A feedback loop, also referred to as a "positive feedback mechanism" or "cumulative causation", in a system (such as global biospheric system - ecosystem) is one in which change processes accelerate by feeding into each other, rather than canceling each other out: the system "responds to perturbation in the same direction as the perturbation.[Wikipedia] "

Ocean acidification, global surface temperature, sea level, and corresponding food and water shortages are all on the rise because all are mutually causal.

A mass extinction event is occurring, wherein an avg of 50,000 species per year are going extinct. The Human race also faces peril.

Thanks to coal, oil, and the industrial revolution. Cheers.

for a good quick low-down on what this means, read: http://www.well.com/~davidu/sixthextinction.html

includes NASA satellite photos and current model projections, and the sound bytes of James Hansen, Paul Ehrlich, Janine Benyus, Peter Annan, Jimmy Carter, Gustave Speth, Jim Lehrer, and other climatologists/ scientists/ environmental policy advocates. ----- (less info)