1. Global Climate Change
Chapter 14

2. Topics Include: Earth’s climate system Human influences on climate
Methods of climate research
Impacts of global climate change
Future trends and impacts
Responding to climate change

3. Central Case Study: Rising Seas May Flood the Maldives
Tourists think the Maldives Islands are a paradise
Rising seas due to global climate change could submerge them
Flood areas, erode beaches
Damage coral reefs
Residents have evacuated the lowest-lying islands
Small nations do not cause of climate change
Yet they suffer

4. What is climate change?
Section 1

5. What is climate change?
Climate change is the fastest-developing area of environmental science
Climate: an area’s long-term atmospheric conditions
Temperature, precipitation, wind, humidity, etc.
Weather: short-term conditions at localized sites
Global climate change: describes modifications in Earth’s climate
Temperature, precipitation, storm frequency
Global warming and climate change are not the same

6. Global warming
Global warming: an increase in Earth’s average temperature
Only one aspect of climate change
Earth’s climate has varied naturally through time
Today’s climate change is happening at an extremely rapid rate
These changes are due to human fossil fuel combustion and deforestation
Understanding climate change requires understanding how our planet’s climate works

7. Three factors influence Earth’s climate
The sun: without it, Earth would be dark and frozen
It supplies most of Earth’s energy
The atmosphere: without it, Earth’s temperature would be much colder
Clouds, land, ice, and water absorb 70% of incoming solar radiation
The remaining 30% is reflected back into space
The oceans: shape climate by storing and transporting heat and moisture

8. The fate of solar radiation

9. Greenhouse gases warm the lower atmosphere
As Earth’s surface absorbs solar radiation, the surface temperature increases and emits infrared radiation
Greenhouse gases: atmospheric gases that absorb infrared radiation
Water vapor, ozone, carbon dioxide, nitrous oxide, methane, halocarbons (chlorofluorocarbons [CFCs])
Greenhouse gases re-emit infrared energy
Some energy is lost to space
Greenhouse effect: the energy that travels downward warms the atmosphere and the planet’s surface

10. Greenhouse gases are not all equal
Greenhouse gases differ in their ability to warm the trophosphere and surface
Global warming potential: the relative ability of one molecule of a greenhouse gas to contribute to warming
Expressed in relation to carbon dioxide (potential = 1)
Nitrous oxide is 298 times as potent as carbon dioxide
Carbon dioxide contributes most to the greenhouse effect
It is less potent, but far more abundant, than other gases
The major type of human-caused emissions

11. Greenhouse gas concentrations are rising
The greenhouse effect is natural
Greenhouse gases have always been in the atmosphere
We are concerned with the anthropogenic (human-caused) intensification of the greenhouse effect
We have increased the concentration of these gases beyond what we have ever experienced
CO2 has increased from 280 ppm (1700s) to 400ppm ( and over!)
The highest in 800,000 (possibly 20 million) years

16. U.S. emissions of major greenhouse gases

17. Why have CO2 levels risen so rapidly?
Burning fossil fuels transfers CO2 from underground deposits into the atmosphere
The main reason CO2 levels have increased
Deforestation contributes to rising atmospheric CO2
Plants store carbon in their tissues
Less CO2 is absorbed from the atmosphere

19. Other greenhouse gases are increasing
Methane: fossil fuels, livestock, landfills, crops (rice)
Levels have increased 2.5 times since 1750
Nitrous oxide: feedlots, chemical manufacturing plants, auto emissions, and synthetic nitrogen fertilizers
Risen 18% since 1750
Ozone levels have risen 36% due to photochemical smog
The Montreal Protocol has reduced halocarbons (CFCs)
Water vapor: the most abundant greenhouse gas
Contributes most to the natural greenhouse effect
But concentrations have not changed

20. Natural factors affecting climate
Section 2

21. Most aerosols exert a cooling effect
Aerosols: microscopic droplets and particles
They have either a warming or a cooling effect
Soot (black carbon aerosols) causes warming by absorbing solar energy
But most tropospheric aerosols cool the atmosphere by reflecting the sun’s rays
Sulfate aerosols from fossil fuel combustion may slow global warming, at least in the short term
Volcanic eruptions reduce sunlight reaching Earth’s surface and cool the Earth

22. Radiative forcing shows changes in energy
Radiative forcing: the amount of change in thermal energy that a given factor causes
Positive forcing warms the surface
Negative forcing cools it
Earth is experiencing radiative forcing of 1.6 watts/m2 more than it is emitting to space—enough to alter the climate

24. Milankovitch cycles also influence climate
Milankovitch cycles: periodic changes in Earth’s rotation and orbit around the sun
Alter the way solar radiation is distributed over Earth
These cycles modify patterns of atmospheric heating
Triggering climate variation
Glaciation: cold temperatures and ice sheets

26. Solar output and oceans influence climate
Solar output: the sun varies in the radiation it emits
Variation in solar energy (e.g., solar flares) has not been great enough to change Earth’s temperature
Radiative forcing is 0.12 watts/m2 —less than any human causes
Ocean absorption: oceans hold 50 times more carbon than the atmosphere
Slows global warming but does not prevent it
As oceans warm, they absorb less CO2, accelerating warming

27. Ocean circulation influences climate
Ocean circulation: ocean water exchanges heat with the atmosphere
Currents move energy from place to place
The ocean’s thermohaline circulation system affects regional climates
Moving warm tropical water north, etc.
Greenland’s melting ice sheet will affect this flow
El Niño and La Niña events change regional weather
Dry areas get wetter, while wet areas get dryer

28. How did we figure this all out?
Section 3

29. Proxy indicators tell us about the past
Proxy indicators: indirect evidence that serve as substitutes for direct measurements of past climate
Ice caps, ice sheets, and glaciers hold clues to Earth’s climate history
Trapped bubbles in ice cores provide a timescale of:
Atmospheric composition, greenhouse gas concentrations, temperature, snowfall, solar activity
Frequency of fires and volcanic eruptions
Other indicators include pollen preserved in sediment, tree rings, coral reefs

30. 800,000 years of history in an ice core (Vostok Ice Core-National Ice Core)
Concentrations of gas are correlated with temperature
Trapped bubbles contain samples of ancient air

31. Ice Core shows volcanic ash
National Ice Core Laboratory
Longest core to date is over 3,400meters and dates back 68,000years from the West Antarctic Divide Ice Sheet!
Core Freezer!
Ice Core shows volcanic ash

32. Direct measurements tell us about the present
We document daily fluctuations in weather
Temperature, rainfall, wind speed, air pressure
Measuring ocean and atmospheric chemistry began in 1958
Hourly air samples from Mauna Loa Observatory in Hawaii show that…
Atmospheric CO2 concentrations have increased from 315 ppm to 400 ppm since 1958

33. Models help us predict the future
Climate models: combine data from atmospheric and ocean circulation and interactions
To simulate climate processes
If a model accurately reconstructs current climate
It may accurately predict future climate
Modeling is hard because climate and feedback loops are so complex

34. Current and future trends and impacts
Evidence that climate has changed is everywhere
Fishermen in the Maldives, ranchers in Texas, homeowners in Florida, etc.
We cannot blame any single weather event on climate change
But extreme weather is part of a pattern backed by an immense volume of scientific data
The Intergovernmental Panel on Climate Change (IPCC) was established in 1988
Composed of hundreds of international scientists and government representatives

35. The IPCC’s Fourth Assessment Report (2007)
The IPCC report summarized thousands of studies
It documented observed trends in:
Surface temperature, precipitation patterns, snow and ice cover, sea levels, storm intensity, etc.
It predicted future changes on wildlife, ecosystems, and human societies
It discussed strategies to pursue in response to climate change
The authors assigned statistical probabilities to its conclusions and released conservative estimates
We just had the Fifth Assessment Report meeting in April

37. The IPCC’s Fourth Assessment Report (2007)

38. What will the future bring?
Section 5

39. Temperatures continue to increase
Average surface temperatures increased 0.74 °C since 1906
Most of the increase occurred in the last few decades
The 17 warmest years on record have been since 1990
Since the 1960s, each decade has been warmer than the last

40. The future will be even hotter
In the next 20 years, temperatures will rise 0.4C
At the end of the 21st century, temperatures will be 1.8 to 4.0C higher than today’s
We will have unusually hot days and heat waves
Polar areas will have the most intense warming
Sea surface temperatures will rise
Hurricanes and tropical storms will increase in power and duration

41. Temperatures will rise globally
Projected increases in surface temperature for 2090–2099 relative to 1980–1999

42. Precipitation is changing, too
Some regions are receiving more rain and snow
Other areas are receiving less
In the U.S. Southwest, droughts have become more frequent and severe
Harm agriculture, promote soil erosion, reduce water supplies, and trigger fires
In dry, humid regions, heavy rains cause flooding
Kill people, destroy homes, and inflict billions of dollars in damage
Example: 2008 floods in Iowa and the Midwest

43. Projected changes in precipitation
Precipitation will increase at high latitudes and decrease at low and middle latitudes – worsening water shortages in poor nations

44. Melting of snow and ice has severe effects
Mountaintop glaciers are disappearing
Glaciers on tropical mountaintops have disappeared
The remaining 26 of 150 glaciers in Glacier National Park will be gone by 2030
Reducing summertime water supplies to millions
Melting of Greenland’s Arctic ice sheet is accelerating
Warmer water is melting Antarctica’s coastal ice shelves
Interior snow is increasing due to more precipitation
Melting ice exposes darker, less-reflective (lower albedo) surfaces, which causes even more melting

45. Worldwide, glaciers are melting rapidly
Nations are rushing to exploit underwater oil and mineral resources made available by newly opened shipping lanes
Permafrost (permanently frozen ground) is thawing
Destabilizing soil, buildings, etc., and releasing methane
Montana’s Grinnell Glacier has retreated substantially since 1938

46. Rising sea levels will affect millions
Runoff from melting glaciers and ice cause sea levels to rise
As oceans warm, they expand
Leading to beach erosion, coastal floods, intrusion of salt water into aquifers, and storm surges

47. Coastal areas will flood
Storm surge: temporary, localized rise in sea level
Caused by the high tides and winds of storms
A 2004 earthquake caused a tsunami (tidal wave) that killed 100 Maldives residents
Caused $470 million in damages
Cities will be flooded
53% of people in the U.S. live in coastal areas
Vulnerability to storm surges will increase
Rising seas eliminate marsh grasses; dams stop sediment from replenishing deltas

48. Rising sea levels will devastate coasts
Rising seas will displace millions of people from coastal areas
Many will have to invest in costly efforts to protect against high tides and storm surges
Areas that will be most affected include:
Densely populated, poor regions (e.g., Bangladesh)
Storm-prone regions (e.g., Florida)
Coastal cities (e.g., Houston)
Areas with land subsidence (e.g., U.S. Gulf Coast)
Pacific Islands will have to be evacuated

49. Coral reefs are threatened
Coral reefs are habitat for marine species, tourism destinations, and protect coastlines
Warmer waters contribute to coral bleaching
Which kills corals
Ocean acidification: caused by increased CO2
Organisms can’t build their exoskeletons
Oceans have already decreased by 0.1 pH unit
They will decrease 0.15 to 0.35 more units—enough to kill most coral reefs, which will be catastrophic

50. Organisms and ecosystems are affected
Organisms are adapted to their environments
They are affected when those environments change
Global warming modifies temperature-dependent phenomena (e.g., timing of migration, breeding)
Species will move toward the poles or up in elevation
20–30% of species will be threatened with extinction
Rare species will be pushed out of preserves
More CO2 may increase plant growth, but…
Droughts, fire, and disease will decrease plant growth
Fewer plants means more CO2 in the atmosphere

51. Animals and plants have nowhere to go
Animals and plants adapted to montane environments will be forced uphill until there is no place to go
Many bird species have shifted their ranges northward in the past 40 years

52. Climate change affects society
Societies are already feeling impacts of climate change
Agriculture: shortened growing seasons, decreased production, crops more susceptible to droughts
Increasing hunger in many developing nations
Forestry: increased fires, invasive species
Insect and disease outbreaks
Health: heat waves and stress can cause death
Respiratory ailments, expansion of tropical diseases
Disease and sanitation problems from flooding
Drowning from storms

53. Climate change affects economics
Costs will outweigh benefits of climate change
It will widen the gap between rich and poor
Those with less wealth and technology will suffer most
It will cost 1–5% GDP (Gross Domestic Product) on average globally
Poor nations will lose more than rich ones
The Stern Review on the Economics of Climate Change predicts it will cost 5–20% of GDP by 2200
Investing 1% of GDP now could avoid these costs

54. Impacts will vary regionally
Where we live will determine how we experience the impacts of climate change
Temperature changes have been greatest in the Arctic
Melting ice sheets, thinning ice, increasing storms, etc.
Harder for people and polar bears to hunt

55. The U.S. Global Change Research Program
In their 2009 report, scientists reported and predicted:
Temperature increases (2.2 – 6.1C higher)
Worse droughts and flooding
Decreased crop yields
Water shortages
Health problems and diseases
Higher sea levels, beach erosion, destroyed wetlands
Drought, fire, and pests will change forests
More grasslands and deserts, fewer forests
Undermined Alaskan buildings and roads

56. Predictions from two climate models
Temperature increases will be much smaller if emissions are lowered

57. Causes and consequences of climate change

58. Are we responsible for climate change?
Scientists agree that increased greenhouse gases are causing global warming
Burning fossil fuels is increasing greenhouse gases
Despite overwhelming evidence for climate change:
Many in the U.S. deny what is happening
People debate if it is real and if humans are to blame
Think tanks and a few scientists question it
The news media present both sides, despite the evidence of climate change
There is a shift in this thinking recently, and the media is saying that climate change is caused by humans

59. Shall we pursue mitigation or adaptation?
Most people accept that we are changing Earth
They are searching for solutions
Mitigation: pursue actions that reduce greenhouse gas emissions to lessen the severity of climate change
Energy efficiency, renewable energy, protecting soil, preventing deforestation
Adaptation: accept that climate change is happening
Pursue strategies to minimize its impacts on us
Seawalls, coping with drought and less water, etc.
We need to pursue both

60. Solutions
Section 6

61. Developing solutions
Electrical generation: the largest source of U.S. CO2
70% of electricity is from fossil fuels, especially coal
To reduce fossil fuel use:
Conservation, efficiency, cleaner or renewable energy
Cogeneration, more efficient appliances
Carbon capture: removes CO2 from power plant emissions
Carbon sequestration (storage): storing carbon underground (old oil deposits, salt mines, etc.)
We can’t store enough CO2 to make a difference

62. Transportation 2nd largest source of U.S. greenhouse gases
Cars are extremely inefficient
Solutions: drive fuel-efficient, hybrid, or electric cars
Drive less and use public transportation
Live near your job, so you can bike or walk

63. We can reduce emissions in other ways
Agriculture: sustainable land management lets soil store more carbon
Reduce methane emissions from rice and cattle
Grow renewable biofuels
Forestry: reforest cleared land, preserve existing forests
Sustainable forestry practices
Waste management: treating wastewater
Generating electricity by incinerating waste
Recovering methane from landfills
Individuals can recycle, compost, reduce, or reuse goods

64. We need to follow multiple strategies
There is no magic bullet for mitigating climate change
Reductions can be achieved with technology we can use right away
Just 15 strategies can eliminate 15 billion tons of CO2 by 2050
7 of the 15 would stabilize CO2 emissions

65. What role should government play?
To reduce emissions, should the government:
Mandate change through laws and regulations?
Impose no policies and hope for solutions?
Give private entities incentives to reduce emissions?
Many businesses and politicians have opposed all government action
Fearing it will cost industry and consumers
In 2007 the U.S. Supreme Court ruled that the EPA could regulate CO2 as a pollutant

66. Where are we now with legislation?
The 2009 House of Representatives’ cap-and-trade system did not pass the Senate
Industries would compete to reduce emissions for financial gain
Responsibility for emissions now goes to the EPA
It began developing regulations in 2011
Emission limits will be phased in over years, while increasing efficiency and renewable energy
This will minimize economic impacts and political opposition
After most recent report this past May, we will be seeing changes in legislation hopefully soon

67. The FCCC
U.N. Framework Convention on Climate Change: a plan to voluntarily reduce greenhouse gas emissions
To 1990 levels by 2000
This voluntary approach did not succeed
Signatory nations created a binding international treaty requiring emission reductions
The Kyoto Protocol (1997): signatory nations must reduce emissions of six greenhouse gases
To levels below those of 1990 (by 2008–2012)

68. The Kyoto Protocol tried to limit emissions
This treaty took effect in 2005
After Russia became the 127th nation to ratify it
The United States will not ratify the Kyoto Protocol
It requires industrialized nations to reduce emissions
But it does not require industrializing nations (China and India) to reduce theirs
Other countries resent the U.S. because it emits 20% of the world’s greenhouse gases but won’t take action
This undermines the treaty’s effectiveness
Signatory nations have increased emissions 7.9%

69. Climate negotiations have progressed
The Kyoto Protocol ended in 2012
The 2009 Copenhagen conference ended in discord
China wouldn’t allow international monitoring
Obama would not promise more than Congress had agreed to
Cancun’s 2010 meeting was more productive
Developed nations will help developing nations with technology and with mitigation and adaptation
Nations that reduce deforestation will be rewarded
China and India will reduce emissions (in principle)

70. Will emissions cuts hurt the economy?
The U.S. Senate, China, and India feel reducing emissions will hurt the economy
Economic vitality does not need higher emissions
Germany, England, and France cut emissions while keeping a high standard of living
Industrialized nations gain from developing and marketing new technologies
The future belongs to nations willing to act now

71. States and cities are advancing policies
The U.S. federal government is not acting
So state and local governments are
The Mayors Climate Protection Agreement
Will meet or beat Kyoto’s guidelines
California’s Global Warming Solutions Act will cut emissions 25% by 2020
Regional Greenhouse Gas Initiative (RGGI) (2007)
10 northeastern states
Set up a cap-and-trade program

72. Market mechanisms address climate change
Permit trading programs harness the economic efficiency of the free market to achieve public policy goals
Businesses have flexibility in how they meet the goals
Polluters choose how to cut their emissions
They have financial incentives to reduce them

73. Cap-and-trade emissions trading programs
The Regional Greenhouse Gas Initiative:
Each state decides which polluting sources participate
Each state sets a cap on total CO2 emissions it allows
Each emissions source gets one permit for each ton it emits, up to the amount of the cap
Each state lowers its cap over time
Sources with too few permits must reduce emissions, buy permits from others, or pay for carbon offsets
Sources with too many permits may sell them
Any source emitting more than permitted will be penalized

74. Cap-and-trade programs already exist
Cap-and-trade programs will be self-sustaining
Permit prices fluctuate in the market
The European Union Emission Trading Scheme (2005)
The world’s largest cap-and-trade program
Governments had allocated too many permits
Industries had little incentive to cut emissions
Permits lost 90% of their value
The EU is trying to fix these problems
Permits work only if government policies limit emissions

75. Carbon taxes are another option
Critics say cap-and-trade systems are not effective
Carbon tax: governments charge polluters a fee for each unit of greenhouse gases they emit
Polluters have a financial incentive to reduce emissions
European nations, British Columbia, and Boulder, Colorado, have carbon taxes
However, polluters pass costs on to consumers
Fee-and-dividend: funds from the carbon tax (fee) are passed to taxpayers as refunds (dividends)

76. Carbon offsets are popular
Carbon offset: payment to another entity to reduce the greenhouse emissions that one is unable to reduce oneself
The payment offsets one’s own emissions
Popular among utilities, businesses, universities, governments, and individuals trying to achieve …
Carbon-neutrality: where no net carbon is emitted
Carbon offsets fall short
Rigorous oversight is needed to make sure that the offset money accomplishes what it is intended for
Offsets must fund emissions reductions that would not occur otherwise

77. Corporations are going carbon-neutral
Businesses are using carbon offsets to become more sustainable
But they can also directly reduce their carbon footprint
Pearson Education became carbon neutral in 2009
12% savings: energy-efficient buildings, computer servers, vehicles, reducing business travel
47% savings: buying clean, renewable energy
41% savings: forest preservation projects around the world

78. Should we engineer the climate?
Geoengineering: drastic, assertive steps to change Earth’s climate
Suck carbon out of the air by planting trees, fertilizing the ocean with iron
Block sunlight with dust, seeding clouds, installing mirrors on land, on sea, and in space
These solutions are technically daunting, are decades away, and have unexpected environmental risks
Be careful of hoping for easy technological solutions
Use geoengineering as a back-up plan

79. Cooling the planet through geoengineering

80. You can reduce your carbon footprint
Carbon footprint: the amount of carbon we are responsible for emitting
People may take many steps to decrease their footprint
College students must help drive personal and societal changes needed to mitigate climate change
In 2009, 5,200 events were held in 181 nations
“The most widespread day of political action in the planet’s history”
Global climate change is our biggest challenge
With action, we can avert the most severe impacts

81. Conclusion Many factors influence Earth’s climate
Human activities play a major role
Climate change is well underway
Further greenhouse gas emissions will cause severe impacts
More and more people are urging immediate action
Reducing emissions and mitigating and adapting to a changing climate are the foremost challenges for our society