1. Past, Present, and Probable Future of Atmospheric Carbon Dioxide
Dr. Robert MacKay

2. Outline Introduction/ Motivation
Natural and Anthropogenic sources of change
Recent temperature record
Past CO2
Present CO2
A simple mathematical/conceptual model
Future projections
Future emissions
Discussion

3. Natural and Anthropogenic Climate Forcing

7. No Atmosphere

8. Red circles are infrared photons and yellow are sunlight.
Today’s Atmosphere

9. Greenhouse Gases Water Vapor Carbon Dioxide Ozone Methane
Nitrous Oxide
Chlorofluorocarbons

10. Cooling to offset warming

11.
Most believe that the warming observed before 1950 was a result of increased solar luminosity and the warming after 1950 is from increase levels of greenhouse gases caused by human activity.

12. Increased ocean temperatures and decreased pH levels (increased acidity) can be detrimental to corral growth.

13. pH change between 1751 and 1990s. Estimate are that globally ocean surface water pH levels have decreased by as much as .12 units for atmospheric CO2 change from 280 to 360 ppm.

15. Carbon Dioxide in Prehistoric times
CO2 levels in the early Cenozoic Era (~65 Myr ago) were 4 to 5 times higher than they are today. Some have speculated that the uplift of the Tibetan plateau resulted in increased weathering and a draw down of atmospheric CO2 levels bringing us into our present ice age state.

16. Climate and the carbon cycle have many time scales of interest.

17. The last Glacial Maximum occurred around 18,000 years ago

18. Vostok Ice Core data

19. Preindustrial levels of CO2 were 280 ppm and remained so until ~1800
Preindustrial levels of CO2 were 280 ppm and remained so until ~ Present values are around 383 ppm a 37% increase over preindustrial times. There has been a 70 ppm increase since

23. The Bern Carbon Cycle model is used by the IPCC (Intergovernmental Panel on Climate Change) to estimate future CO2 levels for different assumed emission scenarios.

26. Because of long time delays for the carbon cycle, drastically different scenarios yield very similar results for a 20 year time horizon, but drastically different result for a 50 to 100 year time horizon.

27. Recent results suggest that world wide emissions of carbon from fossil fuel use is growing at a rate corresponding to the largest projected emission scenario suggested by the 2001 IPCC report.

28. For the past 30 to 35 years emissions have been closely linked to population.

30. US Carbon emissions through 2004

31. China’s carbon emission through 2004
China’s total carbon emissions exceeded that of the US in late 2006.

32. Russia’s carbon emission through 2004

33. India’s carbon emission through 2004

34. ~40 yrs Oil ~80 yrs Natural gas ~200 years coal
Fossil Fuel Reserves
~40 yrs Oil
~80 yrs Natural gas
~200 years coal

35. World Population

36. Fossil Fuel Reserves Oil

38. Fossil Fuel Reserves Natural Gas

39. Fossil Fuel Reserves coal

43. A -developing countries B-Industrialize countries