One route to tipping is to push a system past a critical level of forcing. In the Global Tipping Points Report, this is represented as a loss of the previous stable state once a threshold is crossed. For cities, the same idea can be used cautiously to think about infrastructure or service limits, without assuming that every city has one universal tipping temperature.
A system can remain within a relatively stable operating range while climate pressure rises. If forcing becomes large enough, the previous state may no longer be sustainable and the system can shift rapidly into a different state. The key feature is the magnitude of forcing relative to a critical threshold.
Urban examples might include drainage capacity being exceeded during extreme rainfall, electricity demand exceeding available supply during heat, or indoor temperatures moving beyond safe operating conditions. These thresholds are context-specific and depend on infrastructure, exposure, management, and population vulnerability.
The preventive logic is to keep forcing below critical limits where possible and to increase the margin between normal operation and failure. In practice this can involve emissions reduction, demand management, additional infrastructure capacity, heat adaptation, flood protection, and earlier intervention as warning indicators approach operational limits.
