Extreme Weather Events
Extreme weather event frequency and severity have risen with climate warming. Heatwave frequency has roughly tripled since 1970 in many regions. The fraction of major hurricanes (Cat 3-5) has risen as a share of total. Compound events — fire-heatwave-drought combinations — have become more common. Climate attribution science can now quantify the warming contribution to specific events within weeks of occurrence.
Key insights
Heatwaves are the cleanest climate signal
Heatwaves show clearer climate signal than hurricanes or droughts — they're a direct consequence of warming. Frequency has risen 2-3× in mid-latitudes since 1970. 2021 Pacific Northwest heat dome (49.6°C in BC, Canada) was attributed by climate science to be ~150× more likely under current warming than pre-industrial. 2023 European, North American, Asian heatwaves: each ~2-5× more likely under warming. Heat mortality has risen — though improved AC and warning systems have offset some of the rise.
Hurricanes are intensifying, not necessarily more frequent
Hurricane/typhoon total count globally is roughly flat. But the proportion that are major (Cat 3-5) is rising. Rapid intensification (gain of 35+ mph in 24 hours) — like Hurricane Helene (2024) — is becoming more common. Warmer ocean waters provide more energy; warmer air holds more moisture for rainfall. Sea-level rise amplifies storm surge. The composition shift — fewer minor, more major storms — drives most of the increase in damage.
Attribution science has matured
World Weather Attribution and similar groups now produce attribution studies within days/weeks of major events. Methodology: compare event probability in current climate model simulations vs counterfactual pre-industrial climate. For heatwaves and many flooding events, attribution confidence is high. For convective storms and tornadoes, attribution is harder. The science has informed legal cases (climate litigation), policy debates, and public communication.
Climate-related disasters by decade
Number of disasters (EM-DAT criteria), per decade
Key Finding: Climate disasters reported have tripled since the 1970s — partly real increase, partly improved reporting.
Global insured losses from natural disasters by year
USD billions
Key Finding: Insured losses have grown — driven by exposure (more assets in harm's way) and climate-amplified events.
Methodology & caveats
EM-DAT inclusion criteria
CRED EM-DAT counts disasters meeting one of: 10+ deaths, 100+ affected, declaration of emergency, call for international assistance. Reporting has improved over time — earlier decades undercounted. Comparing across decades requires acknowledging improving detection alongside any real increase.
Attribution methodology
World Weather Attribution and Climate Central protocol: run large ensembles of climate models with current GHG levels vs counterfactual pre-industrial. Calculate event probability in each ensemble. Ratio is the 'attribution fraction'. Robust for heat and many precipitation extremes; weaker for convective storms and droughts. Studies produced within days/weeks of major events.
Insured vs total losses
Insured losses (~$382B/year average 2017-2024) are a fraction of total economic losses. Insurance penetration varies — high in OECD, low in developing countries. Total losses likely 2-3× insured. Cost trends are influenced by exposure growth (more assets at risk), not just hazard intensification. Disentangling exposure from hazard is the methodological challenge.