Transcript Global Warming and Climate Change

Global Warming and
Climate Change
“We are embarked on the most
colossal ecological experiment of
all time-doubling the concentration
in the atmosphere of an entire
planet of one of its most important
gases – and we really have no idea
of what might happen.”
Paul A. Colinvaux
Key Points
• How has the earth’s climate changed in
the past?
• How may it change in the future?
• What factors can affect changes in the
average temperature?
• What are the possible side effects of a
warmer earth?
• What can we do to slow or adapt to global
climate change?
18-1: Past Climate Change and
the Natural Greenhouse Effect
17
Average surface tem
perature (°C)
16
15
14
13
12
11
10
9
900
Average surface temperature (°C)
• Over the past
900,000 years
there have been
time periods of
cooling and
warming
• For the past
10,000 years we
have had the
good fortune of a
stable climate
Average temperature over past 900,000 years
800
700
600 500 400 300 200
Thousands of years ago
100 Present
Average temperature over past 130 years
15.0
14.8
14.6
14.4
14.2
14.0
13.8
13.6
1860 1880 1900 1920 1940 1960 1980 2000
Year
2020
What is the Greenhouse Effect
For the earth to maintain a
constant temperature
incoming solar energy
must be balanced by an
equal amount of
outgoing energy
Greenhouse Effect:
gases warm the lower
atmosphere by
absorbing some of the
infrared radiation
radiated from the earths
surface.
The Natural Greenhouse Effect
(a) Rays of sunlight
penetrate the lower
atmosphere and warm
the earth's surface.
(b) The earth's surface absorbs much (c) As concentrations of
of the incoming solar radiation and
degrades it to longer-wavelength
infrared radiation (heat), which
rises into the lower atmosphere.
Some of this heat escapes into
space and some is absorbed by
molecules of greenhouse gases
and emitted as infrared radiation,
which warms the lower
atmosphere.
greenhouse
gases rise, their molecules
absorb and emit more
infrared radiation, which adds
more heat to the
lower atmosphere.
Fig. 6.13, p. 128
Not a Real
Greenhouse
• In a real greenhouse the
air heats up because it
can’t escape by
convection to outside air
• In reality heat is
released and spread
through the atmosphere
by convection
Actual effect:
Tropospheric heating
effect
The Role of the Greenhouse Effect
(GHE)
• Discovered in 1896
• With no GHE the earth would be too cold
• If the GHE acted by itself the average
surface temperature would be 130o F
• Natural cooling takes place by:
– Releasing heat through evaporation
– Water vapor molecules rise to the clouds
and release heat into the upper atmosphere
• Actual average temperature: 59o F
Primary Greenhouse Gases
Evaluation of ancient glacial ice reveals:
•
•
•
Water vapor levels have
been relatively constant
over the past 160,000
years
Carbon dioxide levels have
fluctuated
Fluctuations in global
carbon dioxide levels
correspond with the
fluctuation of the global
temperature
1.2
Temperature change (°C) from 1980–99 mean
1. Water Vapor: Controlled by
the hydrologic cycle
2. Carbon Dioxide: Controlled
by the carbon cycle
Observed
1.0
0.8
Model of greenhouse
gases + aerosols +
solar output
0.6
0.4
0.2
0.0
-0.2
1860 1880 1900 1920 1940 1960 1980 20002010
Year
Climate Change and Human
Activities
Since the Industrial
Revolution (1750) there
has been a sharp rise in:
1. Use of fossil fuels
2. Deforestation and burning
grasslands to raise crops
3. Cultivating rice and using
fertilizer that releases N2O
Largest Contributors to CO2
Emissions
1. Thousands of Coal
Burning power and
industrial plants
2. 700 million gasoline
burning motor vehicles
(555 million of them are
cars)
Emissions from US factories
and power plants
produce more CO2 than
the combination of 146
nations (75% of the world
population)
The role of additional CO2 in the
Atmosphere:
Most climate scientists believe that
the increased input of CO2 will…
1. Enhance the earth’s natural
greenhouse effect
2. Raise the average global
temperature of the atmosphere
near the surface of the earth
“GLOBAL WARMING”
Are we experiencing Global
Warming?
The following facts are based on analysis of ice cores, temperature
measurements in hundreds of boreholes into the earths surface and
atmospheric temperature measurements
• CO2 concentrations are at their highest level
in the past 20 million years
• 75% of human caused CO2 emissions are
from the burning of fossil fuels
• The 20th century is the hottest in the past
1000 years
• Since 1861 the global temperature has risen
1.1 – 0.4o F
• 10 hottest years on record have occurred
since 1990
Global Warming Graph and
Map Information
http://data.giss.nasa.gov/gistemp/
Carbon dioxide
Methane
Nitrous oxide
Index (1900 = 100)
250
200
150
100
1990
2000
2025
2050
Year
2075
2100
Fig. 18.5, p. 451
Evidence of a Warmer Troposphere
• Melting of land based ice
caps and floating ice at the
poles and Greenland
• Shrinking of glaciers
• Average sea level rise of 48” over the past 100 years
• Northward migration of
some fish, tree and other
species to find an optimal
temperature
• Early spring arrival and late
autumn frosts
The Effect of Global Warming
on Glacier National Park
1911
2000
Argentina's Upsala Glacier was
once the biggest in South
America, but it is now
disappearing at a rate of 200
meters per year.
The image on the left is from
an 1859 etching of the Rhone
glacier in Valais, Switzerland,
and shows ice filling the valley.
In 2001, the glacier had
shrunk by some 2.5km, and its
'snout' had shifted about 450
meters higher up.
Rising tides
Some scientists predict that a
warmer climate will trigger more
violent storms, which will cause
increased rates of coastal
erosion. This is a section of
shoreline at Cape Hatteras in
North Carolina in the USA,
pictured in 1999 and 2004. The
southern United States and
Caribbean region were battered
by a series of powerful
hurricanes last year.
The Intergovernmental Panel on
Climate Change (IPCC), a
consortium of several thousand
independent scientists, predicts
that sea levels could rise by
between 9 and 88cm in the next
century.
This would threaten low-lying
islands such as Tuvalu in the
Pacific. These images, taken this
year, show the effects of a higher
than usual tide.
As the climate warms up,
mountainous regions may
experience lower levels of
snowfall. This image shows
Mount Hood in Oregon at the
same time in late summer in
1985 and 2002.
More pests
Tree-eating wood beetles are
likely to benefit from a warmer
climate and reproduce in everincreasing numbers.
These images show damage to
White Spruce trees in Alaska
caused by the pests.
Temperature change (°C) from 1980–99 mean
1.2
Observed
1.0
0.8
Model of greenhouse
gases + aerosols +
solar output
0.6
0.4
0.2
0.0
-0.2
1860 1880
1900
1920
1940
Year
1960
1980
2000 2010
Fig. 18.7, p. 453
What do the changes in climate
mean for humans?
1. Affects the availability
of water resources by
altering rates of
evaporation and
precipitation
2. Shift areas where
crops can be grown
3. Change average sea
levels
4. Alter the structure and
location of the world’s
biomes
6.0
5.5
5.0
Change in temperature (ºC)
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
1850 1875 1900 1925 1950 1975 2000 2025 2050 2075 2100
Year
Fig. 18.8, p. 453
CASE STUDY: Early Warnings
from the Arctic
• The poles are heating faster than the rest of the
earth
• The ice in the Arctic Sea is large enough to
cover the USA and is sensitive to air
temperatures
• Temperatures in the Arctic have increased much
faster than the average global temperature
• The light color of ice reflects 80% of the
sunlight, if it melts the ocean will be dark and
absorb 80%
What will happen if the Arctic Ice
Melts?
• Greatly amplify warming of the Arctic
region
• Reroute warm ocean currents
• Could cause significant cooling in parts of
the northern hemisphere
• Especially bad cooling in Europe and
Eastern North America
• Tundra soil has warmed up so much that it
is releasing more CO2 than it is taking in
Case Study: News from
Antarctica and Greenland
• Antarctica has 70% of the
worlds fresh water and 90%
of the reflective ice
• Since 1947 the temperatures
have increased 10oF in the
winter and 4.5oF in the
summer.
• Ice the size of Delaware have
broken off
• Ice melting off the continent
adds to the water volume to
raise sea levels
Problems in Greenland
•
The worlds largest island (3x
the size of Texas)
• If the glaciers melt as they did
110,000-130,000 years ago:
1. Average sea levels would
rise 13-20 feet
2. Massive flooding in the low
lying coastal areas and
cities
3. Could shut down the Gulf
Stream and North Atlantic
Current which keep Europe
warmer than it naturally
would be
This has nothing to do with global warming!!!
http://images.wikia.com/uncyclopedia/images/8/8b/Cat_toast_swirl.gif
Cell
Clouds
Continent
Land
Ocean
Fig. 18.6, p. 452
Clouds 50–55%
Snow 80–90%
City 10–15%
Forest 5%
Grass 15–25%
Bare sand 30–60%
Oceans 5%
Fig. 18.9, p. 454
0
0
–130
250,000
Height below present
sea level (feet)
Height above or below
present sea level (meters)
Today’s sea level
–426
200,000
150,000
100,000
Years before present
50,000
0
Present
Fig. 18.11, p. 456
Agriculture
•
Shifts in food-growing
areas
•
Changes in crop yields
•
Increased irrigation
demands
•
Increased pests, crop
diseases, and weeds in
warmer areas
Water Resources
• Changes in water supply
• Decreased water quality
• Increased drought
• Increased flooding
Forests
•
Changes in forest
composition and locations
•
Disappearance of some
forests
•
Increased fires from drying
•
Loss of wildlife habitat and
species
Biodiversity
Sea Level and Coastal Areas
•
Extinction of some plant
and animal species
•
•
•
Loss of habitats
•
•
Disruption of aquatic life
•
•
•
Weather Extremes
•
Prolonged heat waves
and droughts
•
Increased flooding
•
More intense
hurricanes, typhoons,
tornadoes, and
violent storms
Rising sea levels
Flooding of low-lying islands
and coastal cities
Flooding of coastal estuaries,
wetlands, and coral reefs
Beach erosion
Disruption of coastal
fisheries
Contamination of coastal
aquifiers with salt water
Human Health
Human Population
• Increased deaths
• More environmental
refugees
• Increased migration
•
Increased deaths from heat
and disease
•
Disruption of food and water
supplies
•
Spread of tropical diseases to
temperate areas
•
Increased respiratory disease
•
Increased water pollution
from coastal flooding
Fig. 18.12, p. 458
Present
range
Future
range
Overlap
Fig. 18.13, p. 459
Prevention
Cut fossil fuel
use (especially
coal)
Shift from coal
to natural gas
Transfer energy
efficiency and
renewable energy
technologies
to developing
countries
Improve energy
efficiency
Shift to
renewable
energy resources
Reduce
deforestation
Cleanup
Remove CO2
from smokestack
and vehicle
emissions
Store (sequester
CO2 by planting
trees)
Sequester CO2
underground
Sequester CO2
in soil
Sequester CO2
in deep ocean
Use sustainable
agriculture
Slow population
growth
Fig. 18.14, p. 461
Waste less water
Develop crops
that need less
water
Move hazardous material storage
tanks away from coast
Prohibit new construction on lowlying coastal areas
N
Stockpile 1 to 5 year
supply of key foods
Expand existing wildlife
reserves toward poles
S
Connect wildlife
reserves with corridors
Fig. 18.15, p. 465
Scientific Consensus About Future
Climate Change and its Effects
• “Most of the global warming
experienced over the past 50 years
is the result of human activity”
• 90-95% chance the average global
temperature will rise 2.5-10.4oF
over the next 100 yrs.
• The average sea level will rise by
35” by the end of the century
The Role of Ice in
Global Warming
The Ice Albedo
Feedback System:
• As the ice melts
the water that
results absorbs
more heat
speeding up the
warming process.
Oceans Moderate the surface
temperatures:
• Removes 29% of the CO2, but water is less
capable of dissolving gas as the
temperature increases
• As the temperature increases CO2 will
bubble out of the oceans.
• Oceans store heat energy deep in the water
and may release it into the atmosphere
• There is a conveyor belt that transfers heat
around the world that runs based on
differences in water density. Fresh water
from melted ice may throw the system off
Cold water melting from
Antarctica's ice cap and
icebergs falls to the ocean floor
and surges northward, affecting
worldwide circulation.
Greenland
Antarctica
Fig. 18.10, p. 456
The Role of Air Pollution on
Climate Change
1. Aerosols actually help reduce
global warming
• At high altitudes aerosols attract water
to form clouds that reflect sunlight
2. Soot is the second biggest
contributor to global warming (1530%)
• Produced as a product of burning of
coal and diesel fuel
How Rapidly Can the Climate Shift?
If it changes quickly in a few decades we
may not have time to…
• Switch food growing regions
• Relocate out of flood zones
• Build levees and dikes
This may lead to large numbers of
premature deaths, social and economic
chaos
Possible Effects of a Warmer World
• Changes in water distribution
• Changes in plant and animal
biodiversity
• Cause the coastlines to move in by
0.8miles putting 200 million people
directly at risk
• Contamination of water
• Extreme weather patterns
• Higher death rates due to higher
temperatures
• Increased spread of tropical diseases
such as malaria
In a recent chilling assessment, the World Health
Organizationn (WHO) reported that human-induced changes
in the Earth's climate now lead to at least 5 million cases of
illness and more than 150,000 deaths every year.