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.