Researchers analysing 285,444 adults in Finland and the UK found that excess mortality associated with extreme heat and cold was more than tenfold higher among people with both pre-existing medical conditions and socioeconomic disadvantage than among those with neither or only one vulnerability. Climate modelling suggested that warming from approximately 1°C to 4°C could increase the proportion of deaths attributable to extreme temperatures from around 1% to more than 5% in both countries.