A new study published in Proceedings of the National Academy of Sciences by researchers from the University of Rochester has uncovered a crucial mechanism behind methane production in the open ocean—one that could strengthen global warming as temperatures rise.
Led by Thomas Weber, along with Shengyu Wang and Hairong Xu, the team found that certain ocean bacteria produce methane when breaking down organic matter—but only under conditions where phosphate, a key nutrient, is scarce.
Methane, a highly potent greenhouse gas, has long puzzled scientists because it is consistently released from oxygen-rich surface waters, despite traditionally being linked to oxygen-poor environments like wetlands. This study helps resolve that paradox by identifying nutrient limitation—not oxygen levels—as the key trigger.
“This means phosphate scarcity acts as the primary control for methane production in the open ocean,” Weber explained.
The implications go beyond explaining current ocean processes. As climate change warms the oceans, it reduces vertical mixing between surface and deep waters. This limits the upward flow of nutrients like phosphate, making surface waters increasingly nutrient-starved—ideal conditions for methane-producing microbes.
The result could be a dangerous feedback loop: warmer oceans lead to more methane emissions, which in turn accelerate warming.
Crucially, this mechanism is not yet accounted for in most climate models. The findings suggest that microscopic ocean processes could have large-scale impacts on future climate projections, highlighting the need to incorporate such feedbacks for more accurate predictions.
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