Researchers from Duke University and UC Santa Barbara have explored the role of mixotrophs—unicellular organisms that can photosynthesize or consume food—in climate change. These microbes, which inhabit various ecosystems including lakes and oceans, play a dual role regarding carbon dioxide (CO2): they can either absorb or release it depending on environmental conditions. As global temperatures rise, it is projected that these organisms may reach a tipping point where they switch from carbon sinks to carbon sources, potentially exacerbating global warming. The study suggests that rising heat could push the abundance of mixotrophs toward a critical threshold, triggering a feedback loop that further increases warming.
However, the findings also offer a glimmer of hope. Monitoring fluctuations in mixotroph populations could provide early warnings of this tipping point, as significant changes in their abundance may signal impending shifts in their metabolic behavior. Nutrient pollution, particularly from agricultural runoff, could complicate these predictions by obscuring early warning signs. The study emphasizes that while the potential for runaway climate change exists, investing in early detection of these shifts could be key to mitigation efforts.
