Climate change futures: health, ecological and economic dimensions

created unstable conditions conducive to mudslides
and avalanches in subsequent seasons, and these
caused property damages and the loss of life.
The implications of the forest changes and tree infestations
include losses for several industries: food industries
(for example, citrus); tourism, due to reduced scenic
quality; maple syrup production; property damage;
and business interruptions from wildfires; loss of hydroelectric
power from degradation of watersheds; constraints
on areas suitable for development, and vulnerability
to landslides due to loss of forests and erosion
caused by the fires and fire-control activities.
Figure 2.24 Bark Beetles
Figure 2.25 Annual Area of Northern Boreal Forest Burned
in North America
Area Burned (million acres)
20
18
16
14
12
10
8
6
4
2
0
Annual
10-year average
1940
1943
1946
1949
1952
1955
1958
1961
1964
1967
1970
1973
1976
1979
1982
1985
1988
1991
1994
1997
Source: National Assessment of Climate Change: Impacts on the
United States.
Bark beetles can bore through spruce tree bark when drought dries
the resin that forms its natural defense.
Image: Rick Delaco, Ruidoso Forestry Department
WILDFIRES
Wildfire is an important outcome of the dynamics of climate
and forest health. Climate-related influences
include drought, reduced fuel moisture content,
changes in wind patterns, shifts in vegetation patterns,
and increased lightning (an important source of ignition).
Consequences for humans include the costs of fire suppression,
property loss, damage to economically valuable
forests (some of which are insured), and adverse
impacts on respiratory health arising from increased
particulates introduced into air-sheds during fires. As
seen in the winter following the large Southern
California wildfires of 2003, there can be important
indirect impacts, also exacerbated by climate change,
such as severe floods and mudflows that arise when
torrential rains fall on denuded forestlands.
A distinct upward trend in wildfire has been observed,
as measured in terms of average number of acres
of Northern boreal forest burned (a doubling since
the 1940s) and peak years (a fourfold increase since
the 1940s).
According to the Insurance Services Office (1997),
wildfires are a pervasive insurance risk, occurring in
every state in 1996. Wildfires consume an average of
5 million acres per year across the United States.
Between 1985 and 1994, wildfires destroyed more
than 9,000 homes in the United States at an average
insured cost of about US $300 million per year. By
comparison, this was triple the attributable number of
homes lost during the three-decade period prior to
1985. Some of this increase is attributed to new home
developments in high-risk areas.
The Oakland/Berkeley Tunnel Fire of 1991 was a
poignant example of the enormous damage potential
of even a single wildfire. The third costliest fire in US
history, it resulted in US $2.4 billion in insured losses
(at 2004 prices; Swiss Re 2005a), including the
destruction of 3,400 buildings and 2,000 cars (ISO
1997). Added to this were extensive losses of urban
infrastructure, such as phone lines, roads and water
systems. The insured losses from this single fire were
twice the cumulative amount experienced nationwide
during the previous 30 years. Swiss Re (1992) and
Lloyd’s of London pointed to global climate changes as
one possible factor influencing the degree of devastation
wrought by this and subsequent wildfires.
The total US losses from catastrophic wildfires (a subset
of the total defined in terms of events tabulated by the
Property Claims Services) was US $6.5 billion (US $
2004) between 1970 and 2004, corresponding to
an average insured loss of just over US $400 million
per fire (Insurance Information Institute).
– E.M.
67 | NATURAL AND MANAGED SYSTEMS
CASE STUDIES