Nascent tech that pulls CO2 from the atmosphere could "significantly" reduce the costs of fighting climate change, but achieving scale is hardly a sure thing and massive deployment would consume lots of energy, a new peer-reviewed study warns.
Why it matters: The paper in Nature Communications arrives amid increasing attention to direct air capture (DAC) and other negative emissions technologies.
- They're important because it looks pretty unlikely that nations will cut emissions enough to meet the goals of the Paris climate deal.
- The firm Carbon Engineering — whose backers include Bill Gates and oil giants Chevron and Occidental — recently announced plans for a big DAC plant in Texas.
What they found: According to the study, widespread deployment down the road would create a longer cushion to achieve steep emissions cuts.
- In one scenario they modeled for holding global temperature rise to 1.5°C, it pushes the horizon for achieving "net-zero" emissions back from 2050 to roughly 2070, which would be "compensated by larger negative emissions thereafter."
Threat level: If policymakers wrongly bet on large-scale deployment, it could lead to a global temperature "overshoot" of up to 0.8 °C. That's a lot, given that Paris aims to limit the total increase to 1.5°C–2°C above preindustrial levels.
- And large-scale deployment (think tens of thousands of big machines under one tech scenario), if even proven feasible would need to be really large, and that's not without consequences.
- In theory, a huge buildout would consume as much as a fourth (!) of global energy demand to power and heat the systems by 2100, the paper notes.
The bottom line: The paper warns that DAC should not be viewed as a crutch, but rather as complementary to emissions-cutting strategies.
- The authors recommend that policymakers speed up development and deployment, but "without easing near-term mitigation efforts" due to risks of the tech underperforming or failing.
Go deeper: Direct CO2 capture machines could use ‘a quarter of global energy’ in 2100 (Carbon Brief)