back to

Avoiding Hothouse Earth


In October issue of the Brooklyn Rail, Peter St. Clair reflects on the frightening climate report recently released by the Proceedings of the National Academy of Sciences, entitled “The Trajectories of the Earth System in the Anthropocene.” The report states that we only have a few years to radically transform our social and economic systems before we pass a threshold that will ultimately lead to a volatile and inhospitable climate. St. Clair’s sobering piece examines the prospects for this radical transformation:

Complex systems have properties not shared with linear systems, in which events add up chronologically in a mathematical progression. The Earth System, being a complex system, consists of interacting entities within a unified whole. Humanity has often been portrayed as existing outside the natural system of the planet and affecting it as an external force, that is, as part of the environment. The concept of the Anthropocene, however, acknowledges that human society is not only a part of the system but a directing force capable of shifting the system out of its present state. Complex systems exhibit features such as cascading feedback loops leading to thresholds that can force the entire system into a new and radically different state. The Earth System is now approaching such a threshold as feedback loops like melting ice caps, deforestation, permafrost melting and increased emission of CO2 from the warming ocean cascade, amplifying the overall rise in temperature. Fearful scenarios involving a cascade of tipping points that have been hypothesized by environmentalists for a decade or more are now being confirmed.

The academic terminology and prosaic tone of the paper can seem at times to understate the magnitude of the consequences we on the planet are facing. For instance the authors write that “the social and technological trends and decisions occurring over the next decade or two could significantly influence the trajectory of the Earth System for tens to hundreds of thousands of years and potentially lead to conditions that resemble planetary states that were last seen several million of years ago, conditions that would be inhospitable to current human societies and to many other contemporary species.” A look at what those conditions actually were in past eras of significantly higher temperatures makes the term “inhospitable” seem a gross understatement.