FUTURE OXYGEN DYNAMICS IN DIVERSE GLOBAL LAKES

The long-term impacts of climate change on lakes worldwide are expected to significantly alter both water quantity and quality, leading to changes in thermal regimes, ecosystem functioning, habitats, and biogeochemical cycling. While recent advances in global-scale models have projected rising surface water temperatures and extended stratification periods, these models often overlook key aspects of water quality and are limited by their focus on single mechanistic approaches, leading to uncertainties. Additionally, most existing ecological models lack the transferability needed for global-scale applications, as they are tailored to specific lake systems. In this study we use a multi-model approach in which three lake models were forced by five different climate model projections to simulate future changes in the stratification duration and hypolimnion temperature patterns of 73 lakes (2015 – 2100) under three Shared Socioeconomic Pathway (SSP) scenarios: SSP1-2.6, 3-7.0, and 5-8.5 using data from the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP). We apply a deep-water dissolved oxygen (DO) depletion model, projecting future hypolimnion DO concentrations at the end of summer stratification for the 73 lakes. Our projections quantify future declining DO levels, especially under SSP-3.70 and 5.85, on a global scale due to rising hypolimnion temperatures affecting depletion rates and longer stratification periods. Mitigation strategies should be considered to preserve ecosystem functioning.

Presentation Preference: Oral

Primary Presenter: Lipa Nkwalale, Helmholtz Center for Environmental Research (lipa.nkwalale@ufz.de)

Authors:

Lipa Nkwalale, Helmholtz Center for Environmental Research - UFZ  (lipa.nkwalale@ufz.de)

Karsten Rinke, Helmholtz Center for Environmental Research - UFZ  (karsten.rinke@ufz.de)

Johannes Feldbauer, Technische Universität Dresden  (johannes.feldbauer@tu-dresden.de)

Jorrit Mesman, Uppsala University  (jorrit.mesman@ebc.uu.se)

Tuba Bucak, Aarhus University  (tbo@ecos.au.dk)

Tom Shatwell, Technische Hochschule Ostwestfalen-Lippe  (tom.shatwell@th-owl.de)

Daniel Mercado-Bettin, Centre for Advanced Studies of Blanes - Spanish National Research Council (CEAB - CSIC),  (daniel.mercado@ceab.csic.es)

Robert Ladwig, Aarhus University  (rladwig@ecos.au.dk)