SEESAW

Team: Larisa Tarasowa, Mariana de Brito, Daniel Doktor, Emanuele Bevacqua

Aims & Content

Climate change is already exacerbating hydroclimatic extremes worldwide, disrupting socio-environmental systems and threatening sustainable development. For instance, complex and cascading extremes such as hot-dry conditions in Germany in 2018, spatially extended droughts in Europe in 2022, and rapid transition from drought to floods in Germany in 2021 caused severe socio-economic damages and widespread deterioration of ecosystems. Such high-impact complex extremes also jeopardise ecosystem services, such as biodiversity, carbon sequestration and climate regulation, and hence threaten the multifunctionality of our landscapes. The currently dominating perspective on single hazards fails to account for the interactions between complex hydroclimatic extremes and their impacts. This potentially leads to maladaptation that worsens future impacts. With advancing climate change, the frequency and intensity of many hydroclimatic extremes will likely increase.

However, our current understanding of the interplay between climate change, society and the complex dynamics of such events is still limited. Compound, complex extremes occur when multiple drivers and/or hazards combine, often producing more severe impacts. Compounding hot-dry hazards can quickly lead to soil moisture deficits, greatly affecting agricultural productivity and causing crop failures. Long-lasting and spatially extensive droughts can lead to water deficit propagation to deep subsurfaces, causing forest die-offs. The socio-economic
impacts of the rapid hazard cascades, such as drought-to-flood transitions, are challenging to cope with due to the additional vulnerability of the exposed communities.

The SEESAW Cohort will combine new national text-based datasets, hydrometric observations, remote sensing products with climate simulation, as well as data-driven tools to identify the hotspots of high-impact extremes. This will provide an opportunity to move from local scales and singular events to comprehensive impact assessment of hydroclimatic extremes at large scales. With the unique combination oftools and datasets we will be able to disentangle complex interactions between (multiple) hazards and impacts, and assess the effects of human-induced climate change on these extremes. Therefore, the outcomes of the SEESAW will generate a solid basis for comprehensive adaptation policies in Germany.