GLOBAL CLIMATE CHANGE A Warming Planet?

1. GLOBAL CLIMATE CHANGE A Warming Planet? 13

2. STUDENT LEARNING OUTCOMES After reading this chapter, students will be able to • Identify the factors that affect the amount of energy that enters and leaves the Earth’s atmosphere and how this affects global temperature. • Explain the effect of human activity on climate based changes in storages and flows in global biogeochemical cycles. • Explain how detection and attribution are critical to climate change policy. • Describe the positive and negative effects of climate change on environmental and economic systems. • Describe the factors that determine economically efficient climate change policy and what it implies about the Kyoto Protocol.

3. Climate Change and Norse Settlements • Norse farmers set up colonies in Iceland, Greenland, Newfoundland, and North America. • Settlement began in Medieval Warm Period • On Greenland the Norse settlements persisted for 450 years (984 to sometime in early 1400s) • Greenland Norse disappeared suddenly • Arrival of the Inuit and the Little Ice Age • Less farming and more reliant on local wildlife but Inuit better hunters • Lack of food confirmed by bones

4. Weather Atmospheric conditions at particular place and time How it changes from day to day Temperature, precipitation, wind speed, cloud cover, humidity, etc Climate Average weather conditions over a long period Repeating pattern of weather Average temperature and average precipitation Climate versus Weather Climate Change is a shift in the long-run average of weather

5. Climate Change- Rule not Exception

6. The Heat Balance of Planet Earth Climate Change is caused by a change in the planet’s heat balance (energy in versus energy out).

7. The Greenhouse Effect • The ability of the atmosphere to absorb energy with longer wavelengths and convert it to heat • Natural phenomena that warms the lower atmosphere by about 35 degrees Celsius • Greenhouse gases • Water vapor (H2O) • Carbon dioxide (CO2) • Methane (CH4) • Nitrous Oxide (N2O) • Chlorofluorocarbons (CFCs) not natural • Particles and Aerosols

8. Radiative Forcing

9. Residence Time

10. Hemispheric Radiative Forcing Figure 13.4a • Greenhouse gases well mixed throughout entire atmosphere • Sulfate aerosols have variable residence time; and incomplete mixing Figure 13.4b Figure 13.4c

11. Greenhouse Gases Figure 13.5a Figure 13.5b Figure 13.5c Figure 13.5d

12. Carbon Dioxide, Methane, and Temperature Figure 13.6

13. Disrupting the Global Carbon Cycle • Nearly all greenhouse gases and sulfur aerosols at or near maximum value observed over last 500,000 years • Largely due to human activities that have disrupted the global biogeochemical cycles of C,N, and S. • Carbon (as CO2 and CH4) • Fossil fuel combustion (coal releases the most) • Coal mining • Land-Use Change (deforestation and agriculture) • Landfills

14. Carbon Dioxide Futures Figure 13.7

15. Disrupting the Global Sulfur Cycle • Coal combustion • Reflect sunlight and enhance cloud formation • Will sulfur emissions Increase or Decrease? • Pollution abatement technologies are promising • But emissions could increase if world coal increases

16. Detecting Climate Change • Choose an indicator • Direct measurement of mean annual global temperature • Sea level change • Size of glaciers • Remote Sensing of Vegetation (growing season and biomass) • Organism behavior (migrations, leaf out, onset of breeding) • Measure the mean and natural variability • Are recent changes greater than expected based on natural variability?

17. Detecting Climate Change

18. Detecting Climate Change Figure 13.10

19. Attribution • Establishing cause and effect relationship between human activity and the observed change in climate. • The IPCC suggests there is a discernible human influence on climate • Statistical Analyses of Historical Data Figure 13.11

20. Climate Models

21. The Role of Human Activity

22. The IPCC An Interdisciplinary Effort To Make Climate Change Policy states “The warming over the past 100 years is very unlikely to be due to internal variability alone…and is unlikely to be entirely natural in origin…Detection and attribution studies consistently find evidence for anthropogenic signal in the climate record of the last 25-50 years…most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations.”

23. Skeptics? • Reluctance to slow down emissions? • Incomplete understanding of the science? • The State of Fear by Michael Crichton

24. Satellite/Thermometer Discrepancy

25. How Will Humans Affect Climate? • The 460,000 year climate record shows a correlation between greenhouse gases and temperature • But did one cause the other? • “chicken-or-egg problem”

26. Why Does Temperature Rise?

27. The Impacts of Global Climate Change • The 3.5 degree C rise in mean annual global temperature from doubling in the radiative forcing similar to glacial to interglacial • Most of North America covered by ice • Boreal forests covered what is now North Carolina • As climate warmed 10,000 years ago, tree species shifted their range north about 100-400 meters/year

28. Figure 13.18a Figure 13.18b Figure 13.18c Figure 13.18d

29. Impacts to Vegetation • Slow rate of movement important because climate change forecast by models is about 10x faster • Impediments to migration • Cities, highways, agricultural fields • Soils may be different • Forest Biomes could get trapped and collapse • Replaced with simpler systems, lower biodiversity, etc

30. Impact to Food Supplies (Positive?) • Food production would increase in some areas and decrease in others • Doubling of CO2 may increase yield of spring wheat by 8-10 % • Higher concentrations may allow farmers to increase production in arid areas (water use efficiency) • Where growing season is currently too short global warming could allow farming in the future

31. Impact to Food Supplies (Negative?) • Most of world’s best agricultural areas are located in the middle of continents- these are forecast to dry • More suitable habitats for pests and diseases in the future

32. Rising Seas • IPCC forecasts sea level will rise about 0.39 meters • 0.29m is due to thermal expansion • 0.11m is due to melting of mountain glaciers and icecaps • Complete melting of the Antarctic and Greenland ice sheets would raise sea levels by 70 meters • 20% of world’s population lives within 30 km of ocean and 40% live within 100 km • 0.5 meter rise could destroy $20-150 billion human infrastructure in the U.S. • Also reduce area and productivity of estuaries and coastal wetlands

33. Species Extinction • Toads first species to go extinct due to climate change • High altitudes in Central American cloud forests • 9-52% of world’s known terrestrial species could go extinct • Climate envelope • Worst case: 38-52% • Best case: 9-13% • World corals?

34. Climate Change Policy • Human Activity is changing climate • Our activities now will result in future changes • Policy can only slow not prevent climate changes • Not economical to eliminate all activities that emit greenhouse gases • Optimal level of pollution

35. Damage Functions

36. The Kyoto Protocol: A First Step?