Geoengineering, or large-scale modification of the Earth's environment, is a contentious topic among people debating the right response to climate change.
On the one hand, some people believe that efforts to reduce greenhouse emissions are probably going to be too little and too late to prevent major changes to the Earth's climate with substantial impacts to human activities. This group thinks the only way to preserve the current climate is to begin large-scale projects to actively counteract human greenhouse gas emissions. These people are probably right.
On the other hand, other people believe that countering greenhouse gas emissions with active geoengineering is a poor solution to the long-term climate problem. It would be a band-aid at best, temporarily covering up the underlying problem with a short-term solution with unknown side-effects. Worse, it would relieve the urgency to find a real solution, so if we ever stopped geoengineering it could lead to even larger and faster changes in the global climate. These people are probably also right.
As I see it, what both groups are missing is the fact that we humans are already geoengineering. We're just doing it in the stupidest possible way, without any goals or planning and only the vaguest understanding of the consequences of our actions.
So the real argument isn't over whether we should geoengineer the Earth's climate. The time to have that debate was 50-100 years ago, when scientists first began to understand that burning enough fossil fuels would lead to a warming planet. But at the time the problem didn't seem real or urgent, and nobody was paying attention.
Now that we are firmly established on the path of modifying our climate on a global scale, the debates need to be over how and to what ends we are going to engineer the Earth. And these debates won't be easy.
To begin with, it's not clear what the objectives of geoengineering should be. Preventing short-term catastrophe is a good start. But beyond that, there's an implicit assumption on all sides of the climate debate that the goal should be preserving (or restoring) the status quo. I don't think it's that simple, though: we may have changed things too much already for a return to the status quo to be a viable goal.
What's more, there's other possible goals for a geoengineering program which might be even better than just returning to the status quo:
- We may want to have the ability to reduce the impact of major natural disasters. For example, every few hundred years there's a volcanic eruption big enough to cool the Earth for a few years and cause crop failures, famine, and suffering. It may be within our reach to mitigate this.
- We may want to stabilize the Earth's natural climate changes over long periods of time. If we have the ability to prevent another ice age, do we want to use it? (Some scientists think we've already done this, just not intentionally.)
- There will be some winners to the current global warming. Miami isn't going to fare so well, but here in Minneapolis we may appreciate our warmer winters and longer growing seasons. Perhaps there's a way to keep things a little warmer up here but save coastal cities from flooding.
There's a number of geoengineering schemes which have been proposed, but most of them seem a little harebrained. It's true that seeding the stratosphere with particulates or spraying saltwater in the air over oceans seem like plausible ways to cool the climate relatively inexpensively. But we don't really know how well they will work, what the side-effects will be, and what the distribution of regional and global changes will be. Some of these ideas might even backfire.
What's needed is an actual engineering approach to geoengineering. We need to be testing and evaluating the effectiveness, costs, benefits, and side-effects of different ideas. We need to have the difficult political debate about the goals that we, as a species, want to accomplish with our geoengineering efforts. And in the end, we need to develop a set of tools for both short-term and long-term management of the Earth's climate so that we can control the level of greenhouse gasses in the atmosphere in a way that's going to achieve our objectives.
As I've written before, I'm cautiously optimistic that we will somehow muddle through. It won't be easy to get to the point where we're properly engineering our climate for the long-term benefit of humanity and the rest of the species on the planet. It may take a century or longer before the technological and political pieces are all in place, and in the meanwhile there will probably be some major disruptions.
But we really have no choice, since the alternative--just letting things take their course--isn't a recipe for long-term success or survival.