Global ecosystem thresholds driven by aridity

TLDR

Aridity, increasing worldwide due to climate change, affects dryland ecosystem structure and functioning, yet whether aridification causes gradual or abrupt systemic changes remains largely unknown. The study investigated how 20 structural and functional ecosystem attributes respond to aridity in global drylands. The authors examined 20 structural and functional attributes across global drylands to assess their response to aridity. Aridification caused systemic and abrupt changes in multiple attributes, occurring in three phases with abrupt declines in plant productivity, soil fertility, and plant cover and richness at aridity thresholds of 0.54, 0.7, and 0.8, and more than 20 % of terrestrial surface will cross one or several thresholds by 2100, necessitating immediate action.

Abstract

Aridity, which is increasing worldwide because of climate change, affects the structure and functioning of dryland ecosystems. 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. Aridification led to systemic and abrupt changes in multiple ecosystem attributes. These changes occurred sequentially in three phases characterized by abrupt decays in plant productivity, soil fertility, and plant cover and richness at aridity values of 0.54, 0.7, and 0.8, respectively. More than 20% of the terrestrial surface will cross one or several of these thresholds by 2100, which calls for immediate actions to minimize the negative impacts of aridification on essential ecosystem services for the more than 2 billion people living in drylands.