Download Chapter 21 Part 1

Climate Change and Ozone Loss
G. Tyler Miller’s
Living in the Environment
14th Edition
Chapter 21
Key Concepts
 Changes in Earth’s climate over time
 Factors affecting climate
 Possible effects of global warming
 Adapting to climate change
 Human impacts on the ozone layer
 Protecting and restoring the ozone layer
Section 21-1 and 21-2 Key Ideas
• How has the Earth’s temperature changed in
the past?
• How do scientists study past climate changes?
• What role do the natural greenhouse effect
play in Earth’s temperature?
• What are the major greenhouse gases?
Past Climate Changes
CLIMATE VERSUS
WEATHER...what is the
difference?
Temperature and climate
have been changing
throughout Earth’s
history.
Earth 4.6 billion years
Past Climate Change
Over past 4.7 billion years
climate has changed by
• Volcanic eruptions
• Changes in solar output
• Continents moving
• Meteorites
• Natural variations in
CO2
Some changes slow, some
quickly
Past Climate Variations
Glacial and interglacial
periods over last
900,000 years
Last glacial period ended
12,000 years ago
With each temperature
change were changes in
sea level and
precipitation patterns.
Past Climate Changes
 Past global
temperatures
 Recent trends in
global temperatures
Today’s global
average temp 59oF,
15oC
Studying Past Climates
Geologic records and
atmospheric
measurements provide a
wealth of information
about past temperature
and climate.
•
•
•
•
Ice Cores
Lake Sediment
Past 200-300 records
CO2 levels since 1958
Studying Past Climates
Greenhouse Gases
Certain gases in the
atmosphere absorb heat
and warm the lower
atmosphere.
Greenhouse effect
Energy from the sun warms
the earth. Some of that
energy is radiated as heat
and trapped in the
atmosphere by clouds,
water vapor and other
gases.
Greenhouse Gases
Greenhouse Gases
•
•
•
•
Water Vapor
Carbon Dioxide
Methane (CH4)
CFCs
CO2 levels gathered from
ice data closely reflect
changes in temperature.
1764 --- 276 ppm
1995 --- 360 ppm
The Greenhouse Effect
Greenhouse effect Greenhouse gases
(Refer to Table 21-1 p. 464)
Fig. 6-14 p. 110
Section 1 and 2 Review
• How has the Earth’s temperature changed in
the past?
• How do scientists study past climate changes?
• What role do the natural greenhouse effect
play in Earth’s temperature?
• What are the major greenhouse gases?
Section 3: Climate Change and
Human Activities Key Ideas
• How have human activities affected
concentrations of greenhouse gases in the
troposphere?
• What role does the U.S. play in greenhouse gas
emissions?
• Is the troposphere warming?
• What are some visible warning signals coming
from glaciers?
Humans and Greenhouse Gases
• Burning Fossil Fuels
• Clearing and burning
forests and grasslands
• Raising large numbers of
livestock
• Large rice production
• Using inorganic
fertilizers
All these activities have greatly
increased CO2, CH4 and
nitrous oxide (N2O)
CO2 levels appear to
be highest in last
160,000 years
Humans and Carbon Dioxide
42% Coal powerplants
24% transportation
20% industrial processes
14% residential and
commercial usages
Exhale, drive, turn on
light, burn log in fire
1 gallon of gas burned
equals 20 pounds of CO2
U.S. and Greenhouse Gases
4.6% of the world’s
population, yet 24% of
emissions of CO2
From just U.S. coal
burning exceeds 146
other nations with 3/4th
of world population
Per capita yearly 500 tons
Also large CH4
Is the troposphere warming?
There is considerable and
mounting evidence that
the troposphere is
warming “quickly”
• Rate of change
IPCC found:
1) 20th Century warmest
in past 1,000 years
Is the troposphere warming?
2) Since 1861 global avg. temp
increase 0.80C or 1.40F
(mostly post 1980)
3) 16 of the warmest years on
record occurred since 1980
(hottest 1998 followed by
2001 and 2003)
4) Glaciers around world
melting quickly and poles
warming more pronounced
5) Global sea levels rose 4-8
inches during 20th Century
and continue to rise.
Is the troposphere warming?
Few skeptics still exist,
most just argue it is not
human caused
warming
• Global warming versus
Global climate change-- what is the difference?
Do NOT confuse it with
ozone depletion
Warning Signals From Glaciers
The world’s floating ice and
land-based ice is slowly
melting, reflecting less
incoming solar energy
and warming the
troposphere further.
Largest Glaciers:
Greenland and Antarctica
Floating Ice: Arctic Ocean
Warning Signals From Glaciers
Due to wind currents
poles will warm more
quickly than midlatitudes.
Arctic Ocean free of ice
summer 2050???
Albedo: reflectivity of
different surfaces
1979
2003:
shrunk by
9%
Albedo of different surfaces
Warning Signals From Glaciers
Positive Feedback: more
ice melting = more
warming = more ice
melting….
Melting floating ice has
little impact on sea
level rise (WHY?)
“Fresher” water in ocean,
what are the
consequences?
Warning Signals From Glaciers
Greenland melting
• Sea level rise 7m or 23 feet
• 3oC (5oF) would melt entire
continent over next several
centuries
Warming has become
more evident in polar
regions like Alaska
Permafrost melting (a
positive feedback)
Warning Signals From Glaciers
Mount Kilimanjaro
glacier free in 15 years?
80% of South American
glaciers gone also in 15
years?
• Less fresh water
sources
• Tourism loss
Any good impacts?
Riggs Glacier
Alaska
Glacier
National Park,
Montana
1913 and 2005
Section 4 Climate Models Looking Into
The Future Key Ideas
• How do scientists model changes in the earth’s
temperature and climate?
• IPCC consensus about future changes in
earth’s temperature.
• Why should we be concerned about a warmer
earth?
Projecting Future Changes in Earth’s
Climate
Climate models
Apparent influence of human activities
Could be natural changes
Climate models
Scientists have developed
complex mathematical
models of the earth’s
climate system.
Inputs:
• Solar energy
• Earth’s land
• Ice
• Greenhouse gases
• Clouds, winds, water
vapor
IPCC Reports “Best Science”
IPCC (Intergovernmental
Panel on Climate
Change)
1990, 1995, 2001 and
now 2007 reports
Three Major Finding
From 2001
1) Latest climate models
closely match changes
since 1850
IPCC Reports “Best Science”
2) “There is strong
evidence that most of
the warming observed
over the last 50 years is
attributable to human
activities.”
3) It is likely that the
world will warm 1.4oC
to 5.8oC (2.5oF to
10.4oF) between 2000
and 2100
Why Be Concerned?
RAPID changes give little
time for humans and
other species time to
adapt to changes.
Fastest change during the
last 1,000 years
• Water resources and
precipitation changes
• Ocean currents
• Agriculture
Why be concerned?
• Flooding
• Extreme Weather
• Changes to world
biomes
• Diseases may spread
• Displaced nations
A threat to the world’s
economy and stability?
Section 5 Factors Affecting the
Earth’s Temperature
• Can oceans store more carbon dioxide and
heat?
• How might changes in cloud cover affect the
troposphere’s temperature?
• What impact does air pollution have on
temperature?
• Can photosynthesis be stimulated thus storing
more carbon dioxide?
Factors Affecting the Earth’s
Temperature
Positive (amplify) vs. Negative (dampen)
Feedbacks, Give example of both types
Changes in solar output
Changes in Earth’s albedo
Moderating effect of oceans
Clouds and water vapor
Air pollution
Ocean Storage of CO2 and Heat
Ocean currents act to
redistribute heat
arriving at equator
moving it north.
Example: Gulf Stream
Deep ocean currents not
well understood.
Ocean Storage of CO2 and Heat
Evidence has shown that
ocean currents have
shifted and even stopped
during times in the past.
Effect of salinity levels
(cold, salty water more
dense)
“Day After Tomorrow”
movie effect…more
Hollywood than science
Ocean Storage of CO2 and Heat
Oceans also act to trap
about 29% of CO2
released into the
atmosphere as part of
global carbon cycle.
Cloud Cover
Warmer Troposphere =
More Evaporation =
More Clouds =
WARMER OR COOLER?
Why might it be a
positive feedback?
Why might it be a
negative feedback?
Cloud Cover
• Day versus Night
Impacts
• Thick clouds versus
thin clouds
• High clouds versus Low
clouds
• Latent heat release
during cloud formation
Air Pollution
Soot and other pollutants
can warm or cool the
troposphere.
Complex interactions
between air pollutants
and their location in the
atmosphere may warm
or cool the troposphere.
Solar dimming effect
Photosynthesis
More CO2 =
More Plant Growth =
Less CO2 in atmosphere
Right?
Or is this temporary?
• Young vs. Old Plants
• Once dead
Summer versus Winter
Methane Gas
Warmer air release more
methane caught up in:
• Bogs and wetlands
• Permafrost in tundra
CH4 is a more powerful
greenhouse gas than
CO2
Section 5 Review
• Can oceans store more carbon dioxide and
heat?
• How might changes in cloud cover affect the
troposphere’s temperature?
• What impact does air pollution have on
temperature?
• Can photosynthesis be stimulated thus storing
more carbon dioxide?
Permafrost
Section 6 Some Possible Effects of
a Warmer World
• What are some possible effects of a warmer
troposphere?
• Ecosystem changes
• Agricultural changes
• Rising Sea Level
• Project presentations:1) Agriculture, water
resources, forests, biodiversity, sea level,
weather extremes, human population, human
health.
Some Possible Effects of a
Warmer World
Possible Benefits from a Warmer
Atmosphere
 Less severe winters
 More precipitation in some dry areas
 Less precipitation in some wet areas
 Increased food production in some areas
 Expanded population and ranges of some species
Refer to Fig. 21-13 p. 476
Section 7 Dealing with the Threat of
Climate Change
• What are our best options?
• What can be done to reduce the threat?
• What about storing carbon dioxide (carbon
sequestration)?
• How can government play a role in reducing
impacts?
• What is carbon trading?
• What are the costs of not acting?
Dealing with the Threat of Climate
Change
There is little disagreement
that our planet is
warming, where most
disagreement lies is in
what to do about it.
1) Are economic costs of
reducing greenhouse
gases higher than
benefits?
Dealing with the Threat of Climate
Change
2) Developed or developing
countries, how should
take responsibility?
3) Voluntary cuts or
mandatory laws?
Arguments transcend
politics, economics,
scientific, cultural….
Solutions: Dealing with the Threat
of Climate Change
Options
 Do nothing
 Do more research
 Act now to reduce
risks
 Precautionary
principle
Fig. 21-17 p. 479
What can be done?
• Improve energy
efficiency
• Reduce fossil fuel use
• Renewable energy
sources
• Reduce population
growth
• Reduce deforestation
• Carbon sequestration
Removing CO2 from the Atmosphere
Fig. 21-18 p. 480
How can the government help
• Tax emissions (carbon
tax)
• Increase subsidies for
energy efficiency and
renewable energy
• Cut subsidies for fossil
fuels
• Help induce technology
transfer
Emissions Trading
Buying and selling
“carbon” credits on the
open marketplace.
CAP and Trade System
Set a nationwide goal and
allow markets to decide
how to reach the goal.
Acting Later May Cost More
It is likely to cost us less
to help slow and adapt
to global climate
change today than deal
with effects later.
Costs versus Benefits
Section 8: What is being Done?
• Kyoto Protocol: What is it? What are the
problems with it?
• What are some other countries, states,
businesses doing?
• What can we do to prepare for warming?
• Why is global warming such an “Inconvenient
Truth”
Reducing Greenhouse Gas Emissions
 Kyoto Treaty (1997)
 U.S. withdraws from Kyoto Treaty (2001)
 Other reductions in CO2
Refer to Fig. 21-18 p. 483
Kyoto Protocol
December 1997 – 2,200
delegates from 161
nations
39 Developed countries
cut greenhouse gas
emissions 5.2% below
1990 by 2012
Developed countries no
cuts until later
Kyoto Protocol
Kyoto would only be a
first start (5.2% below
1990 is not much)
Ratified by more than 120
nations.
Pres. Bush withdraws in
2001
Kyoto Protocol
Several ideas floated, but
no real negotiations.
Next steps????
What some are already doing
Some countries,
companies, U.S. states
and cities are beginning
to make voluntary cuts
Great Britain went below
1990 levels and aims to
cut by 60% by 2050
BP has met goals of
Kyoto
What some are already doing
Why are some
states, cities, or
even countries
acting alone a
waste when it
comes to global
warming?
How to prepare for warming
Humans need to adapt
lifestyles to fit warming
already “built in.”
• Conservation of water
• Moving from coastal zones
• Expand wildlife preserves
toward poles
• Preparing for expanded
disease areas
• Recreational, agriculture
shifts
Insurance industry beginning
to prepare.
Why is climate change so
difficult of a problem
“An Inconvenient Truth”
• Long term issue (political system
short term)
• Consequences in future
• Slow change on human time
scale
• Uncertainty built up by industries
• Changing lifestyles
• International issue
• Hopelessness
Section 8 Review
• Kyoto Protocol: What is it? What are the
problems with it?
• What are some other countries, states,
businesses doing?
• What can we do to prepare for warming?
• Why is global warming such an “Inconvenient
Truth”