1. 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

2. 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?

3. 18-1: Past Climate Change and the Natural Greenhouse Effect
Average temperature over past 900,000 years
Thousands of years ago
900
800
700
600
500
400
300
200
100
Present
Average surface tem
perature (°C) 9 10 11 12 13 14 15 16 17
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 surface temperature (°C)
Average temperature over past 130 years
Year
1860
1880
1900
1920
1940
1960
1980
2000
2020
13.6
13.8
14.0
14.2
14.4
14.6
14.8
15.0

4. 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.

5. The Natural Greenhouse Effect
Rays of sunlight penetrate the lower atmosphere and warm the earth's surface.
The earth's surface absorbs much 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.
As concentrations of greenhouse
gases rise, their molecules absorb and emit more infrared radiation, which adds more heat to the
lower atmosphere.
(a)
(b)
(c)
Fig. 6.13, p. 128

6. 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

7. 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

8. Primary Greenhouse Gases
Water Vapor: Controlled by the hydrologic cycle
Carbon Dioxide: Controlled by the carbon cycle
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
Year
1860
1880
1900
1920
1940
1960
1980
2000
2010
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Observed
Model of greenhouse
gases + aerosols +
solar output
Temperature change (°C) from 1980–99 mean

9. Climate Change and Human Activities
Since the Industrial Revolution (1750) there has been a sharp rise in:
Use of fossil fuels
Deforestation and burning grasslands to raise crops
Cultivating rice and using fertilizer that releases N2O

10. Largest Contributors to CO2 Emissions
Thousands of Coal Burning power and industrial plants
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)

12. The role of additional CO2 in the Atmosphere:
Most climate scientists believe that the increased input of CO2 will…
Enhance the earth’s natural greenhouse effect
Raise the average global temperature of the atmosphere near the surface of the earth
“GLOBAL WARMING”

17. 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

18. Global Warming Graph and Map Information

19. Carbon dioxide Methane Nitrous oxide 250 200 Index (1900 = 100) 150
1990
2000
2025
2050
2075
2100
Fig. 18.5, p. 451
Year

20. 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 4-8” 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

21. The Effect of Global Warming on Glacier National Park
1911
2000

22. 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.

23. 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 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.

24. 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 ever-increasing numbers.
These images show damage to White Spruce trees in Alaska caused by the pests.

25. Temperature change (°C) from 1980–99 mean
1.2
Observed
1.0
Model of greenhouse
gases + aerosols +
solar output
0.8
0.6
Temperature change (°C) from 1980–99 mean
0.4
0.2
0.0
-0.2
1860
1880
1900
1920
1940
1960
1980
2000
2010
Year
Fig. 18.7, p. 453

26. What do the changes in climate mean for humans?
Affects the availability of water resources by altering rates of evaporation and precipitation
Shift areas where crops can be grown
Change average sea levels
Alter the structure and location of the world’s biomes

28. Change in temperature (ºC)
6.0
5.5
5.0
4.5
4.0
3.5
3.0
Change in temperature (ºC)
2.5
2.0
1.5
1.0
0.5
1850
1875
1900
1925
1950
1975
2000
2025
2050
2075
2100
Fig. 18.8, p. 453
Year

29. 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%

30. 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

32. 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

33. Problems in Greenland The worlds largest island (3x the size of Texas)
If the glaciers melt as they did 110, ,000 years ago:
Average sea levels would rise feet
Massive flooding in the low lying coastal areas and cities
Could shut down the Gulf Stream and North Atlantic Current which keep Europe warmer than it naturally would be

34. This has nothing to do with global warming!!!

35. Cell Clouds Land Continent Ocean
Fig. 18.6, p. 452

36. 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

37. present sea level (meters)
Today’s sea level
Height below present
sea level (feet)
present sea level (meters)
Height above or below
–130
–426
250,000
200,000
150,000
100,000
50,000
Years before present
Present
Fig , p. 456

38. Sea Level and Coastal Areas
Agriculture
Water Resources
Forests
Shifts in food-growing areas
Changes in crop yields
Increased irrigation demands
Increased pests, crop diseases, and weeds in warmer areas
Changes in water supply
Decreased water quality
Increased drought
Increased flooding
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
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
Extinction of some plant and animal species
Loss of habitats
Disruption of aquatic life
Weather Extremes
Human Health
Human Population
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
Prolonged heat waves and droughts
Increased flooding
More intense hurricanes, typhoons, tornadoes, and violent storms
Increased deaths
More environmental refugees
Increased migration
Fig , p. 458

39. Present
range
Future
range
Overlap
Fig , p. 459

40. Prevention Cleanup Cut fossil fuel use (especially coal) Remove CO2
from smokestack
and vehicle
emissions
Shift from coal
to natural gas
Transfer energy
efficiency and
renewable energy
technologies
to developing
countries
Store (sequester
CO2 by planting
trees)
Sequester CO2
underground
Improve energy
efficiency
Sequester CO2
in soil
Shift to
renewable
energy resources
Sequester CO2
in deep ocean
Reduce
deforestation
Use sustainable
agriculture
Slow population
growth
Fig , p. 461

41. Develop crops that need less water Waste less water
Move hazardous material storage
tanks away from coast
Prohibit new construction on low-lying coastal areas
Stockpile 1 to 5 year supply of key foods
Expand existing wildlife
reserves toward poles
Connect wildlife
reserves with corridors
Fig , p. 465

42. 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 oF over the next 100 yrs.
The average sea level will rise by 35” by the end of the century

43. 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.

44. 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

45. Cold water melting from Antarctica's ice cap and
icebergs falls to the ocean floor
and surges northward, affecting
worldwide circulation.
Greenland
Antarctica
Fig , p. 456

47. The Role of Air Pollution on Climate Change
Aerosols actually help reduce global warming
At high altitudes aerosols attract water to form clouds that reflect sunlight
Soot is the second biggest contributor to global warming (15-30%)
Produced as a product of burning of coal and diesel fuel

48. 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

49. 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

50. 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.