Saturday, April 9, 2011


Climate change and evolution
Despite a frenzied last-minute drive involving snowstorms in Europe and the
eastern United States, planet Earth failed to save itself from another last-place
finish in 2010: once again, it was the least cold year on record. The World
Meteorological Organization announced its finding last week that global mean
temperatures for the year were 0.53°C above the 1961-1990 mean, 0.01°C
warmer than 2005 and 0.02°C above 1998. With the comparison having a margin
of uncertainty of 0.09°C, the three years are considered tied for the hottest year
on record. That followed results the previous week from NOAA, which found 2010
and 2005 tied as the hottest years ever, and NASA, which found the same thing.
(They both think 1998 was a bit colder.)
The fact that every one of the twelve hottest years on record has come since
1997 is a little harder to wave away. 2010 was also the wettest year ever,
corresponding to the expectation that higher heat means more water vapour.
More countries set national high-temperature records in 2010 than ever before,
including the biggest one, Russia. Arctic sea ice in December was at its lowest
level ever, temperatures across a broad swathe of northern Canada have been
20° C higher than normal for the past month, the record temperatures are
coming despite the lowest levels of solar activity in a century and a La Nina effect
that should be making Canada colder rather than warmer, and so on. It is of
course possible that global warming plateaued this year; it's also possible that it
plateaued this morning. One can always hope! For now, though, this is the basic
shape of things:
There have been tons of new feather-bearing fossils unearthed over the past 15
years, and scientists can now use microscopic analysis and knowledge of how
modern feathers work to actually figure out what color some of the feathers on
these dinosaurs were. It's pretty clear that the development of feathers came
long before they had anything to do with flight, but it's still not so clear whether
feathered dinosaurs evolved into birds or whether they (and feathered protocrocodiles!)
shared a common feathered ancestor. Anyway, towards the
beginning of the article comes this:
The origin of this wonderful mechanism is one of evolution's most durable
mysteries. In 1861, just two years after Darwin published Origin of Species,
quarry workers in Germany unearthed spectacular fossils of a crow-size bird,
dubbed Archaeopteryx, that lived about 150 million years ago. It had feathers
and other traits of living birds but also vestiges of a reptilian past, such as teeth
in its mouth, claws on its wings, and a long, bony tail. Like fossils of whales with
legs, Archaeopteryx seemed to capture a moment in a critical evolutionary
metamorphosis. "It is a grand case for me," Darwin confided to a friend.
Think about how that must have looked to contemporaries. Darwin publishes his
theory that species develop through evolution from other species. Many people
think, wild idea, but can one species really change so deeply over time that it
becomes a different species? Wolves into dogs, sure, but fish into lizards and so
forth? Then, two years later, a fossil is discovered that suggests dinosaurs
evolving into birds. To first have a theory presented that suggests these
outlandish transformations, and then to have an example turn up that perfectly
describes the theory's most improbable consequences, with no possibility of prior
knowledge—this is an extremely convincing sequence of evidence.
But if you grew up, say, 150 years after "The Origin of Species" was published,
you didn't experience that remarkable sequence of evidence. You get the theory
of evolution and the fossil background presented at the same time. So if you
want to be an evolution sceptic, the fossil record just becomes another set of
data you can poke holes in, along with the theory. After all, nobody understands
what function feathers served before they were used for flight. If they were for
mating displays, why did they turn out to be perfect for aerodynamics? How come
nothing has feathers anymore that doesn't fly, or isn't descended from something
that did? Darwin's theory can't explain it! And so on.
Now, back to global warming. The thesis that rising global temperature data were
due to a greenhouse effect produced by industrial emissions of CO2 and other
gases, and that this might lead to environmental disaster, was something we first
encountered as a mind-bending idea being thrown around by scientists in the
mid-1980s. If, after 1988, global temperatures had stopped rising, or had started
to exhibit a lot of volatility. Instead, for a decade and a half, global mean
temperatures kept going up and up. They bounced around a bit in the mid-2000s,
and have now resumed rising again.
For people my age or older who were paying attention over the past couple of
decades, that really ought to be convincing. But for people who just joined the
conversation when "An Inconvenient Truth" came out, things are different. For
them, the evidence of global warming was presented at the same time as the
theory. And so they're susceptible to people trying to poke holes in the data or
the theory. The temperature rise from 1998-2008 isn't statistically significant,
tree ring data is unreliable, and so forth. Give them another two decades, and
they'll probably come around. Unfortunately, by that time an enormous amount
of damage will already have been done.

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