Disappearing islands and climate refugees are signifiers that circulate with frequency in public discourse, yet the role that these representations play in the cultural politics of climate change has not been extensively examined. In particu- lar, low-lying islands are being described as ‘litmus tests’ for global climate change by cos- mopolitan environmental activists and in the media, a discourse which thus far has operated largely under the radar of critical analysis. The purpose of this paper is to explore how the legacy of the island laboratory enables the exer- cise and justification of cosmopolitan activism towards climate change that speaks in part through space. What follows is an exploration of the disappearing island in terms of cosmo- politan imaginative geographies of climate change. Drawing on narratives centred on the Pacific nation state of Tuvalu, I argue that islands imagined as laboratories appropriate the space of an already marginalised population; these are imaginings by cosmopolitans who demand, for various and at times conflicting reasons, that disappearing islands provide tangible manifes- tations of the statistical abstractions that domi- nate climate science.