Whether they realized it or not, some 7.6 billion people — 96 percent of humanity — have felt the effects of global warming on temperatures over the past 12 months, researchers said.

However, some regions felt this much more strongly and frequently than others, according to a report based on peer-reviewed methods by Climate Central, a climate science think tank.

Humans in tropical regions and on small islands surrounded by heat-absorbing oceans have been disproportionately affected by man-made temperature increases to which they made little contribution.

Among the 1,021 cities analyzed between September 2021 and October 2022, the South Pacific capitals Samoa and Palau experienced the clearest climate fingerprints, the researchers said in the report released Thursday.

Temperature spikes in these locations were generally four to five times more likely to occur than in a hypothetical world that had never experienced global warming.

Lagos, Mexico City and Singapore were among the most exposed major cities, with man-made heat increasing health risks for millions.

Climate Central researchers, led by chief scientist Ben Strauss, were looking for a way to close the gap between global warming on a planetary scale – which is usually expressed as the Earth’s average surface temperature compared to a previous reference period – and people’s everyday lives Experience.

“By diagnosing climate fingerprints, people know that their experiences are symptoms of climate change,” Strauss told AFP. “This is a signal and shows that we have to adapt.”

Using seven decades of high-resolution daily temperature data from the European Center for Medium-Range Weather Forecasts (ECMWF) and two dozen climate models, Strauss and his team have created a tool – the Climate Shift Index.

The tool calculates the probability that unusually warm weather in a given location on a given day is due to climate change.

For example, 26 cities had at least 250 of the 365 days beginning October 2021 with temperature increases that were at least three times more likely to be due to climate change.

Most of these cities were in East Africa, Mexico, Brazil, small island nations, and the Malay Archipelago — a chain of some 25,000 islands belonging to Indonesia and the Philippines.

“The effect of warming is much more noticeable in the equatorial belt because historically there has been less temperature variation there,” Strauss told AFP.

This is why even a relatively modest increase in local temperatures caused by global warming registers so clearly on the index, he explained.

“Island temperatures are strongly influenced by the temperature of the ocean around them,” said Strauss, who has also mapped the projected impact of sea level rise on coastal areas worldwide.

“To see that small island nations have essentially already lost their historical climates – even as they face losing their lands to rising seas – feels very unfair and tragic.”

The urgent need for cash to help vulnerable tropical nations adapt to climate impacts will come squarely on the table when nearly 200 countries gather in 10 days for the United Nations climate talks in Egypt.

Wealthy nations must deliver on a decades-old pledge to increase climate finance for developing countries to $100 billion a year, even though the UN climate change advisory body IPCC estimates that annual adaptation costs could reach $1 trillion by 2050 if warming continues apace.

The map-based Climate Shift Index Tool can be found here: https://csi.climatecentral.org/csi-contour-map/tavg/2022-10-27/