Descartes targets the aggregate gap in severe storm reinsurance

Hurricane names get the attention. In the U.S. property-catastrophe market, a quieter number keeps arriving without fanfare: Gallagher Re puts 2026 year-to-date severe convective storm losses above $35 billion, at least the fourth consecutive year past that mark. Artemis reports that Descartes Underwriting, the parametric risk-transfer specialist, argues the industry should stop treating that drumbeat as noise.

In its new research, Descartes says it sees no sign of reversal or stabilisation in the trend. The U.S. has the highest frequency of extreme severe convective storms, and the firm expects them to become more apparent over time. The mechanism is straightforward in outline, if not in pricing: a warming lower atmosphere intensifies storms; more energy and moisture produce more severe events; and the value of exposed property keeps climbing while roofs age and repair costs inflate. Multiple storm events may occur, each significant, but none large enough to attach to the lower layers of conventional reinsurance programmes, the company wrote.

Descartes cites a stark set of facts. The 11 years before 2025 were the warmest on record. The past three years all averaged more than 1.5°C above pre-industrial temperatures. Descartes's chief insurance officer and co-founder Sébastien Piguet adds that industry losses have exceeded $50 billion in each of those years. The past, he argues, no longer reliably predicts severity patterns. Building development in rural areas prone to severe storms, along with repair-cost inflation, has turned hazard trends into claims trends.

This is an aggregate-loss argument. A conventional program attaches to a single event, while several moderate storms in one season can exhaust a cedant's retention without ever triggering the layer. Descartes proposes highly responsive parametric solutions that track the cumulative weight of a season's events and pay on an index threshold rather than a claims adjustment. The responsiveness qualifier matters: a product that cannot keep up with a string of events would miss exactly the accumulation it is meant to cover.

The argument lands at an awkward moment for the traditional market. AM Best reported this month that midyear property-cat pricing fell 16%, the steepest drop in decades, even as attachment points rose and terms tightened. Higher attachments enlarge precisely the sub-attachment zone Descartes wants to address. The traditional price for covering that zone has, in relative terms, gone down; the modeled cost of bearing that risk has gone up.

Reinsurers have not ignored severe convective storms; the peril is already a permanent line in their budgets. Descartes proposes a different structure, priced and triggered by the total weight of a season rather than by any single storm. Whether cedants buy it alongside their occurrence programs will show up at the January renewals. The numbers suggest they will get the chance.