Wildfire smoke is sticking around for longer in California, impacting lake ecosystems

As large wildfires stick around for longer periods of the year in California, so does the smoke they emit. New research from UC Davis says that’s impacting lake ecosystems. 

The study analyzed the effects of lingering wildfire smoke on 10 lakes located throughout California. It focused particularly on big wildfire years — 2018, 2020 and 2021. Its authors say that during those years, the lakes they looked at experienced an average of 33 days of high-density smoke coverage between July and October. 

“California no longer just has smoke events,” said Adrianne Smits, the study’s lead author and a research scientist at UC Davis. “We really have a smoke season.” 

Smits said this can impact the way lake ecosystems operate. The study found that smoke coverage blocked about 20% of the sunlight hitting the lakes the researchers studied. This cooled lake temperatures and impacted how ecosystems functioned. 

“The photosynthesis performed by things like algae and phytoplankton in many cases decreased substantially during those smoky periods,” she said. 

It wasn’t always like this. Growing up in California, Smits said she remembers seeing a lot less smoke during the hotter months. 

The data from this study only affirmed that: Both the time smoke lingers and the space it covers has increased in California between 2006 and 2022. During the big wildfire years of 2020 and 2021, the study reports that as much as 70% of California was covered in smoke for parts of the year. 

Right now, there’s not a lot of research on the topic of how wildfire smoke impacts ecosystems like those present in lakes. As big wildfires become more frequent in California, Smits said more research will be necessary to understand why some lakes may see more severe impacts than others and the extent of those impacts.