Presentation on theme: "Elevated CO 2 and Ozone: Causes & Consequences Bill Holmes University of Michigan School of Natural Resources & Environment."— Presentation transcript:
Elevated CO 2 and Ozone: Causes & Consequences Bill Holmes University of Michigan School of Natural Resources & Environment
Presentation Outline Part I: Rising atmospheric CO 2 & tropospheric ozone –Sources & trends Part II: Impacts on plants & ecosystems –Research questions, approaches, and findings Part III: Activities –Calculate your carbon footprint –View ozone maps, action day alerts
The Greenhouse Effect
Major Sources of CO 2
Global Carbon Budget
Distribution of Emissions 1995 annual totals by region Carbon Dioxide Information Analysis Center 2003
Atmospheric CO 2 Record 370 ppm today 299 ppmv, highest in last 420,000 years
Seasonal Oscillations in Atmospheric CO 2 Concentration
Major Consequences I Rising temperatures –Increase in U.S. of 5-9 ºF by 2100 Extreme weather –More frequent heavy precipitation events –Some regions get drier Coastal and permafrost areas vulnerable –Sea level change –Storm surges –Sinking buildings and roads in Alaska
Major Consequences II Water quality impacts –Floods and droughts wreak havoc, especially in developing countries Public health concerns –Floods, water borne diseases –Heat stress, air pollution Agriculture & forestry impacts –CO 2 promotes productivity, but… –More droughts, fire, and pest damage
Major Consequences III Ecosystem changes –Climate will change faster than ecosystems can migrate or adapt –Changes in plant competition –Grasslands invade forests in southeast U.S –Change in disturbance regimes – more fire!
Tropospheric Ozone Record 20 40 60 1870 189019101930195019701990 80 0 O 3 Concentration (ppbv) 20 40 60 1870 189019101930195019701990 80 0 O 3 Concentration (ppbv) Redrawn from: Marenco et al. 1994. J. Geophy. Res. 99: 16,617-16,632 J. Geophy. Res. 99: 16,617-16,632
Good Ozone, Bad Ozone Too little there... CFCs 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.
Sources of Ground-Level Ozone NOx, VOC + sunlight Ozone
Global Distribution of Tropospheric Ozone
Tropospheric Ozone Circulation
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
Part II: Impacts on Plants & Ecosystems Climate Change temperature air pollution carbon dioxide ozone Ecosystem Function plant growth nutrient cycling carbon sequestration ?
Carbon and Nitrogen Cycling in Terrestrial Ecosystems Plant Productivity Microbial Community Composition & Function Substrate Availability Soil Nitrogen Availability Plant Litter Biochemistry
Carbon and Nitrogen Cycling in Terrestrial Ecosystems Plant Productivity Microbial Community Composition & Function Substrate Availability Soil Nitrogen Availability Plant Litter Biochemistry Atmospheric N Deposition Atmospheric CO 2 & O 3
Carbon and Nitrogen Cycling in Terrestrial Ecosystems Plant Productivity Microbial Community Composition & Function Substrate Availability Soil Nitrogen Availability Plant Litter Biochemistry Atmospheric N Deposition Atmospheric CO 2 & O 3 Temperature & Precipitation
Free-Air CO 2 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
Free-Air CO 2 Enrichment (FACE) Sites
Eastern U.S. FACE Sites Cedar Creek, MN Oak Ridge, TN Rhinelander, WI Durham, NC
Aspen FACE Experiment Rhinelander, WI
Experimental Design 4 treatments x 3 blocks = 12 rings Elevated CO 2 Elevated O 3 Elevated CO 2 + O 3 Ambient Control ppm CO 2 : ppb O 3 : 360 32 560 32 360 56 560 56
Aspen FACE Site Aspen- Maple Aspen- Birch Aspen
Global Geographic Distribution (white & stippled areas) Why Study Aspen & Birch?
Research Questions Will more or less CO 2 be sequestered by forest trees or in soil as CO 2 levels rise? Will elevated CO 2 alleviate other stresses (e.g. ozone, drought, low fertility)? What are the interactive effects of CO 2 and ozone?
CO 2 and Ozone Effects CO 2 effects: + photosynthesis + growth + water use efficiency O 3 effects: – photosynthesis – growth + leaf senescence
Cell-level Ozone Damage Large starch grains Normal aspen chloroplast Intact thylakoid membranes Ozone damaged chloroplast Disintegration of thylakoid membrane Membrane degradation material Small starch grains
CO 2 and O 3 Effects on Tree Growth 0 2000 4000 6000 8000 Aspen Aspen-Birch Aspen-Maple Cumulative Net Primary Productivity g m -2 Stems & Branches Fine Roots Coarse Roots Foliage Control CO 2 O3O3 CO 2 + O 3 Control CO 2 O3O3 CO 2 + O 3 Control CO 2 O3O3 CO 2 + O 3 a c a a a a bb b a a ab
Research Findings I Tree growth increases under elevated CO 2 and decreases under O 3 Carbon sequestration under elevated CO 2 is overestimated in models which do not consider O 3 impacts O 3 reduces the protective coating of leaves and damages leaf tissues CO 2 reduces the damaging effects of O 3 and O 3 reverses growth stimulation by CO 2
Research Findings II Biogeochemical cycling of C and N increases under elevated CO 2, but effects differ among FACE sites O 3 counteracts most CO 2 -induced enhancements in ecosystem processes (soil respiration, N availability…) Plant response to CO 2 may be limited by N availability or co-exposure to O 3 or other factors. Elevated CO 2 delays normal autumn leaf senescence, predisposing some trees to winter dieback Aspen and birch insects and diseases increase under elevated CO 2 and O 3
Part III: Activities What you and your students can do… –Find ways to reduce CO 2 emissions –Learn about ozone action days Get on the web! –Calculate your carbon footprint –View ozone maps and action day alerts
Reduce CO 2 Emissions Reduce home heating & cooling energy use Reduce transportation energy use Increase energy efficiency Learn about implementation of Kyoto protocol guidelines in other countries (Canada, UK) Carbon offsets: reforestation and forest conservation programs
Avoid and Reduce Bad Ozone Check local air quality forecast –Limit physical exertion outdoors in afternoon and early evening Ozone action days –Conserve energy –Avoid driving or filling up fuel tank –Avoid using lawn mower or other two-stroke powered equipment
Ideas Find and compare different carbon calculators Build your own carbon calculator Look up unit conversions Ex: CCF to therms for natural gas Brainstorm ideas for CO 2 offsets Learn about Kyoto protocol