Aral Sea Drying Emitted 748 Million Tons of Carbon

The Aral Sea, once the fourth-largest inland body of water, has been largely depleted over the past 60 years due to irrigation for cotton crops, leaving behind a vast salty plain. New research published in the journal Science reveals that this ecological disaster has also become a significant driver of climate change by releasing stored carbon into the atmosphere. Lakes and other bodies of water typically act as carbon sinks, accumulating organic matter in their sediments over long periods. However, when these water bodies dry up, the trapped carbon is released, transforming them into carbon sources.

A research expedition in 2022, led by Rafael Marcé, a research scientist at the Centre for Advanced Studies in Blanes, Spain, collected sediment samples along the receding shorelines of the Aral Sea. This allowed the team to reconstruct the lake's carbon emissions as it evaporated. The findings indicate that between 1960 and 2022, the Aral Sea released an estimated 748 million metric tons of carbon dioxide into the atmosphere. This amount is equivalent to three times the annual emissions of Spain.

Marcé explained that the release of carbon dioxide is rapid initially and then slows down. Approximately half of the total carbon dioxide emissions occurred within the first 15 years after a section of the lake became exposed. The study also found that nearly one-fifth of these emissions originated from the dry, exposed lakebed. The research highlights the substantial, and previously underestimated, climate impact of large-scale water body desiccation.