Environmental Engineering Reference
In-Depth Information
from -25% to +25% per degree C of global warming; thus, the sign of future
changes in number of storms is uncertain. {4.3}
Ocean Circulation
The Meridional Overturning Circulation (MOC) in the Atlantic Ocean
is expected to slow down in the 21st century due to warming associated
with increased greenhouse gases and associated increased ocean strati-
fication.
As a result, warming in the northern North Atlantic Ocean and
surrounding maritime regions is expected to be smaller than other oceanic
regions. Changes in fisheries and marine ecosystems could also result from
a MOC slow-down, but these impacts are poorly understood. {5.8}
CHANGES IN ICE, SNOW, AND FROZEN GROUND
Sea Ice
Arctic and Antarctic sea ice extent and volume are projected to de-
crease over the 21st century if greenhouse gas emissions continue to in-
crease.
Models project a clearly defined linear relationship between annual
Arctic sea ice area decreases and global averaged surface air temperature.
According to an analysis of an ensemble of models, annually averaged Arctic
sea ice area reductions of about 15% are expected per degree C of global av-
erage warming (see Figure O.4). Greater reductions are expected for summer
FIGURE O.4 Changes in annually averaged Arctic sea ice extent versus time from 13 CMIP3 models (left).
The same information is plotted versus global mean temperature in the righthand panel. {4.7}
