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Intergovernmental Panel On Climate Change Climate Change 2007 The Physical Science Basis. Chapter 2: Changes in Atmospheric Constituents and in Radiative Forcing Sections 2.1-2.3 Presented by Stephen Falk. Section 2.1: Introduction and Scope. What will this chapter focus on?
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Intergovernmental Panel On Climate ChangeClimate Change 2007The Physical Science Basis Chapter 2: Changes in Atmospheric Constituents and in Radiative Forcing Sections 2.1-2.3 Presented by Stephen Falk
Section 2.1: Introduction and Scope • What will this chapter focus on? • Trends in forcing agents and their precursors • Anthropogenic greenhouse gas changes, aerosol changes, aviation induced contrails and cirrus changes, surface albedo changes, natural solar and volcanic mechanisms • Long Lived Greenhouse Gases (LLGHGs)
Section 2.2: Concept of Radiative Forcing • Radiative Forcing – “The change in net irradiance at the tropopause after allowing for stratospheric temperatures to readjust to radiative equilibrium, but with surface and tropospheric temperatures and state held fixed at the unperturbed values”
A few definitions…. • Anthropogenic – Caused or produced by humans • Net Irradiance – The difference in incoming radiation energy and outgoing radiation energy in a given climate system (W/m2) • Tropopause – The atmospheric boundary between the troposphere and the stratosphere
How have humans impacted climate change? • Increase in Greenhouse Gas concentrations • Carbon Dioxide • Methane • Nitrous Oxide • Halocarbons
Other important Greenhouse gases… • Ozone • Water Vapor • Aerosols
Radiative Forcing due to Natural Causes • Solar changes can directly heat the system and also affect the abundance of some greenhouse gases • Volcanic eruptions can create short lived negative forcing • Changes in radiative forcing due to natural causes from 1750-2005 are much less significant than changes due to human causes.