Actuarial science

Climate-conditioned PML

Probable maximum loss recalculated to incorporate the drift in peril frequency and intensity under climate change.

Definition

The climate-conditioned PML is a probable maximum loss recalculated to incorporate the expected evolution of perils under climate change, rather than assuming a stationary climate calibrated on history. Traditional catastrophe models rely largely on distributions estimated from past data, an increasingly fragile assumption once the frequency and intensity of certain perils drift. Conditioning the PML on climate requires adjusting severity-frequency curves using prospective scenarios, SSPs and warming trajectories, and attribution science. For the insurer and reinsurer, this adjustment changes the sizing of capital and reinsurance programmes: a PML underestimated by purely retrospective calibration exposes to insufficient cover against a worsening risk. The central difficulty lies in projection uncertainty, which widens the estimation range and complicates forward-looking pricing.

Example

A reinsurer recalibrating its flood PML on projections of future rainfall rather than history alone obtains a noticeably higher capital estimate.

Related terms
Also known as

climate-conditioned PML, PML conditionnée climat, perte maximale probable climatique