As the Great Salt Lake shrinks, habitats shrivel, toxic dust storms worsen and migratory birds lose a crucial food source.
Now, new research has revealed another consequence: microorganisms breaking down organic matter previously covered by water are a big source of planet-warming emissions.
The Great Salt Lake’s lakebed emitted carbon dioxide and methane that together were the equivalent of 4.1 million tons of carbon dioxide in 2020, a recently published study from Utah State University researchers found.
This is the first time that greenhouse gas emissions from the lake have been measured.
The U.S. Energy Information has reported that Utah generally emits 60 million tons of carbon dioxide per year from burning fossil fuels.
Including the lake’s emissions — which are tied to humans diverting water for farming, mining and to serve a growing population — resulted in a 7% increase to Utah’s total.
“For something that’s not even been accounted for at all in mitigation plans, it’s a really big number,” said lead author Melissa Cobo, who graduated from Utah State University with a master of science in watershed science last year.
And that figure is likely on the conservative side, said Soren Brothers, a co-author of the study who was an assistant professor and Cobo’s adviser.
Microorganisms release carbon dioxide as they feed on materials exposed as the Great Salt Lake’s lakebed dries.
And recently exposed areas emit more greenhouse gas than spots that have been uncovered for a while, Brothers said. The recent study measured emissions from areas that have been exposed for over a decade.
Since the lake is terminal — meaning that it has no outlets, like rivers, leaving it — “everything that’s flowed into that lake over the last 10,000 years or so since it’s existed has ended up on that big lake bottom,” Brothers said.
As the lakebed has been exposed to air, “it’s a huge buffet for bacteria to consume. Suddenly they have access to 10,000 years of deposited organic matter that’s been off-limits until then,” Brothers explained.
The Great Salt Lake’s water level hasn’t changed much since the data in this study was collected, and as a result, Cobo said, the lake’s annual emissions likely haven’t changed since 2020.
In 2020, the lake’s elevation ranged from about 4,192 to 4,194 feet above sea level. The lake’s elevation was measured at 4,193.7 feet above sea level as of July 27.
“It’s good that people understand that there are consequences to our actions and how we’re dealing with our waters, and this is arguably the most global of those consequences,” Brothers said about the drying lake’s contributions to global warming.
Tim Davis, Utah’s deputy Great Salt Lake commissioner, said it’s not surprising that the Great Salt Lake emits carbon dioxide as its lakebed is revealed.
“But the findings of the study reinforce the state’s goal to help the Great Salt Lake get to its healthy target range,” he said, “in order to maintain a healthy ecosystem, sustain the health of the communities around the lake, preserve the brine shrimp population and support the local economy.”