Register of the Early Warning Indicators

This document provides a synthesis of early warning indicators (EWIs) for major climate tipping elements, whose tipping risk is increasing under anthropogenic pressure. It combines approaches based on critical slowing down and understanding of physical processes to identify signals of impending abrupt transitions. The main contribution is the development of EWI registers for key systems (SPG, AMOC, Greenland and Antarctic ice sheets, and Arctic sea ice), compiling precursors, available and missing observations, threshold estimates, timescales, and indicator reliability. The analysis highlights significant observational gaps and uncertainties across many indicators, and offers recommendations to strengthen monitoring systems. Overall, this work establishes a structured foundation for developing operational early warning systems for climate tipping risks.

This is a living document maintained by the main author: Didier Swingedouw <didier.swingedouw@u-bordeaux.fr>

Each table includes the following information:

• Precursors, key processes, and associated early warning indicators,

• Observations for EWI: available datasets and those missing, and which are required for allowing the EWI to be correctly monitored (highlighted in dark red colour),

• Threshold estimates for precursor variables,

• Time scale of early warning,

• Reliability of CSD-based indicators,

• Sources of knowledge and supporting simulations.

The title of each table indicates the tipping element analysed. In addition, the lowest warming level at which the tipping point is crossed in some models, as well as the time length of the transition towards a new state following the crossing of the tipping point , are provided in parentheses. The acronym “n/a” means “not available” when no information on the topics seems to exist.

Details on how this document has been developed and set up can be found on this page