In order to stave off catastrophic effects on the ecosystem, we need to keep global warming below 2°C. Even world leaders have agreed on that. But it's not going to happen. As it stands, we're looking at more like 3.6 to 6°C of global average warming. This is bad.
To keep global warming below 2°C, we have about four years for global carbon emissions to peak. After that, they need to start coming down—fast, at a rate of around 4 percent per year. That's also not going to happen.
If we won't cut our emissions, and we want to keep the Earth operating basically the same way it has for the entire history of human civilization, well, we're quickly running out of options. This leaves us with geoengineering—the deliberate manipulation of the Earth's atmosphere or climate system to control the weather.
Very understandably, says a new report, people don't trust geoengineering. Many geoengineering schemes carry a lot of unknowns, and more than a faint whiff of hubris.
There are many types of geoengineering that we could do, but in general they can be broken down into two major camps: ones that try to hide the problem, and ones that try to stop it. The “hiding” group includes a lot of sci fi-esque schemes, like installing giant mirrors, meant to reflect the sun's light, in space. Some recent research suggests that these projects might not even work. But say they did. There's still a big problem: if we ever stopped doing them for some reason—say, because of a war—it would be a catastrophe.
The champion of the "try to stop it" camp is carbon capture and storage, a plan to pull carbon dioxide out of the air and lock it away.
As reported by Reuters yesterday, a new United Nations draft report says if we're going to come anywhere close to hitting our climate goals, we're going to need to start undoing what we've done and start pulling carbon dioxide out of the air.
It says the world is doing too little to achieve a goal agreed in 2010 of limiting warming to below 2 degrees (3.6 Fahrenheit) above pre-industrial times, seen as a threshold for dangerous floods, heatwaves, droughts and rising sea levels.
To get on track, governments may have to turn ever more to technologies for "carbon dioxide removal" (CDR) from the air, ranging from capturing and burying emissions from coal-fired power plants to planting more forests that use carbon to grow.
Carbon capture and storage at the scale we'll need it is a long way off. Test projects of the technology, says the New York Times, are being closed down, “despite a consensus among scientists and engineers that such projects are essential to meet international goals for slowing the buildup of climate-changing gases.”
The aversion to carbon capture and storage, says David Biello for Scientific American, is mostly an economics problem (though other issues do exist).
If we don't cut our emissions and we don't deploy an industrial-scale carbon capture and storage program, we're locking ourselves into at least 10,000 years of warming, says a new study—10,000 years of global average temperatures higher than anything we've seen since the advent of agriculture. That's a long time to try to keep the space mirrors flying.