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Understanding Radiative Forcing: Presentation

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    IPCC (Intergovernmental Panel on Climate Change)

    • Review of all data relevant to climate change
    • Over 800 scientists from almost 40 countries
    • Five reports: 1990 – 2014
      • Nobel Peace Prize in 2007
      • 2014: over 3500 pages

    Reports.png

    Photo courtesy IPCC

    Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850 (see Figure SPM.1). In the Northern Hemisphere, 1983-2012 was likely the warmest 30-year period of the last 1400 years (medium confidence). {2.4. 5.3}

    Temperature.pngLikelihoodScale.png

    Figure & Text courtesy IPCC Summary for Policymakers

    • Radiative Forcing (RF): the affect a factor has on the Earth’s radiation budget
      • Factors: atmospheric constituent, land-use change
      • Positive RF: the factor warms the atmosphere
      • Negative RF: the factor cools the atmosphere
      • Relative to 1750 (pre-industrial revolution)

      Radiation_Incoming,Outgoing.png

      RF = Incoming Radiation – Outgoing Radiation

      • CO2 has increased from 280 ppm (1850) to 400 ppm
        • RF = 1.68 W m–2
          • Today, every m2 of the Earth’s surface atmosphere is warmer by the equivalent of 1.68 W due to CO2
      • CO2 = 1.68 W m–2
      • Other factors: CH4, N2O, CFCs, land use change…
      • Overall RF ~ 2.29 W m–2
        • Uncertain: 1.13-3.33 W m–2

    Total radiative forcing is positive, and has led to an uptake of energy by the climate system. The largest contribution to total radiative forcing is caused by the increase in the atmospheric concentration of CO2 since 1750 (see Figure SPM.5). {3.2, Box 3.1, 8.3, 8.5}

    Text courtesy IPCC Summary for Policymakers

    Chart_RadiativeForcing.png

    Figure courtesy IPCC Summary for Policymakers

    Chart_RadiativeForcing_Notes1.png

    Figure courtesy IPCC Summary for Policymakers

    Chart_RadiativeForcing_Notes2.png

    Figure courtesy IPCC Summary for Policymakers

    Chart_RadiativeForcing_Notes3.png

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