Radiative Forcing of Climate Change: Expanding the Concept and Addressing Uncertainties - PowerPoint PPT Presentation

Loading...

PPT – Radiative Forcing of Climate Change: Expanding the Concept and Addressing Uncertainties PowerPoint presentation | free to download - id: 6b23f3-OGFhM



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Radiative Forcing of Climate Change: Expanding the Concept and Addressing Uncertainties

Description:

Radiative Forcing of Climate Change: Expanding the Concept and Addressing Uncertainties Report from the NRC Committee on Radiative Forcing of Climate – PowerPoint PPT presentation

Number of Views:1
Avg rating:3.0/5.0
Date added: 23 October 2020
Slides: 10
Provided by: astaudt
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Radiative Forcing of Climate Change: Expanding the Concept and Addressing Uncertainties


1
Radiative Forcing of Climate Change Expanding
the Concept and Addressing Uncertainties
  • Report from the NRC Committee on Radiative
    Forcing of Climate
  • released December 2004

2
Committee on Radiative Forcing of Climate
  • DANIEL J. JACOB (Chair), Harvard University
  • RONI AVISSAR, Duke University,
  • GERARD C. BOND, Lamont-Doherty Earth Observatory
  • STUART GAFFIN, Columbia University
  • JEFFREY T. KIEHL, National Center for Atmospheric
    Research
  • JUDITH L. LEAN, Naval Research Laboratory
  • ULRIKE LOHMANN, Dalhousie University
  • MICHAEL E. MANN, University of Virginia
  • ROGER A. PIELKE, SR., Colorado State University
  • VEERABHADRAN RAMANATHAN, Scripps Institution of
    Oceanography
  • LYNN M. RUSSELL, Scripps Institution of
    Oceanography

3
Conceptual framework of climate forcing,
response, and feedbacks
  • CLIMATE FORCING AGENTS
  • Emissions of greenhouse gases and precursors,
    aerosols and precursors, and biogeochemically
    active gases
  • Solar irradiance and insolation changes
  • Land-cover changes

NATURAL PROCESSES Sun, orbit, volcanoes
  • HUMAN
  • ACTIVITIES
  • Fuel, industry,
  • agriculture

Non-radiative Forcing
  • CHANGE IN CLIMATE SYSTEM COMPONENTS
  • Atm. lapse rate
  • Atm. composition
  • Evapotranspiration

Direct Radiative Forcing
Societal Impacts
Indirect Radiative Forcing
Feedbacks
CLIMATE RESPONSE Temperature, precipitation,
vegetation, etc.
4
Climate change research and policy has relied on
global top-of-atmosphere (TOA) radiative forcing
TOA forcing from 1750 to present IPCC, 2001
5
Strengths and limitationsof TOA radiative
forcing concept
Strengths Limitations
Linearly related to equilibrium change in global mean surface temperaure in GCMs Simple, physical, robust, easy to compute Enables comparison of different forcing agents Enables comparison of different models Has established use in policy analysis Directly observable from space Inferable from observed changes in ocean heat content Does not account for vertical structure of forcing Does not characterize regional response Does not characterize hydrological response Does not accommodate nonlinear response from large perturbations
The TOA radiative forcing concept should be
retained and expanded
6
Account for vertical structure of radiative
forcing
The relationship between TOA radiative forcing
and surface temperature is affected by the
vertical distribution of forcing within the
atmosphere, particularly for absorbing aerosols
and for land-use driven changes in
evapotranspiration.
Aerosol radiative forcing
Priority recommendations
  • Test ability of climate models to reproduce
    observed vertical structure of forcing
  • Characterize dependence of climate response on
    the vertical structure of radiative forcing.
  • Report global mean radiative forcing at both the
    surface and the TOA in climate change
    assessments
  • .Develop practical tools for incorporating
    surface radiative forcing in policy analyses and
    integrated assessment models.

7
Determine the importance of regional variation
in radiative forcing
Regional variations in radiative forcing may have
important regional and global climatic
implications that are not resolved by the concept
of global mean radiative forcing.
JJA forcing by tropospheric ozone
Priority recommendations
  • Quantify and compare climate responses from
    regional radiative forcings in different climate
    models, and report results in climate change
    assessments
  • Use climate records to investigate relationships
    between regional radiative forcing and climate
    response.

8
Determine the importance of non-radiative forcings
Several types of forcingsmost notably aerosols,
land-use and land-cover change, and modifications
to biogeochemistryimpact the climate system in
non-radiative ways, in particular by modifying
the hydrological cycle and vegetation dynamics.
Historical changes in land cover
1700
Priority recommendations
  • Improve understanding and parameterizations of
    aerosol-cloud thermodynamic interactions and
    land-atmosphere interactions in climate models
  • Develop improved land-use and land-cover
    classifications at high resolution for the past
    and present, as well as scenarios for the future.

1900
1990
9
Addressing Key Uncertainties
  • 1. Conduct accurate long-term monitoring of
    radiative forcing variables
  • Spectrally resolved radiances from space, ocean
    heat content
  • 2. Advance the attribution of decadal to
    centennial climate change
  • Mine climate forcing and trend records for past
    1000 years
  • 3, Reduce uncertainties associated with indirect
    aerosol radiative forcing
  • Improve parameterizations used in models
  • 4, Better quantify the direct radiative effects
    of aerosols
  • Improve understanding of aerosol sources, mixing
    states, sinks
  • 5. Better quantify radiative forcing by ozone
  • Improve understanding of strat-trop exchange,
    lightning NOx
  • 6, Integrate climate forcing criteria in
    environmental policy analysis
  • Examine climate impacts of policies directed at
    air quality and land use, develop GWPs for
    short-lived agents, determine additivities of
    forcings,,,
About PowerShow.com