Route 45 · Impacts: insurance and catastrophe

ENSO tells an insurer which perils, not the size of the bill.

The year's U.S. total of billion-dollar disasters shows no regime signal at all: – count and cost tests pass, and neither does the total crop-insurance loss cost (–). Exposure growth and a single landfalling hurricane decide a year's total. The regime does shift particular perils: Atlantic hurricanes were fewer than the neutral trend in – seasons while a strong El Niño developed (it survives the correction), and crop-insurance drought losses per dollar insured ran above trend in – La Niña crop years (–, not significant after the correction across the cause tests). Correlated crop failure across countries, the risk a global reinsurer carries, clusters in multi-year La Niña (agriculture).

Losses are set against the ENSO year of the event (July to June); crop years against the winter that opened them (“after”) or the event developing through them (“during”); the Atlantic season of year y against the winter that follows. Log losses have their trend removed on neutral years; NOAA retired the billion-dollar database after 2024.