Climate warming will significantly affect future restoration and level of ecosystem services in Lake Erhai

Freshwater ecosystems have been degraded under the recent impacts of global warming and human activities. Reducing external nutrient loadings is the primary strategy for restoring lake state and ecosystem services, but overlooking the impact of warming may hinder its long-term effectiveness. In order to investigate such an impact, this study simulated potential ecosystem responses between 2020 and 2050 using the PCLake model in a typical lake under restoration (Lake Erhai) in southwestern China. Calibrated based on observations from 1990 to 2020, the model could well simulate the long-term changes in Lake Erhai, including the regime shift around 2002. Under further bivariate scenarios, results of current nutrient input showed that warming above 1.2 °C would cause declines of macrophyte coverage 0–7 years in advance. In 2050, the overall change of ecosystem services would be positive if warming remains below 1.2 °C but negative if warming exceeds 2.2 °C. The above warming levels could be viewed as delineations of the safe and dangerous warming zones for ecosystem status and service in Lake Erhai under current restoration strength. The impact of warming would be more intuitive under the absence of nutrient control, i.e., both slow and fast warming would advance macrophyte decline and decrease overall ecosystem services. This study combined perspectives of regime shift and ecosystem service loss to highlight the need for climate-adaptive management, which may provide a new research paradigm to evaluate warming impacts on lake restorations beyond the study site.