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Memories of the 28th Century

Reversing Global Warming, part three

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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.



http://www.geo.mtu.edu/~hnlechne/con..._eruptions.htm
http://www.geo.mtu.edu/~hnlechne/vol...ngineering.htm
http://www.scienceforums.net/topic/5...nic-eruptions/

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