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 very difficult to meet the Paris Agreement goal of capping global warming below two degrees Celsius.