Carbon dioxide removal (CDR), also known as negative CO2 emissions, is a process in which carbon dioxide gas (CO2) is removed from the atmosphere and sequestered for long periods of time. Similarly, greenhouse gas removal (GGR) or negative greenhouse gas emissions is the removal of greenhouse gases (GHGs) from the atmosphere by deliberate human activities, i.e., in addition to the removal that would occur via natural carbon cycle or atmospheric chemistry processes. In the context of net zero greenhouse gas emissions targets, CDR is increasingly integrated into climate policy, as a new element of mitigation strategies. CDR and GGR methods are also known as negative emissions technologies (NET), and may be cheaper than preventing some agricultural greenhouse gas emissions.