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Remote sensing reveals lake response to European double heatwave

1 August 2022

Plymouth Marine Laboratory have contributed to a paper investigating lake chlorophyll-a (an indicator of algae) responses to the 2019 European double heatwave, examining seasonal growth of algae as the heatwave developed.  
Sunset over lake

Image credit: Professor Stefan Simis

The paper reveals a notable response, with chlorophyll-a increasing with temperature, while lake depth influences how quickly this process took place.  

Professor Stefan Simis, Earth Observation Scientist at PML, was part of the team who provided the chlorophyll-a data for the study through the European Space Agency (ESA) Climate Change Initiative, using satellites to map water quality in lakes and reservoirs around the world. He said:  

“Compounded weather events like heatwaves - increasingly common phenomena due to climate change - are likely to progressively impact freshwater ecosystems in the future.” 

“Lakes are expected to respond to climate change – environmental and climatic changes in the catchment basin ultimately finds its way down to lakes. We know that algae growth is often positively linked with higher temperatures, but ultimately ‘blooms’ of algae depend on nutrients washed down from land and rivers. Both the warming of water during the heatwave, and the storms that usually mark the end of heatwaves are impactful, as these bring a great deal of rain, often suddenly, and therefore nutrients into the lakes.” 

“What happens next is down to individual lake hydrology, for example, how quickly does the water mix, lake depth, lake altitude, etc. Factors that are unique to each lake.”  

“Lakes integrate responses over time, and globally distributed lakes can capture different elements of climate change. This is why we sometimes refer to lakes as ‘Sentinels of climate change’, and why consistent global observational data is so important.” 

“From the lakes studied, we can see a clear response to these heatwave events, but we need to study even longer-term series across the globe to give better predictions of the impact it may have on lake biology and people who depend on healthy waterbodies. The way our lakes have behaved in the past is no guarantee for their future, owing to climate change driving some major shifts in lake hydrology and ecology. Our models and management of lakes will  need adapting.” 

Colleagues at CNR-IREA took the lead in the study, with Plymouth Marine Laboratory contributing through the Lakes Climate Change Initiative funded by the European Space Agency

Read the full paper here >> 


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