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1. 15-1

2. Housekeeping Items • We will briefly go over the mid-term today. • Just a reminder that the Weather Channel will be having a teach-in on climate and environment issues next Thursday from 7 p.m. on • At some point today, I want to show a short video: www.filmsforaction.org/watch/wake_up_freak_out_then_get_a_grip/. • Suggested resources: “White Water, Black Gold,” which is owned by our library; see also the short video: http://www.youtube.com/watch?v=HHP9Rh-ooh0.

3. Describe Earth’s climate system and explain the many factors influencing global climate change Characterize human influences on the atmosphere and global climate Summarize modern methods of climate research Outline current and future trends and impacts of global climate change Suggest ways we can respond to climate change Upon successfully completing this chapter, you will be able to

4. Central Case: The Retreat of The Athabasca • The Athabasca Glacier has been retreating since 1844 • Since then, it has lost half of its volume • Currently retreating at a rate of 2-3 metres per year • Is it retreating due to climate change or is it just a natural continuation of the retreat of glacial ice that began 12,000 years ago? • The Rockies may be ice-free by the end of this century “We’re in a giant car heading towards a brick wall and everyone’s arguing over where they’re going to sit.” – David Suzuki

5. Our Dynamic Climate 15-5

6. Our dynamic climate • Climate influences everything around us • The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) made it clear that: • Climate is changing, we are the cause, and this change is already exerting impacts that will become increasingly severe if we do not take action • Climate change is the fastest-moving area of environmental science today, and the Fifth Report is due quite soon

7. What is climate change? • Climate = an area’s long-term atmospheric conditions • Temperature, moisture content, wind, precipitation, etc. • Weather= conditions at localized sites over hours or days • Global climate change = describes trends and variations in Earth’s climate • Temperature, precipitation, storm frequency • Global warming = an increase in Earth’s average temperature • Earth’s climate has varied naturally through time • The rapid climatic changes taking place now are due to human activity: fossil fuels, combustion, and deforestation

8. The Sun and atmosphere keep Earth warm • Four factors exert more influence on climate than all others: • The Sun (supplies planet’s energy) • The atmosphere (absorb 70% of incoming solar radiation) • The oceans (shape climate by storing and transporting heat and moisture) • Albedo = reflectivity of a surface

9. Our planet absorbs solar radiation

10. Greenhouse gases warm the lower atmosphere • As Earth’s surface absorbs solar radiation, the surface increases in temperature and emits infrared radiation • Greenhouse gases = atmospheric gases that absorb infrared radiation (radiatively active gases) • Water vapor, ozone, carbon dioxide, nitrous oxide, methane, chlorofluorocarbons (CFCs) • Greenhouse gases differ in their ability to warm the troposphere and surface

11. Greenhouse gases warm the lower atmosphere (cont’d) • After absorbing radiation, greenhouse gases re-emit infrared energy • Some energy is lost to space • Greenhouse effect = some energy travels back downward, warming the troposphere and the planet’s surface • Global warming potential = the relative ability of one molecule of a given greenhouse gas to contribute to warming • Expressed in relation to carbon dioxide (potential = 1) • Nitrous oxide is 296 times as potent as carbon dioxide

12. Carbon dioxide is the anthropogenic greenhouse gas of primary concern • Not the most potent greenhouse gas, but it is extremely abundant • The major contributor to global warming • Human activities have boosted atmospheric concentrations from 280 parts per million (ppm) to 389 ppm in 2010

13. Human activity has released carbon from sequestration in long-term reservoirs • Human activities accelerate the fluxes of material from one reservoir to another in biogeochemical cycles • Burning fossil fuels transfers CO2 from lithospheric reservoirs into the atmosphere • Deforestation transfers CO2 from terrestrial reservoirs into the atmosphere • Sinks = reservoirs that accept more of the material than they release • Ocean

14. Other greenhouse gases contribute to warming • Methane from fossil fuel deposits, livestock, landfills, and crops such as rice • Nitrous oxide from feedlots, chemical manufacturing plants, auto emissions, and synthetic nitrogen fertilizers • Ozone from photochemical smog • Halocarbons (CFCs and HFCs) • Water vapor = the most abundant greenhouse gas and contributes most to the greenhouse effect

15. There are many feedback cycles in the climate system • Positive feedback cycle • Warming leads to water vapour which leads to further warming causing still more evaporation, and so on • Negative feedback cycle • Warming leads to evaporation which leads to water vapour causing increased cloudiness slowing global warming • Aerosols = microscopic droplets and particles that have either a warming or cooling effect

16. Radiative forcing expresses change in energy input over time • Radiative forcing= the amount of change in energy that a given factor causes • Positive forcing warms the surface; negative forcing cools it • Compared with the pre-industrial Earth, Earth is experiencing radiative forcing of 1.6 watts/m2 • Enough to alter the climate

17. The atmosphere is not the only factor that influences climate • Milankovitch cycles = periodic changes in Earth’s rotation and orbit around the Sun • Solar output = drives temperature change on Earth’s surface • Ocean absorption = the ocean holds 50 times more carbon than the atmosphere and absorbs it from the atmosphere (acts as a sink) • Ocean circulation = ocean water exchanges tremendous amounts of heat with the atmosphere, and ocean currents move energy from place to place • Thermohaline circulation

18. Milankovitch cycles

19. In Atlantic, warmer surface water flows north, cools and sinks, forming the North Atlantic Deep Water (NADW)

20. The Science of Climate Change 15-20

21. Proxy indicators tell us about the past • Proxy indicators = types of indirect evidence that serve as substitutes for direct measurements • Ice caps, ice sheets, and glaciers hold clues to past climate • Trapped bubbles in ice cores show atmospheric composition, greenhouse gas concentration, temperature trends, snowfall, solar activity, and frequency of fires

22. Stable isotope geochemistry is a powerful tool for the study of paleoclimate • Stable isotope geochemistry = studying stable isotopes of elements • Fractionation = separation and differential concentration of isotopes of slightly different mass • Proxy indicators like stable isotopes often give us information about local or regional areas so scientists combine multiple records from various areas

23. Direct atmospheric sampling tells us about the present • Atmospheric carbon dioxide concentrations have increased from 315 ppm in 1958 to 392 ppm in 2011 • There are seasonal variations in levels due to photosynthetic uptake • More carbon dioxide absorbed during northern summer 15-23

24. Models help us understand climate • Climate models simulate climate processes • Use information about: • atmospheric circulation • ocean circulation • interactions • feedback mechanisms

25. Models help us understand climate (cont’d) • Effectiveness of models are tested by entering data from the past and running the model toward the present

26. Current and Future Trends and Impacts 15-26

27. Current and future trends and impacts • Evidence that climate conditions have changed since industrialization is now overwhelming and indisputable • The way each of us experiences these impacts will vary tremendously • The impacts on Canada could be particularly severe, depending on where we live

28. The IPCC summarizes evidence of climate change and predicts future impacts • Trend = a pattern that persists within a data set, even after short-term fluctuations and anomalies have been accounted for • Intergovernmental Panel on Climate Change (IPCC) • 2007: Fourth Assessment Report • Consensus of scientific climate research from around the world • Trends in surface temperature, precipitation patterns, snow and ice cover, sea levels, storm intensity, and other factors

29. Temperature increases will continue • The IPCC report concludes that average surface temperatures on earth have been rising since 1906, with most of the increase occurring in the last few decades (0.74 ̊ C) • Fifteen years from 1997-2011 among the 20 warmest years on record • Permafrost = perennially frozen ground • Thawing in the Arctic

30. Projected increases in surface temperature • More frequent heat waves • Temperature change will vary by region • Stronger storms

31. weighingtheissues Climate Change and Human Rights In December 2005, a group representing North America’s Inuit sent a legal petition to the Inter-American Commission on Human Rights, demanding that the United States restrict its greenhouse gas emissions, which the Inuit maintained were destroying their way of life in the Arctic . After a year, the commission dismissed the petition with a terse three-sentence letter. • Do you think Arctic-living people deserve compensation from industrialized nations whose emissions have caused climate change that has disproportionately affected the Arctic? • Do you think climate change can be viewed as a human rights issue? • What ethical issues, if any, do you think climate change presents? How could these best be resolved?

32. Changes in precipitation will vary by region • Some regions are receiving more precipitation than usual, and others are receiving less • Droughts have become more frequent and severe • Harming agriculture, promoting soil erosion, reducing drinking water supplies, and encouraging forest fires • Heavy rains have contributed to flooding

33. Projected changes in June-August precipitation, 2090-2099

34. Melting ice and snow have far-reaching effects • Mountaintop glaciers are disappearing • Have lost an average of 14 m since 1980 • Risks of sudden floods as ice dams burst • Reducing summertime water supplies • As ice melts, darker, less-reflective surfaces are exposed and absorb more sunlight, causing more melting • Melting permafrost makes slopes unstable and could release soil gases leading to further warming

35. The Arctic is changing dramatically • Less snow cover • Melting immense ice sheets (Greenland ice sheet) • Canada’s ice shelves have shrunk by 90% over the past 100 years (Ayles Ice Shelf) • Warming is accelerating • as snow and ice melt, darker, less-reflective surfaces are exposed • Earth’s capacity to reflect light decreases

36. Rising sea levels will affect hundreds of millions of people and coastal zones • As glaciers and ice melt, increased water will flow into the oceans • As oceans warm, they expand

37. An Ice-Free Northwest Passage and Canada’s Arctic Sovereignty weighingtheissues Now that the Northwest Passage – the long-coveted sea route from the Atlantic to the Pacific via the Arctic Ocean – may soon be ice-free, northern nations are anxious to confirm its sovereignty over Arctic waters at an international conference held in Greenland recently, and Prime Minister Stephen Harper pledged to spend billions of dollars defending Canada’s interests in the Arctic if necessary. In addition to the sea route, the Arctic subsurface may hold as much as 25% of the world’s undiscovered oil and gas reserves. • The U.S. argues that the High Arctic does not belong to Canada, or to anyone else. What do you think? • Who should control Arctic Ocean waters, and for what purposes? • How much of Canadian taxpayers’ money should be spent to assert and maintain Canada’s sovereignty in the Arctic?

38. Climate change affects organisms and ecosystems • Global warming modifies temperature-dependent phenomena • Timing of migration, breeding • Spatial shifts in the range of organisms • Animals and plants will move towards the poles or upward in elevation • 20-30% of all species will be threatened with extinction • Plants act as carbon sinks; fewer plants means more CO2 in the atmosphere

39. Environmental Refugees? weighingtheissues The Pacific island nation of Tuvalu has been losing 9 cm of elevation per decade to rising seas. Appeals from Tuvalu’s 11,000 citizens were heard by New Zealand, which began accepting them in small numbers as of 2003, although the government has not officially categorized them as environmental refugees – people driven from their homelands as a result of environmental change or natural disaster. Tuvaluans have been particularly vocal about global warming, but several other small Pacific island nations have joined in voicing their concerns. • Will there come a time when neighbouring countries should begin to treat people who leave small island nations as environmental refugees? • Should they be doing it now? • What will happen to these people after relocation – do you think a national culture can survive if its entire population is relocated?

40. Climate change exerts societal impacts – and vice versa • Agriculture: • growing seasons shortened, crops more susceptible; crop production will decrease, worsening hunger • Forestry: • increased insect and disease outbreaks, increased chance of forest fires

41. Climate change exerts societal impacts – and vice versa (cont’d) • Health: • heat waves can cause death, respiratory ailments, expansion of tropical diseases, increased chance of drowning if storms become intense, hunger-related ailments • Economics: • some costs and some benefits; costs will outweigh the benefits, widen the gap between rich and poor, will cost roughly 5-20% of world GDP

42. Are we responsible for climate change? • The IPCC concluded: • It is more than 90% likely that most of the global warming recorded over the past 50 years is due to the well-documented increase in greenhouse gas concentrations in our atmosphere • Today the debate concerning the human role in climate change is largely over • Shift in public perception • Al Gore’s 2006 “An Inconvenient Truth”

43. Responding to Climate Change 15-43

44. Responding to climate change • We will likely either keeping on pursuing economic growth at all costs, which will require more and more resources to fix the damage (what ecological economists call ‘dis-economies of scale’), and will eventually lead to social, economic, and population crash, or • We will make sustainability our first priority, aim for a ‘soft landing’ and create a steady-state economy.

45. Shall we pursue mitigation or adaptation, or intervention? • Mitigation = pursue actions that reduce greenhouse gas emissions, in order to lessen severity of future climate change • Renewable energy sources, farm practices to protect soil integrity, preventing deforestation • Adaptation = accept climate change is happening and pursue strategies to minimize its impacts on us • Criticized as sidestepping • Both are necessary

46. Shall we pursue mitigation or adaptation, or intervention? • Intervention = set of possible large-scale technological modifications to the global climate system • Causes of concern: • Interfering with global-scale Earth’s systems • Abandon mitigation efforts • Geo-engineering – grand scale intervention • Increase fluxes of greenhouse gases • Reduce incoming solar radiation

47. We can look more closely at our lifestyle • Conservation and efficiency • High-efficiency light bulbs and appliances • Reduce electricity consumption • Life-style choices • Sources of electricity • Alter types of energy we use • Natural gas cleaner than oil; oil cleaner than coal • Carbon capture and storage = remove CO2 from power plant emissions

48. Transportation is a significant source of greenhouse gases; likewise buildings • Automotive technology • make vehicles more fuel-efficient, hybrid cars • Driving less and using public transportation • Public transportation is the most effective way to conserve energy, reduce pollution • Live nearer your workplace, so you can bike or walk

49. Conventional cars are extremely inefficient

50. We can reduce emissions in other ways as well • Use advances in agriculture, forestry, and waste management • Grow renewable biofuels • Rapid reforestation of deforested areas • Recovering methane from landfills • Recycling, composting, and reduction or reuse of materials