The PMIP4 contribution to CMIP6 – Part 1: Overview and over-arching analysis plan

Abstract

Abstract. This paper is the first of a series of four GMD papers on the PMIP4-CMIP6 experiments. Part 2 (Otto-Bliesner et al., 2017) gives details about the two PMIP4-CMIP6 interglacial experiments, Part 3 (Jungclaus et al., 2017) about the last millennium experiment, and Part 4 (Kageyama et al., 2017) about the Last Glacial Maximum experiment. The mid-Pliocene Warm Period experiment is part of the Pliocene Model Intercomparison Project (PlioMIP) – Phase 2, detailed in Haywood et al. (2016).The goal of the Paleoclimate Modelling Intercomparison Project (PMIP) is to understand the response of the climate system to different climate forcings for documented climatic states very different from the present and historical climates. Through comparison with observations of the environmental impact of these climate changes, or with climate reconstructions based on physical, chemical, or biological records, PMIP also addresses the issue of how well state-of-the-art numerical models simulate climate change. Climate models are usually developed using the present and historical climates as references, but climate projections show that future climates will lie well outside these conditions. Palaeoclimates very different from these reference states therefore provide stringent tests for state-of-the-art models and a way to assess whether their sensitivity to forcings is compatible with palaeoclimatic evidence. Simulations of five different periods have been designed to address the objectives of the sixth phase of the Coupled Model Intercomparison Project (CMIP6): the millennium prior to the industrial epoch (CMIP6 name: past1000); the mid-Holocene, 6000 years ago (midHolocene); the Last Glacial Maximum, 21 000 years ago (lgm); the Last Interglacial, 127 000 years ago (lig127k); and the mid-Pliocene Warm Period, 3.2 million years ago (midPliocene-eoi400). These climatic periods are well documented by palaeoclimatic and palaeoenvironmental records, with climate and environmental changes relevant for the study and projection of future climate changes. This paper describes the motivation for the choice of these periods and the design of the numerical experiments and database requests, with a focus on their novel features compared to the experiments performed in previous phases of PMIP and CMIP. It also outlines the analysis plan that takes advantage of the comparisons of the results across periods and across CMIP6 in collaboration with other MIPs.

A New Volcanic Stratospheric Sulfate Aerosol Forcing Emulator (EVA_H): Comparison With Interactive Stratospheric Aerosol Models

“…While the volcanic forcing constructed from EVA_H does not significantly differ for high-altitude tropical volcanic injections, it is significantly lower for high-latitude or low-altitude emissions. As a consequence, we expect that the forcing produced by EVA_H would be similar for most experiments of VolMIP (Zanchettin et al, 2016) but may have significant differences with EVA(eVolv2k) (Toohey & Sigl, 2017), the reference volcanic forcing data set used in PMIP (Jungclaus et al, 2017;Kageyama et al, 2018).…”

“…A major application of EVA (Toohey & Sigl, 2017;Toohey et al, 2016) is to produce forcing data sets for the experiments of the Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP; ; Zanchettin et al, 2016) and the Paleoclimate Modeling Intercomparison Project (Jungclaus et al, 2017;Kageyama et al, 2018). For VolMIP, the large spread among predictions from state-of-the-art aerosol-chemistry-climate models indeed prevented the identification of consensual forcing data sets derived from these models, motivating the use of an idealized model.…”

Impact of Multiscale Variability on Last 6,000 Years Indian and West African Monsoon Rain

“…The initial state of each experiment comes from a 1,000-year-long simulation performed with the corresponding model version and the Paleoclimate Modeling Intercomparison Project 6,000 years BP boundary conditions (Kageyama et al, 2018). Then, Earth's orbital parameters and atmospheric composition derived from ice-core reconstructions (Otto-Bliesner et al, 2017) were updated each year from 6,000 ka BP to 0 ka BP (1950 which is the reference for Earth's orbital parameters; Berger, 1978).…”

Science Directions in a Post COP21 World of Transient Climate Change: Enabling Regional to Local Predictions in Support of Reliable Climate Information

“…Skill can only be achieved through improved basic representation of the hydrological cycle in climate models, including airsea exchanges of heat, fresh water, and momentum and by testing these models on a wide range of climate conditions, including paleoclimate (Braconnot et al, 2012;Kageyama et al, 2018). For example, improving the resilience to climate change and extreme weather events, particularly for megacities located in coastal tropical and subtropical regions, requires reliable predictions of available water resources.…”

“…For example, improving the resilience to climate change and extreme weather events, particularly for megacities located in coastal tropical and subtropical regions, requires reliable predictions of available water resources. Skill can only be achieved through improved basic representation of the hydrological cycle in climate models, including airsea exchanges of heat, fresh water, and momentum and by testing these models on a wide range of climate conditions, including paleoclimate (Braconnot et al, 2012;Kageyama et al, 2018).…”