This is part
three of a series of blog posts on reversing global warming. In the first part
I proposed trying iron dust on the oceans to cause phytoplankton blooms that
would eliminate atmospheric CO2, which would (in theory) reduce global warming.
The second method would be to cut down on heating from the Sun. And this third
part is about cheaper ways to reduce the amount of sunlight reaching the Earth.
In addition to
the methods for shielding the Earth from the radiation from the Sun already
mentioned, there are some other methods that are rather time honored. You are
probably aware that the Year Without Summer was caused by an eruption of Mount
Tambora, a volcano in Indonesia. And more recently Mount Pinatubo in the
Philippines caused a slight worldwide cooling when it erupted. I realize that
humans don’t have much control over the eruptions of volcanos, but neither have
humans tried to set off a volcano, yet.
Volcanos put
huge amounts of dust and chemicals into the atmosphere and those can, and do,
reflect sunlight. With some careful calculation and playing with fire it should
be possible modulate the eruptions of some volcanos. Efforts have already been
made to control volcanos, and further research is being conducted, see links
below.
If eruptions
can be controlled or stopped, then they can be started in a limited way, so
that only gases and dust that would decrease the amount of sunlight getting to
Earth. We certainly don’t want another
Year Without a Summer, but it might be nice to use something that would
otherwise be damaging to improve the world.
Research would
also have to be done into the amount of material that would have to be teased
out of the volcanos. It certainly would depend, in part, on the locations, and
each volcano has its particular blend of effluvia. The altitude to which the
material would rise would also be an issue.
Material that rises to greater heights would tend to stay in the
atmosphere longer. Sulfur dioxide is a common component of
volcanic gas and it is well known for reflecting sunlight, but some volcanos
eject vast amounts of carbon dioxide. It might be necessary to pick and choose
and to balance the outputs of different volcanos.
As yet little research has been done into this
system for controlling global warming, but there is great potential for
research grants. As part of the research it would be a good idea to consider
other sources for gases that would reflect sunlight. In recent times industrial
gases ejected into the atmosphere included sulfur dioxide in considerable
quantity. Industrial operations also produced nitrous oxides, which tend to
trap heat, so there was some balancing done; although it was unplanned. Many of
the industrial processes that produced relevant gases are still being done, and
the waste gas that was formerly released into the atmosphere is now treated and
discarded in controlled ways. The controls could simply be removed and the gas
allowed to go into the atmosphere.
While that would amount to allowing air
pollution, it would be for a good purpose, and it could be regulated. In fact,
careful regulation would be necessary to ensure that additional greenhouse
gases would not be released into the atmosphere. Laws would have to be changed
in most of the world, but it seems that China is already doing its part to
reverse global warming by using air pollution. I don’t know if they have
improved upon what Western countries did, but it would be worthwhile to ask.
Anyone who
lived in a developed country before 1970 surely remembers the clouds of
particulates that floated above the cities. Those clouds were composed of a
mixture of gases that had little effect on temperature, because some of the
particulates and gases were absorbing heat, while others were reflecting the
sunlight back into space. We need to specialize and have clouds that only
reflect the heat back into space. Water vapor would be ideal, if only it
weren’t such a good greenhouse gas. It might be safer to use dust. We might
even use some of the iron dust that we would be spreading on the oceans. It the
particles were small enough, then they would stay in the stratosphere for
years, so did the dust from Tambora.
The choice
isn’t obvious. There are downsides for every alternative, but something has to
be done. And in our hearts we know what it needed.
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