EC-WG1-TIPMIP

Climate tipping elements are critical, large-scale components of the Earth system that have the potential to exhibit threshold behaviour (McKay et al. 2022). They can undergo abrupt and irreversible transitions to a qualitatively different state when subjected to small perturbations beyond a certain level of global warming. These transitions can have significant impacts on ecosystems, human societies, and global biogeophysical climate feedbacks. Therefore, identifying and understanding climate tipping elements is essential for assessing climate risks and informing mitigation and adaptation policies. However, tipping point research faces many challenges, such as uncertainty, nonlinearity, cascading effects and telecoupling. Earth system modelling can help address these challenges by integrating data and knowledge from different disciplines and sources, representing complex dynamics and physical feedbacks among different components of the Earth system, exploring scenarios and projections under different assumptions and uncertainties, and providing insights for decision-making. While modelling is an effective tool to study and quantify tipping points, it poses challenges such as incorporating paleoclimatic evidence and conceptual understanding, accounting for interactions among different tipping elements, and dealing with uncertainties arising from different model assumptions, parameterizations, and outputs. To address these challenges, systematic intercomparison studies among different models using common frameworks for analysis are necessary.

The aim of the tipping model intercomparison project (TIPMIP) is to systematically advance our understanding of tipping dynamics in various Earth system components, and to assess the associated uncertainties. TIPMIP specifically aims at answering the following questions: What is the risk of crossing individual tipping points in the cryosphere, biosphere and core circulation systems at different levels of anthropogenic forcing? What are the key biophysical processes and feedbacks associated with tipping elements? What are the characteristics (spatial and time scales, abrupt or gradual, etc.) of the individual tipping elements? Are the respective changes reversible, and if so, on which timescales? Which are the most critical biophysical feedbacks involved in crossing different tipping points, and between elements affecting the overall stability of the Earth system? What are the quantitative uncertainties in our assessment of thresholds of tipping points corresponding to various tipping elements and the feedback strengths? To this end, it foresees three major sets of experiments: A baseline experiment to analyse the historical and projected response of selected tipping elements to different climate and land-use change scenarios, a commitment experiment to assess the long-term consequences of surpassing different temperature and CO2 levels, a reversibility experiment to probe the reversibility of impacts and potential hysteresis behaviour. Given the complexity and scale of this effort, the first phase of TIPMIP will focus on core tipping elements with global impact, namely the Greenland and Antarctic Ice Sheet, the AMOC, boreal permafrost as well as tropical and boreal forests.