1. Climate and Climate Change Chapter 11
Natural Hazards, 2e
Climate and Climate Change
Chapter 11

2. Learning Objectives
Understand the difference between climate and weather, and how their variability is related to natural hazards
Know the basic concepts of atmospheric science such as structure, composition, and dynamics of the atmosphere
Understand how climate has changed during the last million years, through glacial and interglacial conditions, and how human activity is altering our current climate

3. Learning Objectives, cont.
Understand the potential causes of climate change
Know how climate change is related to natural hazards
Know the ways we may mitigate climate change and associated hazards

4. Climate and Weather
Weather refers to atmospheric conditions over short periods of time.
Climate refers to characteristic atmospheric conditions over a long period of time.
Climate zones
Defined using Koeppen System
Uses monthly average temperature and precipitation associated with different types of vegetation

5. Koeppen’s Classification System
A-tropical, temp>18oC (64oF) year round
B-Dry, evaporation > precipitation
C- Mild Mid-latitude, 18oC (64oF)>coldest month> -3oC (27oF)
D- Severe Mid-latitude, coldest month< -3oC (27oF)
E – Polar, temp < -3oC (27oF) year round
H-Highland, Mountain areas

7. Atmospheric Conditions
Permanent gasses
Gasses whose proportions stay constant
Ex. Nitrogen
Variable gasses
Gasses whose proportions vary with time and space
Ex. Carbon dioxide

8. Permanent Gasses Percentages in atmosphere remain essentially constant
Nitrogen, oxygen, and argon
Compose approx. 99% by volume
Relatively unimportant to atmospheric dynamics

9. Variable Gasses – Carbon Dioxide (CO2)
Extremely important, but small in percentage (approx %)
Describe in parts per million (ppm) or billion (ppb)
Released naturally by volcanic activity, plant and animal respiration, decay of organic material
Removed through photosynthesis, chemical weathering in soil, and mixing of air and seawater

10. Variable Gasses – Carbon Dioxide (CO2), cont.
Anthropogenic sources
Burning of fossil fuels increases CO2 .
Deforestation decreases amount used by trees, increasing ppm in atmosphere.
Natural processes that remove CO2 don’t work as rapidly as amounts are increasing.
Levels increase by 2 ppm per year.

11. Variable Gasses – Water Vapor
Created from evaporation at Earth’s surface.
Returns to surface through hydrologic cycle.
Air temperature is primary control of water vapor content.

12. Variable Gasses – Ozone O3
Forms when atomic oxygen (O) collides with oxygen molecule (O2)
Mostly found in stratosphere
Acts as a shield for ultraviolet light and is essential to life on earth
Chlorofluorocarbons (CFCs) partially destroyed ozone shield
Increases skin cancer, cataracts, caused local crop failures
Can also be found in smog

13. Variable Gasses – Methane (CH4)
Primary constituent of natural gas
Occurs naturally from bacterial decay, intestinal tracks of termites, cows, and sheep
Anthropogenic sources: coal mines, oil wells, leaking natural gas pipelines, rice cultivation, landfills, and livestock
Levels have doubled since 1700 and is a significant contributor to warming

14. Variable Gasses – Nitrous Oxide (N2O)
Natural sources include microbiological processes in soil and ocean and wildfires.
Anthropogenic sources include fertilizers and burning fossil fuels.
Contributes to atmospheric warming.

15. Variable Gasses – Halocarbons
Chemical compounds containing halogen elements bonded with carbon
Include CFCs and are almost entirely anthropogenic
Used in industrial processes, fire fighting, and as fumigants, refrigerants, and propellants
Contribute to warming in troposphere and ozone depletion in stratosphere

16. Aerosols
Microscopic liquid or solid particle that acts as nuclei for water particles to condense to form clouds
Associated with air pollution
Natural sources: desert dust, wildfires, sea spray, and volcanoes
Anthropogenic sources: burning of forests and fossil fuels
Effects are complex

17. Structure of Atmosphere, revisited
Defined by changes in air temperature
Troposphere is where weather happens
Stratosphere dry, cold layer
Little weather occurs here
Strong winds circulate aerosols
Figure 8.7

18. Atmospheric Circulation
Responsible for location of climate zones
At equator, warm air rises towards poles
As it rises, it cools and loses moisture as rain
Dry air descends between 15o and 30o North and South
Descending air produces high pressure and low rainfall
High pressures at North and South Poles
Polar deserts

19. Figure 11.2a

20. Climate Change Currently, the climate is warming
Based on 30 years of warming in atmosphere
Also, global increase in sea temp, widespread melting of snow, glaciers, ice sheets, and permafrost, and sea level rise
Referred to as global warming
90% probability that humans are responsible
Ecosystems capable of adjusting, but changes are too fast for these to take place
Studies changes in atmosphere and linkages with lithosphere, cryosphere, hydrosphere, and biosphere

21. Cryosphere Part of the hydrosphere where most of the water is frozen
Includes permafrost, sea ice, ice caps, glaciers, and ice sheets
Glaciers
Flow from high to low elevations under weight of accumulated ice
Have budgets with input and output
Periods of continental glaciation called glacial intervals
Interglacial intervals occur in between

22. Glaciations Refer to multiple advances and retreats of glaciers.
Rare during the earth’s 4.6 billion year history.
Several in the last 1 billion years.
We are now living during one of those events that began 2.5 million years ago.

23. Pleistocene Epoch Multiple ice ages
Glaciers covered 30% of Earth (today 10%)
Maximum extent 21,000 years ago
Global sea level >100 m (330 ft) lower than today
Figure 11.3

24. Causes of Glaciation Mostly unknown Related to position of continents
Changes in amount of solar radiation influence advance and retreat
Milankovitch cycles
Changes in Earth’s orbit around Sun, tilt and wobble of Earth’s axis of rotation
Correlate well with minor changes in global temperatures
Explain the “Medeival Warming Period” and the “Little Ice Age”
They are not the primary cause of glaciation or global temperature changes.

25. Glacial Hazards Huge, actively flowing masses of ice and debris
Hazards include: property damage, injuries, and deaths
People can fall into deep crevasses.
Can expand to overrun villages, etc.
Produce an ice jam to cause flooding.
Blocks of ice may fall.
Calving produces icebergs in ocean.

26. The Greenhouse Effect
Discovered by Joseph Fourier in 1824: the Sun’s energy passes through, but reradiated heat is absorbed by, Earth’s atmosphere.
Fourier also described the planetary balance of heat gain and loss ( the “heat budget”)
The greenhouse effect was first reliably experimented on by John Tyndall in the year 1858 and first reported quantitatively by Svante Arrhenius in his 1896 paper.
The mathematics were first proposed by Jožef Stefan in 1879, based on experiments by John Tyndall.
Thermodynamic formulas describing the effects of greenhouse gas concentrations of the heat balance of Earth were developed by Ludwig Boltzmann, 1884.

27. The Greenhouse Effect
In 1896, Swedish scientist Svante Arrhenius was the first to claim that fossil fuel combustion may eventually result in enhanced global warming.
He proposed a relation between atmospheric carbon dioxide concentrations and temperature.
He found that the average surface temperature of the earth is about 15oC because of the infrared absorption capacity of water vapor and carbon dioxide.
This is called the natural greenhouse effect.

28. The Greenhouse Effect
Arrhenius suggested a doubling of the CO2 concentration would lead to a 5oC temperature rise.
He and Thomas Chamberlin calculated that human activities could warm the earth by adding carbon dioxide to the atmosphere.
This research was a by-product of research of whether carbon dioxide would explain the causes of the great Ice Ages.
This was not actually verified until 1987.

29. The Greenhouse Effect
In 1972, eminent atmospheric scientist J.S. Sawyer summarized what was known about the role of carbon dioxide in enhancing the natural greenhouse effect, and made a remarkable prediction of the warming expected at the end of the twentieth century. He concluded that the 25% increase in atmospheric carbon dioxide predicted to occur by 2000 corresponded to an increase of 0.6 °C in world temperature. (Nature 239, 23-26; 1972).
In 1988, NASA scientist Jim Hansen gave congressional testimony showing model projections of continued global warming. In spite of being one of the earliest transient climate model experiments, there is an impressive match between the recently observed data and Hansen’s projections.

30. Scientific Agreement
By the early 1990’s, climatologists generally agreed that humans were making significant contributions to climate change.
In 1995, the National Academy of Sciences reported that the research strongly supported anthropogenic warming. By this time, the burden of proof had now shifted to scientists who disagreed with these findings.
Since this time, the research has not provided evidence to refute the basic findings. On the contrary, thousands of papers have been published providing further evidence of anthropogenic warming.
Since 2007, no scientific body of national or international standing has maintained a dissenting opinion.
In a recent University of Illinois at Chicago survey sent to 10,257 Earth Scientists, 97.4% of the climatologists who responded answered "yes" when asked "do you think human activity is a significant contributing factor in changing mean global temperatures?"

31. The Greenhouse Effect Earth’s temperature depends on three things:
Amount of sunlight received
Most is ultraviolet with short wavelength
About 2/3 is absorbed to warm the atmosphere
Amount of sunlight reflected
Mostly reflected as infrared radiation
Degree to which the atmosphere retains heat
Water vapor, carbon dioxide, methane, nitrous oxides, and halocarbons absorb IR radiation
Gasses act as “blanket” to retain heat in troposphere

32. Figure 11.5

33. The Greenhouse Effect, cont.
Greenhouse effect is a natural and necessary process.
Earth would be 33o colder without it.
All surface water would be frozen.
Little life would exist.
Natural effect is from water vapor.
Absorption by greenhouse gasses (carbon dioxide, methane, nitrous oxide, halocarbons)
Enhance the greenhouse effect

34. Carbon Dioxide and The Greenhouse Effect
Carbon dioxide accounts for most of the anthropogenic greenhouse effect.
It is the most studied.
Figure 11.6

35. Air Temperature and Carbon Dioxide
CO2 concentrations from air bubbles in glacial ice in Antarctic ice sheet
Figure 11.7

36. Atmospheric Carbon Dioxide Concentrations
Since the burning of fossil fuels, CO2 concentration has increased exponentially.
Measurements are from glacial ice and from Mauna Loa in Hawaii.
Figure 11.8b

37. Atmospheric Carbon Dioxide Concentrations, cont.
Atmospheric concentrations continue to rise and are likely to continue.
Data from Mauna Loa in Hawaii.
Figure 11.8a

38. Global Temperature Change–Last 800,000 Years
Low temperatures coincide with major continental glaciations, high temperatures with interglacial periods
Figure 11.9a

39. Global Temperature Change–Last 150,000 Years
Last major interglacial period, Eemian, sea level was 4–6 ft higher than today
Figure 11.9b

40. Global Temperature Change–Last 18,000 Years
Cold interval, Younger Dryas, occurred 11,500 years ago, followed by warming to Holocene maximum.
Recent cooling, called Little Ice Age, 15th–19th centuries.
Figure 11.9c

41. Global Temperature Change–Last 1000 Years
Several warming and cooling trends
Warming in 11–1300 allowed Vikings into Iceland, Greenland, and North America
Figure 11.9d

42. Global Temperature Change–Last 140 Years
1750, warming trend begins until 1940s.
1910 to 1998, global temperatures rise.
Temperatures in past 30 years are warmest since monitoring began.
Figure 11.9e

43. Why Does Climate Change?
Milankovitch Cycles
Natural changes in Earth’s Orbit, tilt, and precession
Explain some changes, but not the observed large-scale changes
Ocean conveyor belt
Circulation of ocean water in oceans
Can cause fast changes in climate
Keeps Northern Europe warmer than without it

44. Ocean Conveyor Belt –Atlantic Ocean
West side, strong warm current flows northward to Arctic.
At Greenland, it is cool and salty and sinks to bottom.
Cold, dense water flows southward around Africa.

45. Figure 11.10

46. United Nations Intergovernmental Panel on Climate Change
UN report found that shutdown of conveyor belt current has occurred historically, but there is no evidence that it will occur again this century.
There is sufficient evidence to state:
There is widespread evidence of human influence on global climate.
Warming is now occurring.
Mean surface temperature of Earth will likely increase between 1.80 and 40 C (30 and 70 F) during this century.

47. Solar Forcing
There is a relationship between changes in solar energy and climate change.
Medieval Warm Period (A.D. 1000–1300) corresponds to increased solar radiation.
Little Ice Age corresponds to decreased solar radiation.
Partially explains climate change, but effect is very small.

48. Volcanic Forcing
Ash from eruptions becomes suspended in the atmosphere, reflects sunlight having a cooling effect.
Mount Tambora, 1815 eruption contributed to cooling in North America and Europe.
Mount Pinatubo in 1991 counterbalanced global warming during 1991 and 1992.

49. Anthropogenic Forcing
Mathematical models of climate can isolate human causes from solar and volcanic forcing of climate change.
Models found that present warming greatly exceeds natural variability.
Models agree with climate change predicted from greenhouse gas forcing.

50. Figure 11.12

51. Effects of Climate Change
Figure 11.13

52. Climate Patterns Climate important to agriculture
Rainfall patterns, soil moisture, etc.
Northern Canada and Eastern Europe may be more productive.
Lands closer to equator become more arid.
Violent storms may intensify
Warmer oceans provide more energy.

53. Changes in Hydrosphere
Increased sea surface temperature
Increased precipitation in polar and temperate regions
Decreased precipitation in tropical and subtropical regions

54. Changes in Hydrosphere, cont.
Rising sea level
Thermal expansion of ocean
Melting glaciers
Increases coastal erosion
Increases vulnerability of structures to waves
Flood low-lying Pacific and Indian Ocean islands
Flood coastal cities, New York, Boston, Tampa, Washington, D.C.

55. Changes in Cryosphere Global warming effects occur more rapidly here.
Shrinking permafrost.
Decreased Arctic Ice cap, ice sheets, and glaciers
Affects communities dependent on snowmelt for water supply

56. Changes in Biosphere Shifts in range of plants and animals
Changes in plant and animal habitat
Mosquitoes are moving to higher elevations.
Northward movement of butterflies in Europe and birds in U.K.
Expansion of sub-alpine forests in Cascades.
Sea ice melting stresses seabirds, walruses, and polar bears.
Warming in Florida Keys bleaching coral reefs.
Seawater increasing in acidity, threatening coral animals and algae.
These are areas of extreme animal diversity.

57. Desertification and Drought
Climate change increases human induced conversion of land to desert
Causes soil and natural vegetation degradation
Long-term loses for agriculture and grazing
Increase in drought events

58. Wildfires Wildfire events will increase due to global warming.
Both in in frequency and intensity

59. Minimizing the Effects of Climate Change
Focus on reduction of greenhouse gasses
Most scientists believe that we have a decade to reduce gas emissions to avoid catastrophe.
Reduction of gasses must be done on an individual, community, national, and international level.
Carbon sequestration
Necessary as we make transition to new energies

62. International Agreements
Montreal Protocol
1987 agreement to limit depletion of ozone layer by CFCs
CFCs have declined since 1989
Kyoto Protocol
United Nations Framework Convention on climate change
Establishes targets to reduce greenhouse gas emissions by 2012
Copenhagen
No binding agreement was achieved. The U.S. Congress did not pass new laws in advance, and President Obama attended without any real authority to take meaningful action.

63. Carbon Sequestration
Capture and store carbon dioxide before it enters atmosphere
Biological sequestration
Planting more trees
Oceanic sequestration
Injecting CO2 into oceans
Geologic sequestration
Power plants capture CO2
Inject it, under pressure into wells in the earth

64. Fossil Fuels and Future Threat of Climate Change
Two scenarios for global warming in which there is rapid economic growth with population peaking and declining
A1–More efficient energy technologies, but still fossil fuel intensive
B1 – Clean resource-efficient technologies, economic structures change

65. A1–More efficient energy technologies, but still fossil fuel intensive
B1 – Clean resource-efficient technologies, economic structures change
Figure 11.18a
Figure 11.18b

66. Climate and Climate Change
End
Climate and Climate Change
Chapter 11
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