Climate change made July hotter for four out of five people on Earth: study

More than 80 percent of people on earth experienced hotter temperatures in July than they would have without the impacts of climate change, according to research released Wednesday by Climate Central.

The nonprofit analyzed the July climate for 4,711 cities around the world and found that for more than 6.5 billion people, or over 80 percent of the world population, there was at least one day in the past month with a Climate Shift Index (CSI) of at least three, or high temperatures made at least three times more likely due to the effects of human-caused climate change.

The research also found that at least 2 billion people worldwide experienced a CSI level of at least 3 on every day of July. The number of people experiencing that level of heat peaked on July 10, when the nonprofit projected 3.5 billion people experienced a CSI level of at least 3.

Island states were particularly vulnerable to climate impacts, echoing frequent warnings by those nations’ leaders. Of those states, including 11 Caribbean nations, 16 were among the 28 countries with an average CSI of 5 for the month — that is, conditions that climate change made at least five times more likely.

Nearly 900 cities worldwide had at least 25 days in July with a CSI level of 3 or higher, many of them in the Middle East or the global south. They include Mexico City; Tampa, Fla.; Havana; Alexandria, Egypt; and Algiers, Algeria.

Although the end of July was too recent for most research, including that of Climate Central, to be peer-reviewed, early data indicate July was on track to be the hottest month ever recorded. The United Nations’ World Meteorological Organization and the European Union’s Copernicus Climate Change Service both determined last week that the first three weeks of the month was the hottest three-week period on record, with July 6 the hottest single day ever recorded.