Earth's dryland ecosystem covers 41% of the world's surface and roughly a third of the world’s population calls these ecosystems home. What exactly is a dryland ecosystem? Drylands include cultivated lands, scrublands, shrublands, grasslands, savannas, semi-deserts and true deserts – i.e. any land characterized by a lack of water.
New research published in the journal Science suggests that intensifying aridity due to climate change is affecting dryland ecosystems and resulting in frightening consequences. The research was led by Dr. Rocio Hernandez-Clemente, a senior lecturer from Swansea University's Department of Geography, in collaboration with an international team of researchers from the Dryland Ecology and Global Change Lab at the University of Alicante.
Researcher Dr. Berdugo from the University of Alicante, commented: "The purpose of our work was to look at how these ecosystems change as we move towards more arid zones in order to better understand what we may expect in the future as the climate becomes drier, and more arid, in drylands worldwide."
The team analyzed the largest compilation of empirical data to date in order to determine ecosystem changes in drylands along aridity gradients. As they write in their report, “Whether aridification leads to gradual (versus abrupt) and systemic (versus specific) ecosystem changes is largely unknown. We investigated how 20 structural and functional ecosystem attributes respond to aridity in global drylands.”
The study found that aridification indeed leads to abrupt changes, which can be described by three phases. First, the study observed significant drops in plants’ capacity to photosynthesize. In subsequent observations, the researchers noted decreasing soil fertility and finally, eventual vegetation extinction. Frighteningly, the authors say that by 2100, we can expect over 20% of land on Earth may cross one or several of the thresholds identified in this study.
"Life will not disappear from drylands with forecasted aridity increases, but our findings suggest that their ecosystems may experience abrupt changes that will reduce their capacity to provide ecosystem services more than 2 billion people, such as soil fertility and biomass production," lamented Dr. Berdugo.
Dr. Rocio Hernandez-Clemente concluded: "The reduced global ability of the land to sustain life is predicted to become an increasing problem with climate change. This study demonstrates the possibility of detecting abrupt changes and monitoring how land turns into desertification processes with remote sensing data. The use of satellite image data helps scientists to monitor, predict and quantify the consequences of the increasing aridity in drylands ecosystems worldwide. International cooperation is essential for assessing land degradation and abrupt shifts. The next steps of our research will be focused on the use of earth observation data to look for changes of desertification processes."