Workshop: Using Paleo-Climate Model/Data Comparisons to Constrain Future Projections

REGISTRATION

Registration

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Organising Committee

Eric Guilyardi (IPSL / University of Reading)
Masa Kageyama (LSCE / IPSL)
Jeff Kiehl (NCAR)
Michael Mann (PSU)
Valerie Masson-Delmotte (LSCE / IPSL)
Gavin Schmidt (NASA)
Axel Timmermann (University of Hawaii)

Venue

Bernice Pauahi Bishop Museum, Honolulu: www.bishopmuseum.org

Agenda

The draft agenda can be downloaded here (pdf, 1MB).

Context

For the first time in climate modelling history, there is a substantial component of coordinated paleo-climate modelling being performed with the same models and with the same protocols as the projections of future climate change. We have heard for many years the claim that understanding paleo-climate is the key to understanding future potential changes, and indeed, much work has already been done (via PMIP 1 and 2, and many individual studies). However, there has been a lack of quantitative analysis that truly links the future simulations or forecasts with skill or sensitivity in the paleo-climate simulations or forecasts with skill or sensitivity in the paleo-climate simulations, most often because paleo-simulations were not done with the same models currently being used for future projections and through a lack of suitable paleo-climate skill metrics.

As part of the CMIP5 protocol and archive, the paleo-component (PMIP3) consists of simulations for the Last Glacial Maximum (LGM), the Mid-Holocene (MH - 6000 yrs BP) and the Last Millennium (LM, specifically 850 AD-1850 AD) (Taylor et al., 2011). For this database, these simulations will be true 'out-of-sample' tests in that there will not have been enough time to 'tune' any of these models to produce better paleo simulations. (Note that this is not necessarily unwise, but it would complicate some of the potential analyses.)

Many of the issues highlighted in the IPCC AR4 report (such as sub-tropical rainfall changes, ENSO, the N. Atlantic meridional circulation, the fate of Arctic sea ice, etc.) can potentially be illuminated by targeted analyses of the paleo-climate simulations since many of these subsystems have changed in the past and left decipherable proxy records (Schmidt, 2010). Unfortunately, the majority of skill metrics taken from the historical (20th Century) simulations are not constraining the future projections (i.e. models that are either good or bad at simulating some aspect of modern climate - the climatology, seasonal cycle, or interannual variability - give essentially the same spread of future projections) (Santer et al., 2010; Knutti et al.). Paleo-climate offers a substantially larger signal than climate changes in the 20th Century (albeit with substantial noise and difficulties in interpretation) and so is unique in potentially being able to constrain future change.

The problems in dealing with paleo-climate data are well-know but progress is being made. Issues related to proxy interpretation are being helped by the development of forward models for proxies, and by the using of multi-proxy interpretation are being helped by the development of forward models for proxies, and by the using of multi-proxy approaches and new techniques of Bayesian inference. The increase in scope of coherent databases of paleo-climate information (including uncertainties) is helping push model-data comparisons away from metrics based on single proxies or merely qualitative comparisons towards global, multi-proxy quantitative comparisons.

The next IPCC report (AR5) is due in 2013, with final deadline for submitted papers being July 31, 2012, and 'in press' deadlines for papers to be assessed is March 15, 2013. Many of the studies that will be assessed for AR5 will use the initial contributions to the CMIP5 archive (thought the archive itself will continue to grow until 2015). Thus the early part of 2012 is a key time period for thinking about and producing key work that will feature in the AR5 and set the agenda for similar studies and programmes in the future.

Workshop Aims

Given that the co-locations of the paleo-simulations and future projections is a novelty in CMIP5, the successful use of this kind of information does not have much of a track record. Thus a workshop whose aims are to a) ensure that the community is aware of how suitable techniques should be assessed right from the start, b) highlight the rich range of possible analyses, and c) produce timely and informative summaries of the state of these analyses, is both welcome and necessary.

We envisage a directed and productive workshop that will be charged with assessing what has been done so far, where are the missing gaps, and what can be done better in the future. We want to highlight the unique aspects of the paleo-climate simulations for evaluating the models in time for further analyses to be done in time for AR5 (although this kind of approach is not solely tied to the IPCC process or questions deemed interesting by those authors).

We will aim to produce a number of products. Some of these will be concrete - such as a 'best practice' review paper by participants to help guide the wider community in these kinds of analyses, but also some less tangible products - such as fostering a greater appreciation from the CLIVAR/WGCM/WCRP communities of the benefits of considering paleo-climate data and models, and encouraging a greater discipline i the paleo-climate community when it comes to making the links and encouraging a greater discipline in the paleo-climate community when it comes to making the links to future changes, the importance of synthesis of paleo data and a better appreciation for what questions can be usefully posed to, and answered by, the modellers.

In order to start the workshop off on a productive note we will be asking participants to have looked at some key fields/diagnostics ahead of time. In particular, various aspects of the regional hydrological changes in the paleo-climate simulations and in the future projects will be processed ahead of time and made available for participants. These metrics will involve rainfall, lake levels, soil moisture, forward models for water isotopes etc. for which there is plentiful evidence (and gridded datasets) of change during the periods covered by the paleo simulations (i.e. LGM, Mid-Holocene and Last Millennium). Dealing with these diagnostics and comparison with available paleo-data will serve as a template for any proposed approaches and techniques. Key issues will be getting as wide a spread of models as possible, ensuring that the forcings for each model are appropriately characterised, making clear demonstrations that any chosen skill metric does actually correlate to differences in projections, and the establishment of 'perfect model' test protocols (i.e. does any technique for creating an improved projection actually work if one assumes that one of the models is 'truth'). Each of these issues were highlighted in the 'Good Practice Guide' arising from last year's IPCC Expert Meeting (Knutti et al., 2010).

By creating a standard in one particular case, we will hope to maintain these standards in studies that workshop participants will be doing individually, and that might get done elsewhere.

Accommodation and Local Transport

Recommended hotels in Waikiki:

Waikiki Sand Villa Hotel: www.sandvillahotel.com
Park Short Hotel: www.parkshorewaikiki.com
Kaimana: www.kaimana.com
Ala Moana Hotel: www.alamoanahotelhonolulu.com
Diamond Head B&B: www.diamondheadbnb.com

The Ala Moana Hotel has a block booking that can be accessed using the following link: https://resweb.passkey.com/Resweb.do?mode=welcome_ei_new&eventID=8228816

Recommended hotels on the east side of the island (10 miles away from Bishop Museum):

www.alternative-hawaii.com/beachlane/
www.paradisebayresorthawaii.com

To travel to the meeting venue by public transport, take the Number 2 bus or City Express B 'School St / Middle St' bus. The nearest stop to the museum is the intersection of School St and Kapalama Ave (see map, pdf 200KB).

Contact

The CLIVAR contact for the CLIVAR/PAGES working group is Catherine Beswick.

The PAGES contact for the working group is Thorsten Kiefer.

The local contact is Axel Timmermann.