 The basic ethical question is: What ought to be done about anthropogenic climate change, and by whom? The question arises because there is good evidence that climate change is already having harmful impacts on both humans and non-human nature, and because continued high rates of greenhouse gas emission can be expected to bring additional and more devastating harms in the future (Field et al. 2014). Attempting to address this basic ethical question, however, leads to further, complex questions of global and intergenerational justice, as well as to questions regarding our ethical obligations to non-human nature. Here are just a few examples: Do some nations, including those that have emitted large quantities of greenhouse gases in the past, have an obligation to bear more of the costs of climate change mitigation and adaptation than other nations? (See, e.g., Baer et al. 2009; Caney 2011; Singer 2016: Ch.2.) When considering actions to mitigate climate change, how should the harms and benefits to future generations be weighed against those affecting people today? (See, e.g., Broome 2008; Gardiner 2006.) How should impacts of climate change on non-human nature, including loss of biodiversity, be taken into account? (See, e.g., Palmer 2011.) Are there circumstances in which proposed geoengineering solutions—such as injecting sulfate aerosols into the stratosphere or seeding the oceans with carbon-absorbing phytoplankton—are ethically acceptable? (See, e.g., Gardiner 2010; Preston 2013.) There is a large and growing philosophical literature engaging with these and related questions; some anthologies and book-length works include Arnold 2011; Broome 2012; Gardiner 2011; Gardiner et al. 2010; Garvey 2008; Maltais and McKinnon 2015, Preston 2016; Shue 2014; Singer 2016.