Climate change futures: health, ecological and economic dimensions

CCF-II: GRADUAL WARMING
WITH INCREASING VARIABILITY:
SURPRISE IMPACTS
Even within the conditions of climate change underlying
the first impact scenario — gradual warming and
increasing variance — there is the possibility of sudden
and catastrophic impacts on health, ecosystems
and economies. Widespread epidemics, explosive
crop and forest infestations, and coral reef collapse
could severely damage the social fabric.
Note again: This is not a scenario of abrupt change in
the physical climate system; it is a scenario of surprises
and widespread impacts due to growing instability in
climate. The effects of “climate shocks” and potential
triggers for abrupt climate change outlined above
extend far beyond these impact scenarios, and the
implications of such major transformations in the global
climate system are too vast as to be considered in
monetary terms.
In this scenario of non-linear impacts, disruptions would
be greater and the economic costs of natural catastrophes
would rise abruptly. Recurrent devastating storms
would render current adaptation methods less effective
and more costly. With non-linear impacts appearing in
many regions simultaneously, the ability of business,
governments and international organizations to
respond would become critically taxed. This scenario
would be more challenging for insurers and other risk
managers due to increasing uncertainty.
Extreme heat catastrophes become more common and
widespread in CCF-II. Events on a par with that seen
in Europe in the summer of 2003 affect many parts of
the globe. Temperature records are broken in numerous
megacities as they are subjected to oppressive
and unhealthy air masses. Heat-related morbidity and
mortality rise from 200% to 500% above long-term
averages. The potential decrease in winter illnesses is
negated by increasing variability of temperatures
(Braga et al. 2001) and more sudden cold spells, plus
rain, snow and ice storms. Winter travel and ambulation
become extremely hazardous during some years
(EPA 2001).
The increase in epidemics of infectious diseases,
especially following disasters, strain existing health
care and public health infrastructure, halting or reversing
economic growth in some underdeveloped
nations. More frequent disease outbreaks also take a
toll on productivity, tourism, trade and travel, crippling
the climate of investment in “emerging markets” and
the availability of insurance in some sectors.
Air quality deteriorates. The combination of rising
pollen and soil mold counts from CO 2
-fertilization;
greater heat, humidity and particulate-filled hazes;
smog and oppressive nights; respiratory irritants from
widespread summer fires; and dust clouds transported
from expanding deserts exacerbates upper and lower
airway disease and cardiovascular conditions (Griffen
et al. 2001).
The changing climate alters the prevalence and
spatial extent of crop pests and diseases around the
globe. Populations of insect herbivores like locust
explode in some regions — as they did in northern
Africa and southern Europe in the summer of 2004 —
greatly decreasing crop yields. Increased CO 2
contributes
to more vigorous weed growth and the worldwide
crop losses today attributed to pests, pathogens
and weeds increases from the current 42% (Altaman
1993; Pimentel and Bashore 1998) to over 50% of
potential yields. Crop damage from drought, storms,
floods and extreme heat episodes compound the disease-related
losses. Yields are decimated in some
regions, leading to widespread famine, debilitating
epidemics and political instability.
Looming in such a scenario is the potential for a rapid,
widespread climate- and disease-induced dieback of
forests. The combination of multi-year droughts; warm,
dry winters leaving little mountain snowpack; and an
explosion of pests, such as bark beetles, leaf miners,
opportunistic fungi and aphids affecting weakened
trees, would create vast dead stands that provide fuel
for wide-scale fires. Such massive losses of forest cover
and transformations of terrestrial habitat would send
reverberations through nature and human society,
affecting birds and other wildlife, lumber and water
quality and availability. As a final insult, widespread
fires in these increasingly flammable forests would
release large carbon pulses, adding to global warming
and altering forest soils that provide an essential
“sink” for storing carbon.
Finally, coral reefs weaken (physically and biologically).
Surface ocean warming and disease compound
the stress on the reefs already generated by overfishing,
and by human and industrial waste. Most of the
globe’s tropical ring of reefs collapses, while sea level
rise and higher storm and tidal surges inundate coastal
29 | THE CLIMATE CONTEXT TODAY