About Those Tipping Points

Last week, we received this scary bulletin out of Berkley, California:

A prestigious group of scientists from around the world is warning that population growth, widespread destruction of natural ecosystems, and climate change may be driving Earth toward an irreversible change in the biosphere, a planet-wide tipping point that would have destructive consequences absent adequate preparation and mitigation.

Since the warning was featured in a prominent journal, many in mainstream media (and the enviro-blogosphere) dutifully treated it as the latest sky-is-falling alert.

The New York Times, taking the sober, detached approach, asked:

Are we nearing a planetary boundary?

That headline is a nod to a much-discussed concept laid out in Nature several years ago (you can read the expanded version here), which made the case for “a safe, operating space for humanity” by identifying thresholds for climate change, ozone depletion, ocean acidification, biodiversity, freshwater use, the global nitrogen and phosphorus cycles, and land use change.

While the main essay got gobs of attention, it’s worth recalling that Nature also hosted separate commentaries (seven of them) on the planetary boundaries thesis. In its introduction, Nature asked:

But do we understand the Earth system well enough to know the real limits to environmental degradation? And if we can define them, even roughly, would doing so ultimately help or hinder efforts to protect the planet?

Those questions have now been taken up by the Oakland-based Breakthrough Institute, in a blunt critique of the planetary boundaries framework, which they consider to be “a misleading guide to global environmental challenges.”

Here’s the thrust of Breakthrough’s report:

The Earth has entered the Anthropocene, a time in which humans are the dominant force shaping all Earth systems. All of the nine systems and processes identified by Rockström et al. are important determinants, albeit in complex ways, of human welfare  “” indeed, they enable life on this planet to exist. They all need to be managed wisely and consciously. The planetary boundaries concept was suggested as a framework for doing so, and it makes several important contributions worth highlighting. It brings resilience thinking and complex systems theory to the center of the debate, and draws attention to the many interrelated elements and processes of the Earth system . However, our review of the framework has identified some serious flaws, which together make planetary boundaries a poor, even misleading, answer to the challenge of planetary stewardship. The implications of this review apply not only to the planetary boundaries concept in itself, but to Earth Science as a whole, especially as regards the way it interfaces with policy making.

In two follow-up posts that will appear tomorrow, I’ll delve more deeply into the specific criticisms made by the Breakthrough Institute, including elaboration from the report’s lead author. Meanwhile, Jon Foley, an earth scientist at the University of Minnesota, and a contributing author of the 2009 planetary boundaries paper in Nature, has responded to Breakthrough’s critique on twitter and to reporters in email, of which this is an excerpt:

Their entire report is based on two or three straw-man arguments.  Sadly, there is nothing substantive here.  And this isn’t sour grapes, believe me.  I would welcome a useful critique of the Planetary Boundaries concept!  In fact, the original publication in Nature included a half dozen sharply worded comments and critiques, and many were extremely useful in improving our collective ideas…I appreciate many of the points they [the Breakthrough Institute] have raised over the years — especially from their original “Death of Environmentalism” essay.  But I think this report fails to raise anything very new or interesting.  Too bad:  I wish they had.  This concept deserves more scrutiny and challenges.

Foley, in an email exchange, has made a more detailed rebuttal. So I’ll be pulling from that in the second post that will look more closely at the Breakthrough Institute’s critique.  A third, related post will specifically examine how biodiversity has come to fit into the planetary boundaries concept.