Extreme heat exposure to more than double by 2050 if warming reaches 2C

A Nature Sustainability study finds that if global warming reaches 2C, an estimated 3.79 billion people (about 41% of the projected 2050 population) would experience extreme heat, and no region would be fully immune.

A new study published in Nature Sustainability maps where and how many people will face extreme heat as human-driven warming rises from about 1C above preindustrial levels toward 1.5C and 2C. The authors defined extremes by annual days departing from a temperate baseline of 18C and used climate models to project changes and population exposure through 2050. The work also looks at how energy demand for heating and cooling is likely to shift across regions. Key findings: - If warming reaches 2C, the projected number of people experiencing extreme heat rises from 1.54 billion (23% of the world in 2010) to 3.79 billion (about 41% of the projected 2050 population). - The largest numbers affected are projected in India, Nigeria, Indonesia, Bangladesh, Pakistan and the Philippines. - The most significant increases in dangerous temperatures were projected for Central African Republic, Nigeria, South Sudan, Laos and Brazil. - The study reports a shift in energy needs: heating demand in the northern hemisphere would fall while cooling demand in the southern hemisphere would rise, and separate research indicates air conditioning demand may overtake heating by century’s end. Summary: The study indicates a large rise in global population exposure to extreme heat if warming reaches 2C, with impacts spread across tropical and northern regions and sizable implications for health, infrastructure and energy systems. Authors say changes appear earlier on the warming trajectory, creating urgency around adaptation and mitigation, while the timing and form of policy responses remain undetermined at this time.