Climate engineering is a term used to describe a process that will intentionally alter the energy balance of the earth. Energy balance simply means that the energy going into (sunlight) a system (the earth) is counted against energy coming out (infrared) to determine if the system is changing or stable. The earth would be very cold without some amount of greenhouse gases (GHGs); these gases act like blankets that reflect some energy back towards the earth keeping us warmer than without them.
Reality is a little more complicated, but this is the basic idea. Climate change is altering this balance by trapping extra infrared energy in the atmosphere. It’s like an added blanket keeping us a little warmer. This gradually warms the air and oceans. To counteract this warming from adding blankets, climate engineering schemes employ two main strategies: blocking sunlight and removing blankets.
It’s just what it sounds like. The potential ideas range from putting huge umbrellas in outer space to spraying reflective materials in the atmosphere to making roofs and pavement light colored.
Whether reflected or blocked, less energy would reach the earth. This could prevent temperature from increasing further or even decrease them (similar to several volcanic eruptions). However without also stopping further emissions, worsening ocean acidification would be a problem. Furthermore, as more GHGs accumulate, more sunlight has to be blocked. The costs of sun blocking, even if relatively cheap, would continue indefinitely.
Another option would be to remove a blanket, so less energy is trapped. The ideas range from planting more trees to burning biofuels for energy and keeping the resultant CO2 underground.
One method, called iron fertilization, aims to give CO2 consuming organisms the iron they need to reproduce rapidly. After the organisms die, the hope is that they will sink to ocean floor and remove the carbon permanently from the atmosphere. Biofuel production would have other unwanted effects; it takes away from the space available for natural ecosystems or food production and still releases non-carbon pollutants.
Since these methods pull GHGs out of the air, we only get permanent relief if we also stop emitting fossil fuel carbon. Otherwise, again we pay continual costs to remove excess GHG.
Lifeline or folly?
Our options for responding to climate change are: adapt, stop emitting GHGs, and climate engineering. It’s necessary to adapt because the climate is already changing. And it’s necessary to stop emitting GHGs; otherwise we face perpetual costs. Climate engineering may play a role as well. It might buy us some time, but it’s impossible to rely upon it solely.
The other scary thing: billionaires and governments have the means to experiment with these techniques and possibly develop them into weapons. Imagine a country that relies heavily on solar being attacked by a sun blocking technique. And since we haven’t funded experimentation with these techniques, even well-meaning governments might accidentally cause droughts or flooding. We should discuss our options, but acknowledge that any effective response includes transitioning to carbon-free resources.