According to a new study, climate change is causing historically humid and temperate areas to behave more like deserts.

By the end of the century, researchers predict that an additional global area about twice the size of the United States will experience soil temperatures and humidity levels equivalent to those of today’s arid regions. .

A better understanding of these processes will be essential to help societies in these transitioning ecosystems adapt, according to the study published Monday in the journal Nature.

That means diving into a blind spot of current climate projections, co-author Heather Throop of Arizona State University said in a statement.

Something that “our models can’t take into account is: what if the rules by which the system operates change?” Throp asked.

This is an increasingly urgent question. Over the next century, such changes will occur across vast regions, his team found. Desert-like conditions – high soil temperatures and minimal soil moisture – will eventually define a large area of ​​currently humid and temperate zones, the team from Arizona State University and the University found. Hebrew of Israel.

These ecosystems are changing over the long term in response to a world where heat and drought are rapidly becoming more extreme. The two hottest years on record were 2016 and 2020, and nineteen of the hottest years on record have occurred since 2000, according to NASA. Extreme droughts are also expected to increase in size, area and frequency, according to the Nature study.

Most of the hotspots of these conditions are found in the boreal forest of North America and the tropical rainforest of Southeast Asia, South America and equatorial Africa – whose humid biospheres harvest both the biodiversity and therefore carbon.

Talking about climate change often refers to a change in weather patterns, such as a greater incidence of drought, hurricanes or fires.

However, the new research goes beyond that, looking at how ecosystems function over the long term – how adaptations help life survive as conditions of relative abundance change to conditions of hardship and scarcity.

In a rainforest, for example, ecosystems depend on cool temperatures and abundant water. The canopy and the ground are in constant competition for moisture; the trees are adapted to low levels of rainfall and a rich layer of plants, insects and microbes that decompose detritus and dead plants and animals.

In dryland environments, by contrast – deserts, grasslands, steppes, dry forests and savannahs – the punishing sun and wind drive a world of scarce resources and a thriving ecology, scientists have found.

With intermittent rains and a landscape that heat and dry air have turned into water-repellent clays, life must adapt to conditions of scarcity, interrupted by occasional periods of dangerous abundance.

In these environments, the sun and the wind, and not insects and microbes, break down organic waste. With less rain, dead plants and leaves benefit from the dew and ambient humidity in the air. Air moving under an oak canopy cools the earth, not the evaporation of water from the evergreens. Deep-rooted plants secure water and nutrients in the soil.

In a subtle but important transition, as landscapes become too hot and dry for grasses and shrubs to survive, the base of the ecosystem shifts from plants to thin “crusts” of bacteria and lichens – which transform the carbon and nutrients in the soil.

These ecosystem dynamics have traditionally been overlooked in favor of the rules that govern the temperate regions where most people live – and where, historically, most of the world’s resource universities were located.

Nature’s study suggests that neglect is no longer sustainable. “This new knowledge can help advance our adaptive capacity to withstand climate extremes and reduce their impacts on nature and people,” Throop said.