1. The Maldives:

2. Rising seas may flood the Maldives
Island paradise
Rising seas due to global climate change could submerge them
Erode beaches, cause flooding
Damage coral reefs
Contaminate fresh water
Residents have evacuated
the lowest-lying islands

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

4. Global warming
Global warming = an increase in Earth’s average temperature
Only one aspect of climate change
Climate change and global warming refer to current trends
Earth’s climate has varied naturally through time
The current rapid climatic changes are due to humans
Fossil fuels and deforestation

5. The sun and atmosphere keep Earth warm
Four factors exert most influence on climate:
The sun = without it, Earth would be dark and frozen
Supplies most of Earth’s energy
The atmosphere = without it, Earth’s temperature would be much colder
The oceans = shape climate by storing and transporting heat and moisture
How Earth spins, tilts, and moves through space influences how the climate varies over long periods of time

6. The fate of solar radiation
The atmosphere, land, ice, and water absorb 70% of incoming solar radiation – 30% is reflected back

7. Greenhouse gases warm the lower atmosphere
Earth’s surface absorbs solar radiation, warms up, 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 then re-emit infrared energy, to earth and space
Greenhouse effect = greenhouse gases keeping the surface warm

8. The greenhouse effect is natural
Greenhouse gases have always been in the atmosphere
We are not worried about the natural greenhouse effect (we need it)
Anthropogenic increase is worrisome

9. Carbon dioxide is of primary concern
It is not the most potent greenhouse gas, but there is a lot of it
The major contributor to the greenhouse effect
CO2 exerts six times more impact than methane, nitrous oxide, and halocarbons combined

10. What caused levels of CO2 to increase?
Burning fossil fuels moves CO2 from lithospheric stores into the atmosphere
The main reason for increased atmospheric CO2
Deforestation contributes to rising atmospheric CO2
Forests serve as reservoirs for carbon
Removing trees reduces the carbon dioxide absorbed from the atmosphere
Humans have increased atmospheric CO2 from 280 parts per million (ppm) to 389 ppm
The highest levels in more than 800,000 years
OMG right?

11. Fluxes of carbon dioxide

12. Other greenhouse gases add to warming
Methane = fossil fuels, livestock, landfills, crops (rice)
Nitrous oxide = feedlots, chemical manufacturing plants, auto emissions, and synthetic nitrogen fertilizers
Ozone levels have risen 36% due to photochemical smog
Halocarbon gases (CFCs) are declining due to the Montreal Protocol
Water vapor = the most abundant greenhouse gas
Contributes most to the natural greenhouse effect
Concentrations have not changed

13. U.S. emissions of major greenhouse gases

14. Feedback complicates our predictions
Tropospheric warming will transfer more water to the air
But the effects are uncertain
A positive feedback loop? = more water vapor … more warming … more evaporation … more water vapor …
A negative feedback loop? = more water vapor … more clouds … shade and cool Earth
Minor modifications of the atmosphere could lead to major effects on climate

15. Most aerosols exert a cooling effect
Aerosols = microscopic droplets and particles
Can have either a warming or a cooling effect
Soot (black carbon aerosols) causes warming by absorbing solar energy
Most tropospheric aerosols cool the atmosphere by reflecting the sun’s rays

16. Milankovitch cycles influence climate
Milankovitch cycles = periodic changes in Earth’s rotation and orbit around the sun
Alter the way solar radiation is distributed over Earth
Modify patterns of atmospheric heating
Triggering climate variation
For example, periods of cold glaciation and warm interglacial times

17. Solar output and ocean absorption 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
Ocean absorption = the ocean holds 50 times more carbon than the atmosphere
Slowing global warming but not preventing it
Warmer oceans absorb less CO2
A positive feedback effect that accelerates warming

18. Proxy indicators tell us about the past
Proxy indicators = indirect evidence
Ice caps, ice sheets, and glaciers:
Trapped bubbles in ice cores provide a timescale of:
Atmospheric composition, greenhouse gas concentrations, temperature trends
Snowfall, solar activity, and frequency of fires

19. Ice cores from Antarctica
Ice cores let us go back in time 800,000 years

20. More proxy indicators
Cores in sediment beds preserve pollen grains and other plant remnants
Tree rings indicate age, precipitation, droughts, and fire history
In arid regions, packrats carry seeds and plants to their middens (dens)
Plant parts can be preserved for centuries
Researchers gather data on past ocean conditions from coral reefs
Scientists combine multiple records to get a global perspective

21. Models help us predict the future
Climate models = programs combine what is known about:
Atmospheric and ocean circulation
Atmosphere–ocean interactions
Feedback mechanisms
Etc...
Models simulate climate processes to predict climate change

22. Global Climate Models
The State of the Art in Modeling the Climate (2005)

23. Results from three simulations
Figure (a) shows natural climate factors only
Figure (b) shows only human factors
Greenhouse gas emissions
Figure (c) shows both factors
(Red line is observed climate data)

24. Current and future trends and impacts
Evidence that climate conditions have changed since industrialization is everywhere
Fishermen in the Maldives, ranchers in Texas, homeowners in Florida, etc.
Scientific evidence that climate has changed is overwhelming and indisputable
Intergovernmental Panel on Climate Change (IPCC) was established in 1988
Composed of hundreds of international scientists and government officials

25. The IPCC’s fourth assessment report (2007)
The IPCC reports on the synthesis of scientific information concerning climate change
Global consensus of scientific climate research
Summarized thousands of studies
Evidence is overwhelming

26. Temperatures continue to increase
Average surface temperatures increased 0.74 °C since 1906
Most of the increase occurred in the last few decades
Number of extremely hot days have increased
The 16 warmest years on record have been since 1990

27. The future will be hotter
In the next 20 years, temperatures will rise 0.4°C
At the end of the 21st century, temperatures will be 1.8– 4.0 °C higher than today’s
We will have more 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

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

29. Precipitation is changing, too
Some regions are receiving more precipitation than usual, and others are receiving less
Droughts have become more frequent and severe
Harming agriculture, increasing soil erosion, reducing water supplies, and triggering fires
Heavy rains contribute to flooding
Killing people, destroying homes, and inflicting billions of dollars in damage

30. Projected changes in precipitation
Precipitation will increase at high latitudes and decrease at low and middle latitudes

31. Figure SPM.7
Figure SPM.7. Relative changes in precipitation (in percent) for the period 2090–2099, relative to 1980–1999. Values are multi-model averages based on the SRES A1B scenario for December to February (left) and June to August (right). White areas are where less than 66% of the models agree in the sign of the change and stippled areas are where more than 90% of the models agree in the sign of the change. {Figure 10.9}
Relative changes in precipitation (in percent) for the period 2090–2099, relative to 1980–1999. Values are multi-model averages based on the SRES A1B scenario for December to February (left) and June to August (right). White areas are where less than 66% of the models agree in the sign of the change and stippled areas are where more than 90% of the models agree in the sign of the change. {Figure 10.9}

32. Melting snow and ice Glaciers are disappearing
Glaciers on tropical mountaintops have disappeared
The remaining 26 of 150 glaciers in Glacier National Park will be gone by 2020 or 2030
Reducing summertime water supplies
Melting of Greenland’s Arctic ice sheet is accelerating
Warmer water is melting Antarctic coastal ice shelves
Interior snow is increasing due to more precipitation
Melting ice exposes darker, less-reflective surfaces, which absorb more sunlight, causing more melting

33. 2007 vs 2005

34. Melting ice...
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

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

36. Coastal areas will flood
Storm surge = temporary, localized rise in sea level
Caused by the high tides and winds of storms
Cities will be flooded
53% of people in the U.S. live in coastal areas

37. Rising sea levels will devastate coasts
1 million acres of Louisiana’s wetlands are gone
Rising sea levels eat away vegetation
Dams upriver decrease siltation
Pollution from the Deepwater Horizon
Millions of people will be displaced from coastal areas

38. Coral reefs are threatened
Coral reefs are habitat for food fish
Snorkeling and scuba diving sites for tourism
Warmer waters contribute to coral bleaching
Which kills coral
Increased CO2 is acidifying the ocean
Organisms can’t build their exoskeletons
Oceans have already decreased by 0.1 pH unit
Enough to kill most coral reefs

39. Climate change affects organisms and ecosystems
Organisms are adapted to their environments
Global warming modifies temperature-dependent phenomena (e.g., timing of migration, breeding)
Animals and plants will move toward the poles or upward in elevation
20–30% of species will be threatened with extinction
Droughts, fire, and disease will decrease plant growth

40. Animals and plants have nowhere to go
Animals and plants adopted to montane environments will be forced uphill until there is no place to go

41. Climate change affects people
Societies are feeling the impacts of climate change
Agriculture: shortened growing seasons, decreased production, crops more susceptible to droughts
Increasing hunger
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

42. 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
External costs of damages will be $10–350/ton of carbon
It will cost 1–5% GDP on average globally
Poor nations will lose more than rich ones
The Stern Review predicts it will cost 5–20% of GDP by 2200
Investing 1% of GDP now could avoid these costs

43. Impacts will vary regionally
Where we live will determine how we experience the impacts of climate change
Temperature changes have been greatest near the poles
Melting ice sheets, thinning ice, increasing storms, etc.
Harder for people and polar bears to hunt
U.S. temperatures will continue rising
Plant and animal communities will shift north and upward
More intense extreme weather events
The southern U.S. will get drier, the northern wetter
Sea levels will rise and may be worse in the East

44. Impacts of climate change
The Arctic has suffered the most so far
U.S. temperatures will continue to rise

45. Impacts of climate change will vary

46. Are we responsible for climate change?
Scientists agree that increased greenhouse gases are causing global warming
Burning fossil fuels is increasing greenhouse gases
In 2005, scientists from 11 nations issued a joint statement urging political leaders to take action
There is a broad and clear scientific consensus that climate change is a pressing issue
But many people deny what is happening
People will admit the climate is changing
But doubt we are the cause

47. The debate over climate change is over
Conservative think tanks and industry-sponsored scientists cast doubt on the scientific consensus
The news media tries to present two sides to an issue
But the sides’ arguments are not equally supported by evidence
Most Americans accept that fossil fuel consumption is changing the planet

48. Electricity generation
A coal-fired, electricity-generating power plant
The largest source of U.S. CO2 emissions
70% of electricity comes from fossil fuels
Coal causes 50% of emissions
To reduce fossil fuel use:
Encourage conservation and efficiency
Switch to cleaner and renewable energy sources

49. Conservation and efficiency
We can make lifestyle choices to reduce electricity use
Use fewer greenhouse-gas-producing appliances
Use electricity more efficiently

50. Sources of electricity
We need to switch to clean energy sources
Nuclear power, biomass energy, solar, wind, etc.
We need to consider how we use fossil fuels
Switching from coal to natural gas cuts emissions 50%
Cogeneration produces fewer emissions
Carbon capture = removes CO2 from power plant emissions
Carbon sequestration (storage) = storing carbon underground where it will not seep out
We can’t store enough CO2 to make a difference

51. Transportation 2nd largest source of U.S. greenhouse gases
Cars are inefficient
Ways to help:
More efficient cars
Drive less and use public transportation
Ride a bike!
U.S. public transportation saves 4.2 billion gallons of gasoline and 37 million metric tons of CO2 emissions per year

52. Conventional cars are inefficient

53. 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
Store carbon in trees and soil
Waste management: treating wastewater
Generating electricity by incinerating waste
Using the methane from landfills
Individuals can recycle, compost, reduce, or reuse goods

54. We need to follow multiple strategies
There is no magic bullet for mitigating climate change

55. Kyoto Protocol
International agreement to reduce greenhouse gas emissions
NOT ratified by: USA, Afghanistan, Andorra, and S. Sudan (Canada backed out)

56. States and cities are advancing policies
The U.S. federal government is not taking action
State and local governments are
By 2010, 1,000 mayors signed the U.S. Mayors Climate Protection Agreement
To meet or beat Kyoto Protocol guidelines
California passed the Global Warming Solutions Act
To cut emissions 25% by 2020
Regional Greenhouse Gas Initiative (RGGI) in 2007
10 northeastern states
Set up a cap-and-trade program

57. You can reduce your carbon footprint
People may apply many strategies to decrease their footprint
YOU must help drive personal and societal changes needed to mitigate climate change
Global climate change may be the biggest challenge facing us and our children
We can make a difference, remember the ozone!