1. Biogenic Emissions of Organics: Global Budgets and Implications IGAC Conference, Annecy, France September 11, 2008 Colette L. Heald Russ Monson, Mick Wilkinson, Clement Alo, Guiling Wang, Alex Guenther Scot Martin, Qi Chen, Jose Jimenez, Delphine Farmer

2. ISOPRENE: CONTROLLING AIR QUALITY AND CLIMATE C 5 H 8 : Reactive hydrocarbon emitted from plants (primarily broadleaf trees) Annual global emissions ~ equivalent to methane emissions + OH O3O3 Depletes OH = ↑ CH 4 lifetime IPCC, 2007 Beijing CLIMATE AIR QUALITY

3. METEOROLOGICAL AND PHENOLOGICAL VARIABLES CONTROLLING ISOPRENE EMISSION LIGHT  Diffuse and direct radiation  Instantaneous and accumulated (24 hrs and 10 days) TEMPERATURE (Leaf-level)  instantaneous and accumulated (24 hrs, 10 days) T PAR LL TT [Guenther et al., 2006] SOIL MOISTURE  suppressed under drought AMOUNT OF VEGETATION  Leaf area index (LAI) Month LAI SUMMER LEAF AGE  Max emission = mature  Zero emission = new

4. ISOPRENE IN THE FUTURE Isoprene emissions projected to increase substantially due to warmer climate and increasing vegetation density.  LARGE impact on oxidant chemistry and climate  20002100 NPP ↑ Temperature↑ Surface O 3 ↑ 10-30 ppb [Sanderson et al., 2003] Methane lifetime increases [Shindell et al., 2007] SOA burden ↑ > 20% [Heald et al., 2008]

5. A MISSING FACTOR: ISOPRENE EMISSION INHIBITION BY CO 2 Long-Term growth environment: gene adaptation Dependent on ambient CO 2 Short-term exposure: changes in metabolite pools and enzyme activity Dependent on intercellular CO 2 Empirical parameterization from plant studies [Wilkinson et al., GCB, accepted] To what degree does this CO 2 inhibition counteract predicted increases in isoprene (due to T and NPP)?

6. 2100 (A1B): CO 2 INHIBITION COMPENSATES FOR TEMPERATURE INCREASE See that ↑in T activity factor ~ compensated by ↓ in CO 2 activity factor 696 TgC/yr Isoprene emissions in 2100 Decrease when CO 2 inhibition included  31% Dotted=2000 Solid=2100 Global Model: NCAR CAM3-CLM3 (2  x2.5  )

7. CONCLUSION: ISOPRENE EMISSIONS PREDICTED TO REMAIN ~CONSTANT Important implications for oxidative environment of the troposphere… * With fixed vegetation 508 523 696 479 E isop (TgCyr -1 ) 20002100 (A1B) MEGAN MEGAN with CO 2 inhibition

8. UNLESS…CO 2 FERTILIZATION IS STRONG CLM DGVM projects a 3x increase in LAI associated with NPP and a northward expansion of vegetation. [Alo and Wang, 2008]  Isoprene emissions more than double! (1242 TgCyr -1 ) BUT, recent work suggests that NPP increases may be overestimated by 74% when neglecting the role of nutrient limitation [Thornton et al., 2007] [Heald et al., GCB, accepted]

9. PRIMARY BIOLOGICAL AEROSOL PARTICLES (PBAP) POLLEN BACTERIA VIRUSES FUNGUS ALGAE PLANT DEBRIS How much does this source contribute to sub-micron OC? Jaenicke [2005] suggests may be as large a source as dust/sea salt (1000s Tg/yr) Elbert et al. [2007] suggest emission of fungal spores ~ 50 Tg/yr LARGE particles (> 10 µm)

10. PRELIMINARY EMPIRICAL PBAP SIMULATION Based on Elbert et al. [2007] who summarize observed PBAP concentrations and estimate 50 Tg/yr of fungal spores emitted over entire size range. Global Annual Mean Burden 1.4 1.0 POASOAPBAP fine PBAP int < 1  m 1-3  m Tg 0.15 0.03 Global Model: GEOS-Chem (2  x2.5  ) Surface: June ??

11. ANY INDICATION OF PBAP IN AMAZE-08? **PRELIMINARY AMS obs: Scot Martin, Qi Chen (Harvard). Jose Jimenez, Delphine Farmer (CU Boulder) SIMULATED OC Early Feb: Fire influence Field site: close to Manaus, Brazil (in Amazonia), Feb-Mar No obvious indication of an important sub-micron PBAP in the “pristine” Amazon… What about “intermediate” size range?? NEED: (1) better understanding of emission drivers (2) More observations of PBAP

12. ACKNOWLEDGEMENTS Mick Wilkinson, Russ Monson Clement Alo, Guiling Wang Alex Guenther Qi Chen, Scot Martin Delphine Farmer, Jose Jimenez Andi Andreae