Ocean plankton microbes might become carbon emitters due to the warming climate.

New research finds that a warming climate could upend globally abundant microbial communities from carbon sinks to carbon emitters, potentially triggering tipping points in climate change. The results are published in functional ecology.

Heterotrophic microbes are organisms that can switch between photosynthesizing like plants (absorbing carbon dioxide) and eating like animals (releasing carbon dioxide). They are abundant globally, commonly found in freshwater and marine environments, and are estimated to make up the majority of marine plankton.

By developing computer simulations that modeled how heterotrophic microbes gain energy in response to rising temperatures, researchers at Duke University and UC Santa Barbara have found that, under warming conditions, heterotrophs shift from being carbon sinks to emitters of carbon.

The results mean that as temperatures rise, these extremely abundant microbial communities can change from a net cooling effect on the planet to a net warming effect.

Dr Daniel Wiczynski of Duke University and lead author of the study said: “Our findings reveal that promiscuous microbes play a more important role in ecosystem responses to climate change than previously thought. By converting microbial communities to net carbon dioxide sources in response to warming, warming can Mixed materials further accelerate warming by creating a positive feedback loop between the biosphere and the atmosphere.”

Dr. Holly Mueller of the University of California Santa Barbara and co-author of the study added, “Because hybrid cells can capture and emit carbon dioxide, they are like ‘switches’ that can help reduce or exacerbate climate change. These errors are small, but their impact can be significant.” It’s already increasing. We need models like this to understand how to do that.”

Dr. Jean-Philippe Gibert of Duke University and another co-author of the study said: “The latest predictive models for long-term climate change currently only explain microbial influence in a severely reduced, partial, or sometimes completely wrong way. Therefore, there is an urgent need for research like this.” To improve our broader understanding of the vital controls over the processes of the Earth’s atmosphere.”

early warning system

The researchers’ model also revealed that before communities of mixed-feeding microbes turn to emitting carbon dioxide, their abundances begin to fluctuate dramatically. Detecting these changes in nature by observing the abundance of mixed-feeding microbes offers hope that these microbes can act as early warning signals of tipping points in climate change.

Dr. Wieczynski said, “These microbes may act as early indicators of the catastrophic effects of rapid climate change, which is particularly important in ecosystems that are currently major carbon sinks such as peatlands, where nutrient mixes are abundant.”

However, the researchers also found that these early warning signals can be silenced by increasing nutrients such as nitrogen in the environment, which typically results from runoff from agriculture and wastewater treatment facilities.

When larger amounts of these nutrients were included in the simulations, the researchers found that the range of temperatures at which alarming fluctuations occur begins to narrow until the signal eventually disappears and the tipping point is reached without apparent warning.

“Detecting these warning signs is going to be difficult. Especially if they get more subtle with nutrient contamination.” d said “However, the implications of losing them are enormous. We could end up with ecosystems in a much less desirable state, adding greenhouse gases to the atmosphere rather than removing them.”

In the study, the researchers ran simulations using 4-degree temperatures, from 19 to 23 degrees Celsius. Global temperatures are likely to rise 1.5 degrees Celsius above pre-industrial levels over the next five years, and are on track to break two to four degrees before the end of this century.

The researchers cautioned that the mathematical modeling used in the study relied on limited empirical evidence to investigate the effects of warming on microbial communities. Dr. Wieczynski said, “Although models are powerful tools, theoretical results must ultimately be tested empirically. We strongly advocate for more experimental and observational testing of our findings.”