Adapted from Elevated CO 2 and Ozone: Causes & Consequences

1. Adapted from Elevated CO2 and Ozone: Causes & Consequences Bill Holmes University of Michigan School of Natural Resources& Environment 2008

2. Free-Air CO2 Enrichment (FACE) Experiments Open-air control of atmosphere conditions Fairly large scale Longer term than previous chamber experiments Major investment of research money Large teams of researchers

3. Free-Air CO2 Enrichment (FACE) Sites

4. Eastern U.S. FACE Sites Cedar Creek, MN Rhinelander, WI Oak Ridge, TN Durham, NC

5. Aspen FACE ExperimentRhinelander, WI

6. Experimental Design 4 treatments x 3 blocks = 12 rings AmbientControl ElevatedCO2 ElevatedO3 ElevatedCO2 + O3 360 32 560 32 360 56 560 56 ppm CO2: ppb O3:

7. Aspen FACE Site Aspen-Birch Aspen Aspen-Maple

8. Research Questions • Will more or less CO2 be sequestered by forest trees or in soil as CO2 levels rise? • Will elevated CO2 alleviate other stresses (e.g. ozone, drought, low fertility)? • What are the interactive effects of CO2 and ozone?

9. Aspen Face Results

10. CO2 and O3 Effects on Tree Growth 8000 Foliage Aspen Aspen-Birch Stems & Branches b b Coarse Roots Fine Roots 6000 a a Cumulative Net Primary Productivity g m-2 a Aspen-Maple b a 4000 c ab a a a 2000 0 CO2 CO2 CO2 Control Control Control O3 O3 O3 CO2 + O3 CO2 + O3 CO2 + O3

11. Research Findings I • Tree growth increases under elevated CO2 and decreases under O3 • Carbon sequestration under elevated CO2 is overestimated in models which do not consider O3 impacts • O3 reduces the protective coating of leaves and damages leaf tissues • CO2 reduces the damaging effects of O3 and O3 reverses growth stimulation by CO2

12. Research Findings II • Biogeochemical cycling of C and N increases under elevated CO2, but effects differ among FACE sites • O3 counteracts most CO2-induced enhancements in ecosystem processes (soil respiration, N availability…) • Plant response to CO2 may be limited by N availability or co-exposure to O3 or other factors. • Elevated CO2 delays normal autumn leaf senescence, predisposing some trees to winter dieback • Aspen and birch insects and diseases increase under elevated CO2 and O3

13. The Greenhouse Effect

14. Greenhouse Gases

15. Major Sources of CO2

16. Global Carbon Budget

17. Distribution of Emissions1995 annual totals by region Carbon Dioxide Information Analysis Center 2003

18. 370 ppmtoday Atmospheric CO2 Record 299 ppmv, highest inlast 420,000 years

19. Seasonal Oscillations in Atmospheric CO2 Concentration

20. 80 80 60 60 40 40 20 20 0 0 1870 1870 1890 1890 1910 1910 1930 1930 1950 1950 1970 1970 1990 1990 Tropospheric Ozone Record O3 Concentration (ppbv) O3 Concentration (ppbv) Redrawn from: Marenco et al. 1994. J. Geophy. Res. 99: 16,617-16,632

21. Good Ozone, Bad Ozone Too little there... CFC’s and halons from air conditioners and refrigerators break down the protective ozone layer. Too much here... Vehicles, power plants and factories emit air pollution that forms ground-level ozone.

22. Sources of Ground-Level Ozone NOx, VOC + sunlight Ozone Hot sunny days

23. Global Distribution of Tropospheric Ozone

24. Tropospheric Ozone Circulation

25. Effects of "Bad" Ozone • Human Health • Coughing, throat irritation, lung damage • Worse when working or exercising outdoors • The Environment • Damages vegetation and ecosystems • Increases susceptibility of trees to other stresses (pests, diseases, weather extremes) • Forest and crop losses