|Planetary boundaries according to Rockström et al. 2009 and Steffen et al. 2015. The green areas represent human activities that are within safe margins, the yellow areas represent human activities that may or may not have exceeded safe margins, the red areas represent human activities that have exceeded safe margins, and the gray areas with red question marks represent human activities for which safe margins have not yet been determined. (Text and figure from Wikipedia).|
The earth is finite and therefore natural resources are too. Humanity has over time deforested the planet, depleted soils, overfished the oceans, and so on. On top of that, add different kinds of pollution, plastic in the oceans, toxic waste from industry and emissions of greenhouse gases. Obviously, this has been known for a long time, but Rockström and co-workers (2009) have skillfully illustrated the concept in one simple figure. An updated version of the figure was published by Steffen et al. (2015). The figure to the right is taken from Wikipedia, which also hosts a discussion about counterarguments which have been raised against some of the boundaries. The three boundaries for which the thresholds are estimated to be exceeded are:
- Climate (carbon dioxide level in the atmosphere),
- Loss of biodiversity (species extinction), and
- Nitrogen and phosphorus cycles.
It may be obvious that these boundaries can not be predicted with high accuracy, but that does not invalidate the principle that boundaries exist and that we need to consider the interplay between them. We need to apply the precautionary principle, implying that human activities should be kept within the boundaries by a good margin. While climate change may be mitigated by halting the use of fossil fuels and storing carbon dioxide in ecosystems (approximately half of all plant mass has disappeared because of humanity), it will take a very long time for biodiversity to recuperate. Biodiversity is further jeopardized when forests are felled in order to save the climate. This is both meaningless and counterproductive. Decisions we make today will have an impact for thousands of years to come. Read more about this under Solutions.