Global Warming
Facts that nobody
disputes:
There is a greenhouse effect.
If certain gasses -- mostly water vapor -- didn't absorb Earth's radiation and
reflect it back, the planet would be freaky cold, averaging about -25° F.
So the greenhouse effect is big, and from our point of view,
good.
The biggest greenhouse gas is
water vapor. CO2 probably accounts for about 10% of the
effect.
CO2 levels have risen over the
past 150 years due to humans, by about
20%.
Temperatures during the same time
have gone up by about 1 degree Celsius. There's a ton of variability from year
to year, so it's not such a big change that you really notice until you look at
a lot of data.
Some places are cooling,
while other places are heating more dramatically. There are lots of factors at
work besides the greenhouse effect.
Sea
levels have risen by maybe seven inches in the past 150 years. Even under the
ugliest warming models, it seems unlikely they'll rise more than about a meter
in the next century.
Humans generate so
much CO2 that early models said that the levels should be rising much, much
higher than they actually are. The planet seems able to absorb lots of CO2 in
ways we don't really understand.
Plants
seem to like the extra CO2, and grow faster now than they did 150 years ago.
The increased temperature may also be a net benefit to
plants.
Humans are having a large
effect on our atmosphere. We do not understand the long term effects of our
changes.
We're definitely making the
temperature go up, but we don't know how high, or how fast. We also don't know
if overall this is a good or bad thing. It will definitely be good for some
places and bad for others.
It is
possible that small sea temperature changes could lead to more severe
hurricanes, on average -- though year-to-year variability will still be larger.
We don't really know.
It is possible
that we'll see both heavier storms and more severe droughts. We don't really
know.
It is possible that we could, in
time, overcome some of the natural feedback mechanisms of the planet that
regulate temperature, essentially killing the planet. It seems unlikely, but we
don't really know.
It is possible that
human-caused global warming could help stave off the cyclic ice age that should
be in process now, actually preventing massive glaciation. We don't really
know.
We should be concerned about
global warming, and should continue to study the issue. It wouldn't hurt to
work toward reducing our greenhouse gas emissions, because it's possible that
with further study we'll find that it's an absolute necessity. We don't really
know.
We shouldn't panic. It's
probably manageable.
We shouldn't
ignore it. It may require
management.
We don't really
know.
Filed Mon - June 26, 2006, 12:57 PM in
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