This issue of Limn on “Ebola’s Ecologies” examines how the 2014 Ebola outbreak has put the norms, practices, and institutional logics of global health into question, and examines the new assemblages that are being forged in its wake.

The polar ice cap rapidly recedes; colonies of honeybees collapse in alarming numbers; androgynous fish are detected in rivers and streams. These reports not only describe recent events, but also function as signs of an ominous and rapidly encroaching future. In this issue of <em>Limn</em> we focus on how this future makes its appearance in the present. Many of the threats we now find most alarming-climate change, environmental radiation, emerging disease, endocrine disrupters, toxic chemicals-are not immediately perceptible to human senses. We rely on non-human indicators, whether animals or detection devices, to alert us to their possible onset.

Systemic risk has become a central topic of expert discussion and political debate amidst the financial crisis that began in 2008, but it also has resonances across many other domains in which catastrophic threats loom – including internet security, supply chain management, catastrophe insurance, and critical infrastructure protection. In this issue, we invited scholars to contribute genealogical and conceptual framings that inform critical inquiry into this increasingly important concept. The result is not a traditional collection of academic articles but a set of brief, preliminary reflections, prepared on short notice, that address a common set of questions, along with a handful of documents, links, images and videos that illustrate different aspects of the concept.