A study published in June in the journal Nature Climate Change reveals that global thermal stress has risen dramatically since the 1970s, and its conclusions resonate particularly strongly in Cuba, where extreme heat is compounded by prolonged blackouts and an energy crisis that hinders access to cooling.
The research, titled "Global heat stress intensification and its expanding footprint on the human population", was published by the official media outlet Cubadebate, which summarized its central finding: "Thermal stress is changing not only in intensity but also in frequency, duration, and geographic extent."
The study utilizes the Universal Thermal Climate Index (UTCI), which combines temperature, humidity, wind, and solar radiation to measure how the human body actually perceives the environment, and analyzes data from the 1970-2024 period provided by the Copernicus Climate Change Service.
Among its most striking data: the proportion of the global population exposed to at least one day of extreme heat stress per year increased from 16% to 22%, which amounts to approximately one billion additional people.
Moreover, those who experience at least 90 days of extreme heat stress per year have increased from 55% to 70% of the global population.
In subtropical regions —including the Caribbean— there are recorded up to 50 more days a year with severe thermal stress than in the 1970s, according to the study.
A concerning factor that worsens the situation is nighttime behavior: the warmest nights are warming at a faster rate than the hottest days, at a pace of 0.32 °C per decade compared to 0.27 °C per decade, which reduces the body's recovery time.
For Cuba, the local context makes these global figures take on an even more urgent dimension.
A study from the University of Albany identified Cuba, Haiti, Puerto Rico, and the Dominican Republic as some of the Caribbean locations showing the clearest signs of increasing heat waves, and the regional forecast CARICOF projected between 15 and 21 days of intense heat episodes across much of the island during the period of April to September 2026, with August and September being the most critical months.
The ongoing summer has confirmed those projections with concrete records: Camagüey recorded 38.1 °C on July 30 at the Ignacio Agramonte airport, surpassing the previous record of 36.0 °C set in July 1963.
Weeks earlier, La Palma, in Pinar del Río, reached 37.6 °C on June 13, a historic record for that station and for the province in that month.
In June, the dust from the Sahara added to those extremes, which intensified the heat sensation in Cuba amidst the power outages.
Previous research has documented that heatwaves result in an excess of mortality on the island, particularly among the elderly, children, pregnant women, and patients with chronic illnesses, and that heatwaves are leaving increasingly visible marks in Cuba, according to specialists quoted by local media.
The United Nations warned in May 2026 that there is a 91% probability that at least one year between 2026 and 2030 will temporarily exceed the threshold of 1.5 °C above pre-industrial levels, indicating that the scenario described in the study by Nature Climate Change will continue to deteriorate in the coming years.
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