Sustaining the Terrestrial Biosphere in the Anthropocene: A Thermodynamic Earth System Perspective

Abstract

Many aspects of anthropogenic global change, such as shifts in land cover, the loss of biodiversity, and the intensification of agricultural production, threaten the natural biosphere. The implications of these specific aspects of environmental change are not immediately obvious; therefore, it is hard to obtain a bigger picture of what these changes imply and distinguish the beneficial from the detrimental, where human impact is concerned. In this paper, I describe a holistic approach that allows us to obtain such a bigger picture and use it to understand how the terrestrial biosphere can be sustained in the presence of increased human activity. This approach places particular emphasis on the free energy generated by photosynthesis—energy that is required to sustain both the dissipative metabolic activity of ecosystems and human activities (with the generation rate being restricted by the physical constraints of the environment). Thus, one can then identify two types of human influence on the biosphere and their resulting consequences: the detrimental effects caused by enhanced human consumption of this free energy and the beneficial effects that allow for more photosynthetic activity and, therefore, more dissipative activity within the biosphere. I use examples from the terrestrial biosphere to illustrate this view and global datasets to indicate how this can be quantified. Thereafter, I discuss how certain aspects of modern technology can enhance free energy generation within the terrestrial biosphere, which can, in turn, safeguard its sustenance even as human activity increasingly shapes the functioning of the Earth system.