A recent study published in June by Nature Climate Change highlights a dramatic increase in global heat stress since the 1970s, a revelation that resonates powerfully in Cuba. The island nation faces not only extreme heat but also prolonged power outages and an energy crisis that limits access to cooling.
The research, titled "Global Heat Stress Intensification and Its Expanding Footprint on the Human Population," was shared by the state-run outlet Cubadebate. It summarizes the study’s central finding: "Heat stress is changing not just in intensity, but also in frequency, duration, and geographical reach."
The study employs the Universal Thermal Climate Index (UTCI) to assess how humans truly perceive environmental conditions by integrating temperature, humidity, wind, and solar radiation. It examines data spanning from 1970 to 2024 from the Copernicus Climate Change Service.
One of the most striking findings is that the global population exposed to at least one day of extreme heat stress annually has risen from 16% to 22%, representing roughly one billion additional people.
Moreover, the percentage of people experiencing at least 90 days of intense heat stress each year has jumped from 55% to 70% of the world's population.
Subtropical Regions Hit Hard
In subtropical areas, which include the Caribbean, the study notes an increase of up to 50 additional days of severe heat stress annually compared to the 1970s.
Compounding the situation is the behavior of nighttime temperatures: warmer nights are heating up more rapidly than the hottest days, at a rate of 0.32°C per decade compared to 0.27°C per decade, reducing the body's recovery time.
A Dire Situation for Cuba
For Cuba, these sobering global statistics take on an even more urgent dimension. A study from the University of Albany pinpointed Cuba, Haiti, Puerto Rico, and the Dominican Republic as Caribbean locations with clear signs of increasing heat waves. The CARICOF regional forecast projects 15 to 21 days of intense heat episodes across much of the island from April to September 2026, with August and September being the most critical months.
This summer has already validated these forecasts with record-breaking temperatures: on July 30, Camagüey reached 38.1°C at Ignacio Agramonte Airport, surpassing the previous record of 36.0°C from July 1963.
In June, La Palma in Pinar del Río recorded 37.6°C on the 13th, setting a historic high for both the station and the province during that month.
Adding to these extremes, Saharan dust in June worsened the heat sensation amid power cuts in Cuba.
The Human Toll of Heatwaves
Previous research has documented that heatwaves lead to excess mortality on the island, particularly affecting the elderly, children, pregnant women, and individuals with chronic illnesses. Specialists cited by local media note that the impact of heatwaves is becoming increasingly visible in Cuba.
In May 2026, the United Nations warned of a 91% likelihood that at least one year between 2026 and 2030 will temporarily exceed the 1.5°C threshold above pre-industrial levels, indicating that the scenario detailed in the Nature Climate Change study is likely to worsen in the coming years.
Understanding Global Heat Stress in Cuba
What is the Universal Thermal Climate Index (UTCI)?
The Universal Thermal Climate Index (UTCI) is a measure that combines temperature, humidity, wind, and solar radiation to assess how humans perceive environmental conditions.
How has global heat stress changed since the 1970s?
Since the 1970s, global heat stress has intensified, increasing not only in intensity but also in frequency, duration, and geographical reach, as identified by the study.
Why is Cuba particularly vulnerable to heat stress?
Cuba is particularly vulnerable due to its extreme heat conditions, combined with prolonged power outages and an ongoing energy crisis that limits access to cooling solutions.