What about other forms of geoengineering?

The idea of using technology to remove carbon dioxide from the atmosphere represents a form of what is called geoengineering , which is the general name given to schemes intended to alter Earth’s climate in ways that might counter the planetwide effects of global warming. As discussed in this section, active carbon dioxide removal is a very promising idea, because it offers the hope that we might someday undo some or all of the climate damage that has already been done.

But several other forms of geoengineering have also been proposed. For example, some people have proposed seeding the atmosphere with tiny particles (sometimes called “aerosols”) that would reflect sunlight back to space, or even deploying giant sunshades in space, in order to cool our planet by allowing less sunlight to reach the ground. Wouldn’t these strategies also be useful?

Unfortunately, these “other” geoengineering strategies all suffer from three very significant drawbacks:

• First, these strategies would allow the carbon dioxide concentration to continue to increase, which means they do nothing at all about the problem of ocean acidification . As we’ve discussed, this problem is probably at least as serious as any of the other consequences of global warming, so a “solution” that leaves it unaddressed does not seem to be a real solution.
• Second, most geoengineering schemes require active maintenance. For example, the idea of putting small particles into the atmosphere requires continually adding more of them to replace those that rain out, and even the sunshades in space would likely need occasional orbital adjustments. If the maintenance ever failed — whether now or centuries from now — global warming would immediately resume, and if we’d continued adding carbon dioxide in the interim, it would be far worse than it is today.
• Third, these types of geoengineering introduce global climate factors that do not exist naturally and therefore are difficult to account for in models. As a result, we don’t have any good way to predict the full consequences of these schemes, so even if they successfully stopped the rise in Earth’s average temperature, we could not be confident that they wouldn’t create other climate disruptions.

Despite these drawbacks, these strategies might still prove useful as “last resort” measures if global warming continues to worsen. For that reason, research into them is continuing. You can read more about them elsewhere, but here, we’ll focus on assuming that the global community will act before we reach the point of needing “last resort” strategies.