[extropy-chat] Global warming news
mstriz at gmail.com
Sat Mar 25 02:58:04 UTC 2006
On 3/24/06, "Hal Finney" <hal at finney.org> wrote:
> > Even without glacier melting, the thermal expansion of the top strata
> > of the ocean is estimated to be about 50 cm per centigrade rise in
> > ocean temperature.
> That's a little higher than estimates I have seen. For example
> http://www.cru.uea.ac.uk/cru/info/slr/ estimates that the last 0.5
> degrees C rise in ocean temperature has raised sea level 2 - 7 cm due to
> thermal expansion alone. That would correspond to 4 - 14 cm per degree C.
> But I gather that this is an area of some controversy.
The estimate I used is from here: http://striz.org/docs/meehl-2005-sealevel.pdf
Actually it's 50 cm over 3 degrees, not 1, so that's closer to your
upper bound. However, not all regions would expand equally, and some
could expand half a meter by the first degree rise.
> > How long will it take to process a volume of air that is 2 billion
> > cubic miles (200 million square mile surface x 10 mile elevation)?
> Air is well mixed over the relevant time frames, from what I understand.
> But your point is well taken. The question is, how much carbon needs
> to be removed from the air? Running some numbers it looks like a
> daunting task.
> This Peak Oil web site had a good summary of the carbon budget by Stuart
> Staniford, one of their best commentators:
> http://www.theoildrum.com/story/2006/1/26/0299/33391 .
> This shows that we are presently adding a net of about 4 gigatons of
> carbon per year, from this graph:
> http://www.theoildrum.com/uploads/12/net_carbon.jpg .
> What I imagine with nanotech or biotech is some easily replicated,
> inexpensive technology to remove or fix carbon from the air. To get an
> idea of the scale, I look at what would be needed per person. It's not
> literally that every person on earth would have such a device, but this
> gives an idea of the scale. 4 gigatons per year with a population
> of 6 billion is 2/3 of a ton per person per year. Sequestering that
> amount would just match the amount being added to the atmosphere, so we
> would need to do several times that in order to start cleaning the air
> of carbon.
2/3 of a ton is the global average, which is quite amazing, because
the average carbon footprint in the United States is more like 20
tons. You wouldn't even need to proliferate that technology to the
undeveloped world. The US and Europe are responsible for 40% of the
CO2 output (China accounts for another 15% -
http://en.wikipedia.org/wiki/Carbon_dioxide_emissions). If everyone
cut their carbon footprint in half through sensible lifestyle changes
(vehicle purchases, etc.), which is pretty painless, that's a
significant reduction in CO2 output right there. And we can do that
now. We don't have to wait for nanotech. And that would diminish the
crap you have to clean up later.
> That amounts to several tons per person per year, or perhaps 10 pounds
> per person per day. That's clearly a substantial amount. It doesn't
> have to turn into diamond, just some kind of stable, storable form
> of carbon. We would need to put it somewhere that it wouldn't get into
> the atmosphere.
With the advent of nanotech, one would hope that we would move beyond
the burning of fossil fuels for energy, which would solve the problem
at the source, and you don't have to run the risk of a grey goo
accident washing out the troposphere.
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