Transcript Climate Change Impacts

Climate Change Impacts in
the Gulf Coast
Philip B. Bedient
Civil & Environmental Engineering
Rice University
Climate Change History



Earth’s climate has
always been changing
– Ice age (2 m.y.a.),
glacial periods, polar
ice caps
– 18,000 yrs ago: cold
spell & continental
glaciers
Last 100 yrs, surface has warmed about 0.6°C
In past 10,000 yrs, global temp. has never
varied more than 1.5°C
Why has it been changing?




Various theories
Intricate & complex relationship b/w
ocean, atmosphere, ice, and other
elements
No climatic element in systems is isolated
Influences path of ocean currents,
transport of heat, global wind system, and
climates
Key Predictions for Future








Increased warming
– 5-9°F increase next 100 yrs
Differing regional impacts
Vulnerable ecosystems
Widespread water concerns
Secure food supply
Near-term forest growth increase
Damage in coastal/permafrost areas
Adaptation determines health
Greenhouse effect





Delicate balance of incoming & outgoing energy
in earth-atmosphere
Atmosphere gases (water vapor, CO2, CH4,
halocarbons, O3) absorb Earth’s heat
Radiate some heat back to Earth, some passes
through into space
Humans change atmosphere
– burn coal, oil, natural gas, destroy forests
– CO2 risen 30%, CH4 150% in past 100 yrs
Heat energy can’t pass into space
Increasing Greenhouse
Gases





Unusual rapid warming of
0.6°C in 20th century
Human activities major
cause of warming
Carbon emissions have
increased from 1 to over
7 billion metric tons/year
Lifetimes of gases last
centuries
CO2 Predicted to triple by
2100
Climate Assessment Tools



Historical records &
climate simulations
General Circulation
Model (GCM)
– model Earth’s
climate
– incomplete, but still
state-of-science
Two main modelsHadley & Canadian
Hadley & Canadian Models






Principles driving models are similar
Differ in representation of effects of important
processes
Thus, different views of 21st century climate
Hadley predicts wetter climate
Canadian predicts greater temp increase
Uncertainties
– how to represent clouds & precipitation
– how emissions of greenhouse gases will
change
Past & Future Temperature
Change
Precipitation Change



Large increases in
20th century
(510%)
Due to frequency &
intensity growth
Increasingly frequent
heavy precipitation
events in 21st
century
Soil Moisture




Critical for agriculture &
natural ecosystems
Levels set by
precipitation, run-off,
evaporation, soil
drainage
Higher temp increases
evaporation, removing
moisture
Models differ due to
different temp &
precipitation predictions
Future Ecosystem Changes

Vegetation response to
CO2 concentrations double
present levels
Multiple stresses


Climate only one of changes in global environment
Effects of climate & other environmental changes
Common Climate
Changes

Predict increased warming,
precipitation, evaporation
Midwest
Pacific
northwest
Islands
Northwest
West
Common Issues






Weather extreme increase
Natural ecosystem, species, and biodiversity
changes
Water resource changes (lake levels, snow
melting)
Public health and
safety
Shifts in tourism and
recreation
Sea-level variability
Southeast






Half of remaining wetlands
located here
Rapid growth (30%
population increase b/w
1970 & 1990)
Produces half of U.S. timber
supplies
Warming and thus higher evaporation predicted
Lower soil moisture
Significant precipitation increase also predicted
Southeast: Future Climate
Scenarios
Southeast: Impacts on
Humans

Weather-related stresses
– frequent weather disasters: drought, hurricane
– flooding in Texas (low-lying coast counties)
– high heat index & poor air-quality to increase
death rate
– southern heat wave & drought of 1998: $6
billion in damages & over 200 deaths
– 8 to 15° heat index
increase for
southernmost states
Southeast: Climate Effects


Crop and economy impact
– will vary according to area and crop
– adaptation: switch crops, vary planting
dates, water usage, crop rotations,
fertilizers
Water quality stresses
– sewage, dead animals, fuel, chemicals from
flooding
– high temp- decrease dissolved oxygen
Southeast: Climate effects


Coastal area threats
– sea-level rise will impact ecosystems
– Obvious impacts on coastal flooding
Forest productivity shifts
– greater CO2: production increase in north
– Pine trees
Climate Change Summary



Warmer temp will lead to more vigorous
hydrological cycle- severe droughts &/or
floods
Uncertain predictions, especially in timing,
magnitude, & regional patterns of climate
change
Balance of evidence shows there is
discernible human influence on global climate