Sustainable development and sustainability have been key terms in environmental thought and practice since the time of the Brundtland Report. Because of being firmly situated in the humanist tradition, these terms and their associated approaches have been appealing to social workers tackling environmental concerns. Given the significant and inexorable changes being wrought by global warming and the lack of similitude between Earth prior to anthropogenic warming and the incipient Eaarth introduced by global warming, examining the continued relevance of the terms sustainable development and sustainability is warranted. This chapter explores these terms in the context of climate change and points toward a responsibility approach based on environmental and social justice principles consistent with social work strengths and values.