The Skin — Our Protective Barrier as a Victim of Climate Change: The Impact of Thermal Stress

Climate change is no longer a distant problem that seemed to concern only polar bears. It is a challenge that affects everyone equally! Record-breaking increases in the Earth’s temperature, invisible pollution, and ozone holes — all these factors have a major impact on our largest and most important organ, the skin.
The skin is the body’s first line of defense. Climate change represents a global threat that affects not only ecosystems but almost every aspect of human health. The skin, the body’s largest organ, is particularly vulnerable and responds first to environmental changes.
That’s why, when we look at global warming statistics, we must understand: these statistics are directly reflected on our faces. The climate not only increases the risk of skin cancer, but, as scientists claim, accelerates the aging process. Our skin is no longer just an aesthetic issue — it is now a victim of a global crisis….
Traditionally, ultraviolet (UV) radiation was considered the main cause of premature skin aging. However, in recent years, evidence has accumulated indicating that thermal stress (the increase in temperature and humidity) is an independent risk factor that accelerates both physiological and molecular aging of the skin (Schikowski et al., 2024).

1. IUF (Germany, Düsseldorf) study – This was the first epidemiological study that questioned the exclusivity of UV and proved that thermal stress (heat) is just as important an independent risk factor.
   The study was conducted on data from 1,510 Indian women (India was chosen because of its high temperature and humidity).
   • Factor: The researchers used the Heat Index (HI), which combines ambient temperature and relative humidity. They analyzed the average five-year exposure to HI in the participants’ residential areas.
   • Control (exclusion): The accuracy of the study lay in the fact that statistical modeling excluded (took into account) the known aging factors of age and UV exposure.

Main findings (what was proven?)
The IUF’s conclusion was clear: the higher the long-term HI value, the more pronounced the signs of skin aging — hyperpigmentation, elastosis, and an increase in wrinkles, even when age and UV exposure were controlled. The study was the first to prove that thermal stress is a factor independent of UV.

2. Taiwanese population epigenetic study
   The population-based study by Huang et al. (2024) (n = 2,084) showed that increases in ambient temperature and humidity are associated with acceleration of DNA methylation age (epigenetic age acceleration). This result indicates that thermal stress affects the epigenetic regulation of aging, which goes beyond only superficial changes in the skin.

3. Mechanisms of environmental stressors
   According to Krutmann et al. (2021), thermal and environmental stressors cause an increase in the activity of matrix metalloproteinases (MMP-1, MMP-3, MMP-13), which leads to the breakdown of collagen and elastin. At the same time, oxidative stress increases and antioxidant activity decreases, which accelerates both photo- and thermo-aging of the skin.

4. Animal model experiments (Japan)
   In the experiment by Choi et al. (2021) on hairless mice, exposure to 43°C (30 minutes, three times a week, for six weeks) showed the formation of skin wrinkles, breakdown of collagen fibers, and a decrease in the activity of antioxidant enzymes, which directly confirms the destructive effect of thermal stress on the skin.

Verified studies have confirmed that thermal stress and humidity act as independent and synergistic factors in the skin aging process. At the mechanistic level, this includes oxidative stress, inflammatory responses, collagen degradation, and disruption of epigenetic regulation.
Under conditions of climate change, especially in regions where temperature and humidity are increasing, it is necessary to reconsider skin protection strategies. Along with UV blocking, it is essential to reduce thermal stress, enhance antioxidant protection, and restore barrier function.

Based on the analysis of international scientific databases (PubMed, Scopus, Web of Science), it appears that since 2020, no reliable (peer-reviewed) studies have been conducted in Georgia that examine the effects of climate, temperature, or humidity on skin physiology, aging processes, or epigenetic changes.
Existing national reports (WHO, 2022; UNEP, 2023) review the impact of climate on general health but do not include dermatological aspects.
Accordingly, there is no accurate, locally based information describing the impact of climate on the skin of the Georgian population.

Modern evidence clearly shows that climate change poses a serious risk to skin health. Thermal stress and humidity not only accelerate aging processes but also affect biological age itself.
The absence of such research in Georgia represents a significant knowledge gap that must be filled by conducting local epidemiological and molecular studies.
Interdisciplinary collaboration at the levels of dermatology, environmental hygiene, and biomolecular sciences will form the foundation for new, climate-adapted strategies for skin health protection.