Climate Change Experts Tap Microbes to Protect the Planet

Climate Change Experts Tap Microbes to Protect the Planet

The Earth's climate is changing—oceans are warming, glaciers are melting and extreme weather events are increasing in frequency and intensity. These changes threaten all life, with climate change considered the “biggest health threat facing humanity” by the World Health Organization (WHO). Microbes, like humans, are not immune to these environmental changes. In fact, microbes are already adapting to a changing climate, causing serious implications for society.

Climate change can disrupt microbial community structure, perturb production of greenhouse gases and increase prevalence of plant and animal pathogens. These fluctuations can, in turn, affect food production and human health. Conversely, microbes can also be used to help mitigate the deleterious effects of climate change.

Understanding the role of microbes in climate change is therefore critical to protecting the health of the planet. Around the world, scientists from multiple disciplines, including ecology, microbial engineering and medicine, are engaging in important research and developing microbe-based techniques and frameworks to address the problem. Many of these scientists convened in Houston, Texas, at ASM Microbe 2023 to participate in a special "Climate Change and Microbes (CCM)" guest track; some of the topics discussed are highlighted below.

Climate Change and Microbes Impact Each Other

In the last 150 years, the Earth’s average global surface temperature increased at a rate “unprecedented” for at least the last 2,000 years. While human activity has been a main driver of climate change, microbes are also a major factor. As the most abundant organisms on Earth, microbes both affect, and are affected by a changing climate. Newly evolved microbial activities can lead to positive or negative feedback on climate change and its effects. Understanding this feedback will be vital to combat the harmful impacts of climate change on society.

Relevant research pertaining to microbes, climate change and society can be broken into the following main areas:

  • Microbial influences on greenhouse gases.
  • Microbial adaptation to climate change.
  • Microbes, health and the environment.

Microbial Influences on Greenhouse Gases

Greenhouse gases are atmospheric gases that emit and absorb heat—trapping it in the Earth's atmosphere and leading to global warming. Such warming makes food more perishable, diseases more prevalent and natural disasters more extreme, and thus more expensive to clean up. Microbes found in soil and aquatic environments contribute directly to the ongoing rise in greenhouse gas emissions by producing key greenhouse gases: carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O).

Diagram of microbes in aquatic and terrestrial ecosystems and the flux of CO2, CH4, and N2O in each environment caused by microbes. Microbes in aquatic and terrestrial environments produce and consume the greenhouse gases CO2, CH4 and N2O. Soil and aquatic microbes produce these gases when decomposing organic matter to provide nutrients for plants and marine life, respectively.
Source: National Library of Medicine

Methane is about 25 times more efficient at trapping heat
than carbon dioxide. This makes lowering methane concentrations in the atmosphere a faster way to slow global warming in the short term, according to Mary Ann Bruns, Ph.D., Professor of Soil Microbiology at The Pennsylvania State University. Bruns explained that understanding how microbes produce methane will aid in the development of strategies to curb emissions of this potent, heat-trapping greenhouse gas.

Cows grazing on green grass. Rumen microbes that live in livestock animals such as cows produce over 25% of human methane emissions each year. Scientists are working on compounds to reduce rumen methane production to slow global warming.
Source: Wikimedia
More than 50% of methane emissions come from human activities—especially raising livestock, such as cattle and sheep, for meat and dairy products. Bacterial, archaeal, protozoan and fungal microbes live in the animal's digestive compartment called the rumen and digest plant feedstock through fermentation. The rumen microbiome converts plant sugars into energy for the animal, producing methane as a byproduct that is released to the atmosphere through belching. In fact, rumen microbes are responsible for more than 25% of anthropogenic methane emissions.

Scientists are actively learning about the rumen microbiome and ways to control associated methane production. An international team of scientists found that feeding cows an inhibitor of a key archaeal enzyme responsible for methane formation decreased enteric methane emissions by 30%. Building on this observation, those researchers are using omics and models to reveal how the inhibitor affects the cattle microbiome. Bruns, who was not involved in these studies, noted that this information will be crucial in understanding how methanogens interact with the whole microbiome so that cattle feed can be modulated to reduce the production of methane during rumination. “Production and consumption of greenhouse gases occurring at the microbial level play a crucial role in determining ecosystem responses to climate changes caused by humans,” Bruns said. Bruns convened the CCM session at ASM Microbe 2023, “Microbial Technologies to Mitigate Methane Emissions,” to explore additional ways microbes can be used to mitigate methane emissions.

Microbial Adaptation to Climate Change

As the environment changes, so do microbes. Microbes’ fast growth rates, large population sizes and ability to share genetic information with one another allow them to adapt quickly to environmental variability. "Changes in microbial activity, diversity, community structure and interactions with other organisms are all shaped by climate change," said Mengting “Maggie” Yuan, Ph.D., Assistant Project Scientist at the University of California, Berkeley, who is studying microbial communities in soil. Yuan examines how climate warming and reduced precipitation influence relationships among grassland soil microbes. “We try to find out what factors shape the below-ground microbial food web that consumes, transports and processes photosynthetic carbon,” Yuan said. “Answers to these questions are fundamental to climate change predictions and potential solutions.”

Cut away of roots of grass. Cutaway view of roots of grass.
Source: iStock
Microbes can adapt in a multitude of ways. Bacterial respiration has been shown to increase with warmer temperatures while bacterial cell size decreases. Viruses found in cooler oceans have evolved to encode proteins related to cold shock response, allowing them to survive at lower temperatures. Warmer and drier soils, as well as warming oceans, are associated with shifts in microbial community composition, which may result in changes to carbon and nutrient cycling in those ecosystems.

Viruses that infect soil and aquatic microbes can also promote changes in microbial activity and community structure. For instance, infection of cyanobacteria by viruses called cyanophases can shut down carbon dioxide fixation during infection, which results in greater availability of greenhouse gases to enter the atmosphere. However, more research is needed to understand the full role of the virome on microbial adaptation to climate change.

Understanding how microbial fluxes of carbon and greenhouse gas emissions will change over time can help scientists predict climate change’s impacts for all society. “Microbes are small but mighty. They change the trajectories of climate,” Yuan said.

Yuan was also a presenter for the CCM session “Ecological and Evolutionary Responses of Microbial Communities to Climate Change” at ASM Microbe 2023. The session explored how grassland soil microbes are adapting to environmental change.

Microbes, Health and the Environment

Round plate of raw oysters.Consuming raw seafood contaminated with Vibrio spp., such as oysters, is a major source of vibriosis.
Source: Wikimedia
Pathogens must also adapt to a changing environment. Warmer temperatures and environmental shifts can help pathogens and vector species expand their spatial range. For example, warmer oceans at higher latitudes in the North Sea are linked to a higher incidence of infections with Vibrio spp. Vibrio are marine bacteria that live in warm and coastal waters and can cause diarrhea, nausea, vomiting, dehydration and fever when ingested with contaminated seafood. As global oceans have warmed, Vibrio spp. have expanded to these warmer waters and caused more infections in areas not previously endemic. Warmer waters are also associated with more intense hurricanes, cyclones and flooding. Such storms can lead to increased human exposure to pathogens. Warming temperatures may also select for warm-adapted fungal pathogens, such as the opportunistic fungal pathogen Candida auris.

Thus, climate change-induced environmental shifts have profound impacts on animal and plant pathogens and human health. “It is increasingly evident that if we want to advance our understanding of the microbial world, and of pathogens in particular, we need to widen our span of view to include the intersection between the environment, the animal world and humans. In this regard, climate change will obviously play a major role [in] shaping the evolution of microbial organisms in the coming years,” said José M. Munita, M.D., who specializes in infectious diseases and antimicrobial resistance at the Clinica Alemana - Universidad del Desarrollo Faculty of Medicine in Santiago, Chile, and also holds an adjunct appointment at the University of Texas Health Science Center, Houston.

Munita explores the evolution of bacterial pathogens and their mechanisms of antimicrobial resistance and offered the CCM talk “Environmental Pollution as a Driver of Evolution of Methicillin-Resistant Staphylococcus aureus (MRSA).” MRSA is a human pathogen that causes over 80,000 infections and 11,000 deaths annually in the U.S. Munita hopes his research on how climate change and natural disasters, like earthquakes, have affected the evolution of MRSA will provide clues on future pathogen evolution in a changing environment. This knowledge can then inform strategies and public health measures to contain and mitigate pathogen spread.

Microbes as Solutions for Climate Change

Though microorganisms contribute to the negative effects of climate change, they can also help mitigate its impacts. Brajesh Singh, Ph.D., Director of the Global Centre for Land-Based Innovation and Distinguished Professor at Western Sydney University, views microbes as solutions to the problem. “Growing evidence suggests that microbial tools can provide effective solutions for both mitigation and ecosystem adaptation to climate change,” Singh said. “For successful outcomes from this line of research and innovation, studying climate change at microbial levels is critical.”

Rows of plants growing out of dried soil.Rows of plants growing out of dried soil.
Source: USDA/
Singh studies how climate change affects the relationships between soil biodiversity and ecosystem functions. Soil microbes drive nutrient turnover needed for crop growth and can make crops more resilient to environmental stress. Environmental changes like drought and heat waves threaten agriculture and the entire food supply. In the CCM session “Microbes and Climate Crisis - Problems and Solutions,” Singh shared how soil microbes are impacted by climate change and the consequences for the resilience of ecosystems. Singh explained that soil microbes can be “harnessed” to make ecosystems—especially agricultural ecosystems—more resilient to the negative effects of climate change. For example, Singh reported that certain microbial communities provide protection against pathogens for plants or confer resilience to ecosystems and plant productivity after droughts.

Microbes can be harnessed as climate change solutions in other ways as well. Bruns, the Professor of Soil Microbiology at The Pennsylvania State University, highlighted that microbes that consume greenhouse gases are being investigated as solutions to counter rising emissions. Raising of livestock, manure management, rice paddies, landfills and oil and gas operations are all major sources of methane. Methanotrophs, which are bacteria and archaea that consume methane, are being investigated for their ability to reduce emissions when introduced to these methane-producing systems. By facilitating methane capture and feeding it to methanotrophs, scientists hope to reduce overall methane emissions into the atmosphere. Since methane traps radiative heat in the atmosphere better than carbon dioxide, these microbial solutions could be a way to help mitigate the impacts of global warming and climate change on society.

Join the Climate Change and Microbes Community

As experts in climate change conversations, microbiologists have an opportunity to take action on this major threat to society. ASM Microbe 2023's special CCM guest track gave scientists the opportunity to discuss and address issues at the intersection of climate change, microbiology and human health and well-being. CCM sessions explored the impacts of a changing climate on microbes and their relationships with humans and the environment to find effective solutions and inform policies to address climate change.

CCM track leader Jay T. Lennon, Ph.D., Professor of Biology at Indiana University, is optimistic for new ideas, partnerships and integration of tools aimed at microbial solutions to climate change arising from the CCM track. “This will bring together a diverse group of scientists to use microbes to address one of the most urgent, important and complex global problems.”

The CCM guest track was part of ASM’s larger Climate Change & Microbes Scientific Portfolio initiative to provide opportunities for microbiologists to contribute their expertise and knowledge to addressing climate change. Acknowledging the strong ties between climate change and microbiology, the American Academy of Microbiology—the honorific leadership group and scientific think tank of ASM—established a 5-year plan in 2019 to focus on broadening scientific understanding of climate change and microbes.

You can participate in these conversations by joining a global community to combat climate change and sign up to receive updates about the latest science and resources about climate change and microbes.

Author: Rachel Burckhardt

Rachel Burckhardt
Rachel Burckhardt is a scientific literature reviewer for ASM, where she connects scientists to the latest COVID-19 research. She earned her Ph.D. in microbiology from the University of Georgia, studying bacterial physiology and antimicrobial resistance.