20
Global Climate Change
Overview of Chapter 20

Introduction to Climate Change
 Causes

of Global Climate Change
Effects of Climate Change
 Melting
Ice and Rising Sea Level
 Changes in Precipitation Patterns
 Effects on Organisms
 Effects on Human Health
 Effects on Agriculture

Dealing with Global Climate Change
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Reforestation in Ghana


Question is “how can we mitigate effects of
climate change?”
Carbon Mitigation Initiative
 Most
dangerous
consequences at doubling of
pre-industrial levels
 Certain steps in many areas
can reduce effects
 Increase
fuel economy
 Carbon capture and storage
 Many more
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Introduction to Climate Change: Mean
Annual Global Temperature 1960–2010
20 warmest
years (since
~1880) have
occurred
since 1990
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Climate Change Terminology

Greenhouse Gas


Positive Feedback


Gas that absorbs infrared radiation
Change in some condition triggers a response that
intensifies the changed condition
Infrared Radiation

Radiation that has a wavelength that is longer than that of
visible light, but shorter than that of radio waves
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Climate Change Terminology

Greenhouse Effect


Natural trapping of heat in the atmosphere; greenhouse
gases absorbs energy and keeps it from leaving
Radiative forcing

Capacity of a gas to affect the balance of energy that
enters and leaves Earth’s atmosphere
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Introduction to Climate Change

Evidence for Climate Change
 20
warmest years since mid-1800s have occurred
since 1990
 Phenological spring in N. hemisphere now begins
6 days earlier (date the buds of specific plants
open)
 Sea level rise - <2cm/decade for most of 20th
century, now ~3cm/decade

Warming is not due to natural causes
 Human
produced greenhouse gases are most
plausible explanation
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Greenhouse Gases

Greenhouse gas concentrations are increasing
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Causes of Climate Change

Increased
concentration of
CO2 (right)
 Burning
fossil
fuels in cars,
industry and
homes
 Deforestation
 Burning of forests
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Greenhouse Effect

Enhanced
greenhouse effect
 Build
up of
greenhouse gases
(CO2 and others)
due to human
activities
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Pollutants That Cool the Atmosphere

Atmospheric Aerosols
 Both
human and natural sources
 Tiny particles (or sulfur) that remain in
troposphere for weeks or months
 Sulfur-laden layer in the atmosphere reduces the
amount of sunlight reaching earth


Complicates models of climate change
Aerosol effect
 Atmospheric
cooling that occurs where and when
aerosol pollution is the greatest
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Climate Models

Climate affected by:
 winds,
clouds, ocean currents, and albedo
 Albedo – measure of reflectivity (ice greater
albedo than asphalt)



Used to explore past climate events
Advanced models can project future warming
events
Models are only as good as the data and law
used to program them
 They
have limitations
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Climate Models
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Climate Models

Environmental feedbacks are complicated
 Positive
or negative feedbacks
 More cloud production can result in a negative
feedback

Most models project climate a few decades or
a century from now
 Based
on different abatement strategies which
will affect future CO2 concentration
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Unpredictable and extreme climate
change

We are projecting future climate with incomplete
knowledge of environmental feedbacks


Using solid scientific understanding, however
environmental complexities abound
Tipping points?
A large rapid change occurs
 Examples

Ocean conveyor belt affected by melting of freshwater in
Arctic
 Polar vortex – cold air from poles move toward equator

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Effects of Global Climate Change

Wildfire in California
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Effects of Global Climate ChangeMelting Ice and Rising Sea Levels


IPCC projects sea-level rise of18-59cm by
2100
Sea level rise caused in 2 ways
 Thermal
Expansion
 Melting of land ice

Melting has positive feedback
 Increased
melting decreases ice, which
decreases albedo leading to further warming
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Grinnell Glacier, Glacier National
Park
1938
1998
1981
2005
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Case-In-Point Impacts in Fragile
Areas


Eskimo Inuit live
traditional life dictated
by freezing climate
Climate change is
altering their existence
 Wildlife
displaced
 Reduced snow cover
and shorter river ice
seasons
 Thawing of permafrost
(right)
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Effects of Global Climate ChangeChanging Precipitation Patterns

Some areas will get more water, some areas
will have greater droughts
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Effects of Global Climate ChangeEffects on Organisms

Zooplankton in parts of California Current have
decreased by 80% since 1951




Affecting entire food chain
Species have shifted their geographic range
Migrating birds are returning to summer homes earlier
Ecosystems at greatest risk of species loss (short term):

coral reefs,
mountain
ecosystems,
coastal wetlands,
tundra, and polar
areas
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Effects on Organisms - Coral
Reefs

Coral reefs can be bleached (right) due to
increase in water temperature
 Affects
coral symbiontes and makes them more
susceptible to diseases
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Effect on Organisms - Vegetation
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Effects on Human Health
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Effects on Agriculture

Difficult to anticipate






Productivity will increase in some areas and decrease
in others
Rise in sea level will inundate flood plains and
river valleys (lush farmland)
Increase in drought frequency
Effect on pests is unknown
Warmer temperatures will decrease soil
moisture - requiring more irrigation
Location (i.e., elevation and altitude) where
certain crops can be grown will change
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International Implications of
Climate Change

Developed vs.
Developing
countries
 Differing
self-
interests
 Differing ability to
meet the
challenges of
climate change
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Dealing with Global Climate
Change

Two ways to manage climate change
 Mitigation:
Limiting greenhouse gas emissions to
moderate global climate change
 Adaptation:
Learning to live with environmental
changes and societal consequences brought
about by global climate change
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Relationship Between Mitigation
and Adaptation
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Dealing with Global Climate
Change - Mitigation





Locate/invent alternative fuels to fossil fuels
Increase efficiency of cars and trucks
Carbon Capture and Storage
Plant and maintain trees to naturally sequester
carbon
Geoengineering
 Global
scale projects to mitigate effects
 Example: seeding ocean with iron to stimulate
phytoplankton growth and CO2 storage in deep
ocean
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Dealing with Global Climate
Change - Adaptation

Rising sea levels and coastal populations
 Move
inland
 Construct dikes and levees



Adapt to shifting agricultural zones
NYC sewer line
Climate change refugees
 People
having to leave homes because of climate
change effects
 Example:
rising sea levels, storm surges
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International Efforts to Reduce
Greenhouse Gas Emission

Kyoto Protocol
 Legally
binding
 Provides operational rules on reducing
greenhouse gases
 By 2014, 192 countries had ratified it
 US
has not sign it - it will be difficult to implement
without US backing
 EPA is taking it upon itself to define laws associated
with CO2 reduction in U.S.
 Obama administration meetings with other nations
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