Dynamics of the Earth System and the Ice-Core Record (DESIRE) Project submitted to the joint QUEST-INSU AO

650 kyr of clues from EPICA and Vostok! Siegenthaler et al., 2005; Spahni et al., 2005; Petit et al., 1999

Mudelsee (based only on Vostok data): pCO 2 = * δD t-2000 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

State of the art: CH 4 G-IG jumps, 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

new coupled models that cover the CH 4 domain different G-IG transitions with different climate changes millennial events encompassing much of the G-IG range QUEST-Deglaciation will look at G-IG change, but in DESIRE we will have the advantage of:

State of the art: CO 2 G-IG ramps, ~ ppmv in last 450 kyr Lower CO 2 in early IG ( 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

Quaternary QUEST is also working on the CO 2 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?

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, CO 2 and CH 4 3 years, starting in ??? 07

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) CH 4 change, (b) CO 2 change, (c) the links between these changes and climate change in the coupled system

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

Current partners 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,….) Expertise 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)

Strand 1: CH 4 and atmos chem 1.1 Fire modules and integration of methane- related components into IPSL-ESM C 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

Strand 2: CO 2 and C cycle CO 2 in ice 2.2 Marine sediment constraints on C cycle (including CaCO 3 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

Strands 3 (models and zoos) & 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

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

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

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

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

Key deliverables Improvements in modelling tools available to UK/Fra researchers New constraining datasets (e.g. 13 C), 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 CO 2 and CH 4 Enduring partnership of top UK and French researchers

End

Hypotheses CH 4 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 CO 2 and insolation are enough to explain the ig-ig and g-g variability observed –Effectively test climate sensitivity using warm periods only CO 2 changes result from a combination of (mainly SO) mechanisms –Improve the mechanisms in models and narrow the error bars for the effect of each