Human Activities, CO2 Emissions and Concentrations, and Climate Change The Ocean in a High CO2 World An International Science Symposium Jae Edmonds, Hugh Pitcher, and Steve Smith 10 May 2004 Joint Global Change Research Institute Paris, France

Organizers of the meeting US DOE Office of Science Thanks to Organizers of the meeting US DOE Office of Science EPRI Other sponsors of the GTSP Nebojsa Nakicenovic, Brian Fisher, Hugh Pitcher, Charlette Geffen 2

Key Question for Today What are the sources of CO2 emissions? How much carbon is there? What are the fundamental drivers of CO2 emissions? What range of CO2 emissions trajectories could be anticipated (reference and stabilization)? What temperature regimes might be anticipated? 3

Final Thoughts Reference case fossil fuel and land-use change carbon emissions are a major source of uncertainty in CO2 loading of the atmosphere and oceans. FF emissions range in 2100 from ~3 PgC/y (SRES B1T MESSAGE) to >35 PgC/y (SRES A1C AIM) Cumulative emissions 1990 to 2100 range from <775 Pg to (SRES B1T MESSAGE) >2,500 Pg (SRES A1C AIM) The high end of these ranges are truncated in stabilization scenarios. Emissions uncertainty combined with uncertainty in climate sensitivity implies a wide range of possible future carbon-climate regimes. 4

Sources of Anthropogenic CO2 Emissions Fossil fuel use (6.5 PgC/y in 1999) Natural gas 13.7 TgC/EJ Oil 20.2 TgC/EJ Coal 25.5 TgC/EJ Industrial process emissions (e.g. cement) 0.2 Pgc/y Land-use change emissions (1.7; 0.6-2.6 PgC/y) Deforestation Soil cultivation 5

Fossil Fuel Carbon Emissions 1999 Source: Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory. 6

Land-use Carbon Emissions 1999 Range of Land-use Emissions Source: Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, based on Houghton. Source: IPCC WG1 Third Assessment Report. 7

Global Primary Energy Source: IIASA 8

Historical Fossil Fuel CO2 Emissions 1751 to 1999 Source: Carbon Dioxide Information Analysis Center. 9

Land-use Emissions 1850 to 2000 Source: Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, based on Houghton. 10

ENERGY RESOURCES Will the Problem Go Away on Its Own? Won’t the limited conventional oil and gas resource force a transition in the near term to a world based on energy efficiency and renewable and nuclear energy forms? 11

Atmosphere 790 PgC 12

Scenarios of Future Emissions Scenarios of future anthropogenic carbon emissions to the atmosphere use complex energy-economy-land-use models. 13

Future Carbon Emissions Scenarios Which of the literally thousands of parameters are most important to determining future emissions of greenhouse gases? Uncertainty analysis conducted to explore precisely this question. Edmonds, Reilly, Gardner and Brenkert (1986) Scott, Sands, Edmonds, Liebetrau and Engel (2000) Others include Nordhaus and Yohe (1983), Hammitt (1992), Manne and Richels (1993), Alcamo, et al. (1994), Dowlatabadi (1999), Gritsevskyi and Nakicenovic (1999) 14

Results From an Uncertainty Analysis Technology is the broad set of processes covering know-how, experience and equipment, used by humans to produce services and transform resources. (Not just devices) 15

Demographics Future global population is relatively certain in the near term, But uncertain in the long term. Forecasts of population growth have risen, peaked and declined over the past 25 years. The present best guess population is about where it was in 1978. Future populations are aging rapidly. 16

Population Trajectories Are Falling Population estimates have declined recently Many scenarios show global populations declining at the end of the 21st century. Lutz et al., 1997, 2001 17

Increased Life Expectancy Exacerbates Aging and Increases Population Both use TCF=1.9 18

Labor Productivity GDP = Labor productivity * Labor(hours) Labor productivity growth rates are the major determinant of the scale of economic activity. They are relatively stable in the developed world. They are highly varied in the developing world. Uncertainty in developing country labor productivity growth is a major source of uncertainty in carbon emissions. 19

Growth in labor productivity 20

Stabilizing CO2 Base Case and “Gap” Technologies Assumed Advances In Fossil Fuels Energy intensity Nuclear Renewables Gap technologies Carbon capture & disposal Adv. fossil H2 and Adv. Transportation Biotechnologies Soils, Bioenergy, adv. Biological energy The “Gap” 21

Range of Reference Case Fossil Fuel Carbon Emissions Source: IIASA Median SRES 2100 emission = 14.4 PgC/y Open literature 2100 emissions ~20 PgC/y 22

Range 765 to 2,531 PgC Median 1,500 PgC 23

Uncertainty in Stabilization Trajectories Stabilization of CO2 concentrations implies that emissions peak and decline. 24

Cumulative Emissions and Stabilization 25

Cumulative Emissions and Stabilization 26

Technology Alone Won’t NECESSARILY Stabilize CO2 Concentrations Energy Related Carbon Emissions A reference case with advanced technology development of carbon capture and H2, but no climate policy. A reference case with continued technology development, and no climate policy. Emissions path that stabilizes CO2 concentrations at 550 ppm. 27

Land-use change emissions depend on Land Use Emissions Land-use change emissions depend on Population Income Technology Climate (including water) Policy (including climate policy) Land use emissions are uncertain, but Generally lower than fossil fuel emissions. 28

IPCC SRES Reference Case Land-Use Change Emissions Scenarios 29

Land-Use Emissions are Sensitive to Agricultural Productivity Growth Rates and to Energy Policy Temperature stabilization scenario MiniCAM B2 Reference scenario 30

CO2 Concentrations 31

Climate change is more than CO2 15 Greenhouse Related Gases Tracked by MiniCAM Carbon Dioxide Methane 15 Source Sectors Energy, Human Wastes, Agriculture, Land-Use Nitrous Oxide 12 Source Sectors Energy, Human, Industrial, Agriculture, Land-Use Halocarbons, etc. 15 Source Sectors (7 gases) Reactive Gases NOx, VOC, CO Sulfur Dioxide Carbonaceous Aerosols Black Carbon & Organic Carbon 19 Source Sectors each (Energy & Land-Use Combustion) 32

Range of Global Mean Surface Temperatures: 2000 to 2100 Source: IPCC WG1 Third Assessment Report. 33

Uncertainty Analysis Scott, et al. (2000) Distribution of Temperature Increase Base Case Number of observations 34

Final Thoughts Reference case fossil fuel and land-use change carbon emissions are a major source of uncertainty in CO2 loading of the atmosphere and oceans. FF emissions range in 2100 from ~3 PgC/y (SRES B1T MESSAGE) to >35 PgC/y (SRES A1C AIM) Cumulative emissions 1990 to 2100 range from <775 Pg to (SRES B1T MESSAGE) >2,500 Pg (SRES A1C AIM) The high end of these ranges are truncated in stabilization scenarios. Emissions uncertainty combined with uncertainty in climate sensitivity implies a wide range of possible future carbon-climate regimes. 35