12.84 GLOBAL CLIMATE CHANGE: E ONOMICS, SCIENCE AND POLICY Air Pollution Pollution and Climate Interactions Interact ions Jason ohen April 1 , Lecture C Contents ontents 1. 2. 3. 4. 5.. 5 6. that at is relevant to climate? What is air pollution th How does this air pollu pollution tion impact climate? What is the global exte extent nt of this air pollution? How does climate imp impact act this air pollution? How can we model thi this? th is? Current Scientific Unce Uncertainty tha att is relevant to climate? What is air pollution th 1. Species which are either emitted or chemically produced in large amount amounts in urban areas and: consequences for human health • Have negative consequ chemical and physical processing • Have non-linear chemi indirect ct consequences on the 2. Must have direct or indire radiative balance of the Earth Earth’s ’s atmosphere impact other systems of the 3. These species may impac Earth’s climate, such as Ic Ice, Land, or Ecosystems. direct, ect, and indirect effects Aerosols: direct, semi dir effects,, (lifetime of CH4, etc.) CO, NMVOC: OH effects PAN): Ozone Chemistry CO, NMVOC, NOx (also PAN): etc. c.:: Acid Formation SOx, NOx, NHx, et NMVOC, SOx, NOx, NHx, etc.: Secondary Aerosol How does this air poll pollution ution impact climate? Incoming sunlight is reflected or 1. Direct Effect: Incoming scattered back to spac space e (bright aerosols) Incoming oming sunlight is 2. Semi Direct Effect: Inc absorbed in the atmos atmosphere phere (dark aerosols) longer cloud lifetime due to 3. Indirect Effects: longer more particles on sam same sa me e H2O; more bright clouds due to smaller cloud droplets absorber, ber, ecosystem effects 4. Ozone: UV & IR absor lifetime e of CH4, HCFC, etc. 5. OH: Controls the lifetim effects 6. Acids: ecosystem effec How does climate imp impact act this air pollution? 1. Higher Temperatures lead to faster chemical reactions and changes changes in biogenic emissions leads to more or less 2. Rainfall changes leads washout of aerosols a and nd water soluble species Temperature will change 3. Changes in Surface Te vertical mixing vertical mixing and and ad adv advec vection v ection tion vegetation type will change the 4. Changes in vegetation boundary layer proper properties ties How can we (I) (I) model this? Urban Properties Emissions Model (E (EP PPA) PA) Statistical Representation of Results from Urban Model with Model with full full Chemistry, Chemistry, Physics, and different meteorology. Radiative Transfer Model My Model: Other Models: Different Global Meteorological Representations Chemical Transport Models Chemical (3D Global Model) with (3D different assumptions different Deposition and Land Uptake Model Current Scienti Scientific Uncertainty Results of the urban mode model, using 49 equally likely input scenarios, yield enhancement factors which are highly variab variable: (I define EF = emissions / flux out ) CO: Range 1.0 1.0 – 1.4 1.4 NOx: Range 0.1 – 1.0 NOy: Range 0.6 – 1.0 BC Aerosol: Range 0.75 – 0.95 OC Aerosol: Range 0.75 – 6.5