Work plan of TiPACCs
The TiPACCs project is structured around four primary objectives, with a dedicated work package (WP) for each objective. WP1 concentrates on the ocean tipping point, WP2 on the ice tipping point, WP3 on tipping points in the coupled system, and WP4 on informing and disseminating the knowledge of WP1-WP3 to a general public, policy makers and governmental panels. These work packages are glued together by project management, which is dealt with in WP5.
Sketch of a cross-section of the Antarctic Ice Sheet. Grounded ice flows into the ice shelf. Interactions between the grounded ice, ice shelf and surrounding ocean are central in TiPACCs. TP = tipping point.
WP1: Ocean tipping point
Here we investigate the processes in the Antarctic continental shelf seas. Under which atmospheric surface forcing will these shelf seas switch from a ‘cold’ to ‘warm’ state (tipping point 1)? What are the relevant processes, and how does the warmer water end up in the ice cavities below ice shelves? How does this warmer water affect the ice-shelf basal melting? And how imminent is a tipping point for the various Antarctic ice shelves? These questions are being investigated using three ocean models (FESOM, NEMO, and MITgcm).
WP2: Ice tipping point
In WP2 we focus on the stability of the Antarctic Ice Sheet. Are the current grounding lines (the “line” where ice, land and ocean meet) stable? Will they become unstable when ice-shelf melting is increased? Is a small and short perturbation of additional ice-shelf melt rate enough to cause a large and irreversible grounding line retreat? And what happens with the ice sheet under larger-amplitude perturbations? When grounding lines retreat, the ice sheet loses mass, which causes global sea-level rise. Sea level was higher than today during past warm periods. In TiPACCs we will assess if the ice tipping point was crossed during the Last Interglacial, and quantify the related impact of Antarctic Ice Sheet retreat on global mean sea level. In WP2 we will apply three ice-flow models (PISM, Úa, Elmer/Ice).
WP3: Tipping points of the coupled ocean-ice system
After investigating the processes determining the tipping points in the ocean and ice sheet separately, in WP3 we look at the coupled system. Do both tipping points also arise in a coupled system? Is the ocean tipping point affected by feedbacks mechanisms between ice-shelf geometry and ocean circulation? And how much is the ice tipping point impacted by evolving ice-shelf geometry and ice-shelf melt rates, when the ocean is already tipped over to a warm state? Here we will use three fully coupled ice-ocean models (PISM+FESOM, Úa+MITgcm, Elmer/Ice+NEMO).
WP4: Communication, Dissemination, Expploitation and Decision Support
Here we will synthesize our result from WP1-WP3 and will communicate and disseminate our improved understanding to various audiences. Besides this website, we use Twitter (@TiPACCs_EU) and press releases through all our partner insitutes. Links to TiPACCs news, publications and other outreach activities are available through this website. One specific outcome suitable for a wide audience is our introductory video explaining the project: see here.