Capturing the imagination

Large scale negative emissions arguably rely on the cost-effective development of direct air capture (DAC) technologies which could draw down Carbon dioxide (CO₂) using chemicals that bind with it. The basic technology of DAC has been used in submarines and spacecraft. At its simplest, DAC works by absorbing CO₂ from the air onto a chemical receptor, which has a strong attraction for the CO₂, in a similar way as a sponge absorbs water. DAC is not expected to be an alternative to conventional mitigation nor to point-source abatement through carbon capture and storage. Rather, it is intended as a supplement to such responses, providing a means to reduce ambient atmospheric concentrations of CO₂ or to offset dispersed emissions that are difficult to mitigate directly, such as those from air travel. Large scale DAC remains a "technological imaginary". It is no silver bullet for the climate problem, despite being almost certainly essential to long-term reductions of atmospheric CO₂.