After two years of record-breaking heat that brought a surge of deaths and health emergencies, several states have enacted or are considering measures designed to protect residents — with a new focus on younger people whose vulnerability is rising with the temperatures. Climate change is making the problem more urgent: Heat waves have been steadily rising in number and duration since the 1960s, and minority groups and people with low incomes will suffer disproportionately. A new report says worldwide heat-related deaths could nearly quintuple by 2050.