Plankton can go from sink to carbon emitter due to climate

June 1 () –

climate warming can turn the world’s most abundant microbial communities from carbon sinks to carbon emitters, triggering tipping points.

the new studio, published in ‘Functional Ecology’reveals that in a warmer climate, oceanic plankton and other single-celled organisms, known as mixotrophic microbes, can switch from being carbon sinks to carbon emitters.

The research also concludes that changes in the behavior of these organisms just before they change may act as an early warning signal for climate change tipping points.

However, increasing levels of nutrients in the environment, such as nitrogen from agricultural runoff, you can silence these warning signs.

Mixotrophic microbes are organisms that can alternate between photosynthesising like plants (absorb carbon dioxide) and feeding like animals (releasing carbon dioxide). They are abundant throughout the world, found in fresh and marine waters, and are estimated to make up the majority of marine plankton.

Researchers at Duke University and the University of California at Santa Barbara have developed a computer simulation that shows how mixotroph microbes acquire energy in response to heating and have discovered that, under heated conditions, mixotrophic microbes go from being carbon sinks to carbon emitters.

This means that as temperatures rise, these abundant microbial communities could shift from having a net cooling effect on the planet to having a net warming effect.

Dr. Daniel Wieczynski, from Duke University and lead author of the study, notes that these findings “reveal that mixotrophic microbes are much larger players than previously thought in ecosystem responses to climate change. By converting communities microbials in net sources of carbon dioxide in response to warming, mixotrophs could further accelerate warming by creating a positive feedback loop between the biosphere and the atmosphere”Add.

Study co-author Dr. Holly Moeller of the University of California, Santa Barbara adds, “Because mixotrophs can both capture and emit carbon dioxide, they are like ‘switches’ that could help slow climate change or make it worse. These critters are tiny but its impact can be very great. We need models like this to understand how“, it states.

For his part, Dr. Jean-Philippe Gibert, from Duke University and another co-author of the study, explains that “currently, the most advanced models for predicting long-term climate change only take into account microbial action in an extremely reductive, biased, or sometimes erroneous way. Research like this is therefore much needed to improve our overall understanding of biotic controls over Earth’s atmospheric processes.”

The researchers’ modeling also revealed that just before communities of mixotrophic microbes switch to emitting carbon dioxide, their abundance begins to fluctuate wildly. These changes could be detected in nature by monitoring the abundance of mixotrophic microbes. and offers hope that these microbes could act as early warning signals of climate change tipping points.

Wieczynski notes that “these microbes could act as early indicators of the catastrophic effects of rapid climate change, which is especially important in ecosystems that are currently large carbon sinks, such as peatlands, where mixotrophs are highly abundant.”

However, the researchers also discovered that these early warning signals can be silenced by increases in nutrients such as nitrogen in the environment, typically caused by runoff from agriculture and sewage treatment facilities.

When higher amounts of these nutrients were included in the simulations, the researchers found that the range of temperatures in which the telltale fluctuations occurred began to narrow until eventually the signal disappeared and the tipping point arrived with no apparent warning.

“Detecting these warning signs is going to be quite a challenge. Especially if they become more subtle with nutrient contamination,” says Dr. Moeller. “However, the consequences of not detecting them are enormous. We could end up with ecosystems in a much less desirable state, adding greenhouse gases to the atmosphere instead of removing them.

In the study, the researchers ran simulations using a 4 degree temperature range, from 19 to 23 degrees Celsius. Global temperatures are likely to rise 1.5 degrees Celsius above pre-industrial levels in the next five years and to exceed 2 to 4 degrees Celsius before the end of the century.

Thus, they warn that the mathematical modeling used in the study is based on limited empirical evidence. to investigate the effects of warming on microbial communities.

“Although models are powerful tools, theoretical results must ultimately be tested empirically,” Wieczynski said. “We strongly advocate further experimental and observational testing of our results.”