I
just turned 26. When I was in high school our environmental education
was very good, compared to what has been taught for most of human
history. Silent Spring had been out for decades, and most people had
seen An Inconvenient Truth. We knew a lot more about the science of
the environment, and as students we were painted a bleak future of
doom-soon extrapolating graphs. The urgency of the material and
environmentalist exhortations of individual action was undercut by
our teachers' (sometimes unconcealed) feeling of powerlessness. Scaring
people in environmentalism is a double-edged sword; you push some
people into action, but for many others it becomes easier to detach
emotionally: “we're all screwed, so what do I care?” And the more
dire predictions you use, the more like a millenarian cult leader you
sound. We're running out of tungsten! No more lightbulbs! Then it
turns out LED lights are more energy efficient anyway. People stop
listening when you're constantly predicting a rapture that never
comes.
And
yet this was the tone of much of the environmental and biological
literature I read for this project. Even when dispelling myths like
the 50,000 species some say are going extinct a year (which is based
on a completely made up number), one of their primary concerns is
inspiring donations and grants for their research. Not that this is a
bad thing; research on current extinctions is very important, and the
true number that occur per year is undoubtedly still a scary one. But
knowing that the articles in a lot of the books were recommending
very specific courses of action made me warier of them. If not the
numbers themselves, but the picture they were painting with them. I
hate being sold, even on a good cause. I'd much rather come to the
same conclusion on my own.
Even
so, biologists talking about the current human-led biodiversity loss
basically agreed that convincing people of the importance of
biodiversity loss is the foremost challenge of the 21st
century. If I'd originally been asked to say why biodiversity is
important, I wouldn't have had a ready answer but I could have
reasoned my way into a few. Now I had several: biologists, eager to
convince readers of the importance of biodiversity, have long lists
of reasons why it's important. They all made sense and yet, I kept
thinking, the species we have lost in recorded history have mostly
been localized, fragile ones. Island species, ones with very specific
eating habits or habitats, ones without much competition. It's easy
to romanticize the loss of the dodo, but hard to see what the
extinction of a strange flightless bird on a single island means for
the future of our planet. As did more practical concerns like cures
for diseases that have yet to be discovered, compounds for industry
that have yet to be extracted from endangered Amazonian beetles. And
more abstract ones, like the existence of a tipping point which once
passed will cause massive chains of extinction. Mourning the loss of
things we don't have yet and theoretical problems we may face; I
could see why getting people to care about these things would be a
challenge!
Ironically, it took me reading less alarmist paleontological sources to start to get worried. Especially when they came to the same conclusions as the biologists had. The history of mass extinctions is interesting; we know of at least five that meet the threshold we created, but large extinction events have been happening almost continuously since there has been life on Earth. Paleontologists are generally divided on their causes, but I read good summaries of their consensus opinions.
Two things that I learned stuck out to me. One was just how variable the Earth's climate has been over both the short term and long term. The gas composition of the atmosphere, the temperature, the sea level and its chemical composition, all of these things fluctuate massively all the time. The current sea level is almost the lowest it's ever been in the Earth's history, as is the level of CO2 in the atmosphere. It surprised me that even though the short term increase in CO2 that we worry so much about may have dire implications for our planet, in terms of hundreds of millions of years, a lack of CO2 is predicted to be a bigger problem, as trees gradually convert virtually all of it into oxygen. It was also fascinating how much life determines its own conditions. Changes in microorganisms can completely shift chemical conditions in the oceans, for example. Runaway reproductive success for one type of organisms was always a key component in theories of mass extinction.
Paleontology
is all about time scale, and the long one is often counter-intuitive.
Paleontologists generally agree that a large meteorite only had a
hand in one of the mass extinctions, the C-T one that killed the
dinosaurs. Except the fossil record seems to show that most dinosaurs
were already extinct by then, and only two groups were wiped out.
Like when I researched the near-extinction of the bison and found
evidence that their numbers had already been falling for centuries
before the arrival of Europeans, extinction seems to not usually be
that dramatic. More often, it's a gradual fading away of an old
species in its sleep rather than a young species in its prime.
That
said, cascading chains of extinction can and have taken out otherwise
successful species. The second thing I found striking was that in
mass extinctions, there was always an accompanying drop in biomass,
the amount (not diversity) of life on Earth. Maybe this is obvious,
but I didn't see why having lots of types of organisms go extinct
would necessarily mean there would be less tons of living stuff,
worldwide. If some things were out-competed by others, aren't
successful species then more numerous to make up for it? Apparently
yes, but not in the long term, because of the extreme variability of
the Earth's climate. So if Australia gets a couple degrees cooler,
the cane toads, a newly introduced species, might all die because
they can't take it, whereas the older established species that they
wiped out would have survived (because the very fact that they're old
species means they've probably survived a similar cooling period in
the past).
This
fact, that species exist places because they are best suited to live
there in the long term, and that allowing them to be extirpated can
create lifeless wastelands in the relatively short term, really
convinced me. Life is just something that's managed to make solar
energy useful to itself, hung on through severe climactic variations,
and even had a hand in dictating its own conditions on Earth:
creating an atmosphere, making the planet able to better sustain
life. It's totally possible for the efficiency at which life converts
solar energy into a variety of living things to fall apart until,
like Mars, it's just sunlight
hitting bare rock. The less biodiversity we have, the more delicate
our balance, the more dependent we are on current climactic
conditions staying the same. And they're always changing, that has
never happened! We need as many players as possible ready to step up
when their time comes, and then fade into the background when others
are better suited, slowly changing and branching out to be ready for
when they're needed again.
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