The year 2025 will be remembered as a critical year in terms of climate. January saw the highest temperature ever recorded, with 1.75°C above pre-industrial levels, and the summer brought a series of unprecedented heatwaves. Spain, among other countries, experienced suffocating days that not only affected the human population but also biodiversity.
These extreme episodes have a direct impact on ecosystems. They alter reproduction cycles, affect water and food availability, and create conditions of thermal stress that jeopardize the survival of animals and plants. The impact is not limited to the immediate: extreme heat is even altering the way genes are passed down from one generation to the next.
Recent research reveals that high temperatures can alter fertility and sex determination in various species, especially reptiles and fish. This finding confirms that heatwaves are not just meteorological phenomena but biological forces capable of transforming the basic mechanisms of life.
Biodiversity, already under pressure from pollution and deforestation, faces a new challenge. If reproduction and genetics are conditioned by the climate, the future of many species becomes uncertain, generating chain effects on the trophic networks that sustain terrestrial and aquatic ecosystems.
## The Heat and Its Impact on Genetic Inheritance
A study in Madagascar on the Guibé ground gecko revealed that high temperatures increase genetic recombination events, cause DNA fragmentation, and modify chromosome structure. These changes are significant: they influence how species transmit genetic diversity, which determines their adaptation capacity.
Another case was observed in Australia with the central bearded dragon. It was found that eggs exposed to extreme heat can cause genetically male individuals to develop as functional females. This phenomenon, known as sexual reversal, highlights how climate can directly intervene in biological development.
The consequence of these alterations is profound: as extreme heat events become more frequent, more species could experience modifications in their reproductive processes. This reduces the stability of their populations and compromises their long-term survival.
## The Rise in Temperature, a Phenomenon Redefining Life on the Planet
The global temperature rise is not just an environmental issue, but a phenomenon redefining life itself. Studies on reptiles and fish show that heat can reprogram genetic inheritance, while in humans and economic activities, the consequences are increasingly visible.
If these effects accumulate over time, genetic diversity will decrease, along with the adaptation capacity of numerous species, including our own. Breaking this vicious circle requires reducing emissions, protecting ecosystems, and developing policies that integrate public health, food security, and conservation.
Global warming is no longer a future threat; it is a reality that transforms how humanity lives and how life is transmitted.
## Consequences of Heatwaves Beyond Animals
While much attention is focused on biodiversity, heatwaves also impact human health, agriculture, and the economy. In cities, rising temperatures increase cases of heatstroke, worsen cardiovascular and respiratory diseases, and raise mortality rates in older people and vulnerable groups.
In agriculture, extreme heat causes crop losses, reduces food quality, and increases pressure on water resources. This not only raises the cost of basic products but also threatens food security in entire regions.
Economically, heatwaves disrupt labor productivity, especially in outdoor activities, and increase energy consumption due to the widespread use of cooling systems. This, in turn, increases greenhouse gas emissions, feeding the same cycle that gives rise to extreme events.
