Accounting for humidity is critical for understanding heat‑related mortality in the Eastern Mediterranean, new CARE-C led study finds

A new study led by researchers of the Cyprus Institute’s CARE-C reveals that the combined effects of high temperature and humidity significantly increase mortality risk in the Eastern Mediterranean, underscoring the need for climate–health assessments that move beyond temperature alone. The findings provide new insights with direct implications for improving early warning systems and public‑health adaptation strategies.

Using Cyprus as a case study, the research, published in PLOS Climate, examined the combined effects of air temperature and atmospheric moisture on cardiovascular and respiratory mortality among adults aged ≥65 years. By analysing daily population-weighted temperature and moisture data across Cyprus for the period 2004–2019, researchers found that both high and low temperature extremes, when combined with varying humidity levels, significantly increase mortality risk, with distinct regional and seasonal patterns. Specifically, cold and dry conditions had a stronger impact in inland areas during winter, accounting for approximately 50–60% of cases. In contrast, high temperatures combined with elevated water vapour pressure (WVP) intensified mortality risk in coastal regions during summer, with effects occurring rapidly, within three days.

The study highlights atmospheric moisture and particularly water vapour pressure, as a critical factor modifying temperature-related mortality, and suggests it may be more informative than commonly used humidity metrics. Accounting for appropriate moisture indicators is therefore essential for improving climate–health risk assessments, early warning systems, and adaptation strategies, especially for ageing populations.

Cyprus and the wider Eastern Mediterranean and Middle East region, has been identified as a global climate change hotspot, warming almost two times faster than the global average, with heat extremes expected to become more frequent and intense. Though the implications from the findings are more widespread. According to the World Health Organization, more than 250,000 excess deaths per year are projected globally between 2030 and 2050 attributable to the direct and indirect effects of climate change.

As lead author, CARE-C Graduate Research Fellow Anna Tzyrkalli, explains: “Although demonstrated for Cyprus, this framework can be applied to other countries in the Middle East and North Africa, where rapid warming and strong moisture gradients occur, as well as across Europe, where heat–humidity extremes are expected to intensify. By incorporating atmospheric moisture into epidemiological analyses, early warning systems can be improved, climate–health risk assessments refined, and more effective adaptation strategies developed.”

Reference:
Tzyrkalli, A., Georgiades, P., Economou, T., Kekkou, F., Giannaros, C., Parliari, D., Neira, M., Tobias, A. and Lelieveld, J. (2026) On the compound effect of humidity and temperature on mortality in the Eastern Mediterranean. PLOS Climate, 5(4): e0000821. https://doi.org/10.1371/journal.pclm.0000821