Ice Sheets and the Anthropocene

Eric W Wolff

doi:10.1144/sp395.10

Abstract

AbstractIce could play a role in identifying and defining the Anthropocene. The recurrence of northern hemisphere glaciation and the stability of the Greenland Ice Sheet are both potentially vulnerable to human impact on the environment. However, only a very long hiatus in either would be unusual in the context of the Quaternary Period, requiring the definition of a geological boundary. Human influence can clearly be discerned in several ice-core measurements. These include a sharp boundary in radioactivity due to atmospheric nuclear testing; increases, unprecedented at least in the Holocene, in Greenland concentrations of sulphate, nitrate and metals such as lead; the appearance in ice-core air bubbles of previously undetectable compounds such as SF6; and the rise, unprecedented in the last 800 ka, in concentrations of carbon dioxide and methane. Some combination of these changes could be used by future generations to clearly identify the onset of a new epoch defined at a particular calendar date. However, it is not yet clear what the character of the fully developed Anthropocene will be, and it might be wise to let future generations decide, with hindsight, when the Anthropocene started, acknowledging only that we are in the transition towards it.

Highlights

Lifeless planets evolve in response to changing energy levels from their Sun, bombardment by material from space, and internal geological forces
Perhaps the most obvious manifestation of this occurs in the carbon cycle, where increased concentrations of carbon dioxide (CO2), well beyond the natural range, are due to anthropogenic emissions
It has been proposed that we are in a new period of time, coined the ‘Anthropocene’, in which humans have become a controlling influence of the Earth system (Crutzen 2002; Steffen et al 2011). This is an interesting concept for describing the extent of human influence on the environment, and for emphasizing the extent of human responsibility for managing that environment. It has been taken further, with some authors proposing that the Anthropocene should be formally recognized as a geological epoch (Zalasiewicz et al 2008, 2011), on a level with the Holocene and Pleistocene that precede it

Summary

Introduction

Lifeless planets evolve in response to changing energy levels from their Sun, bombardment by material from space, and internal geological forces. This shows up in ice-core records worldwide (summarized, for example, in Wolff & Peel 1985) as a huge jump in beta radioactivity in 1954, a further jump in 1964 in response to very large tests in the early 1960s, and a slow decay towards natural background levels as the material was removed from the atmosphere and its radioactivity decayed (Fig. 1).

Results

Conclusion