ALBERT

Description: Despite their importance, wetland ecosystems protected through the Ramsar Convention on Wetlands are under pressure from climate change and human activities. These drivers are altering water availability in these wetlands, changing water levels or surface extent, in some cases, beyond historical variability. Attribution of the effects of human and climate activities is usually focused on changes within the wetlands or their upstream surface and groundwater inputs. However, the reliance of wetland water availability on upwind atmospheric moisture supply is less understood. Here, we assess the vulnerability of 40 Ramsar wetland basins to precipitation changes caused by land use and hydroclimatic changes occurring in their upwind moisture-supplying regions. We use moisture flows from a Lagrangian tracking model, atmospheric reanalysis data, and historical land use change data to assess and quantify these changes. Our analyses show that historical land use change decreased precipitation and terrestrial moisture recycling in most wetland hydrological basins, accompanied by decreasing surface water availability (precipitation minus evaporation) in some wetlands. The most substantial effects on wetland water availability occurred in the tropical and subtropical regions of Central Europe and Asia. Overall, we found wetlands in Asia and South America to be especially threatened by a combination of land use change-driven effects on runoff, high terrestrial precipitation recycling, and recently decreasing surface water availability. This study stresses the need to incorporate upwind effects of land use changes in the restoration, management and conservation of the world’s wetlands.

Description: Humanity is modifying the atmospheric water cycle, via land use, climate change, air pollution, and weather modification. Given the implications of this, we present a theoretical framing of atmospheric water as an economic good. Historically, atmospheric water was tacitly considered a ‘public good’ since it was neither actively consumed (rival) nor controlled (exclusive). However, given anthropogenic changes, atmospheric water is becoming 'common-pool’ (rival, non-excludable) or 'club’ (non-rival, excludable). Moreover, advancements in weather modification presage water becoming a 'private’ good (i.e. rival, excludable). In this research, we explore the implications of different economic goods framings using story-based scenarios of human modifications of the atmospheric water cycle. We blend computational text analysis with expert perspectives to create science fiction prototypes of the future. The economic goods framing highlights that social choices play an enormous role in how the future will unfold with regard to human interaction with the atmospheric water cycle. The narrative scenarios serve two purposes. First, they provide creative artifacts for the investigation of future interactions with the atmospheric water cycle, that are rooted in a scientific evidence base. Second, they articulate trajectories of our coupled social-hydrological world that require deeper interrogation and anticipation in the present.

Description: Tree restoration is an effective way to store atmospheric carbon and mitigate climate change. However, large-scale tree-cover expansion has long been known to increase evaporation, leading to reduced local water availability and streamflow. More recent studies suggest that increased precipitation, through enhanced atmospheric moisture recycling, can offset this effect. Here we calculate how 900 million hectares of global tree restoration would impact evaporation and precipitation using an ensemble of data-driven Budyko models and the UTrack moisture recycling dataset. We show that the combined effects of directly enhanced evaporation and indirectly enhanced precipitation create complex patterns of shifting water availability. Large-scale tree-cover expansion can increase water availability by up to 6% in some regions, while decreasing it by up to 38% in others. There is a divergent impact on large river basins: some rivers could lose 6% of their streamflow due to enhanced evaporation, while for other rivers, the greater evaporation is counterbalanced by more moisture recycling. Several so-called hot spots for forest restoration could lose water, including regions that are already facing water scarcity today. Tree restoration significantly shifts terrestrial water fluxes, and we emphasize that future tree-restoration strategies should consider these hydrological effects.