Enhanced photosynthesis techniques are theoretical geoengineering technologies based on the idea that plants and algae can be genetically modified to absorb and metabolize and therefore store more carbon dioxide.

Microbubbles proposals suggest that by injecting millions of tiny air bubbles into the ocean or spraying sea foam onto surface waters, the albedo of large areas of ocean could be increased, thereby reflecting more sunlight back into space.

Ocean fertilization is a proposed method for CO2 removal in which large quantities of micro- or macronutrients are introduced into marine areas with low biological productivity to stimulate the growth of phytoplankton.

Artificial upwelling aims to artificially pump cooler, nutrient-rich water from the depths of the oceans to the surface in order to stimulate phytoplankton activity and reduce CO2.

Direct Air Capture (DAC) schemes aim to extract carbon dioxide and other greenhouse gases from the atmosphere by chemical and mechanical means, generally using a chemical sorbent and large fans to move air through a filter.

Carbon Capture Use and Storage (CCUS) aims to put carbon dioxide captured from industries such as cement production to an alternative use, such as a feedstock for manufacturing products, where the carbon is then stored.     

Carbon capture and storage (CCS) is a technology proposed for the removal of carbon dioxide, which aims to capture CO2 emitted from processes such as the combustion of fossil fuels and store it underground.

Biochar is produced through pyrolysis, a process where biomass combustion occurs in a low oxygen environment at very high temperatures. It results in a solid carbon-rich charcoal-like substance, which can be mixed into soil where it is theoretically stored.

Enhanced weathering techniques involve spreading large amounts of crushed rocks (particularly silicate minerals) onto farmland or beaches, or dumping them into the sea, in order to react with and fix atmospheric carbon dioxide into the oceans and soils.

Bioenergy with Carbon Capture and Storage (BECCS) involves capturing carbon dioxide from bioenergy applications and then storing it deep in geological formations or using it to manufacture products.