Geoengineering, also referred to as climate engineering, involves large-scale interventions in Earth's natural systems to counteract climate change. It is generally discussed in the context of global warming and is considered as a potential strategy to reduce or offset the effects of increased greenhouse gases in the atmosphere.

Geoengineering can be divided into two major categories:

1. Carbon Dioxide Removal (CDR): This method involves removing CO2 from the atmosphere and sequestering it, either in the ground, in plants, or in the ocean. Examples include afforestation (planting trees to absorb CO2), carbon capture and storage (CCS), bioenergy with carbon capture and storage (BECCS), and enhancing natural weathering processes that remove CO2 from the atmosphere.
2. Solar Radiation Management (SRM): These techniques aim to reflect a small proportion of the Sun's energy back into space, thus reducing the total amount of energy absorbed by the Earth. Examples include the deployment of reflective particles or mirrors in the atmosphere or in space, or making the Earth's surface more reflective.

Geoengineering is controversial. While it could theoretically counteract climate change, there are significant uncertainties and potential risks. These include the possibility of unexpected side effects, challenges related to governance and public acceptance, and concerns that geoengineering could detract from efforts to reduce greenhouse gas emissions, which is the root cause of the problem. Thus, while geoengineering is an area of active research, it is generally viewed as something that could supplement, but not replace, reductions in greenhouse gas emissions.