Even if the world begins drawing down carbon pollution by three, four or five percent each year—and that is a very big “if”—some sectors like cement and steel production, long-haul aviation and agriculture are expected to maintain emission levels for decades.
by Marlowe Hood
The burning question going into the Glasgow climate summit is whether major economies can, by 2050, reduce emissions enough to deliver a carbon neutral world in which humanity no longer adds planet-warming gases to the atmosphere.
Less talked about—but rising quickly on the climate agenda—are tools and techniques to pull CO2 straight out of the air.
Even scientists sceptical about its feasibility agree that without carbon dioxide removal (CDR)—aka “negative emission”—it will be extremely difficult to meet the Paris Agreement goal of capping global warming below two degrees Celsius.
“We need drastic, radical emissions reductions, and on top of that we need some CDR,” said Glen Peters, research director at the Centre for International Climate Research.
What is CO2 removal?
There are basically two ways to extract CO2 from thin air.
One is to boost nature’s capacity to absorb and stockpile carbon. Healing degraded forests, restoring mangroves, industrial-scale tree planting, boosting carbon uptake in rocks or the ocean—all fall under the hotly debated category of “nature-based solutions”.
The second way—called direct air capture—uses chemical processes to strip out CO2, then recycles it for industrial use or locks it away in porous rock formations, unused coal beds or saline aquifers.
A variation known as bioenergy with carbon capture and storage, or BECCS, combines elements from both approaches.
Wood pellets or other biomass is converted into biofuels or burned to drive turbines that generate electricity. The CO2 emitted is roughly cancelled out by the CO2 absorbed during plant growth.
But when carbon dioxide in the power plant’s exhaust is syphoned off and stored underground, the process becomes a net-negative technology.