Is it too late to avert global warming? If we stop all burning of fossil fuels now, the Earth may still continue getting warmer because the carbon we have already released into the atmosphere will still be there. Add to this increased water vapor, diminishing icecaps, and the release of carbon dioxide and methane from permafrost as it thaws and it is thought that the warming will accelerate. Are we doomed? Not necessarily. By using some desperate measures we can counter the effects of global warming, at least temporarily.
Pretty much everyone here believes global warming is real. The evidence is pretty clear. The vast majority of scientists warn us of this threat. We need to reduce greenhouse gas emissions. That is obvious. What scientists are beginning to worry about however is that it may be too late. Many are coming to believe that we have triggered a runaway global warming effect. As glaciers and icecaps melt, they reflect less of the sun's energy. Also, carbon dioxide and methane trapped in the permafrost is released as that thaws do the the warming trend we have started. Even if we stopped all greenhouse gas emissions today and cut fossil fuels cold turkey, the Earth would continue to get warmer and warmer. The carbon dioxide already in the atmosphere will take tens of thousands of years for the Earth to naturally remove it.
So simply stopping greenhouse gas emissions isn't enough to avert catastrophe. What then, do we do? We have to somehow either filter out the excess carbon from the atmosphere which is quite beyond our current capabilities or we have to find some other way to cool the Earth. Enter geoengineering. This is a term that describes efforts to alter the environment of a planet. Here it will refer to methods to cool the Earth. While tinkering with the planet further may seem scary, doing nothing is pretty much a guaranteed disaster so we may simply have no choice.
Remember when Mt. Pinatubo erupted in 1991? It created a cooling effect that lowered global temperatures by about a half a degree celcius for a few years. It was the dust that was thrown up into the atmosphere that did this by preventing some of the sunlight from getting through to the surface. It is thought that man can do something similar through artificial means. By putting reflective dust into the stratosphere it is thought that a certain percentage of sunlight can be prevented from warming the earth. If done correctly, it should be able to counter the warming effect of greenhouse gases with this method.
Some feel uneasy about doing something like this though. Other methods would be to put mirrors or microsattelites into orbit above the equatorial region. Since the equator region receives the most amount of direct sunlight, putting space mirrors or microsatellites into orbit there would have the greatest effect. Some feel that we would be preferable because we could always alter the orbits or take them out of orbit if we had to.
If you want the most bang for your buck you would go with the reflective dust option. Titanium dioxide or aluminum dust could be put into the stratosphere via high altitude balloons, jets, or guns. Sulphur compounds can also be used however those can destroy the ozone layer. Now it would likely be very difficult to persuade the public that we should shoot reflective dust into the atmosphere on purpose. Of course, we have released all sorts of pollutants in the past that have had a similar effect. However, the idea of intentionally altering the temperature of the planet will probably freak some people out. It's also hard to say what the health effects of such small particles in the atmosphere will have. Probably not much worse than the crap we've already been dumping into the atmosphere since the start of the industrial revolution but still a concern.
These options are of course last resort options. No one should consider doing any of these things unless there is no other way to avert disaster. Unfortunately, it looks as though we may already be experiencing a runaway greenhouse effect. Measures such as these are likely the only option left to us. Still, they are only band aids to the problem. If we shoot reflective dust in the atmosphere, we will have to continue shooting this dust every year because the dust will eventually settle. It would be a temporary reprieve only and not a final solution. It kinda reminds me of that Futurama episode where they simply drop a giant icecube every so often into the ocean to cool the Earth. Shooting dust into the stratosphere is kind of our own giant icecube.
My personal belief is that we will eventually need to filter the carbon out of the atmosphere and stick it back in the ground where we got it. This would take a tremendous amount of energy and is beyond our capabilities at the moment. My hope is that with nanotechnology and new materials, we will be able to create super cheap, efficient solar cells that can produce dirt cheap electricity. If in the future we can have access to nearly unlimited supplies of renewable energy, we may be able to have the electricity needed to filter all that carbon out of the atmosphere. I believe this will happen eventually. We just have to survive until we reach that level of technology. Many of the geoengineering tactics discussed may only be a band aid but if we can buy ourselves enough time, the Earth may just survive.