They are generally classified in two main groups:
Solar radiation management (SRM) method: technologies that would increase the reflectivity, or albedo, of the Earth's atmosphere or surface, and Carbon dioxide removal (CDR) method: technologies or practices that would remove CO 2 and other GHGs from the atmosphere. Other proposed SRM methods are at the conceptualization stage. CDR methods include afforestation, ocean fertilization, and the use of biomass to capture and store carbon. However, if geoengineering technologies are deployed by the United States, another government, or a private entity, several new concerns are likely to arise related to government support for, and oversight of, geoengineering as well as the transboundary and long-term effects of geoengineering. Such was the case in the summer of 2012, when an American citizen conducted a geoengineering experiment (ocean fertilization) off the west coast of Canada that some say violated two international conventions. Geoengineering Governance

Geoengineering technologies aim to modify the Earth's energy balance in order to reduce temperatures and counteract anthropogenic climate change through large-scale and deliberate modifications. Geoengineering technologies attempt to mitigate continued warming of the Earth's climate. CDR methods remove CO 2 from the atmosphere. If proven effective and desirable, SRM methods could be deployed faster than CDR methods should the need arise to cool the planet quickly. SRM methods have been described, theoretically, as cheap, fast, and imperfect. Several questions have yet to be answered: Would the space-based reflectors be deployed to alter the climate at a global or regional level? These concerns include: 
the technology is new and unproven, with ongoing and transformative scientific and technical evidence; the impacts of geoengineering activities are uncertain in scope, timing, and intensity; the range of stakeholders potentially affected by geoengineering activities is broad, including most nations, subnational groups, nongovernmental organizations, corporations, and civil societies; the number of actors potentially employing geoengineering activities may be small in comparison to the number of those affected; the global impacts of geoengineering activities—both its benefits and risks—may be unevenly distributed across stakeholders; and the costs of implementing geoengineering activities may be small compared to the economics of their full global impact. The federal government could expand these existing laws to specifically address geoengineering activities or develop new laws. To date, no multilateral treaty has been proposed with the intent of addressing the full spectrum of possible geoengineering activities. The international agreements on climate change are the most likely agreements to have significance for the full spectrum of geoengineering projects because they encourage their parties to implement national policies and mitigation actions to reduce their greenhouse gas emissions. However, these agreements do not currently address geoengineering explicitly. These agreements include: 
United Nations Framework Convention on Climate Change (UNFCCC) . Convention on Biological Diversity (CBD) . In October 2010, the 10 th Conference of the Parties (COP) to the CBD adopted provisions calling for the parties to abstain from geoengineering—including "any technologies that deliberately reduce solar insolution or increase carbon sequestration from the atmosphere on a large scale that may affect biodiversity"—unless the parties have fully considered the risks and impacts of those activities on biodiversity. Currently, many geoengineering technologies are at the conceptual and research stages, and their effectiveness at reducing global temperatures has yet to be proven. Very few studies have been published documenting the cost, environmental effects, socio-political impacts, and legal implications of geoengineering. Nevertheless, if geoengineering technologies are deployed, they are expected to have the potential to cause significant transboundary effects. However, in the United States, there is limited federal involvement in, or oversight of, geoengineering. Fourth, it could work with the international community to craft an international approach to geoengineering by writing or amending international agreements.
Climate change policies at both the national and international levels have traditionally focused on measures to mitigate greenhouse gas (GHG) emissions and to adapt to the actual or anticipated impacts of changes in the climate. As a participant in several international agreements on climate change, the United States has joined with other nations to express concern about climate change. Some recent technological advances and hypotheses, generally referred to as "geoengineering" technologies, have created alternatives to traditional approaches to mitigating climate change. If deployed, these new technologies could modify the Earth's climate on a large scale. Moreover, these new technologies may become available to foreign governments and entities in the private sector to use unilaterally—without authorization from the United States government or an international treaty—as was done in the summer of 2012 when an American citizen conducted an ocean fertilization experiment off the coast of Canada.
The term "geoengineering" describes an array of technologies that aim, through large-scale and deliberate modifications of the Earth's energy balance, to reduce temperatures and counteract anthropogenic climate change. Most of these technologies are at the conceptual and research stages, and their effectiveness at reducing global temperatures has yet to be proven. Moreover, very few studies have been published that document the cost, environmental effects, socio-political impacts, and legal implications of geoengineering. If geoengineering technologies were to be deployed, they are expected to have the potential to cause significant transboundary effects.
In general, geoengineering technologies are categorized as either a carbon dioxide removal (CDR) method or a solar radiation management (SRM) method. CDR methods address the warming effects of greenhouse gases by removing carbon dioxide (CO2) from the atmosphere. CDR methods include ocean fertilization, and carbon capture and sequestration. SRM methods address climate change by increasing the reflectivity of the Earth's atmosphere or surface. Aerosol injection and space-based reflectors are examples of SRM methods. SRM methods do not remove greenhouse gases from the atmosphere, but can be deployed faster with relatively immediate global cooling results compared to CDR methods.
To date, there is limited federal involvement in, or oversight of, geoengineering. However, some states as well as some federal agencies, notably the Environmental Protection Agency, Department of Energy, Department of Agriculture, and the Department of Defense, have taken actions related to geoengineering research or projects. At the international level, there is no international agreement or organization governing the full spectrum of possible geoengineering activities. Nevertheless, provisions of many international agreements, including those relating to climate change, maritime pollution, and air pollution, would likely inform the types of geoengineering activities that state parties to these agreements might choose to pursue. In 2010, the Convention on Biological Diversity adopted provisions calling for member parties to abstain from geoengineering unless the parties have fully considered the risks and impacts of those activities on biodiversity.
With the possibility that geoengineering technologies may be developed and that climate change will remain an issue of global concern, policymakers may determine whether geoengineering warrants attention at either the federal or international level. If so, policymakers will also need to consider whether geoengineering can be effectively addressed by amendments to existing laws and international agreements or, alternatively, whether new laws and international treaties would need to be developed.