Environmental Engineering Reference
In-Depth Information
Movie 2.4.1 Seasonal variation in the Arctic sea ice area 1978-2006
Sea ice freezes and melts due to a combination of factors, including the age of the ice, air
temperatures, and solar insolation. During the winter, the area of the Arctic Ocean covered
by sea ice increases, usually reaching a maximum extent during the month of March. The
area covered by sea ice then decreases, reaching its minimum extent in September most
years. The core of the ice cap is the perennial ice, which survives the summer because it
is suffi ciently thick. However, because it has been thinning year after year, the perennial
ice has now become vulnerable to melt. The disappearing older ice gets replaced in winter
with thinner seasonal ice that usually melts completely in the summer. Movie from Arctic
Climate Research Center at UIUC, with permission [2.9]. This movie can be viewed at:
http://www.worldscientifi c.com/worldscibooks/10.1142/p911#t=suppl
Extreme weather
For many years the conventional wisdom was that a single hot summer
does not provide evidence for climate change; the weather fl uctuates
and occasional very cold winters or hot summers are exactly the type of
fl uctuations one could expect. However, one of the expected outcomes
of climate change is that the probability of extreme weather is going to
increase. Figure 2.4.10 shows some of the recent climate events in the
USA. Individually, each of them could be seen as bad luck of the climate,
or better, weather dice. In a recent study Hansen and co-workers quanti-
fi ed the probability of bad luck [2.11]. As a reference, these authors used
the period 1951-1980. During these three decades the average tempera-
ture was relatively constant. The authors used the data that were col-
lected of the temperatures all over the earth during this period to calibrate
Search WWH ::




Custom Search