
Where to find respite
In a melting world
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