PMIP P2F meeting PAGES, Goa, 14.02.2013
Attending:
Eric Wolff (ewwo@bas.ac.uk),
Kerim H. Nisancioglu (Kerim@uib.no),
Hugues Goosse (hugues.goosse@uclouvain.be),
Jon Harbor (jharbor@purdue.edu),
Kevin Anchukaitis (kja@whoi.edu),
Arjen Stroeven (arjen@geo.su.se),
Anders Carlson (acarlson@geology.wisc.edu),
Paul Valdes (p.j.valdes@bristol.ac.uk),
Andrew Schurer (a.schurer@ed.ac.uk),
Pascal Braconnot (Pascale.Braconnot@cea.fr)
What is the working group for?
The Past to Future (P2F) working group will focus on integrating model and proxy data from multiple time intervals as well as discussing their relevance for our understanding of future climate change.
Different from other PMIP working groups, P2F will not be centered on a specific time period: rather, the focus will be on integrating the results from multiple time intervals. The emphasis will be on existing PMIP, as well as CMIP5 experiments, when available from the same models. Additional dedicated experiments will be identified as required.
The main relevant PMIP intervals identified are: Pliocene, Eemian, Mid-Holocene as well as 2100AD. These past periods are all warm climates where there is a considerable amount of proxy data available for comparisons with the model simulations.
Key questions to address are:
- How do past warm climates compare and how do they relate to a future warm greenhouse climate?
- What can we learn from PMIP experiments about equilibrium climate sensitivity? Are additional dedicated experiments required?
Accessibility of data:
How can P2F contribute to improving availability of data? At a minimum the group can provide documentation of available model and proxy data sets (e.g. PRISM, PIGS etc) on a wiki.
How should the group work?
There was an agreement to organize informal meetings in conjunction with e.g. PMIP/EGU/AGU/PAGES and investigate funding if necessary on a per meeting basis.
There was also a suggestion of creating a virtual meeting space such as “Google Hangout” (Anders Carlson will investigate this option further).
For the P2F wiki to be efficient requires a dedicated moderator. A volunteer for this task is required. It would also be an advantage if an email digest could be provided on the wiki.
The second meeting of P2F should be held at the upcoming EGU conference in Vienna. To include those not present at EGU, a third P2F meeting should be organized as a virtual meeting with the larger group. A product from these two meeting will be a suggestion from P2F on focus and organization to be presented at the PMIP meeting in Belgium in 2014.
Suggestions for additional PMIP experiments:
- Dedicated experiments to estimate equilibrium climate sensitivity
- including consistent approach between model groups
- Transient simulations including forcing from meltwater:
- Eemian, Deglaciation and Holocene
- Unordered List ItemInvestigating monsoons in existing climate models
- integrated approach, covering several PMIP time periods
- relevance for future changes in the monsoon
The above list should be prioritized, suggested order is a suggestion.
Questions raised at the meeting and to be addressed further:
Should we go beyond the next century in our comparison between past and future? I.e. consider long timescales including ice sheets, deep ocean and the carbon cycle? This is particularly important when considering equilibrium climate sensitivity. To what degree do past warm climates from different periods agree/disagree? What are the reasons for differences in climate sensitivity estimated from data versus models?
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Discussion
I think it would be foolish to discard cold intervals at this stage. An a priori belief that they cannot tell us anything about future climate indicates to me a deep misunderstanding of how climate models work.
Especially the Last Glacial Maximum, as it has a relatively good data set compared to other intervals. At present, I consider the mid-Holocene to be the least useful interval - at least it needs a lot of work from other parts of PMIP before we can start to use it to make progress.
Much is still to be made about the LGM indeed (tropics, ocean variability, system stability and polar amplification) that can be linked to future climates. MC.
I second Jule's and MC's comments. Something else we may be able to learn from cold periods is climate-carbon cycle feedbacks.
I would like to chime in and say that I think the LGM remains a critical target. This is exemplified by the prior comments, by the fact that the MARGO-COMPARE initiative is targeting the LGM as an interval where we can refine and improve proxy estimates, and by the insight that Jules and James' 2012 GRL paper offers in terms of using the response of the tropical LGM to constrain climate sensitivity.
I tried to get in yesterday but my computer would not let me send a comment. Unfortunately that delay allowed people to jump on knocking down a strawman that never existed.
Please don't all focus on a false perception that the group in Goa somehow dissed the LGM. This was not the case at all. The only principle we proposed was that this WG would not focus on time periods but on issues (such as climate sensitivity or monsoons), and use whichever periods could best together tell us something useful about that issue. No-one talked about ditching cold periods.
If there is a bias towards warm periods in the notes, it likely reflects the fact that we had several people interested in the long term future of the Greenland and Antarctic ice sheets, for which warmer periods are more helpful.
That's very interesting, since it means that my idea of listing the intervals and what they may be able to tell us is not necessarily the best way to go about it. It might still be the easiest to construct, but we could also consider listing things we want to learn about (ice sheet, climate sensivity, monsoons, abrupt changes) and then stating what paleoclimate tells us (or may potentially tell us).
I'm quite glad your web didn't work for a day, Eric, as it is good to see a bit of discussion!