Human-induced, potentially catastrophic climate change is now firmly established as a major threat to life on earth, including human. Nevertheless, policy action at the international and in many cases, national, level has been slow to emerge. Over-consumption, primarily in the West, is clearly complicit in the continued global increase in greenhouse gas emissions, and any effective response to climate change will have implications for Western consumers. However, liberal-democratic governments are dependent on maintaining consumption levels in order to maintain economic growth. Such governments, especially if they have short election cycles and/or carbon-intensive economies, therefore face a major conundrum: the need to introduce major reforms to reduce greenhouse gas emissions, but the potential for voter backlash if such reforms are perceived as increasing prices and leading to job losses in fossil fuel intensive industries. The international policy response to over-consumption and its contribution to environmental harm, as examined in sustainable consumption scholarship, has been largely based on technological solutions that support economic growth while reducing environmental impacts ‚Äö- the 'myth of decoupling'. Encouraging consumers to purchase 'greener' products is an integral part of such strategies. It is clear that this policy approach has not been successful in reducing GHG emissions to the degree required to avoid catastrophic climate change. The alternative approach, which involves reducing consumption and resource exploitation while still allowing citizens to live satisfying lives, has largely been ignored by governments. Given the importance of consumption, the thesis focuses on the role of the individual in seeking to redress climate change. Its approach is to initially build up an understanding of the theoretical and empirical issues surrounding the individual's role in and response to climate change by initially analysing citizenship theory, which addresses the relationship of the individual to her or his society and polity. The thesis then examines individualism in the context of consumerism, over-consumption and hence climate change, including the international policy approach to addressing unsustainable Western consumption. Having given an account of the problem being addressed, the thesis then turns to analysis of a theoretical approach that potentially offers a framework for citizens' responses to climate change: environmental citizenship. Environmental citizenship theory addresses questions concerning individual responsibility, and is highly pertinent to issues of governmental and societal efforts to deal with climate change. Environmental citizenship seeks to explore and interrogate the recent neo-liberal focus on individual rights with a view to proposing its reversal, so that the individual has a responsibility to behave according to the environmental (and societal) good. Until recently there has been little cross-over between sustainable consumption and environmental citizenship theory. A major area of criticism found in both fields of literature is that a focus on voluntary, individual and household-based action deflects citizens' attention away from the structural ‚Äö- economic and political ‚Äö- causes of environmental problems like climate change. It also legitimises governments', and some NGOs', delegation of responsibility to individuals and households to act on climate change. While agreeing in principle with these criticisms, the thesis finds that the situation is not so straightforward: while it may be that individual and household action is inadequate to the task of reducing GHG emissions, it is also difficult to imagine in individualised Western societies citizens rising up to demand governments redress the structural causes of climate change. The thesis therefore aims to determine whether environmental citizenship theory in the context of sustainable consumption is able to overcome these objections and to provide a framework for citizen action on climate change. The analysis reveals the transformative potential of environmental citizenship, in theory, but also reveals a number of gaps or areas that need further work. An analytical framework devised during research for the thesis is used to examine existing empirical studies; and the thesis presents for the first time in the Australian context a study of environmental citizenship in the context of sustainable consumption, with its target population members of the Tasmanian Greens party. Analysis of the case study results leads to the conclusion that the respondents are indeed environmental citizens; that compared to other Australian studies, the Greens members are much more involved in personal, community and political actions to mitigate climate change; and they also found value in all types of actions even if results are not immediately apparent. However, like other studies, it finds that there are numerous barriers to environmental citizenship in practice, and that even the most aware of citizens tend to take the easiest and cheapest actions, with implications for the potential of environmental citizenship to become widespread among the broader Australian public. The key finding of the thesis is that while environmental citizenship theory does provide a framework for citizen action on climate change in the context of sustainable consumption, it is only through committed environmental citizens acting to raise public awareness and pressure governments, that real change can come about. The challenge for theorists continues to be to find the key that unlocks the gap between theory and widespread practice.