Dynamics of the Earth System and the IceCore Record DESIRE

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Dynamics of the Earth System and the Ice-Core
Record (DESIRE)

• Project submitted to the joint QUEST-INSU AO

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650 kyr of clues from EPICA and Vostok!
Siegenthaler et al., 2005 Spahni et al., 2005
Petit et al., 1999
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The success of approaches using correlations with
Antarctic proxies alone implies the dominance of
Southern Ocean mechanisms?
The correlative approach can only take us so far,
and a mechanistic, model-based approach is now
needed
Mudelsee (based only on Vostok data) pCO2 922
1.646 dDt-2000
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State of the art CH4

• G-IG jumps, 350-700 ppbv
• Very fast changes (200 ppbv) at DO scales
• Various sources (terrestrial except marine
  hydrates) could be involved
• Distinguishable through isotopes
• Changing sinks also implicated
• Little constraint on source/sink balance

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QUEST-Deglaciation will look at G-IG change, but
in DESIRE we will have the advantage of

• new coupled models that cover the CH4 domain
• different G-IG transitions with different climate
  changes
• millennial events encompassing much of the G-IG
  range

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State of the art CO2

• G-IG ramps, 180-280 ppmv in last 450 kyr
• Lower CO2 in early IG (450-800 kyr)
• Very close link to Antarctic temperature
• implies concentration on S. Ocean
• Physical and biogeochemical processes
• Data and models provide some constraints
• But error bars remain very large

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Quaternary QUEST is also working on the CO2
issue, focussed on 1 climate cycle, but we will
use the constraints of multiple cycles

• In weak interglacials, did each mechanism scale
  with temperature, or were some inactive?
• Is the phasing at each termination and inception
  of diagnostic significance?

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Dynamics of the Earth System and the Ice-core
Record (DESIRE)

• Response to the NERC-INSU joint UK-Fra call to
  develop a quantitative and predictive
  understanding of the ice-core record of changing
  atmospheric composition
• Note that this is a huge question, and we have to
  balance ambition with reality
• 0.8 Myrs, CO2 and CH4
• 3 years, starting in ??? 07

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Underlying principles

• Use the new data
• Use the best modelling tools, people and datasets
  available to UK and French researchers
• Use models of appropriate complexity for each
  question being addressed
• Tackle achievable aspects of the overall
  understanding everything call
• WPs arranged around hypotheses relating to (a)
  CH4 change, (b) CO2 change, (c) the links between
  these changes and climate change in the coupled
  system

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Strategy
Explore particular processes
Propose future constraints
Simulations of appropriate periods
Develop/test some new modelling tools
Assess contribution of different mechanisms to
GHG change over 800 kyr
Data constraints
Prepare/compile new diagnostic datasets
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Current partners
Expertise

• BAS (Eric Wolff)
• IPSL/LSCE (Pierre Friedlingstein, Pascale
  Braconnot, Gilles Ramstein, Laurent Bopp, Frank
  Bassinot and others)
• Bristol (Sandy Harrison, Paul Valdes, Andy
  Ridgwell)
• LGGE (Jerôme Chappellaz and several others)
• OU (Neil Edwards)
• Reading (David Marshall)
• UEA (Corinne Le Quéré )
• Cambridge (Harry Elderfield)
• Exeter (Peter Cox)
• Plus some unfunded partners (Steve Barker, Maria
  Sanchez-Goni, Oliver Wild,.)

• Palaeodata - ice (Jerôme Chappellaz, Eric Wolff
  and others)
• Palaeodata - land (Sandy Harrison, Maria
  Sanchez-Goni)
• Palaeodata oceans (Frank Bassinot, Harry
  Elderfield, Elisabeth Michel, Steve Barker)
• Ocean dynamics (David Marshall and others)
• Atmospheric chemistry (Oliver Wild, Dudley
  Shallcross)
• Ocean biogeochemistry (Corinne Le Quéré, Laurent
  Bopp)
• C cycle modelling (Pierre Friedlingstein, Peter
  Cox)
• Ocean modelling (Neil Edwards)
• Coupled climate models (Pascale Braconnot, Paul
  Valdes, Gilles Ramstein)
• EMICs (Neil Edwards, Andy Ridgwell)

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Strand 1 CH4 and atmos chem

• 1.1 Fire modules and integration of
  methane-related components into IPSL-ESM
• 1.2 13C into FAMOUS
• 1.3 Prospects for constraints on source and sink
  for methane (atmos chem)
• 1.4 Wetlands/veg data synthesis at MIS 13/15 DO8
  and DO 19/20 synthesis by collaboration with QQ

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Strand 2 CO2 and C cycle

• 2.1 13CO2 in ice
• 2.2 Marine sediment constraints on C cycle
  (including CaCO3 and dissolution in sediments,
  Chatham Rise, and MIS16/15 and 12/11)
• 2.3 SO physics and biogeochemistry (effect of
  eddies, winds and overturning)
• 2.4 Dust parameterisation (shape, composition)
• 2.5 MGV development

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Strands 3 (models and zoos) 4

• 3.1 Time slices MH, EH, LGM (Q-ESM and IPSL-ESM)
• 3.2 Other interglacials as time slices
  (FAMOUS/IPSL-ESM)
• 3.3 Short transients DO8 and DO19/20 (FAMOUS,
  IPSL-ESM, MGV)
• 3.4 Data/model Compile zoo of ig and g (includes
  workshops about proxies)
• 3.5 Transient simulations of transitions and igs
  (GENIE, MGV) to explore parameters leading to zoo
• 4 Coordination

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Resources

• 23 years of new PDRA time
• Redirected efforts of numerous French researchers
  and research time of UK Co-Is
• Bilateral visits and exchanges in most areas
• Workshops for major data synthesis and proxy
  interpretation efforts

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Management

• Wolff and Friedlingstein responsible to QUEST,
  NERC and INSU
• Co-Is responsible for each WP
• Management board providing direction, dealing
  with problems, organising synthesis
• Project coordinator assists PI, communications,
  workshops
• Project meetings 2 per year, plus management
  board interim meetings and virtual meetings
• Year 3 project meeting will have goal of
  outlining synthesis paper

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International linkages

• Most participants are already strongly linked to
  external collaborators (through e.g. EPICA, PMIP,
  etc.)
• PIs/Co-Is are strongly involved in all the major
  international projects (AIMES, PAGES, IGAC,
  ILEAPS, GCP, ..
• Potential fast-track initiative (PAGES/AIMES)
  around EPICA challenge has recently been
  discussed DESIRE could make natural leaders for
  this

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A testbed for understanding of the Earth System
DESIRE should be a significant step towards
understanding the Earths behaviour in response
to external (or artificial) forcing
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Key deliverables

• Improvements in modelling tools available to
  UK/Fra researchers
• New constraining datasets (e.g. 13C), and
  recommendations for future data needs
• Improved understanding of some key processes
• Flagship simulations of critical time periods
• Synthesis assessment (with uncertainties) of
  contribution of different mechanisms to the
  observed records of CO2 and CH4
• Enduring partnership of top UK and French
  researchers

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End
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Hypotheses

• CH4 changes (g-ig, DO, ig-ig) can only be
  explained by a combination of chnages in both
  source and sink
• Constrain solutions that fit all the data
  suggest new tests
• CO2 and insolation are enough to explain the
  ig-ig and g-g variability observed
• Effectively test climate sensitivity using warm
  periods only
• CO2 changes result from a combination of (mainly
  SO) mechanisms
• Improve the mechanisms in models and narrow the
  error bars for the effect of each