Some Quick Thoughts on Geoengineering

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.

...

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. 

People, People Everywhere!

Yesterday, I posted my thoughts on the maximum sustainable human population, given current technology and land forms. But what if we got rid of those constraints and made some plausible guesses about future technology? How high can we go from 25 billion?

The biggest improvement would come from increasing crop yields. Yesterday's assumptions were a mostly vegetarian diet produced with modern organic yields. However, crop yields are slowly and steadily increasing, including organic at places like Rodale Intitute, a leading organic research farm. Additionally, if you combined organic with genetically modified organisms and otherwise got rid of some of the anti-scientific elements of the organic movement, it is easy to imagine increasing crop yields significantly.

There are other potential tricks up our sleeve as well. For example, climate change will have a mixed effect on crop yields, as CO2 fertilization battles it out with water stress and desertification. If we can mitigate the latter, crop yields for many staples could increase by 10-15%. Or we could get more wild, and used space-based reflectors to alter seasons, cooling the equatorial regions and warming the arctic areas in particular, perhaps by lengthening the evenings in the cooler half of the year. This would result in longer growing seasons (or multiple seasons) than is the current case, increasing yields. We could also engage in cloud seeding and increase rainfall in areas that are water-constrained. All in all, we might be able to increase crop yields by a third or half relative to modern organic practice, feeding an extra 8-12 billion, on current land.

Also, fungi are a possible food source that I did not mention yesterday. They can be grown underground using forest waste as their food source, providing us with just a bit more food. Another trick we might use is ocean fertilization, to increase the productivity of the oceans by seeding the relatively dead areas with the minerals that are constraining biological activity. Of course, land reclamation from the ocean is also possible in some places. This land could be used either for farming directly or more likely, used for living space, freeing up interior lands for farming. Synthetic foods are another real possibility, and may beat out photosynthesis on a total energy basis. If this were ever successful, the maximum population could be substantially higher. It is almost impossible to estimate at this point, however.

If solar PV efficiency increases (and it will), naturally less land will be used. So yesterday's land use assumptions were unnecessarily pessimistic, and the reality would be that some of the land assigned to PV could be reassigned to food production. Also note that we can (and do) get some of our energy from other renewable sources such as hydro, wind, tidal, and geothermal, which are more space efficient. Ignoring these made yesterday's estimates too high. Likewise, I assumed that the new population would live on the same land as we are currently using, but if we wanted to, we could go even higher density than that. It is certainly possible, and this would reclaim more land - often prime farm land - for food production. On top of all this, wide-scale terraforming is possible. Much of the marginal land that was assigned as "Other" or meadows or unfarmable forest is unfarmable precisely because it is hilly. We have bulldozers, and lots of time, making it possible to reclaim some of this land for productive use.

Oh, and there is no reason we cannot change ourselves. Using genetic engineering, we could make ourselves smaller and select for the most energy efficient among us, cutting our caloric needs dramatically.

Combining all this, I can certainly imagine something like 40 or even 50 billion people living on earth, in a sustainable manner, with a level of comfort similar to that of the citizens of modern industrial economies.