Biogenic Emissions of Organics: Global Budgets and Implications

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

2. ISOPRENE: CONTROLLING AIR QUALITY AND CLIMATE C5 H8: Reactive hydrocarbon emitted from plants (primarily broadleaf trees) Annual global emissions ~ equivalent to methane emissions CLIMATE Depletes OH = ↑ CH4 lifetime + OH O3 AIR QUALITY Beijing IPCC, 2007

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 L T PAR AMOUNT OF VEGETATION  Leaf area index (LAI) • LEAF AGE • Max emission = mature • Zero emission = new LAI SUMMER Month SOIL MOISTURE  suppressed under drought [Guenther et al., 2006]

4. ISOPRENE IN THE FUTURE NPP ↑ Temperature↑ 2000 2100 Methane lifetime increases [Shindell et al., 2007] SOA burden ↑ > 20% [Heald et al., 2008] Surface O3 ↑ 10-30 ppb [Sanderson et al., 2003] Isoprene emissions projected to increase substantially due to warmer climate and increasing vegetation density.  LARGE impact on oxidant chemistry and climate 

5. A MISSING FACTOR: ISOPRENE EMISSION INHIBITION BY CO2 Long-Term growth environment: gene adaptation Dependent on ambient CO2 Short-term exposure: changes in metabolite pools and enzyme activity Dependent on intercellular CO2 Empirical parameterization from plant studies [Wilkinson et al., GCB, accepted] To what degree does this CO2 inhibition counteract predicted increases in isoprene (due to T and NPP)?

6. 2100 (A1B): CO2 INHIBITION COMPENSATES FOR TEMPERATURE INCREASE Decrease when CO2 inhibition included Isoprene emissions in 2100 696 TgC/yr  31% Dotted=2000 Solid=2100 See that ↑in T activity factor ~ compensated by ↓ in CO2 activity factor Global Model: NCAR CAM3-CLM3 (2x2.5)

7. CONCLUSION: ISOPRENE EMISSIONS PREDICTED TO REMAIN ~CONSTANT MEGAN MEGAN with CO2 inhibition 696 Eisop (TgCyr-1) 523 508 479 2000 2100 (A1B) * With fixed vegetation Important implications for oxidative environment of the troposphere…

8. UNLESS…CO2 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) ALGAE VIRUSES BACTERIA POLLEN FUNGUS LARGE particles (> 10 µm) PLANT DEBRIS 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 How much does this source contribute to sub-micron OC?

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. Surface: June Global Annual Mean Burden 1.4 Tg 1.0 0.15 0.03 POA SOA PBAP fine PBAP int 1-3 m < 1 m ? ? Global Model: GEOS-Chem (2x2.5)

11. ANY INDICATION OF PBAP IN AMAZE-08? Field site: close to Manaus, Brazil (in Amazonia), Feb-Mar Early Feb: Fire influence SIMULATED OC 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 **PRELIMINARY AMS obs: Scot Martin, Qi Chen (Harvard). Jose Jimenez, Delphine Farmer (CU Boulder)

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