Are humans pushing earth systems towards environmental catastrophe?  Or are we just worrying needlessly about the novel state of the earth that we have now created?  Or both?

In a Nature Feature entitled “A safe operating space for humanity” a team of scientists affiliated with the Resilience Alliance proclaim that “To avoid catastrophic environmental change humanity must stay within defined 'planetary boundaries' for a range of essential Earth-system processes”.   More importantly, the researchers claim that we have or will soon exceed the range within which major planetary systems like the climate system, the nitrogen cycle and biodiversity losses, can safely support human populations.  The work is based on assessments of how far humans have altered a set of key earth systems beyond the environmental range within which human civilization originated, a relatively stable climate period formally known as the Holocene- the geologic epoch since the end of the last ice age about 10,000 years ago. 

This work raises very serious concerns about the potential consequences of pushing earth systems out of the stable state that has for millennia served as the cradle for human civilization.  No one should doubt that as we force earth systems into new territory, we cannot know with any certainty what might happen, and that this might indeed turn out to be catastrophic shifts in environmental and ecological conditions towards a new and stable earth system that is incapable of supporting humanity.  Anyone who is unconcerned with such shifts and their potential consequences must be considered foolhardy.  Uncertainties about how we will fare under new planetary conditions are large and the precautionary principle argues that avoiding these new conditions would be wise.  Though there is no way to know conclusively what will happen when various thresholds are exceeded- do we really want to experiment with our one planet to find out?

The problem is, even now our planet hardly resembles the Earth of even 150 years ago and we are changing it faster than ever.  We have already entered new territory- a new geological epoch called the Anthropocene in which most earth system processes, including climate, have been reshaped by human systems.  Could we ever return the earth to a state resembling that before we appeared on the scene, or even into a state resembling that before the Agricultural and Industrial Revolutions?  More than unlikely I think.  And why would we necessarily want to?  Humans have reshaped the earth to produce more food and support more people at a higher standard of living than would ever be possible with a “pre-Anthropocene” earth.

And “Why do we think humans can't survive under circumstances different from the ones we evolved in?” asked Michael Shellenberger, President of Breakthrough Institute, in an email he sent after reading the article in Nature.  A great question, as our defining characteristic as a species seems to be that we are indeed able to do this - and even thrive (for example, humans have long lived in the Arctic). 

Pushing earth’s limits the way we are is certainly putting us into unknown and potentially highly undesirable territory.  But considering all of the undesirable territory billions of humans now find themselves in (poverty, in a word), even with today's environment, focusing entirely on environmental limits seems unlikely to succeed in improving things.  Paul Ehrlich's focus on the global limits of food production systems in the face of population growth is a good example: populations did explode yet there is now more food available per capita than ever. It would seem that limits to human systems are the source of most misery today- not environmental limits.  And global decision-making based purely on avoidance of potential environmental catastrophes is crisis management: by its very nature it is not a sustainable decision making process. 

The ultimate long-term goal for all of us should be a better planet and a better-off humanity.  And this may involve changing the planet even more.  As Konstantin Tsiolkovsky stated nearly a century ago: "Earth is the cradle of humanity, but one cannot remain in the cradle forever."  Tsiolkovsky was talking about the possibility of humans living outside planet earth, and let’s hope that human survival never requires this.  But the future of the planet is now certainly up to us- and we can change it for the better, or for worse.

Nature Feature, with blogs/comments: http://www.nature.com/news/specials/planetaryboundaries/index.html

Original “Planetary Boundaries” paper at Resilience Alliance: http://www.stockholmresilience.org/planetary-boundaries

Worldchanging blog post "Planetary Boundaries and The Failure of Environmentalism": http://www.worldchanging.com/archives/010551.html