IPCC AR4

1. IPCC AR4

2. Climate Change – Greenhouse Gases • Background • Greenhouse Effect • Gases absorb heat (long-wave radiation) • Natural Greenhouse Effect • Mean planetary temperature = 15 oC vs. -6 oC • Enhanced Greenhouse Effect • Due to GHGs emitted from human activity • Greenhouse Gases • Most important GHG is water vapor • Accounts for ~50% of natural GHE • Historically: Belief that human activities didn’t affect atmospheric moisture content • Recent evidence that humans affect atmospheric humidity (Santer et al. 2007, Willett et al. 2007)

3. Greenhouse Gases

4. US EPA

5. Climate Change – Greenhouse Gases • Greenhouse Gases • Some features of CO2/Temperature relationship don’t correlate well. Why not? • Other factors besides GHGs may influence global climate

6. Climate Change – Other Factors • Cloud Cover • Reflects incoming radiation • Difficult to estimate in climate models • Effects vary in relation to altitude, thickness, composition • Atmospheric Dust • Important factor in cool period from 1930s to 1960s • Overwhelmed effects of rising CO2 during this period • Produced by volcanic eruptions, dust from areas experiencing drought • Cool period following eruption of Mt. Pinatubo in 1992 • Mechanism behind “Nuclear Winter” scenario

7. Climate Change – Other Factors • Volcanism • Affects water vapor, particles, sulfides, nitrates • Generally leads to planetary cooling • Theory about extinctions at P/T boundary • Mt. St. Helens and Mt. Pinatubo eruptions caused planetary cooling, and those were small eruptions • Photosynthesis & Transpiration • Affect CO2, water vapor • As [CO2] rises, some plants • Photosynthesize more rapidly • Grow faster • Incorporate more CO2 into biomass • Keep their stomata open less • Transpiration releases water vapor into atmosphere • Less transpiration when [CO2] is higher (stomata)

8. Climate Change – Other Factors • Solar Output • May affect amount of incoming radiation • Solar output varies – sunspots, solar flares • Sunspots: magnetic storms that appear as dark patches on sun’s surface • Sunspot cycles of 11, 88, 205 years • During sunspot maxima, solar output ca. 0.1% higher than normal

9. http://calspace.ucsd.edu/virtualmuseum/climatechange2/06_3.shtmlhttp://calspace.ucsd.edu/virtualmuseum/climatechange2/06_3.shtml

10. Climate Change – Other Factors • Solar Output • Researchers have correlated sunspot minima with “Little Ice Age” in Europe during 17th and early 18th centuries when sun was 0.25% dimmer than normal • 20th century dominated by sunspot maxima • Some predictions that 21st century will see minima • Controversial • IPCC (2007): Solar output variation is ~14x less influential than GHGs

11.  Global patterns Regional variation Lean 2010

12. Climate Change – Other Factors • Albedo (Reflectivity) • Earth’s surface varies considerably (mean = 0.30-0.36) • Ice/Snow highly reflective (0.9) • Clouds vary in reflectivity • Land generally less reflective • Changes in land use affect albedo • Desertification increases albedo • Melting of snow/ice decrease albedo

13. Climate Change – Other Factors • Many factors affect global climate in multiple ways • Ex – Clouds absorb long-wavelength radiation (heat) and reflect incoming short-wavelength radiation (light) • Net effect = cooling • Ex – Particles in atmosphere reduce re-radiation of long-wavelength radiation and reflect incoming short-wavelength radiation • Net effect probably warming at low levels, cooling at high levels (e.g. following a large volcanic eruption) • Efforts to reduce particulate air pollution facilitate warming • Uncertainty about impact of many factors

14. IPCC AR4

15. IPCC AR4

16. Climate Change – Effects • Negative • Sea Level • Warming  melting of glaciers and ice caps  sea level rise • Warming  thermal expansion of water  additional sea level rise • Melting of all ice  sea level rise of ~70 m

17. http://www.epa.gov/climatechange/science/futureslc_fig1.html

18. Climate Change – Effects • Negative • Sea Level • Since 1880, sea level has been rising at a rate of ~15 cm century-1 • Accelerating since 1940s • Some polar ice sheet loss • Loss of temperate glaciers • Warming should  more atmospheric moisture and precipitation, which should  net growth of polar ice caps • Examples • Bangladesh: Over 20 million people live less than 1 m above sea level • ~40% of food production tied to flood plains • AOSIS (Alliance of Small Island States) – Strong concerns about sea level rise

19. US East Coast –Sea Level Rise 1 m 3 m http://vrstudio.buffalo.edu/~depape/warming/east.html

20. www.panoramio.com/photo/31807235

21. - Sea level rise is not globally uniform http://sealevel.colorado.edu/files/current/sl.pdf

22. Climate Change – Effects • Negative • Rainfall Patterns • Warming should lead to • Reduced precipitation at low latitudes • Increased precipitation at high latitudes • Examples • Reduced snowpack in Sierra Nevada Mountains due in part to rainfall instead of snow • Drought in many parts of the world

23. 1958-2008 US Global Change Research Progam

24. Climate Change – Effects • Negative • Storms • Warming should lead to • More severe storms • Greater storm frequency

25. http://www.ncdc.noaa.gov/extremes/cei/

27. Climate Change – Effects • Negative • Ecosystem Changes • Shifting climatic zones could expand ranges of warmth-tolerant species and contract ranges of warmth-intolerant species • Colder-living species might be displaced poleward as well as upward in elevation • Species unable to adapt or move would go extinct • Predicted rates of 16.9 km/decade and 11.0 m/decade (Chen et al. 2011) • Within an ecosystem, some species will be more sensitive to climate change than others • Species composition of ecosystems almost certainly will change • Changes in CO2 concentrations  pH of ocean

28. Chen et al. 2011

29. Climate Change – Effects • Negative • Ecosystem Changes • Shifting climatic zones could expand ranges of warmth-tolerant species and contract ranges of warmth-intolerant species • Colder-living species might be displaced poleward as well as upward in elevation • Species unable to adapt or move would go extinct • Predicted rates of 16.9 km/decade and 11.0 m/decade (Chen et al. 2011) • Within an ecosystem, some species will be more sensitive to climate change than others • Species composition of ecosystems almost certainly will change • Changes in CO2 concentrations  pH of ocean

30. Climate Change – Effects • Negative • Health • Consistently elevated temperatures can lead to immunosuppression • Allergies could worsen due to increased pollen production, dust (desertification), mold (humidity) • Additional human mortality from severe summer heat

31. Climate Change – Effects • Negative • Tropical Pests and Diseases • Many tropical diseases are transmitted by animal vectors – insects, rodents • Vector distribution often is limited by climatic barriers (e.g. mountain ranges) • Ex: Malaria • Most prevalent vector-borne disease (1-2 million cases/year) • Transmitted by Anopheles mosquitoes • Warming could lead to • Broader geographic range (estimate that +2oC could expand range from 42 to 60% of global land area) • Higher mosquito metabolic rate  More food • Faster maturation  More rapid reproduction • Faster parasite life cycle • Potential spread into large urban areas (Nairobi, Kenya; Harare, Zimbabwe) with immunologically naïve pop’ns • Projections are controversial and highly variable

32. Climate Change – Effects • Positive • Plant Growth • Warmer temperatures and elevated [CO2]  faster plant growth & greater food production per acre • Elevated [CO2] should  more efficient use of water, reduced runoff and less water pollution • Enhanced plant growth should remove CO2 from atmosphere faster (Gaia Hypothesis) • Agriculture • Expansion of agricultural regions • Longer growing season in areas that currently are marginal for agriculture

33. Climate Change – Effects • Positive • Rainfall Patterns • Predictions of increased rainfall in major agricultural regions, especially in northern hemisphere • Reduced irrigation required for plants/crops • Increased precipitation (as snow) should cause glaciers and ice sheets to grow • Milder Winters • Severe winters pose a health and safety risk • Fewer expenses associated with less severe winter weather

34. Climate Change – Projections • Complexity and uncertainty in climate models • Unknown response of earth climate system to a forcing function • Accumulation of GHGs in atmosphere • What should we do?? And why? • Lomborg

35. IPCC AR4

36. Some Responses to Global Climate Change Deny it altogether Stress scientific uncertainty and do nothing beyond calling for more scientific research Geoengineering Adaptation Mitigation

37. Vulnerability Who is most likely to get hit the hardest—suffer the greatest costs—by climate change? Global South Lower income and marginalized communities and the poorer sectors of societies (poor pays, not polluter pays) Non-dominant groups of people in countries with strong ethnic, religious, and other divides Women and children

38. One Attempt to Sort out the Ethical Dimensions of Global Climate Change As per the title “A Perfect Moral Storm: Climate Change, Intergenerational Ethics and the Problem of Moral Corruption” (2006) Stephen M. Gardiner claims that climate change poses nearly insurmountable ethical problems. Climate change involves: dispersion of causes and effects in terms of space and time, fragmentation of human agency in terms of space and time, and institutional inadequacy in terms of space and time, all subject to human corruption.

39. First and Second Spatial Perspectives of the Moral Storm Dispersion of causes and effects of climate change makes it hard to pinpoint moral geographical locations. Fragmentation of human agency makes it difficult to respond to climate change. From an individual’s perspective, it’s rational not to restrict one’s own pollution, while from a collective perspective it’s rational to restrict pollution = tragedy of the commons.

40. Third Spatial Perspective of the Moral Storm Institutional inadequacy hampers efforts to respond to climate change because: There is no effective global governance system. Some nations might wonder if they will be better or worse off because of climate change. Effectively mitigating climate change might require deep and profound changes to economic, political, and social structures.

41. First Temporal Perspective of the Moral Storm Dispersion of causes and effects over time might under-motivate people to effectively respond to climate change because: Climate change is a resilient and substantially deferred phenomenon. Climate change impacts are seriously back-loaded.

42. Second Temporal Perspective of the Moral Storm Fragmentation of human agency across time makes it difficult to respond to climate change. From an individual generation’s perspective, it’s rational not to restrict current pollution, while from a collective intergenerational perspective it’s rational to restrict pollution. This is an intergenerational tragedy of the commons.

43. Third Temporal Perspective of the Moral Storm This intergenerational tragedy of the commons has multiplier effects, namely: Inaction now raises transition costs that might make future change more difficult. Insufficient action now might make some generations suffer unnecessarily (e.g., climate change harms future generations A, B, and C, but current inaction leads to harming future generations D and E as well). Insufficient action now might result in tragic choices for future generations.

44. Moral Corruption Humans are often: Distracted Complacent Unreasonable Self-deceptive Manipulative Selectively attentive Delusional Hypocritical Because of these human characteristics, and because climate change involves a complex convergence of problems, we will often fall prey to moral corruption. How will we ever successfully deal with climate change?

45. Climate Change and Some Dimensions of Environmental Equity and Justice Distributive Justice: What is a fair or equitable distribution of the burdens and benefits of climate change? Intragenerational equity: What steps should be taken to ensure that marginalized and vulnerable people within current generations do not disproportionately suffer from climate change impacts? Intergenerational equity: What steps should be taken to ensure that future generations do not disproportionately suffer from climate change impacts? Ecological Justice: What does the nonhuman world deserve? Compensatory Justice: How should monetary and technological resources be redistributed to compensate those who shoulder disproportional burdens? Procedural Justice: How should responsibilities about what to do be defined and delegated? Participatory Justice: Who gets to delegate the responsibilities and decide what to do and how it should be done? Restorative or Transformative Justice: How can responses to climate change be used to restore or transform what is fundamentally wrong with North-South and other political, economic, and social relations?

46. Some Possibilities for Burden-Sharing • Historical Responsibility: Each country’s GHG reductions depend on its relative contribution to the problem of climate change. Also know as polluter pays or beneficiaries pay. • Common but Differentiated Responsibility: All people bear a common responsibility reduce GHG emissions, but the greatest burden falls to those with the ability to pay and to those who have benefitted the most from GHG-producing activities. • Solvency: Costs are distributed among states according to their ability to pay and their contribution to the problem of climate change. • Grandfathering: The world’s wealthier nations make efforts to reduce their GHG emissions relative to a baseline year. • Per Capita (Equal Entitlements): Specify the size of the emissions budget, and allow for every global citizen to be allocated an equal entitlement to the atmosphere, with rich countries contracting their annual GHG budgets and poor countries increasing their annual GHG budgets to eventually converge with the rich nations.

47. Some More Possibilities for Burden-Sharing • Securing Basic Needs: Countries emitting more than what is deemed “reasonable” to support a consistent, modest standard of living accept far higher mitigation costs than countries facing more poverty. • Compensatory Equity: Powerless, disadvantaged, and socioeconomically vulnerable people who are worst affected by climate change are compensated by those who have benefitted the most from GHG producing activities. • Focus on the Poor: Relative to climate change, improve the situation of the poorest countries of the South, with the long-range intention of mitigating unequal distributions of wealth. • Carbon Intensity: Stabilize the climate as cost-effectively as possible while maximizing global economic growth. • Performance: Countries who use energy more efficiently are rewarded with more benefits.

48. http://vimeo.com/3353504