melts in response to rising temperatures or how temperatures rise in response to
melting sea ice: You also have to understand how the melting ice and the rising
temperatures affect one another. And until you do, your predictions – unlike
Newton’s excellent approximation – may be grossly inaccurate.
Figure 5: Larsen_B_Collapse. In 2002, a 12,000-year-old Antarctic ice shelf the size of Rhode
Island collapsed as a result of rising temperatures. This exposed the dark seawater beneath the
ice, which absorbs more of the sun’s warmth, contributing to further warming. Credit: Robert A.
Rohde
Unfortunately, most human-environment systems (HESs) will behavemore like the climate than like Newton’s planets. Feedbacks are inherent in an
HES: Human behavior impacts the environment, and environmental changes in
turn impact human behavior, forming a feedback loop. Systems like this, with
many interacting parts that change over time, are called complex adaptive
systems. And the mathematics of complex adaptive systems is still poorly
understood.
The field has only emerged in the last thirty years, and it’s a challengingone because the large-scale behavior of such systems as a whole can be
remarkably different from the small-scale behavior of the interacting parts. For
example, ants, which individually behave in thoughtless, preprogrammed ways,
form colonies that can build bridges, carry dead insects hundreds of times an
ant’s bodyweight, and find the shortest path between two points.