Trees are a natural way to bring down CO2 levels in the atmosphere. One study shows we need a trillion of them.

Companies are already removing CO2 from the atmosphere and burying it. Better tech is in the pipeline. How to make money from it though, is still up in the air.

The rock lockdown for CO2. Ground up basalt and olivine may absorb gigatonnes of CO2. Scientists are investigating on a beach in the Bahamas.

Soil stores a massive amount of carbon, about 3000 gigatonnes worth, and there's room for even more.

Microscopic organisms known as phytoplankton floating in the ocean could be behind the world's ice ages. Can they be fertilised with iron to cool down the planet again?

Dr Stuart Licht's new company C2CNT has found a way to convert CO2 in the air into highly priced graphene and carbon nanotubes. Nanotechnology is the next big thing, but will it be enough to use up all the excess CO2 in the atmosphere?