FGHALL1 Greenhouse Gases Carbon dioxide CO 2 Methane CH 4 Water Vapor H 2 O Nitrous Oxide N 2 O Chloroflorocarbons CFC’s Ozone O 3 Absorbing Aerosols Smoke Soot Warming: Greenhouse gases Absorbing aerosols Warming: Greenhouse gases Absorbing aerosols Clouds Soot Greenhouse Gases Cooling: Reflective aerosols CLOUDS DUST VOLCANIC AEROSOLS Natural carbon sequestration Vegetation/Soils Air-sea CO 2 equilibrium Ocean Biota Carbon Smoke Heat ∆Earth’s Heat Balance = Warming - Cooling

FGHALL2 The Global Carbon Cycle Humans Atmosphere + 3/yr Ocean Land ~ 92 ~ 120 ~122 7 PgC*/yr ~90 Over half the CO 2 released by humans is absorbed by oceans and land. Will this continue? *PgC = Peta (10 15 ) grams of carbon 2 to oceans 2 to land

FGHALL3 How will carbon-coupled feedbacks affect future climate ecosystems, and life? Climate Land Ocean How is the earth sequestering carbon at an increasing rate? How long can this continue?

FGHALL4 ‘Photosynthesis’ by Ursula Freer by Ursula Freer Biological Productivity Michael Behrenfeld

FGHALL5 Leaf Photosynthesis Piers Seller’s PAR Diagram

FGHALL6 Photosynthesis Action Spectrum

FGHALL7 Vegetation indices--future topic

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9 Satellite Chlorophyll and Photosynthesis Pigment containing chloroplast membranes CO 2 HCO 3 CO 3 -2 = cellular organelles originating through endosymbiosis

FGHALL10 ~50 ~100

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FGHALL12 Will SUVs start the next ice age?

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FGHALL15 Where the rubber hits the road…

FGHALL16 Industrial Revolution: wood & fossil fuels

FGHALL17 Approaching 50 years of CO 2 data

FGHALL18 Interannual CO 2 variations

FGHALL19 Current Uncertainties Fossil Fuels To Atmosphere To Land/Ocean 5.5±0.3 Land use 1.6 ± 0.8 change Ocean 2.0 ± 0.6 Uptake Unidentified 1.8 ± 1.5 Sink  Current source and sink strengths are uncertain.  Prediction of future climate forcing is therefore uncertain as well. Peta (10 15 ) grams of carbon/year Atmospheric 3.3 ± 0.2 Carbon

FGHALL20 What are the sequestration processes? Oceans –Solubility pump –Biological pump Land –CO 2 Fertilization –Nutrient fertilization –Forest regrowth, fire suppression, woody encroachment, etc. –Response to changing climate NEE R GPP

FGHALL21 Uncertain Futures  Different assumptions project dramatically different futures.  Which is correct? How can we know?

FGHALL22 USGCRP Science Questions What has happened to the CO 2 that has already been emitted by human activities? How do land management and land use, terrestrial ecosystems and ocean dynamics, and other factors affect carbon sources and sinks over time? What will be the future atmospheric CO 2 concentration resulting from environmental changes, human actions and past and future emissions?

FGHALL23 Climate Forcing Factors Forcing Strength (Watts/m 2 ) Greenhouse Gases Other Anthropogenic Forcings Natural Forcings Climate Forcings 0.4 ± 0.2 (indirect via O 3 ) -1.1 ± 0.5 Forced Cloud Changes Tropo- spheric Aerosols N 2 O 0.15± 0.05 CFCs 0.35 ± 0.05 (indirect via O 3 and H 2 O) Volcanic Aerosols (range of decadal means) -0.1 ± ± ± ± 0.2 Sun CO 2 ( ) CH ± 0.15 Other Tropospheric Ozone (indirect via stratospheric ozone) Land Cover Alter- ations -0.2 ± 0.2 Estimated climate forcings between 1850 and 2000  Climate warming from 1850 to 2000 resulted from both human activities and natural causes.  Carbon dioxide played an important role.

FGHALL24 What? Me worry?