Biology Reference
In-Depth Information
E(T)
S(T)
T
−
15
0
5
22
FIGURE 1-17.
Hypothetical graphs of the solar energy absorbed by the Earth, S(T ), and the energy radiated by the
Earth, E(T ), as functions of the average Earth temperature T.
E
XERCISE
9
(a) Using Figure 1-17, sketch the graph of
dT
dt
versus the average Earth
temperature T.
(b) Use the graph from part (a) to show that this model has two stable
equilibrium states.
(c) Tell how the temperature will evolve if at time t
0
we have:
23
C,
(i) T(t
0
)
¼
18
C,
(ii) T(t
0
)
¼
-16
C, and
(iii) T(t
0
)
¼
4
C.
(iv) T(t
0
)
¼
(d) Sketch the time trajectories of the temperature T(t) for the four
cases in part (c).
Example 1-2
.......................
Harvesting a Renewable Resource. As the world's population grows,
humans must be increasingly conscious that natural resources are
limited. The food supply is one resource that can be exploited in
catastrophic ways. For example, overharvesting has led to the collapse of
important fisheries in several areas of the world. The question of
determining ecologically sustainable approaches to harvesting is
