1. 1 Investigating Links between Atmospheric Chemistry, Climate, and the Biosphere Loretta J. Mickley, 4 November 2011 1 with Amos Tai, Lee Murray, Xu Yue, Jennifer Logan, Daniel Jacob, Shiliang Wu, Eric Leibensperger, Dominick Spracklen Wildfires in Quebec, May 31, 2010 Haze over Boston on the same day

2. 2 Atmospheric chemistry examines the mix of gases and particles in the atmosphere. Our group mainly focuses on short-lived species: ozone, particles, mercury and their precursors, with lifetimes days to weeks. Lifetimes in atmospheric chemistry Centuries: SF 6, some CFCs Decades: most greenhouse gases: CO 2, N 2 O,... 9-10 years: CH 4 (methane, precursor to ozone and greenhouse gas) Days-weeks: O 3 (ozone), particulate matter (PM) Seconds: OH, NO Pollution over Hong Kong Air pollution over Hong Kong reached dangerous levels one of every eight days in 2009

3. 3 Surface ozone and particulate matter are harmful to human health. EPA ’ s Technical Support Document for the proposed finding on CO 2 as a pollutant. Cites the threat of climate change to air quality Calculated with standard of 0.075 ppm. Proposed new standards will push more areas into non-attainment. Number of people living in areas that exceed the national ambient air quality standards (NAAQS) in 2008. Short-lived species respond to climate change as well as to trends in emissions. 2009

4. 4 Surface ozone and particulate matter also affect climate. Radiative forcing W m -2 ozone visible infra- red Many particles scatter incoming sunlight (cooling). Ozone absorbs outgoing terrestrial radiation (warming) particles IPCC 2007 Yardstick of warming or cooling effect

5. 5 O3O3 O2O2 h O3O3 Deposition STRATOSPHERE TROPOSPHERE 8-18 km Lifecycle of tropospheric ozone: production is via oxidation of CO, VOCs, and methane in the presence of NOx. NOx Nonmethane volatile organic compounds (VOCs) NOx = NO + NO 2 Human activityFires Biosphere emissions Many processes affected by climate NOx VOCs NOx VOCs CO CH 4 Soup of chemical reactions Ozone is produced in the atmosphere in sunlight.

6. Observations imply importance of biogenic emissions to atmospheric chemistry Probability of ozone exceedance Northeast/ mid Atlantic in summer maximum daily temperature (K) Probability Reasons for increasing probability of ozone exceedances at higher max Temps: Greater stagnation + clear skies Faster chemical reactions. Greater biogenic emissions, e.g. isoprene Lin et al., 2000 1988, hottest on record Days Number of summer days with ozone exceedances, mean over sites in Northeast

7. 7 Life cycle of particulate matter (PM, aerosols) nucleation coagulation condensation wildfires combustion soil dust sea salt...... cycling ultra-fine (<0.01  m) fine (0.01-1  m) cloud (1-100  m) combustion volcanoes agriculture biosphere coarse (1-10  m) scavenging precursor gases Climate change affects many processes, including gas- particle partitioning. Soup of chemical reactions NOx VOCs SO 2 NH 3 SO 2

8. 8 Models are useful tools to interpret observations and to investigate past or future atmospheres. emissions transport dilution chemistry particulate matter (PM) and ozone pollution population GEOS-Chem chemical transport model: Global 3-D model describes the transport and chemical evolution of atmospheric pollutants winds Winds carry pollutants to other boxes. Emissions + chemistry calculated within box Meteorology driving GEOS-Chem can come from observations or climate models.

9. 9 Meteorology driving 3-D chemical models comes from climate models: Two ways to run climate models “nudged” with observations calculated from first principles All climate models depend on basic physics to describe motions and thermodynamics of the atmosphere: E.g., vertical structure is described by hydrostatic equation Climate models also depend on parameterizations for many processes. E.g., microphysics of cloud droplet formation. Physics + Parameterized processes Tilt of earth, geography, greenhouse gas content Weather + Climate Input Climate model Output

10. Validation of models involves scrupulously comparing model results to observations. Since, 1800s, input of reactive nitrogen to ecosystems has increased by more than a factor of 3 globally due to human activity. r = Correlation coefficients NMB = normalized mean biases MNB= mean normalized biases observations model Zhang et al., 2011 Nitrate wet deposition fluxes, 2006

11. Biogenic volatile organic compounds (BVOCs): Emissions Parameterization in GEOS-Chem Base emission for a specified mix of different plant functional types at specified meteorological conditions INPUTS MODEL Base emissions are scaled for local conditions: vegetation type, leaf area index, temperature, solar insolation OUTPUT Gridded BVOC emissions [atoms C cm -2 s -1 ] (includes isoprene and monoterpenes) Guenther et al., 2006 Big isoprene emitters: Oaks, spruce, firs, sweetgum

12. Other parameterizations in GEOS-Chem Soil NOx emissions = f(vegetation type, temperature, precipitation history, canopy reduction, fertilizer usage) Dry deposition = Resistance in series scheme, with these resistances: Aerodynamic resistance to surface Boundary resistance at surface of leaf Canopy surface resistance = f(Leaf area index, direct and diffuse sunlight, gas or particle type) Wet deposition = f(clouds, rainfall, gas or particle type) Difficulty is scaling up from small-scale processes to global scale.

13. How will changing climate affect changing organic carbon particles in the atmosphere? Fine mass of organic particles, annual mean. Southeast is a big contributor due to dense vegetation. Organic particles contribute about 20- 40% of particle mass in the US. What will change in future atmosphere: air temperature biogenic emissions land use vegetation Malm et al., 2004

14. Effects of Future Biosphere Changes on Air Quality Plants Biogenic volatile organic compound (VOC) Secondary organic aerosol (SOA) [Heald et al. 2008] Simulated 2000-2100 changes in annual surface SOA concentrations climate change onlyclimate-driven biogenic emissions change only anthropogenic land use change only ++

15. Effects of Future Biosphere Changes on Air Quality [Wu et al. 2011] Climate- and CO 2 -driven 2000-2100 changes in areal fractional coverage Temperate broad-leaved treesBoreal needle-leaved trees Associated changes in SOA concentrations 20% increase in SOA global burden

16. Effects of Future Biosphere Changes on Air Quality Simulated 2000-2150 changes in surface ozone concentrations Ozone deposition could have consequences for carbon uptake in plants. climate- and CO 2 -driven vegetation change only Plants Leaf surface Ozone loss Biogenic VOC [Wu et al. 2011] + + +- - Ozone increase or loss (depends on NOx) ppb [Wu et al. 2011]

17. 2000-2100 changes gross primary productivity due to ozone changes Increasing ozone due to climate change can decrease gross primary productivity. Sitch et al., 2007 2000 ozone 2100 ozone GPP

18. Observed Area burned Observed Meteorology Regression Model Relationship between area burned + meteorology observations model How will changing climate affect wildfires and air quality? Yue et al., 2011 We build a fire prediction scheme that can capture interannual variability in area burned in the Western US. Area burned = f (temperature, rainfall, Palmer drought index, relative humidity, other indices...) Each ecosystem has its own relationship between area burned and meteorology.

19. Ensemble of climate models predict warmer and drier summers in the west. Temperature Precipitation Relative Humidity DJF JJA 2000-2050 change in meteorological fields, ensemble medians in each gridbox. A1B scenario – moderate increases in greenhouse gases. Yue et al., 2011

20. Meteorology from 15 climate models Regression Model Calculated area burned for present-day and future 20 We calculate changes in area burned for 2000-2050, using an ensemble of IPCC model results. Area burned increases 20-120% across Western US, but models show range of uncertainty. Spracklen et al., 2009 Yue et al., 2011 2000-2050 changes in meteorology from 15 IPCC AR4 climate models. different ecosystems in Western US

21. The total area burned is predicted to increase by 60~120% over western US by the midcentury Years 1986 1990 1995 2000 2051 2055 2060 2065 Present-day observations Ensemble median values of predictions Spread of predictions 1990 2000 2055 2065 Change in area burned is especially large in Southwest US, where area burned doubles. 10 5 ha Yue et al., 2011

22. The length of fire season increases by 3 weeks in 2050s relative to present day. 163 days185 days End day Start day Calculations with observations Ensemble median values of predictions Spread of predictions Yue et al., 2011

23. Can we also simulate the effects of insect outbreaks on forests in a global chemistry model? Arneth and Niinemets, 2010 Both fires and insect outbreaks are influenced by climate. Can we build a probabilistic model of insect outbreaks by ecosystem?

24. Investigations of the oxidation capacity of the atmosphere during the Last Glacial Maximum Ongoing project to look at how changing land cover and climate affect oxidation capacity of atmosphere. Biogenic species could play a role: decreased concentrations could increase OH levels. Murray et al., in progress Emissions of biogenic species Annual mean emissions of isoprene Present-day Preindustrial CLIMAP LGM Webb LGM

25. Comparison to observed sulfate concentrations shows good agreement. Sequence shows increasing sulfate from 1950-1980, followed by a decline in recent years. Most of aerosol has already cleared by 2010. 19501960 19701980 19902001 Leibensperger et al., 2011 Calculated trend in surface sulfate concentrations, 1950- 2001. Trend in aerosols over United States suggests cleaner skies, possible warming. 25

26. Each scenario includes an ensemble of 3 simulations. 26 GISS GCMA1B greenhouse gases constant aerosols A1B greenhouse gases zero US aerosols 1950 1975 2000 2025 2050 We test the effect of changing U.S. aerosols on regional climate. Mickley et al., 2011 Two scenarios.

27. Removal of anthropogenic aerosols over US increases annual mean surface temperatures by 0.5 o C. Summertime temperatures increase as much as 2 o C during heatwaves. Mean 2010-2050 temperature difference: No-US-aerosol case – Control White areas signify no significant difference. Results from an ensemble of 3 for each case. Warming due to 2010-2050 trend in greenhouse gases. Additional warming due to zeroing of US aerosols Mickley et al., 2011 27

28. Calculation of maximum temperatures in climate models is sensitive to choice of parameters having to do with land cover/soil. Lower and upper estimates of JJA maximum temperatures in 2x CO 2 atmosphere Central 80% range of increases for 44 versions of one climate model oCoC Percent variability in Tmax accounted for by vegetation parameters. Clark et al., 2010 28 Forest roughness parameter Vegetation root depth Lower estimateUpper estimate 50%30%6% 0 8

29. Effect of kudzu invasion on surface air quality Hickman et al., 2010 By fixing atmospheric nitrogen at a rapid rate, kudzu invasion leads to significant release of nitric oxide, an ozone precursor. Mean July emissions at 3 sites in Georgia kudzunative NO N 2 O Calculated change in the number of ozone exceedance days in summer due to a 28% increase in soil NOx emissions accompanying large kudzu invasion. days 29

30. 30 Collaborations with ecologists: Enhance knowledge of interactions between biosphere and atmosphere, and how to model those interactions Improve understanding of response of ecosystems to climate change Specific processes that will change with changing climate or changing emissions biogenic emissions, including methane, VOCs deposition of nitrogen, ozone, and other species soil NOx emissions insect-driven outbreaks and their consequences