Just some quick thoughts on geoengineering, the idea of mitigating climb change not by reducing our emissions, but by some less direct method such as recapturing it somehow or blocking sunlight to mitigate the warming. Topics are generally discussed in my order of preference.
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1:
Cloud seeding: The basic idea here is that clouds reflect sunlight
more than land or water, thus cooling the earth. The reason I like this
concept in principle is that if we had sufficient know how, we could do
this in a way that mitigated droughts or other unwanted precipitation
evens as well as cooled the climate. Though it would likely be
expensive, it would generally be better than benign and could have a
significant impact on global warming.
2:
Ocean fertilization: The
idea here is that much of the ocean is essentially a dead-zone due to a
lack of iron in the water, which is necessary for life. Iron salt
solutions would be attached to ships (probably already going about other
business) and poured into the water in strategic places. This spawns
plankton blooms (confirmed) which then presumably works up the food
chain and ultimately sequesters carbon. Unfortunately, any carbon
sequestration appears to be small and speculative, but on the other
hand, if done well, we could use this to increase the biological
capacity of the oceans, both increasing the amount we could harvest AND
increasing the amount of life in the ocean. There is modest promise in
this idea that is stupendously cheap, and it should be pursued.
3:
Biochar: The basic idea here is to char plant material and use it as a
soil amendment. Generally the idea is pretty sound and I don't see a
whole bunch of downsides other than economic issues and a limited capacity, if managed properly.
4:
Space mirrors: I divide these into two types - dumb mirrors whose only
object is to block light, and smart ones which have good control over
when and where the light is delivered. The first is possible with
current technology but expensive. The latter is beyond us for the
foreseeable future. Dumb mirrors, like any light-blocking scheme, have a
huge downside - less light causes less photosynthesis, which means less
life and lower crop yields. Also, it has no effect on ocean
acidification and could disrupt ocean and weather patterns we rely on.
To use any uncontrolled light-blocking scheme is an act of desperation.
Controlled light blocking with smart mirrors, however, is something I
have a hard time imagining our distant descendants not doing. Imagine
moving light from the equator to the northern latitudes, making the
former cooler and the later inhabitable. Imagine, using cloud seeding
and the smart mirrors, turning Antarctica into an even huger block of
ultra-cold ice, in order to offset rising oceans. Imagine using the
smart mirrors to manipulate local weather patterns in order to ward off
extremes. This is all possible in principle, but is not really relevant
to solving climate change because it is still something that is far
beyond our technological capabilities.
5:
Light management with sulfates: This is basically the poor-man's version of dumb mirrors. It's
cheap, but now you are making the air even filthier. Also, there is no
meaningful method of controlling where the sulfate blocks light, so the
technique cannot really evolve or improve towards being smart, as
mirrors could.
6:
Clean coal / carbon sequestration: Mostly a
political farce. It's technically possible, but too expensive, and the
sequestration is almost impossible to guarantee over long time frames. A
limited amount of CO2 is and will be pumped underground in order to
force out gas and oil, but the amount of demand here is trivial and by
using the CO2 to extract fossil fuels, it makes the problem worse, not
better. In the end, it is just thermodynamics. A coal plant would have
to use a quarter of its output (at minimum in theory...in practice even
more) just to compress the CO2 and put it back underground. Unless there
is a pre-existing demand for CO2 nearby, which is rare, there is simply
no way that this process will make financial sense vs wind, solar, or
just about anything else. Also, since the plant would have to burn extra
coal in order to compress and pump the CO2, it would release that much
more soot, SOx, NOx, PAH's, particulates, heavy metals and all the other
junk that continually comes out the smokestacks.
