User Tools

Site Tools



This shows you the differences between two versions of the page.

Link to this comparison view

Next revision
Previous revision
pmip3:cmip6:design:plio:index [2015/03/24 10:14]
jypeter created
pmip3:cmip6:design:plio:index [2016/06/20 17:36] (current)
jypeter Added link to experimental design on PMIP4 web site
Line 2: Line 2:
 ====== PMIP-CMIP6 Experimental Design Discussion: Pliocene ====== ====== PMIP-CMIP6 Experimental Design Discussion: Pliocene ======
 +<note warning>​The PMIP4 experimental design available on the PMIP3 wiki has been **superseded** by the experimental design detailed on the [[https://​​doku.php/​exp_design|PMIP4 web site]]</​note>​
 <note tip>\\ Please submit your comments in the Discussion section at the end of this page</​note>​ <note tip>\\ Please submit your comments in the Discussion section at the end of this page</​note>​
 +===== Brief overview =====
 +The Pliocene epoch was the last time in Earth history when atmospheric CO2 concentrations
 +approached modern values (~400 ppmv) whilst at the same time retaining a near modern
 +continental configuration. The IPCC 5th Assessment report chapter 5 (Masson-Delmotte et al.,
 +2013) states that that model–data comparisons for the Pliocene provide high confidence that
 +mean surface temperature was warmer than pre-industrial (Dowsett et al., 2012; Haywood et al.,
 +2013). Global mean sea surface temperatures have been estimated to be +1.7°C above the 1901–
 +1920 mean based on large data syntheses (Lunt et al., 2010; Dowsett et al., 2012). Exiting
 +climate model simulations have produced a range of global mean surface air temperature of
 ++1.9°C and +3.6°C relative to the 1901–1920 mean (Haywood et al., 2013). Model simulations
 +have indicated that meridional temperature gradients were reduced (due to high latitude
 +warming), which has significant implications for the stability of polar ice sheets and sea level in
 +the future (e.g. Miller et al. 2012). Compilations of vegetation (Salzmann et al., 2008) have
 +indicated that the global extent of arid deserts decreased and boreal forests replaced tundra, and
 +climate models predict an enhanced hydrological cycle, but with a large inter-model spread
 +(Haywood et al., 2013). The East Asian Summer Monsoon, as well as other monsoon systems,
 +may also have been enhanced (Zhang et al. 2013). Although climate model simulations for the
 +Pliocene were assessed in the AR5, these simulations were not derived from the same
 +model/same resolution as the CMIP5 future projections,​ thus reducing the communities’ ability
 +to assess and compare changes in global and regional Pliocene climates, vis-à-vis similar
 +predictions of future climate change (Haywood et al., 2013).
 +We propose a CMIP6 time-slice experiment for the Pliocene to understand the long term
 +response of the Earth’s climate system to a near modern concentration of atmospheric CO2
 +(longer term climate sensitivity or Earth System Sensitivity),​ and to understand the response of
 +ocean circulation,​ Arctic sea-ice, modes of climate variability (e.g. ENSO), as well as the global
 +response in the hydrological cycle and regional changes in monsoon systems. A Pliocene
 +simulation will be of high societal relevance because of its potential to inform policy makers on
 +required emission reduction scenarios designed to prevent global annual mean temperatures
 +increase by more than 2 to 3 °C in the long term (beyond 2100 AD).
 +The proposed CMIP6 simulation for the Pliocene is relevant to two of the WCRP Grand
 +Challenges. This includes Clouds, Circulation and Climate Sensitivity because of the enhanced
 +CO2 forcing (contemporaneous with modern CO2 forcing), providing a unique opportunity to
 +examine an equilibrium climate state to a near modern concentration of atmospheric CO2. The
 +pattern of polar amplification preserved Pliocene climate archives can be compared directly with
 +the latest generation of CMIP models making a valuable contribution towards addressing the
 +potential polar amplification problem. Through the analysis of Pliocene polar amplification in
 +CMIP models, and examining the geological interpretation of a seasonally sea-ice free Arctic
 +Ocean during the Pliocene, our CMIP6 simulation will also address the WCRP Grand Challenge
 +of Changes in the Cryosphere. Whilst uncertainty exists in Pliocene sea level reconstruction,​ IPCC AR5 states with high confidence that Pliocene sea-levels were higher than the preindustrial
 +era, with a number of independent methods indicating a sea-level rise of between 10
 +and 20 m. This indicates potential long term instability of both the Greenland and Antarctic Ice
 +Sheets (Miller et al. 2012) with CO2 concentrations at approximately 400 ppmv.
 +CMIP6 Pliocene experiments will be used within the Pliocene Ice Sheet Model Intercomparison
 +Project in order to better constrain the climatological forcing in ice sheet model simulations for
 +the Pliocene in the future. There is a well-organized and highly active of community of Pliocene
 +climate modellers within PMIP, with the Pliocene working group being one of the most
 +successful working groups within PMIP3. The working group is closely associated with the
 +United States Geological Survey (USGS) who has had a highly productive core program focused
 +on Pliocene environmental reconstruction for the last 25 years, and their data has been used to
 +underpin almost all model-data comparisons performed for the Pliocene. Thus, CMIP6 can
 +expect a high degree of continued support and new Pliocene data sets from the USGS for
 +comparison with model outputs.
 +The experiment will address the broad scientific questions: ​
 +  - How does the Earth System respond in the long term to CO2 forcing analogous to that of the modern?
 +  - What is the significance of CO2 induced polar amplification for the stability of the ice sheets, sea-ice and sea-level?
 +===== Experimental design =====
 +Time slice equilibrium climate experiment modifying CO2 (to 400 ppmv), topography, ice sheet
 +extent and running with dynamic vegetation (if possible).
 +The full description of the experiment can be found on the [[http://​​egpsc/​prism/​7.2_pliomip2_data.html|PlioMIP2 web site]].
 +The proposed **PMIP-CMIP6 experiment** is described as the **PlioMIP 2 STANDARD experiment** on the PlioMIP 2 site, with boundary conditions summarized in the following table. Please read the pdf document available on the PlioMIP 2 site for a detailed description.
 +{{:​pmip3:​cmip6:​design:​plio:​pliomip_bc_standard.png?​400|Click on the table to get a bigger version}}
 +Click on the table to get a bigger version
pmip3/cmip6/design/plio/index.1427188455.txt.gz · Last modified: 2015/03/24 10:14 by jypeter