Climate change brings profound challenges for social movements. The persistent failure to address climate challenges has driven a rapid “climatization” of politics. Spurred by the climate justice movement, social movements across a broad spectrum have become directly engaged with climate issues. Social movements are defined as groupings of people who act intentionally through an organization or via a network or even as a loose affiliation. They must have a collective identification and capacity for sustained action and participation. Their purpose often is to transform the conditions for social change as key agents in creating a “movement society” of mass political involvement. In doing so, social movements engage in a “metapolitics” of creating power and recreating society. Climate movements are increasingly being shown to have this effect. Recent research demonstrates that with climate change, there is a growing realignment in the social movement field to simultaneously address both climate concerns and social agendas. New forms of social agency are emerging under climate change, posing a new kind of climatized “movement society.” Arguably, as demonstrated by the limited efforts at developing international climate policy, mass mobilization on climate issues is a necessary element of any strategy to secure climate stability. Three broad fields of action are evident – politicising the impacts of climate change, contesting the causes, and advancing solutions. In each there is a widening field of agendas as climate concerns overwhelm existing social relations. Distinctive strategies emerge. First, there is growing collective identification among people affected by the impacts of climate change, now or anticipated, with a marked shift from climate advocacy to climate organizing, of acting “with,” not “for” those affected. Second, actions to challenge the legitimacy of the fossil fuel sector have escalated, materializing the causes of climate change in the fossil fuel cycle. With this, there is a move from abstract demands for emissions reduction to much more concrete demands for fossil fuel phase-out. Finally, in terms of solutions, there is a move from a focus on emission-reduction programs to wider policy agendas designed to transform social relations. Emissions reduction is no longer seen as a burden to be shared, but as part of wider social transformation, of benefit to all.