Active wildfire seasons are 'dimming the lights' for some Northern California lakes

Thick smoke from large fires can lead to lower water temperatures and decreased oxygen for wildlife in those waters.

Thick smoke from large fires can lead to lower water temperatures and decreased oxygen for wildlife in those waters.

FOR LOOKING FOR ANSWERS. ON AVERAGE, CALIFORNIA IS SEEING MORE DAYS WITH WILDFIRE SMOKE EACH YEAR, AND ON THOSE DAYS, SMOKE IS COVERING A LARGER AREA. THIS IS PART OF A GLOBAL TREND AS RISING TEMPERATURES AND CHANGING RAIN PATTERNS CREATE MORE DRY WILDLAND FUELS. WILDFIRE HOURS HAVE BEEN INCREASING AROUND THE WORLD. THEY GENERATE MORE AND MORE SMOKE. UM, BUT WHAT WE REALIZED WAS THAT WE DON’T ACTUALLY KNOW WHAT THE SMOKE DOES TO THE ECOSYSTEM IS. THAT WAS DOCTOR ADRIAN SMITH’S PART OF A TEAM OF UC DAVIS SCIENTISTS THAT HAS BEEN STUDYING HOW WILDFIRE SMOKE AFFECTS SEVERAL LAKES IN CALIFORNIA. THEY INCLUDE LAKE TAHOE, EMERALD LAKE, CLEAR LAKE, CASTLE LAKE, AS WELL AS A CLUSTER OF SMALLER LAKES IN THE SEQUOIA NATIONAL FOREST. SMITH SAYS THERE WERE NOTABLE CHANGES IN THESE LAKES DURING THE STATE’S BIGGEST WILDFIRE YEARS, SPECIFICALLY 2018, 2020 AND 2021. THE MAIN AND OBVIOUS EFFECT WAS THAT SMOKE IS ESSENTIALLY DIMMING THE LIGHTS, SO IT’S BLOCKING, ON AVERAGE, ABOUT 20% OF THE SOLAR RADIATION HITTING THE LAKE SURFACE, LESS SUNLIGHT CAN LEAD TO LOWER WATER TEMPERATURES, LOW ALGAL ACTIVITY, AND LOWER LEVELS OF OXYGEN IN THE WATER. ALL OF THOSE FACTORS CAN CHANGE THE WAY A LAKE’S ECOSYSTEM OPERATES, AND EACH LAKE SYSTEM MAY REACT DIFFERENTLY. WE DON’T HAVE THE ANSWER YET FOR WHAT IT’S DOING IN EVERY SINGLE LAKE, BUT IT’S SOMETHING WE SHOULD PAY ATTENTION TO. RESEARCHERS WILL BE ANALYZING DATA FROM THE PAST TWO YEARS, WHICH OF COURSE HAVE BEEN FAR LESS SMOKY COMPARED TO 2020 AND 2021. SMITH SAYS. THIS COULD HELP ANSWER SOME QUESTIONS ABOUT POTENTIAL LONG TERM IMPACTS OF EXCEPTIONALLY ACTIVE FIRE SEASONS. BACK TO YOU. RESEARCHERS HAVE BEEN TRACKING THE CLARITY OF LAKE TAHOE FOR DECADES. SMOKEY YEARS DO IMPACT THE CLARITY AS DO VERY WET WINTERS, SCIENTISTS BELIEVE MICROORGANISMS IN THE WATER CAN HELP CLEAN THE LAKE WITH TIME, RESTORING THE CLARITY. WE SAW THAT LAST

Active wildfire seasons are 'dimming the lights' for some Northern California lakes

Thick smoke from large fires can lead to lower water temperatures and decreased oxygen for wildlife in those waters.

California's most active wildfire years may be "dimming the lights" for some of the state's freshwater habitats. A recent study from UC Davis examined three of California's biggest wildfire seasons: 2018, 2020 and 2021. During each of those years, smoke was persistent and widespread. In some cases, lakes experienced a month of high density smoke conditions. “There’s a lot of research on impacts to human health but not much on impacts to ecosystem health,” said Dr. Adrianne Smits, an aquatic systems ecologist at UC Davis. Smits and her fellow UC Davis scientists are changing that. The group has a network of sensors set up in several lake habitats around California. They include Lake Tahoe, Emerald Lake, Clear Lake, Castle Lake as well as a group of smaller lakes in the Sequoia National Forest. "We had everything from Lake Tahoe, kind of our clearest, coldest lake, all the way to Clear Lake in the coast range, which is quite murky and has a lot of algal growth and is pretty warm," Smits said. Each lake responds a bit differently to wildfire smoke, but Smits said there were similarities across the data. Most notably, water temperatures tended to be lower during years with the most persistent and thick wildfire smoke. This is due to smoke particles in the air blocking sunlight from reaching the water, essentially "dimming the lights." Those temperature changes can be connected to changes in algal productivity and oxygen content in the water. The smoke itself can also lower the clarity of each lake's water. All of this can disrupt the balance of each lake system, but it's not yet clear if that would be brief or could linger long term."We don’t have the answer yet for what smoke is doing in every single lake but we should pay attention to it," Smits said. A connection to climate changeAround the world, wildfire seasons are becoming longer with the risk for large wildfires increasing. This trend is connected to rising global temperatures and changing precipitation patterns, both of which are combining to increase the amount of wildland fuels. There will still be years with less wildfire activity. California has seen proof of this during the past few years. More than 4 million acres burned throughout the state in 2020. In 2021, over 2 million acres burned. But during the last two wildfire seasons, under 400,000 acres burned. Smits said that her team has gathered data from these lower smoke years, t0o. That will be analyzed to see how well lake ecosystems can recover. Historical data in Lake Tahoe shows that that system has seen rebounds in water clarity in the past. See more coverage of top California stories here | Download our app.

California's most active wildfire years may be "dimming the lights" for some of the state's freshwater habitats.

A recent study from UC Davis examined three of California's biggest wildfire seasons: 2018, 2020 and 2021. During each of those years, smoke was persistent and widespread. In some cases, lakes experienced a month of high density smoke conditions.

“There’s a lot of research on impacts to human health but not much on impacts to ecosystem health,” said Dr. Adrianne Smits, an aquatic systems ecologist at UC Davis.

Smits and her fellow UC Davis scientists are changing that. The group has a network of sensors set up in several lake habitats around California. They include Lake Tahoe, Emerald Lake, Clear Lake, Castle Lake as well as a group of smaller lakes in the Sequoia National Forest.

"We had everything from Lake Tahoe, kind of our clearest, coldest lake, all the way to Clear Lake in the coast range, which is quite murky and has a lot of algal growth and is pretty warm," Smits said.

Each lake responds a bit differently to wildfire smoke, but Smits said there were similarities across the data. Most notably, water temperatures tended to be lower during years with the most persistent and thick wildfire smoke. This is due to smoke particles in the air blocking sunlight from reaching the water, essentially "dimming the lights."

Those temperature changes can be connected to changes in algal productivity and oxygen content in the water. The smoke itself can also lower the clarity of each lake's water. All of this can disrupt the balance of each lake system, but it's not yet clear if that would be brief or could linger long term.

"We don’t have the answer yet for what smoke is doing in every single lake but we should pay attention to it," Smits said.

A connection to climate change

Around the world, wildfire seasons are becoming longer with the risk for large wildfires increasing. This trend is connected to rising global temperatures and changing precipitation patterns, both of which are combining to increase the amount of wildland fuels.

There will still be years with less wildfire activity. California has seen proof of this during the past few years. More than 4 million acres burned throughout the state in 2020. In 2021, over 2 million acres burned. But during the last two wildfire seasons, under 400,000 acres burned.

Smits said that her team has gathered data from these lower smoke years, t0o. That will be analyzed to see how well lake ecosystems can recover.

Historical data in Lake Tahoe shows that that system has seen rebounds in water clarity in the past.

See more coverage of top California stories here | Download our app.

Active wildfire seasons are 'dimming the lights' for some Northern California lakes

Thick smoke from large fires can lead to lower water temperatures and decreased oxygen for wildlife in those waters.

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A connection to climate change

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