what is geoengineering?

Geoengineering is deliberate, large-scale intervention in Earth’s natural systems to counteract climate change.

The two most common forms are:

SOLAR RADIATION MANAGEMENT (SRM)

SRM techniques aim to reflect a small proportion of the Sun’s energy back into space, counteracting the temperature rise caused by increased levels of greenhouse gases in the atmosphere which absorb energy and raise temperatures. Methods include: albedo enhancement, space reflectors and stratospheric aerosols.

CARBON DIOXIDE REMOVAL (CDR)

These techniques aim to remove carbon dioxide from the atmosphere, directly countering the increased greenhouse effect and ocean acidification. These techniques would have to be implemented on a global scale to have a significant impact on carbon(4). Methods include: afforestation, biochar, bioenergy capture and sequestration, ambient air capture, ocean fertilization, enhanced weathering and ocean alkalinity enhancement.

A description of the different forms can be found in the following posts:

SRM:

Albedo Enhancement
Space Reflectors
Stratospheric Aerosols

CDR:

Ambient Air Capture
Afforestation
Biochar
Bioenergy Capture and Sequestration
Ocean Fertilization
Enhanced Weathering
Ocean Alkalinity Enhancement