Rogelj names two major processes for carbon dioxide removal: reforestation and bio-energy with carbon capture and storage. Some negative emissions processes, such as reforestation, provide benefits beyond carbon capture, while others may have undesired side effects.
But Rogelj is quick to add that these negative emissions technologies are not “silver bullets.” It’s too soon to know if carbon dioxide removal at a global scale will actually be necessary—we’ll have to get to zero emissions before we can tell. But such technologies could also help us reach zero in the first place.
What else will get us to zero emissions? According to Rogelj, we need “a strong emphasis on energy efficiency, combined with an electrification of end-use sectors like transport and building and a shift away from fossil fuels.” This will require a major shift in investment patterns. We want to avoid “locking into carbon dioxide-intensive infrastructure” that would saddle future generations with a dependency on non-renewable energy, he explains.
Rogelj stresses that his team’s findings are based only on geophysical data. Societal factors are a different matter: It is up to individual countries to decide where reducing emissions falls on their list of priorities.
However, the stipulation in the Paris Climate Agreement that countries periodically update their pledges is a source of optimism. Rogelj, for his part, is cautiously hopeful: “Looking at real world dynamics in terms of costs of renewables and energy storage, I personally think there is room for pledges to be strengthened over the coming five to ten years as countries better understand what is possible and how these pledges can align with other priorities.”
But not everyone in the scientific community shares the hopeful tone struck by Rogelj and his team. An article by the MIT Technology Review outlines “the five most worrisome climate developments” from 2017.