But carbon removal has become a sensitive issue. There are real concerns that the growing focus on reducing greenhouse gases could prompt governments and companies to delay or even avoid the most obvious and direct way to combat climate change: preventing emissions from entering the atmosphere in the first place.
The convenient notion that in the future we may continue to emit large amounts of carbon dioxide and simply clean up the atmosphere is an example of what is known as “moral hazard.” There is a risk that fossil fuel use will continue and the costs of dealing with climate change will be passed on to future generations.
This is a legitimate concern. Some companies have incorrectly suggested This CO2 removal could allow us to keep emissions at almost half of current global levels. But that would require absorbing and storing carbon dioxide at levels almost certainly not technically, environmentally, or economically feasible, or possibly all of the above.
However, there is also a real risk that stigmatizing decarbonization due to moral hazard concerns creates an even greater danger: delaying much-needed investments and jeopardizing our ability to meet future climate goals. Unfortunately, after decades of delay, there are few ways to achieve our climate goals that do not require both cutting emissions today and building capacity to absorb vast amounts of carbon dioxide in the decades to come.
Emission reductions are not enough
Why is carbon removal necessary at all, and why can’t we just stop climate change by getting to “absolute zero” emissions? The latest UN report identifies four different roles for carbon removal in climate modeling scenarios that limit warming to well below 2°C by 2100 compared to pre-industrial levels.
First, while fossil fuels can be replaced by clean energy alternatives in much of the economy, there will be some ongoing carbon emissions from sectors that are difficult to fully decarbonize. These are key industries like aerospace, cement, and steelmaking where we simply don’t have affordable, scalable, zero-carbon technologies available. While more work needs to be done to understand how low our carbon emissions can get, these sectors will likely continue to produce a few billion tons per year that need to be neutralized through carbon removal.
Second, carbon dioxide is not the only greenhouse gas warming the planet. Others, including methane and nitrous oxide from sources such as livestock, animal waste and fertilizer use, are much more difficult to eliminate completely.
The latest UN report found that available technologies could likely reduce emissions of these gases by around 50%, with additional behavioral changes such as dietary changes increasing this to 66%. However, carbon removal would need to offset the significant amount remaining.