We need to draw down carbon—not just stop emitting it

But carbon removal has become a touchy topic. There are real concerns that the growing focus on drawing down the greenhouse gas could encourage governments and businesses to delay or even avoid the most obvious and direct way of addressing climate change: preventing emissions from reaching the atmosphere in the first place. 

The convenient perception that we might be able to continue pumping out large levels of carbon dioxide and simply clean up the atmosphere in the future is an example of what’s known as a “moral hazard.” It risks perpetuating the use of fossil fuels and pushing off the costs of dealing with climate change onto future generations.

This is a legitimate concern. Some companies have erroneously suggested that carbon removal could allow us to keep emitting at nearly half current global levels. But that would necessitate sucking up and storing away carbon dioxide at levels that are almost certainly technically, environmentally, or economically infeasible, or possibly all of the above.

There is, however, also a real risk that stigmatizing carbon removal over moral hazard concerns creates an even greater danger: deferring much-needed investment and imperiling our ability to reach future climate goals. Unfortunately, after decades of delay, there are now simply few paths to meeting our climate goals that don’t require both slashing emissions today and building the capacity to suck up vast amounts of carbon dioxide in decades to come. 

Emissions cuts aren’t enough

Why is carbon removal needed in the first place, and why can’t we just stop climate change by getting to “absolute zero” emissions? The recent UN report identifies four different roles for carbon removal in climate modeling scenarios that limit warming to well below 2 ˚C over preindustrial levels by 2100. 

First, while fossil fuels can be replaced with clean energy alternatives across much of the economy, there will be some ongoing carbon dioxide emissions from sectors that are hard to fully decarbonize. These are major industries, like aviation, cement, and steel production, where we simply don’t have affordable, scalable carbon-free technologies available. While more work needs to be done to understand just how low our carbon dioxide emissions can get, these sorts of sectors will likely continue to produce a few billion tons per year that need to be neutralized through carbon removal.

Second, carbon dioxide isn’t the only greenhouse gas that is warming the planet. Others, including methane and nitrous oxide from sources like cattle, animal waste, and fertilizer use, are much more difficult to fully eliminate. 

The recent UN report found that available technologies could probably reduce emissions of these gasses by around 50%, with additional behavior changes such as dietary shifts pushing that to 66%. However, carbon removal would have to counterbalance the sizable amount remaining.