The overall goal of this WP is to obtain quantitative estimates of the likelihood that the TEs AMOC, Amazon, European Mediterranean, Indian summer monsoon, and the polar ice sheets will tip to a different state in the near future due to different anthropogenic forcing factors. Particular focus will be put on EWSs for the potential transitions of these TEs: Using a hierarchy of models, and comparing the results with recent observations, the specific physical mechanisms responsible for the statistical EWSs will be addressed. The combination of advanced statistical and physical characteristics of EWSs will pave the way toward quantifying lead times for associated forecasts in a probabilistic manner, which will be directly useful in terms of establishing scientifically informed adaptation and mitigation policies in WP6.
The concrete objectives of WP3 are:
- To assess the risk of an AMOC shutdown in the near future due to global warming, and to identify corresponding EWSs from simulations.
- To quantify the risk that the Amazon rainforest will tip to a savannah state due to global-warming-induced precipitation changes and due to deforestation, to identify EWSs for such a transition, and to provide an assessment of the climatological, ecological and socio-economic impacts of a potential dieback of the Amazon.
- To estimate the response of the Indian summer monsoon to various scenarios of regional and global forcings in order to allow to define safe operating spaces that exclude future dangerous conditions in the hydroclimatology of the region, and to quantify EWSs of a potential regime shift of the monsoon.
- To assess the impacts of TP crossings on a range of relevant climate properties in Europe, such as the statistics of atmospheric blocking, weather regimes and extremes, to identify worst case scenarios in this regard, and to establish associated EWS.
- To constrain the stability and future ice-sheet evolution in the mid-long term of the Antarctic and Greenland ice sheets, and to identify suitable precursor signals of a future stability loss.