Depiction of two glacial climate states: a stable "cold"
mode (bottom) and an unstable "warm" mode (top). Surface ocean
currents are shown in red and deep currents in light blue. In a new
global climate model, abrupt ice-age warming events are triggered by
small changes in the salinity of the northern North Atlantic; the small
changes effectively act as random fluctuations (noise) causing a temporary
transition from the cold to the warm mode.
This model provides evidence for the occurrence of a phenomenon called
stochastic resonance in the realm of climate, in which random fluctuations
or noise can enhance the effects of a weak signal (in this case, a faint
climate cycle of presently unspecified origin.) For other examples of
stochastic resonance, see Physics News Updates 121,
Reported by: Andrey
Ganopolski and Stefan Rahmstorf, Physical Review Letters,
21 January 2002.
Image courtesy of the authors and Physical
Review Letters. Caption
adapted from Physical Review Letters,
with additional information
from the authors. Reprinted with permission.
Physics News Update