Climate change futures: health, ecological and economic dimensions

In 2001 the IPCC fully recognized that the impacts of
future changes in climate are expected to fall disproportionately
on the poor (McCarthy et al. 2001).
Changes in water for consumption, cooking, washing,
waste disposal, agriculture, hydropower, transport,
manufacturing and recreation are likely to grow critical
in large parts of the world in the coming decades.
THE ROLE OF CLIMATE
Warming affects water quality, while precipitation patterns
affect groundwater aquifers, surface waters,
snowpack accumulation and water quality. Outbreaks
of waterborne diseases, large freshwater and marine
algal blooms, and increased concentrations of agricultural
chemicals and heavy metals in drinking water
sources have all been linked to increased temperatures,
greater evaporation and heavy rain events
(Chorus and Bartram 1999; Levin et al. 2002;
Johnson and Murphy 2004), which can increase
microbial, nutrient and chemical contamination in
waterways and water delivery systems.
Figure 2.35
Increased Evaporation
of Surface Water,
Decreased Precipitation
in Some Areas
Drought in Some Areas
Higher Concentrations,
of Contaminants in
Surface Water
Increased
Precipitation
and Extreme
Weather
Warmer Air
Temperatures
Increased Runoff
Contamination of
Surface Water,
Increase in
Waterborne-Disease
Outbreaks
Increased Melt
of Polar Ice, Sea Ice,
Glaciers
Ambient temperatures and precipitation influence the
range, survival, growth and spread of pathogenic
microbes. Sewage and urban, agricultural, and industrial
wastes are the primary sources of contamination,
and microbes must enter source water in relatively high
concentrations to initiate a waterborne disease outbreak
(WBDO). The microbes must be transported to a
treatment plant and pass through the treatment
process, or enter the water supply through cross-contamination
with untreated water. The latter can happen
when contaminants enter breaks in distribution pipes or
when combined sewer systems overflow (Rose et al.
2001). Poor infrastructure and inadequate centralized
drinking water treatment greatly magnify the risk of illness
from WBDOs.
Water quantity is also very sensitive to precipitation
patterns and temperature. These parameters directly
affect the amounts that fall, that which is available in
surface waters, that which is absorbed and stored in
underground aquifers, that which is stored in polar
and mountain snow and ice fields, and the timing and
quantities that flow during melting.
Global
Climate
Change
Warmer Water
Temperatures
Sea Level
Rise
Increased Saltwater
Intrusion into
Coastal Aquifers
Warmer Winter
Temperatures,
Earlier Springs
Increased
Microbial Growth
in Surface Water
and Distribution
Systems
Decreased
Snowpack,
Decreased
Runoff From
Snow Melt
Pathways by which climate change can alter health and agriculture via changes in precipitation patterns, water/ice/vapor balance, sea level,
water quality and snowpack spring runoff. Source: Rebecca Lincoln
CASE STUDIES 87 | NATURAL AND MANAGED SYSTEMS