The “carbon removal budget” and how that’s a problem

Here’s a Bloomberg Green article about this paper:

To achieve net-zero emissions, where emissions and removals of greenhouse gas pollution balance each other out, governments and corporations must do two things: cut emissions as much as possible and remove any residual pollution from the atmosphere. To gauge the speed at which emissions must be reduced, analysts often use the so-called carbon budget, a well-established framework for calculating the amount of greenhouse gases that can be emitted to remain at or below a given level of global warming. (World leaders have committed to holding the increase in the global average temperature to well below 2C above pre-industrial levels, and ideally to 1.5C).

But quantifying the amount of carbon dioxide removal available to help realize such temperature goals is a less well-trodden area of analytical focus. So University of Oxford researchers just devised a “carbon removal budget” to address the issue. Think of carbon removals as the “net” in net zero. CO2 can be removed in many ways, including via nature-based approaches like restoring forests or peatland. There are also technologies like direct air capture and storage, so-called biochar and bioenergy and carbon capture and storage (BECCS).

But much of this technology hasn’t reached its full potential — and time is running out. The planet is warming so fast that without rapid and drastic action, it’s near certain to overshoot the critical 1.5C threshold. As such, the need to scale technologies and projects that can pull down billions of tons of planet-warming gases to lower global temperatures becomes essential. The Oxford academics who authored the paper, Ben Caldecott and Injy Johnstone, argue that while it’s essential for this industry to grow if we are to have any chance of hitting net zero, CO2 removal will always be “a fundamentally finite resource” that should be allocated responsibly.

“Carbon removals are not free and face some significant economic constraints,” Caldecott said in an interview. “So if a company that could easily abate emissions decides instead to use a chunk of the available carbon removal budget, what will that mean for other actors? There has to be equity in the way this finite resource is distributed, and there will undoubtedly be tradeoffs.” In other words, industries that can more easily cut emissions should maximize that effort, leaving more of the world’s limited capacity to remove carbon from the atmosphere for those that, because of their very nature, are limited in their ability to do so. Companies in so-called “hard to abate” sectors like steelmakers and airlines might have greater need for such removals under certain scenarios, the authors said.