What early warning systems are there for environmental shocks?

This paper offers a new classification of environmental shocks from a dynamical systems perspective, and reviews early warning systems for environmental shocks, particularly in climate systems and ecosystems. Three main categories of environmental shock are identified; extreme events, abrupt swings, and tipping points. The factors determining the predictability of different shocks and hence the prospects for early warning are outlined. Lessons from existing early warning systems for extreme events and abrupt climate swings are summarised. Then the potential for early warning of bifurcation-type tipping points is explained, and contrasted with the lack of warning when stochastic internal variability triggers a shift in the state of a system. The scientific and technological progress needed to improve early warning capability is outlined. Then the framework is applied to the Foresight project on Migration and Global Environmental Change, with its focal eco-regions of drylands, low-elevation coastal zones, and mountainous regions. Priority targets for early warning systems are identified and the need for an integrated approach to early warning is highlighted, which considers the interactions between different types of environmental shock.

► Environmental shocks are defined and classified.
► Lessons from existing early warning systems are summarised.
► The potential for early warning of tipping points is explained.
► Priority targets for early warning systems are identified.
► The need for an integrated approach to early warning is highlighted.