Monday, September 26, 2011

The folly of broad statements about adapting to climate change

In my climate change course, we devote a week to discussing climate and past civilizations. Among the goals of that week is to erase the notion that climate change is inherently "bad", or inherently "good", from the student's minds. The effects of climate change on any system, whether a society or an ecosystem, depends on the adaptive capacity and the rate of the climate change. The same climate change that spelled the end of the Norse settlements in Greenland did not affect (ed. crowd-sourced copy editing) the well-adapted Inuit of the region.

A recent, and controversial, book hypothesizing that the Easter Islanders were not done in by "ecocide", as argued by Jared Diamond and most archaeological evidence suggests, led to some discussion about the societal resilience to climate change. All roads lead to climate these days, I guess.

Judith Curry concludes a post on the subject with this statement, which supports a dangerously simple view of adaptation to climate change:

Occam’s razor suggests that we should tend towards simplest theories.  However, in complex coupled social-ecological-environmental systems, simple theories are almost certain to be too simple.  The complexity of such coupled systems precludes simple cause-effect analyses.   If we are arguing about such a system on the scale of Easter Island, what hope do we have of understanding and managing such interactions on  continental or even global scales? Ecosystems eventually adapt to climate change and insults from humans.

The comments about Easter Island notwithstanding - we argue about places like Easter Island because it all happened in the past and thus evidence is disputable, not because we can't understand complex systems - this statement concludes with exactly the type of simple, blanket view of complex problems that we should be teaching students to avoid. Theories like "Ecosystems eventually adapt to climate change and insults from humans" are indeed too simple!

Ecosystems do adapt. In a broad sense. But the question is not if they can eventually adapt, because we don't live in eventually. And, regardless of the time frame, we must remember that adapt itself is a vague term. To estimate the impacts of climate change, or other human insults, in the real world, we need to delve deeper and dispense with the vague generalities:

1. Define eventually: At what rate can the system adapt? Is the change happening faster than ecosystems, or people, can adapt such that they stay in the present state?
2. Define adapt: What exactly does adaptation look like? Say, coral reefs can "adapt" (in a collective, rather than an individual biological sense) to climate change by killing off the less resilient species and growth forms. That, for example, may be what is happening in South Tarawa where I do field work. You've got reefs dominated by a single, weedy species, and little habitat diversity. This new adaptation may not be desirable for those who depend on the ecosystem.

That's science. You don't just assume away an answer ("oh, we'll be just fine") based on a pre-conceived notions of what's "good" or "bad". You gotta analyse the data, do the math, unpack how the system works.


Anonymous said...

We have a term for adaptable species, well two - weeds and pests.

Disruption of any environment leads to the loss of specialists and the gain of ruderal species. This is well known in ecology.

For Curry to state "Ecosystems eventually adapt to climate change and insults from humans" misses two large points 1: The adaption phase involving a larger pest/weed burden on the ecosystem (and their knock-on effects on utilisers of the system in question). 2: (possibly more important) the fact that humans rely on non-natural ecosystems (agriculture & urban) for survival. Systems whose natural progression is arrested through various methods (e.g. soil imporovement, herbicides, fertiliser etc.) and may not adapt in ways we can predict.

Chris S.

EliRabett said...

In the long run we are all dead but sometime in the short run.