1. Earth’s Changing Environment Lecture 13 Global Warming

2. The Earth is in an Interglacial Period  Last Glacial Maximum was 18,000 years ago and Global temperature was approximately 10 F colder than now  The last ice age ended 11,000 years ago.

3. Pleistocene: Includes Last Ice Age Holocene: Since last Ice Age

4. Average Earth Temperature increased 0.6 o C (1 F) during 20 th Century

5. Temperature Conversions   T (F) = 1.8  T( o C) Temperature rise of 5 o C is equivalent to a temperature rise of 9 F  T (F) = 1.8 T(C) + 32 F 5 o C is equivalent to 41 F

6. Current temperature: highest in 1000 years.

7. Greenhouse Gases  Greenhouse gases are emitted by human activities.

8. Greenhouse Warming The surface temperature of the earth is determined by the balance between the energy gain from solar radiation and the energy loss by IR radiation.

9. Greenhouse Warming: Greenhouse Gases Greenhouse gases allow sunlight to reach the surface, but absorb IR radiation from the surface. These effects cause the surface of the Earth to get hotter.

10. Greenhouse Gases  Carbon dioxide – fossil fuel combustion.  Methane – fossil fuel production, decomposition of organic wastes.  Nitrous oxide - agricultural and industrial activities, as well as during combustion of solid waste and fossil fuels.

11. Impacts  Rising global temperatures are expected to raise sea level,  Change precipitation and other local climate conditions.  Changing regional climate could alter forests, crop yields, and water supplies  Damage ecosystems.  Deserts may expand into existing rangelands.

12. Sea Level Rise – thermal expansion and melting ice caps and glaciers

13. Global warming is anthropogenic.

14. Increasing atmospheric CO2 concentration Atmospheric increase = Emissions from fossil fuels + Net emissions from changes in land use - Oceanic uptake - Terrestrial sinks

15.  Humans emit 24 billion tons per year.  60% stays in atmosphere  Increases atmospheric CO 2 by 0.4% / year.  25% increase from 280 ppm to 350 ppm Atmospheric CO 2

16. CO2  550 ppm to 1000 ppm in 2100

17. Temperature Increase: 1.5 o C – 6 o C by 2100

18. Extinction of Species

19. Recent Letter in “Nature” Extinction risk from climate change Nature 427, 145 - 148 (08 January 2004); doi:10.1038/nature02121 On the web at www.nature.com

20. Results of the Study “ When the average of the three methods and two dispersal scenarios is taken, minimal climate-warming scenarios produce lower projections of species committed to extinction (18%) than mid-range (24%) and maximum-change (35%) scenarios.”

21. Rapid Temperature Change Temperature rise over the next 100 years will be so rapid 0.3 o C per decade that plants and animals will not be able to migrate north or to higher altitude rapidly enough to survive

22. Biodiversity  10 million species  1.6 million identified species  Mammals & birds known  Insects & plants unknown

23. Biodiversity  Biodiversity increased over the last 600 million years  Occasional mass extinctions  Last major extinction (K-T) 65 million years ago.  Human activities will cause the next mass extinction

24. Extinctions  Recovery from mass extinctions takes millions of years.  Species are extinct forever.

25. KT Extinction  All dinosaurs became extinct.  65 million years ago.  Caused by meteor impact.

26. CO2 effects are long-term

27. Long term impacts depend on emissions

28. Adaptation and Mitigation

29. Mitigation  Reduce CO2 emissions by reducing consumption of fossil fuel.  Protection of rainforests and other CO2 sinks.

30. Carbon Emission Coefficient (Million Metric Tons of Carbon/QBtu) Coal26 Oil19 Natural Gas14

31. Global Carbon Emission  Global Carbon Emission of C in the form of CO2: 6.6 billion metric tons  Convert to CO2: 44/12 x 6.6 billion metric tons = 24 billion metric tons

32. Calculate US Carbon Emissions US Carbon Emission = 26 MMT/QBtu x 22 QBtu + 19 MMT/QBtu x 38 Qbtu + 14 MMT/QBtu x 23 QBtu = 1.6 Billion Metric Tons

33. Calculate US Carbon Emissions US / Global = 1.6 BMT / 6.6 BMT = 24 % The US emits 24% of Global CO2.

34. Kyoto Protocol The US does not support the Kyoto Protocol, an international treaty to reduce global warming.

35. US Objections to Kyoto  Developing nations not bound, initially.  Reducing fossil fuel use would disrupt US and global economy.

36. The US has not developed a CO2 Reduction Plan Bush administration emphasizes energy production and consumption.

37. Mitigation: Reduce Carbon Emissions We will address this issue in the next part of the course.

38. Mitigation: Carbon Sequestration

39. What are some adaptation steps?  Protect endangered species with larger refuges.  Avoid flooding risks.  Protect water supplies.  Protect grasslands and agricultural lands against overuse.

40. Global Warming  Ice Age?