Climate Primer #7: The Sixth Planetary Boundary – Freshwater Consumption

Each day, I’m working to further compress the synopsis as these “Climate Primers” accrue: Climate crisis is the defining issue of the 21st century. The buildup, in Earth’s atmosphere, of greenhouse gases (emitted owing to human activity) drives global heating, the chief signal of climate crisis, but there are, in fact, a number of intersecting planetary boundaries – the broaching of any one of which would threaten the viability of organized human life on Earth. Thus far, these posts have addressed the following planetary boundaries: stratospheric ozone depletion, biodiversity loss, toxic substance contamination, climate change (paradoxically, both a sub-component of “climate crisis” and its most defining feature), and ocean acidification.

Today’s post centers freshwater, or, as the Stockholm Resilience Center puts it, in heading the description which follows, “Freshwater consumption and the global hydrological cycle”:

The freshwater cycle is strongly affected by climate change and its boundary is closely linked to the climate boundary, yet human pressure is now the dominant driving force determining the functioning and distribution of global freshwater systems. The consequences of human modification of water bodies include both global-scale river flow changes and shifts in vapour flows arising from land use change. These shifts in the hydrological system can be abrupt and irreversible. Water is becoming increasingly scarce – by 2050 about half a billion people are likely to be subject to water-stress, increasing the pressure to intervene in water systems. A water boundary related to consumptive freshwater use and environmental flow requirements has been proposed to maintain the overall resilience of the Earth system and to avoid the risk of ‘cascading’ local and regional thresholds.

Here, as elsewhere, is made manifest the centrality of the rapid changes in the Earth’s climate to the manifold and intersecting planetary crises that are now converging, but so too, in this description, is evident the complex interconnections amongst the different boundaries, such that changes in climate and human (that is, very often, corporate) land-use patterns (that also play a significant role in zoonoses and the propagation through human populations of novel pathogens) emerge as key drivers in the hydrological cycle and the availability (to humans) of freshwater.

Regular readers will know that the health, ecological, and economic impacts of the fracking boom in the United States have been a central concern for me in recent years, and while the SRC doesn’t address the connection between toxic substance contamination and freshwater availability, in many parts of the world (including parts of Pennsylvania and Texas, among other US states) contamination from fracking, extractive or other industry, or industrial agriculture (or failing infrastructure, as in Flint, Newark, and some parts of New York City) has left people with limited or no access to clean freshwater.

For readers interested in learning a little about New York City’s infrastructure, today’s bonus recommendations are two paired pieces of mine from 2019 on the City’s remarkable waterworks and its ailing, but equally remarkable sewer system. The title of the latter piece – “Shit in the Water” – touched a nerve with many readers when it was first published, and given that it’s been raining recently, there is almost certainly some combined sewer overflowage, at present, in the water bodies of our great estuarial metropolis. Enjoy, if not the fecal coliform (please don’t!) than at least the reading material!