What they are
Greenhouse Gas Removal (GGR) and Solar Radiation Management (SRM) are terms describing a range of technologies that aim to counteract human-caused climate change by deliberate large-scale intervention in the Earth’s natural systems. They are sometimes referred to as ‘geo-engineering’ or ‘climate engineering’.
GGR technologies actively remove greenhouse gases from the atmosphere. Examples include afforestation, bioenergy with carbon capture and storage (BECCS), direct air capture and storage (DACCS), and marine fertilisation. Those that specifically remove carbon dioxide (CO2) from the atmosphere are also known as Carbon Dioxide Removal (CDR) technologies.
SRM technologies reflect some of the Sun’s energy that reaches Earth back into space. Examples include the brightening of marine clouds and injection of aerosols into the stratosphere. While these would be likely to reduce the Earth’s temperature, they would not reverse ocean acidification (unlike GGRs).
Our priority is to tackle the root cause of climate change by reducing emissions of greenhouse gases from human activities, and adapting to those impacts that are unavoidable. Mitigation of climate change by reducing emissions and protecting natural carbon sinks remains the main focus of our efforts to increase our chances of avoiding dangerous climate change.
Why they are needed
In order to deliver on the commitment the UK made by signing the Paris Agreement, the UK has legislated for a net zero emissions target by 2050.[footnote 1] Our independent advisers, the Committee on Climate Change (CCC), have made it clear that GGRs will be essential to realising this target, to offset remaining emissions in the sectors where it is most difficult to cut them.[footnote 2]
Read more: UK government’s view on greenhouse gas removal technologies and solar radiation management