Warming climate could turn ocean plankton microbes into carbon emitters

According to recent findings, a rising climate might cause plentiful microbial populations worldwide to switch from being carbon sinks to emitters, potentially reaching climate change tipping points. Functional Ecology has reported the findings.

bacteria that can flip between feeding like animals and photosynthesizing like plants to release carbon dioxide are known as mixotrophic bacteria. They are thought to make up the bulk of marine plankton and are widely distributed around the world. They are also frequently found in freshwater and marine habitats.

Researchers from Duke University and the University of California Santa Barbara discovered that under warming conditions, mixotrophic microbes change from being carbon sinks to carbon emitters by creating a computer simulation that modeled how they acquire energy in response to warming.

According to the findings, these extremely numerous microbial communities may start to have a net warming impact instead of a net cooling effect on the globe as temperatures rise.

Our results show mixotrophic bacteria are far more important participants in ecosystem responses to climate change than previously anticipated, according to main author Dr. Daniel Wieczynski of Duke University. Mixotrophs might speed up warming by establishing a positive feedback loop between the biosphere and the atmosphere by transforming microbial populations into net carbon dioxide sources in response to warming.

Co-author of the study and University of California Santa Barbara professor Dr. Holly Moeller stated, "Mixotrophs are like'switches' that might either assist slow down or accelerate climate change since they can both collect and emit carbon dioxide. Despite being small, these bugs may have significant effects. Such models are necessary for us to comprehend how.

The study's co-author and Duke University's Dr. Jean-Philippe Gibert stated, "State-of-the-art prediction models of long-term climate change now only account for microbial activity in a very reductive, incomplete, or even downright incorrect manner. Therefore, further study like this is required to expand our knowledge of the biotic influences on Earth's atmospheric processes.

A warning mechanism

The mixotrophic microbe communities' abundance begins to vary drastically just before they start producing carbon dioxide, according to the researchers' model. It gives optimism that mixotrophic bacteria may serve as early warning systems for tipping points in climate change since these changes might be observed in nature by observing the abundance of these microbes.

According to Dr. Wieczynski, "These microbes may act as early indicators of the catastrophic effects of rapid climate change, which is especially important in ecosystems that are currently major carbon sinks like peatlands, where mixotrophs are highly abundant."

However, the researchers also discovered that nutrient additions to the environment, often brought on by runoff from agricultural and wastewater treatment plants, might mask these early warning signs.

Higher concentrations of these nutrients were shown to have an adverse effect on the temperature range across which the telltale variations occur. Eventually, the signal vanishes and the tipping point arises without any prior warning, the researchers discovered.

It will be difficult to recognize these warning indications. especially if the nutrient poisoning is becoming increasingly subtle. Dr. Moeller said. The consequences of missing them, nevertheless, are severe. Ecosystems can end up in a considerably less favorable state as a result of adding greenhouse gases to the atmosphere rather than eliminating them.

Simulated temperatures ranging from 19 to 23 degrees Celsius, a 4-degree range, were used in the study. Within the next five years, the average global temperature is projected to rise by 1.5 degrees Celsius above pre-industrial levels, and by the end of the century, it is expected to have exceeded 2 to 4 degrees.

The study's mathematical modeling, which looked at how warming affects microbial populations, is based, the researchers warn, on scant empirical data. Although models are effective tools, theoretical conclusions must finally be confirmed empirically, according to Dr. Wieczynski. We fervently urge more experimental and observational testing of our findings.