Understanding and managing climate-carbon feedbacks

1. Understanding and managing climate-carbon feedbacks Rich Conant Natural Resource Ecology Laboratory & School of Global Environmental Sustainability Colorado State University

2. How much C can we emit? Acceptable world-wide average: 0.35 tC capita-1 yr-1 (Chakravarty et al. 2009)

3. A modest proposal for US climate policy 1.65 Pg C yr-1 4.2 tC capita-1 yr-1 (US EPA emission inventory 2009)

4. CO2 Global Carbon Cycle Atmosphere800 Gt C+3-5 per year 57Photosynthesis 55Respiration & Decomposition ~12 Gt C

5. CO2 Global Carbon Cycle Atmosphere800 Gt C+3-5 per year CO2 ~12Gt C CO2

6. Terrestrial C trajectories System carbon Disturbance Management change Time

7. A modest proposal for US climate policy 1.65 Pg C yr-1 -0.31 Pg C yr-11 1.32 Pg C yr-1 3.3 tC capita-1 yr-1 (Pacala et al. 2003 Science)

8. Asia: uptake=0.5 (e=3.5) North America: uptake=1.7 (e=1.6) Tropics/S. America: uptake=-1.1 (e=0.7) A modest proposal for US climate policy (Fan et al. 1998 Science)

9. A modest proposal for US climate policy • Continue to sequester more C in land than released by fossil fuel burning • Contribute to other nations’ C management strategies by exchanging C emission offsets with them

10. A modest proposal for US climate policy- what’s wrong with it? • Reduces incentives to deal with emissions – delays implementation of emission reduction and de-carbonization policies

11. Does it delay implementation of other emission reductions?

12. A modest proposal for US climate policy- what’s wrong with it? • Reduces incentives to deal with emissions – delays implementation of emission reduction and de-carbonization policies • These practices are not additional – they don’t alter the current trajectory of CO2 rise

13. Practices that sequester carbon in grasslands often

14. a b a b C stocks Assuming constant baseline, SOC offset = b-a time C stocks Other factors can drive SOC gains or SOC losses; offset ≠ b-a time (Conant et al. 2009)

15. A modest proposal for US climate policy- what’s wrong with it? • Reduces incentives to deal with emissions – delays implementation of emission reduction and de-carbonization policies • These practices are not additional – they don’t alter the current trajectory of CO2 rise • Carbon sequestered is subject to reversals – losses due to fire, tillage, etc.

16. Terrestrial C trajectories ??? System carbon Management change Time

17. Benefits of policies that favor C sequestration • Technical potential for carbon sequestration is large

18. Technical potential for C sequestration is large (IPCC AR4 SfPM)

19. Benefits of policies that favor C sequestration • Technical potential for carbon sequestration is large. • Sequestration is inexpensive and easy to implement with current technology.

20. Technical potential for C sequestration is large (IPCC AR4 CH8)

21. Benefits of policies that favor C sequestration • Technical potential for carbon sequestration is large. • Sequestration is inexpensive and easy to implement with current technology. • Sequestration can lead to environmental, social, and economic co-benefits.

22. Sequestration/GHG reduction co-benefits: (IPCC AR4 CH8)

23. Benefits of policies that favor C sequestration • Technical potential for carbon sequestration is large. • Sequestration is inexpensive and easy to implement with current technology. • Sequestration can lead to environmental, social, and economic co-benefits. • Unlike emission reductions C sequestration can be used to draw-down atmospheric CO2 concentrations.

24. CO2 concentrations are increasing: • Human activities are driving increases in atmospheric CO2

25. Benefits of policies that favor C sequestration • Technical potential for carbon sequestration is large. • Sequestration is inexpensive and easy to implement with current technology. • Sequestration can lead to environmental, social, and economic co-benefits. • Unlike emission reductions C sequestration can be used to draw-down atmospheric CO2 concentrations. • Developing nations could be engaged in climate agreements via sequestration

26. Developing nations could be engaged (Conant: WIRES 2010)

27. Benefits of policies that favor C sequestration • Technical potential for carbon sequestration is large. • Sequestration is inexpensive and easy to implement with current technology. • Sequestration can lead to environmental, social, and economic co-benefits. • Unlike emission reductions C sequestration can be used to draw-down atmospheric CO2 concentrations. • Developing nations could be engaged in climate agreements via sequestration • Sequestration could foster adaptation

29. Carbon cycle science • What don’t we know? • We still have limited information on how management influences C stocks • How widely practices that sequester carbon can/will be implemented • Impacts of carbon-sequestering practices on environmental co-benefits • Impacts of carbon-sequestering practices on other greenhouse gas emissions • Upstream – energy use, inputs • Downstream – transport, CH4 emissions

30. Food production is part of the C cycle human respiration CO2 livestock respiration Forage consumption How does harvesting biomass affect ecosystem carbon stocks? Are there ways to maximize both harvest and ecosystem carbon stocks? Soil carbon Stocks

31. Perspective • Climate change science timeline 2007 IPCC AR4: effects of warming evident; cost of reducing emissions far less than damage they will cause 1995 IPCC 2nd report: “signature of human activities” 1956 Phillips: 1st somewhat realistic global climate model 1897 Chamberlin: model of global C exchange 1938 Callendar: CO2 greenhouse global warming is underway 1896 Arrhenius: 1st calculation of anthropogenic global warming 1988 IPCC established; 1st report 1990 1976 Deforestation recognized as important driver of climate change 1859Tyndall: some gasses absorb IR; could drive climate change 1930s Global warming trend since late 19th century reported 1958 Keeling: Atm. CO2 measurements begin at Mauna Loa

32. Perspective • Climate policy timeline 2008-2012: 1st Kyoto compliance period A modest proposal? Near-term implementation of a global policy that affects all parts of everyone’s lives. 2005: Kyoto into effect 2001: Marrakech accords 1997: Kyoto Protocol 1992: US Energy policy act; incl. Section 1605(b) 1992: Rio Treaty – establishes UNFCCC

34. Agroecosystems Research at NREL Regional analysis & Integrated assessment Auditing Projections Monitoring sites Auditing Agroecological models Process Studies Interpretation Field Experiments Model Validation Improvement Driving variables Past/current regional land use statistics, climate, soil, etc. Agroecozone delineation Future land use scenarios

36. Carbon flow in grassland ecosystems • What do we know? • Carbon flow in grassland ecosystems • The things we do on the land impact carbon stocks • Grazing intensity/seasonality • Species composition • Soil fertility • Other factors influence carbon stocks • Climate • Soil characteristics • Past land use • Given information about these things, soil carbon stocks can be predicted • Current stocks • gains or losses w/ changes in management CO2 livestock respiration Forage consumption Soil carbon Stocks

38. Filling the gaps: measurements on the ground • Data are very sparse globally. • We measure soil C stock changes (either before/after or neighboring fields) • This limits our ability to extrapolate from sparse observations. • One way forward: more data, better models, tighter data-model linkages. (Conant and Paustian 2002)

39. Carbon cycle science • What don’t we know? • We still have limited information on how management influences C stocks • We have a growing database of on-the-ground studies • Data are still limited • Little consistency between sources • Synthesis still challenging

40. Carbon flow in grassland ecosystems • What don’t we know? • The things we do on the land impact carbon stocks • Grazing intensity/seasonality • Species composition • Soil fertility • Other factors influence carbon stocks • Climate • Soil characteristics • Past land use • Given information about these things, soil carbon stocks can be predicted • Current stocks • gains or losses w/ changes in management CO2 livestock respiration Forage consumption Soil carbon Stocks

44. Carbon cycle science • What don’t we know? • We still have limited information on how management influences C stocks • We have a growing database of on-the-ground studies • Data are still limited • Little consistency between sources • Synthesis still challenging • Data availability constrain model refinements

45. Management impacts carbon stocks System carbon Disturbance Management change Time

46. Economic potential differs from technical potential (IPCC AR4 CH8)

47. Carbon cycle science • What don’t we know? • We still have limited information on how management influences C stocks • How widely practices that sequester carbon can/will be implemented • Technical potential differs from – and is easier to assess than – economic potential • Technical potential is just one piece of the equation • Activity data are limited in the US, but much (MUCH!) more-so world-wide

48. Rangeland C sequestration co-benefits: (IPCC AR4 CH8)

49. Carbon cycle science • What don’t we know? • We still have limited information on how management influences C stocks • How widely practices that sequester carbon can/will be implemented • Impacts of carbon-sequestering practices on environmental co-benefits • Habitat, water quality, erosion, etc.

50. Carbon cycle science • Some recommendations • Expand on-the-ground data collection • Coordinate data collection and presentation to lower barriers to meaningful synthesis • Take a systems perspective and seek to understand sequestration within the larger context of economic benefits, environmental co-benefits, and greenhouse emissions