Great Salt Lake dry-up may be increasing greenhouse gas emissions: Study

As the Great Salt Lake falls prey to human-induced drought conditions, its increasingly exposed seabed is emitting greenhouse gases and accelerating climate change, a new study has found.

About 4.1 million of such gases were released from the dried-out lake floor in 2020 alone, with carbon dioxide making up 94 percent of those emissions, according to the study, published on Thursday in One Earth.

“Human-caused desiccation of Great Salt Lake is exposing huge areas of lake bed and releasing massive quantities of greenhouse gases into the atmosphere,” lead author Soren Brothers, climate change curator at the Royal Ontario Museum, said in a statement.

“The significance of lake desiccation as a driver of climate change needs to be addressed in greater detail and considered in climate change mitigation and watershed planning,” Brothers added.

The Great Salt Lake's annual water level can vary drastically from year to year, as this threshold is largely dependent upon the volume of snowmelt that flows into the basin from the surrounding mountains, the authors noted.

Yet the ever-increasing volumes of human-related water consumption — via agriculture, industry, mining and municipal uses — are responsible for depleting the lake, according to the researchers.

Similar circumstances affect other saline basins around the world, such as the Aral Sea, Lake Urmia and the Caspian Sea — destroying critical habitats for area biodiversity, creating dust-filled air pollution and emitting carbon dioxide and methane, per the study.

To draw their conclusions, the scientists measured carbon dioxide and methane discharges in exposed Great Salt Lake sediments from April through November 2020. They then compared those results with aquatic emissions estimates, to quantify the anthropogenic influence on the greenhouse gas releases.

The 4.1 million tons of carbon dioxide and methane emitted from the lake bed in 2020 were responsible for an approximately 7-percent surge in the state of Utah's human-induced greenhouse gas emissions.

Inland lakes and seas are vital to the global carbon cycle, as they can both emit large amounts of carbon dioxide and methane to the atmosphere but also bury similar quantities of organic carbon beneath them, per the study.

Yet that carbon cycle is sensitive to human activities, the researchers warned. The seasonal desiccation — and resultant sediment exposure — of these inland carbon sinks produce what the authors described as "a blind spot in global carbon cycle assessments."

Conditions at the Great Salt Lake — the world's eighth largest salt lake — could serve as a warning for other such basins across the globe. Saline lakes, the researchers noted, are responsible for about 44 percent of the volume and 23 percent of the surface area of lakes worldwide.

"The emissions are high enough to be accounted for in regional carbon budgets and warrant efforts to halt and reverse the loss of saline lakes around the world," the authors concluded.