Substantial increase in minimum lake surface temperatures under climate change

R Iestyn Woolway,Stephen C Maberly,Gesa A Weyhenmeyer,Christopher J Merchant,Martin Schmid,Martin T Dokulil,Elvira De Eyto,Linda May

doi:10.1007/s10584-019-02465-y

Abstract

The annual minimum of lake surface water temperature influences ecological and biogeochemical processes, but variability and change in this extreme have not been investigated. Here, we analysed observational data from eight European lakes and investigated the changes in annual minimum surface water temperature. We found that between 1973 and 2014, the annual minimum lake surface temperature has increased at an average rate of + 0.35 °C decade−1, comparable to the rate of summer average lake surface temperature change during the same period (+ 0.32 °C decade−1). Coherent responses to climatic warming are observed between the increase in annual minimum lake surface temperature and the increase in winter air temperature variations. As a result of the rapid warming of annual minimum lake surface temperatures, some of the studied lakes no longer reach important minimum surface temperature thresholds that occur in winter, with complex and significant potential implications for lakes and the ecosystem services that they provide.

Highlights

Several studies have investigated the impacts of climate change on lake surface water temperature (Livingstone 2003; O’Reilly et al 2015; Magee et al 2016)
Noteworthy are the lakes for which the number of years in which the annual minimum lake surface temperature cooled to 4 °C, near the temperature of maximum density of fresh water, has decreased (Fig. 1)
A positive least-squares trend was calculated for the annual minimum surface temperature in each lake from 1973 to 2014, the years in which all lakes had available data (Table 1)

Summary

Introduction

Several studies have investigated the impacts of climate change on lake surface water temperature (Livingstone 2003; O’Reilly et al 2015; Magee et al 2016). These have provided overwhelming evidence that lakes are warming on a global scale, with some lakes warming faster than local surface air temperatures (Austin and Colman 2007; Schneider and Hook 2010; O’Reilly et al 2015). Climatic Change (2019) 155:81–94 trends, investigating either single-point observations (Schneider and Hook 2010; O’Reilly et al 2015), lake-wide averages (Woolway and Merchant 2017) or spatially resolved temperatures from satellites (Woolway and Merchant 2018). The cold extreme of minimum lake surface temperature attained within any given year is highly pertinent to a large variety of physical, chemical and biological processes

Methods

Results

Discussion

Conclusion