Long-term trends in Americans’ climate attitudes show increased understanding that global warming is happening and harming Americans. Between 2010 and 2023, the share of Americans who recognize that global warming is happening grew by 14 percentage points in Yale and GMU’s data (from 59% to 73%). The percentage who attribute global warming to human activities also increased by double digits, from 48% in 2010 up to 59% in 2023. The belief that global warming is either harming people in the U.S. now or will do so within the next ten years has increased sharply since 2010, from 38% up to 57%. Over that same time period, Americans have become 13 points more likely to say that global warming will harm them personally (from 33% to 46%). Growth in climate understanding is largely driven by Democrats, with additional gains among center and center-right voters. Yale and GMU’s trends show that Democrats have become much more unified in their climate beliefs over the past decade or so. Large and growing majorities of liberal Democrats (87%, +26 since 2010) and non-liberal Democrats (74%, +25 since 2010) say that global warming is either harming Americans now or will do so in the next 10 years.