ipcc (2007) and the nas/nrc committee on radiative forcing effects on climate
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IPCC (2007) and the NAS/NRC Committee on Radiative Forcing Effects on Climate. Susan Solomon, co-chair, IPCC WGI and senior scientist, NOAA Aeronomy Laboratory. An NRC report that was an important input to the TAR. IPCC (2007): Solomon (USA) and Qin (China), co-chairs. Climate Change 2007 - PowerPoint PPT PresentationTRANSCRIPT
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE (IPCC) Working Group I
IPCC (2007) and the NAS/NRC Committee on Radiative Forcing
Effects on Climate
Susan Solomon, co-chair, IPCC WGI
and senior scientist, NOAA Aeronomy Laboratory
IPCC - WGI
IPCC (2001): Houghton (UK)and Ding (China), co-chairs
Climate Change 2007 The Physical Science Basis
IPCC (2007): Solomon (USA) and Qin (China), co-chairs
An NRC report that was an important input to the TAR
This committee: an important opportunity for similar synergy through dialogue
IPCC - WGI
Time Line Issues
WGI panelJan 2007
Lead Author meeting 4 (TBD)Jun 2006
Second draft completeFeb 2006
Lead Author meeting 3 (Christchurch)Dec 2005
First draft completeAug 2005
Lead Author meeting 2 (Beijing)May 2005
Second scoping meeting Sep 2003
Zero order draft completeFeb 2005
Lead Author meeting 1 (Trieste)Sep 2004
Lead author teams selected by WGI BureauApr 2004
Panel approval of outlines for reportsNov 2003
First scoping meetingApr 2003We are here:
the outline is in final form and is about to be submitted to the Plenary for approval
This committee’s report is due just before WGI authors begin first formal draft
IPCC - WGI
What does UNFCCC want?
• Strong scientific messages telling an integrated story – not a grab bag of topics
• Clear expository graphics, avoiding “mathematical magic”
• Clear explanation of uncertainties and limits to understanding
• Address key questions
• Skip unnecessary repetition of earlier reports (very important) - this forced tough choices
• Shorter and “more focussed”
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Radiative Forcing: A key topic, as in past reports…assess anthropogenic and natural influences on radiative balance
• Review/update past and estimated future radiative forcing for greenhouse gases, and..
• ..for aerosols including indirect effects (sulfate, nitrate, organic, soot….)
• Land use/surface albedo effect
• Aviation (e.g., new studies on cloud interactions)
• Compare with natural forcings (solar, volcanic).
• Roles of short-lived vs long-lived species
• Forcing/response relations in the global mean - use and limits of the radiative forcing concept;
• GWP and other metrics for comparing emissions
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CO2 Solar UT O3
LS
O3
An updated and improved assessment of:•Solar•Aviation•Land use•Aerosols!• esp. soot!• Gases!•GWPs and other metrics
Joshi et al (2003)
More information on dependence of climate change
on forcing mechanism
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How to best convey our message?
Many key
warming agents
live for decades or more
All known coolin
g agents
are short-lived
AR4: stronger emphasis on timescales
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Paleoclimate: More links to forcing • Use paleoclimatic information to provide greater clarity on what may be
natural versus manmade (globally and regionally)
• Illuminate key vulnerabilities to changes in radiative forcing
• Paleoclimate as a basis for testing cause and effect relationships (e.g., volcanoes and solar)
• What happened in the past and why – focus on observations and processes
• Discuss paleo measurements in greater depth - tree rings, ice cores, etc.
• More careful analysis of how anomalous the last century has been
• Review/ update what is known of abrupt climate changes – the potential wild card
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Compare to models (including volcanoes, solar, and anthropogenic forcing) for more than 1000 years
7 NH records
Model with volcanoes, solar,
and GHG/aerosol Tambora
From Crowley, personal communication
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Couplings between changes in the climate system and biogeochemistry: “Beyond radiative forcing”
• Describe the emerging linkages in understanding and simulating the fully coupled system
• Carbon cycle / climate interactions – increasing respiration vs photosynthesis, coupling of C and N biogeochemistry, aerosol/diffuse flux linkages….
• Global atmospheric chemistry and climate change - processes influencing global ozone and methane in a coupled system, coupling of stratosphere to surface change, ….
• Air quality and climate change - interactions on new scales, where increasing numbers of people live
• Aerosols – aerosol/hydrological cycle feedbacks; regional and global scale analyses of coupled aerosol/ chemistry / climate interactions, ….
• Land surface / hydrology including e.g., fires, dynamic vegetation models
• Should better identify possible ‘wild cards’ that could emerge in an altered climate state
IPCC - WGI
One example of a coupled interaction:Sea-salt emissions = function (wind speed)Transport (advective, convective) and deposition =function(climate)==> “in my opinion an assessment is needed in AR4” - O. Boucher, Marrakech, 2003
A need to go “beyond radiative forcing” to the fully coupled system of human/climate interactions.
IPCC - WGI
Interesting new papers on aerosol forcings and responses at various levels: A key assessment challenge for WG I
Menon et al.: black carbon (soot) and Asian precipitation.
How well understood are the forcings? Surface fluxes/TOA?
Aerosols potentially influence precipitation at microphysical level (precipitation efficiency); sub-grid scale (altered convection); and large scale (altered circulation patterns).
Rostayn and Lohmann: suggesting a link of aerosols to the drought in Africa. See also work by Rosenfeld and others on other aerosol processes that could play a role.
IPCC - WGI
Some areas of focus that this committee may wish to consider:
• Definitional issues: How should we think about surface / tropopause / TOA forcings? What is a forcing and what is a feedback?
• Aerosols: direct and indirect effects; aerosol linkages to land use effects (e.g., biomass burning, wind stress, etc.)
• Air quality/climate: a two-way story• Solar and volcanic forcings: satellite era and before,
including paleo. What is a forcing and what is a feedback, across a range of time scales?
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Top-of-the-atmosphere Surface (Wm-2)
March 97
Definitions:Radiative processes and their spatial distributions
Implications for radiative forcing?
And the more general question: what is a forcing and what is a feedback?
IPCC - WGI
• Particle number, size, precipitation efficiency, liquid water content are all factors in climate
• Do continental clouds have different feedbacks to aerosols than marine clouds?
• New research on black carbon (soot) and on gradients in radiative forcing (sulfate)
• Coupling of land use/vegetation/fires/aerosols issues
Aerosols: A Major Issue
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UN, World Urbanization ProspectsThe 2002 Revision
Air Quality/Climate: More people are living the experience
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Mexico City from Satellites GOME NO2 December average
Data courtesy J. Burrows, U. BremenProcessing by S. Massie, NCAR
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FAR SAR TAR AR4
Solar Forcing: Three full solar cycles of direct observations of the solar irradiance. What are the constraints on solar/volcanic effects over the past three cycles, compared to human activities?
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QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Past climates: what do they tell us about radiative forcing and responses, as well as feedbacks?
Last Ice age
Lastinterglacial
IPCC - WGI
Concluding remarks
• There are many opportunities for synergy; this presentation is a ‘sampler’.
• Timing IPCC/NRC is complementary
• Thanks for this initial discussion