Heat-related deaths reached about 710,000 worldwide in 2023, with more than 71 percent linked to human-caused warming, the 2026 Lancet Countdown report finds, ABC News and ABC Australia report. Deaths tied to heat have climbed sharply since the 1990s, the report says. Authors warn that climate change is already a global health emergency.

ABC Australia notes nearly 3 million deaths from 2016 through 2023 could be connected to a warming planet, with about two-thirds of heat deaths tied to human-caused climate change. Heat also cut work hours and income. The report estimates more than a trillion dollars in lost potential income in 2025 from heat cutting work hours, the third straight year above that mark.

The share of deaths tied to warming comes from a model that compares today's climate with a world without human-caused warming. The count does not credit heat adaptation such as cooling centers or early-warning plans. Authors still say the toll now tops deaths from malaria or HIV in the years studied.

Dr. Marina Romanello, executive director of the Lancet Countdown, said climate change is a health emergency and that delay is costing lives. She said leaders must treat climate action as an urgent health response.

Outside the report, Western Sydney emergency doctor Aditya Vyas said heatwaves are a "silent killer," ABC Australia reported. He said health workers saw a 13 percent jump in emergency visits during heatwaves. He co-wrote a separate Oceania climate and health report, not the global Countdown.

What we know: The Lancet Countdown ties most 2023 heat deaths to human-caused warming and calls climate change a health emergency.
What we don't: Whether governments will fund the adaptation and emissions cuts the authors say are needed.