A study by researchers at the University of Alicante and published in the Science magazine indicates that, once certain levels of soil aridity have been overcome, the changes will not be proportional, but drastic. Arid lands make up 45% of the planet’s non-aquatic surface and provide livelihood for almost 2.5 billion people through livestock or agriculture. These soils are especially sensitive to climate change.
According to this investigation, the intensification of aridity will not occur gradually, as the temperature rises. Instead, this kind of terrain will respond to changes disproportionately, which will result in a more abrupt desertification than previously thought.
The areas most exposed to this process are those that already have a more arid climate. In Spain, the most threatened areas are Alicante, Murcia and Almeria, as well as Lanzarote and Fuerteventura, according to the researchers. Vegetation productivity or the fertility of these soils react non-linearly to increases in aridity, such as those expected with climate change, but respond disproportionately.
Three levels of desertification
Three critical thresholds of aridity of ecosystems have been established in the investigation. When one of them is reached, the intensification of the aridity accelerates in an increasingly abrupt way. According to Fernando Maestre, director of the Laboratory of Arid Zones and Global Change of the University of Alicante, responsible for research, the first threshold corresponds to levels of aridity similar to those in the Mediterranean area.
On the other hand, the second threshold has similar values to those in the southeast of the Iberian Peninsula, which results in a deterioration of vegetation development. In the third and most critical threshold there is a drastic fall in the coverage and diversity of plants, which ends up leading to the appearance of deserts.
The conclusion of this study is that desertification of ecosystems is not a gradual process, but it increases dramatically when each one of these three points of no return is exceeded. Researchers have indicated that in the year 2100 up to 18% of the global land area will have passed through at least one of the three thresholds detected. In Spain the figure is higher, hovering between 60% and 75% of the country’s surface.
This study will be essential to foresee, manage and minimize the climatic damage, since it is expected that there will be very serious reductions in plant diversity and coverage. According to Maestre, this will result in the degradation of the natural ecosystems of these areas and their desertification. Although life will not disappear from the most arid zones with climate change, it is important to be prepared for the changes that may occur.