How do scientists know if climate change made a heat wave, extreme storm or wildfire worse?

People try to stay cool on the sweltering streets of Manhattan during a heat wave in July 2025. Spencer Platt/Getty Images When a devastating heat wave, hurricane, flood or wildfire strikes, people often want to know: How much did human-caused climate change influence this event, if at all? For many years, scientists could answer that question only in general terms. They knew that human-caused climate change was increasing the frequency or intensity of some kinds of extreme weather, but…