Agriculture And Our Planetary Carrying Capacity

The planet is at a crossroads, a junction between human “progress” or survival. It’s been called “the anthropocene,” an epoch in which human activity shapes the Earth and its systems, through technology, urbanization, extensive agriculture, and more. For some time, scientists have discussed the “planetary boundaries” of our Earth, and how crossing those boundaries could have disastrous consequences.  There are nine planetary boundaries that scientists discuss: land-system change; freshwater use; biogeochemical flows (the nitrogen and phosphorous cycles); biosphere integrity; climate change; ocean acidification; stratospheric ozone depletion; atmospheric aerosol loading; and introduction of novel entities. Agriculture in general, and intensive agriculture in particular, is pushing Earth (or various sub-regions) over one boundary or another.

The quantification of planetary boundaries can be difficult (and indeed, is “the subject of ongoing research and debate”), but in this paper, researchers attempt to do just that. Their reasoning is that, even though numbers may shift with improved measurement, “the concept provides a useful basis for assessing the effects of agriculture on the Earth system, and can be used to stimulate urgent transformation of the food and agriculture sector.” To this end, they go through each of the nine boundaries above and highlight some of the best available data that sheds light on the severity of our situation.  Their findings include:

• Croplands and pastures now make up ~40% of the Earth’s land surface. New agricultural land generally comes at the expense of other ecosystems, and future expansion of agriculture will be no different.
• Human-made sources now contribute more nitrogen to the Earth system than all natural terrestrial processes combined. The excess leads to soil and air pollution, drives biodiversity loss, pollutes coastal marine waters and watersheds.
• Some models predict extinction rates of less than 5% per decade. although the impact of climate change on extinctions is particularly uncertain.
• Agriculture is one of the most important anthropogenic activities contributing to climate change in terms of production of CO2. In a cyclical way, climate change will influence the conditions for agriculture and so on.
• Carbon dioxide emissions to the atmosphere have already caused a 34% increase in seawater acidity since 1800. Unless CO₂ emissions are reduced, this process could cause a 150% increase in surface ocean acidity by 2100, which would be “the fastest rate of chemical ocean change for millions of years.”

These are just some of their findings, all of which paint a relatively grim picture of the past couple of hundred years, as well as the next 100 years or so.

For animal advocates, this type of information may be overwhelming, even leading to a loss of hope. However, rather than falling into despair, the hope is that this type of information helps to motivate advocates – and the general public – into immediate action. Though the researchers make the bold claim that “nothing less than a radically transformed system will be required, with numerous changes made to all aspects of production,” they also note that, since the food system is so vast, and since every level of it is related in some way, changes to the system “offer a wide range of mitigation possibilities.” We still have a chance to stay within our planetary boundaries, but to do so, we need to act now.