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In the era of climate change, how will life evolve to a rapidly fluctuating environment? More importantly, will humans be quick enough to adapt? These questions are on the minds of many, as the negative impacts of climate change, like abnormal weather patterns, rising temperatures, increased storms and flooding become more apparent. Climate change influences every living organism on Earth, from humans to the tiny zooxanthellae algae residing in coral reefs. Yet this is not the first time the planet has changed—somehow, some viruses, bacteria and archaea have persisted through extreme and changing conditions for over 3 billion years.

"For a complex problem like climate change, we need to think different. We may need novel approaches, new tools and unconventional mindsets,” - Arturo Casadevall, M.D., Ph.D., Chair of Academy Governors

With smaller genomes and rapid reproduction cycles, microscopic life forms often have a major advantage over more complicated organisms when it comes to adapting to novel environments, from deep-sea hydrothermal vents to glacial ice. The organisms that survive in these extreme environments are often capable of performing biochemical reactions—making or breaking minerals, transforming elements from one form into another and producing compounds—that dramatically alter the microbe’s immediate surroundings and impact the entire planet.

“Microbes have been living in our planet for billions of years and have persisted through many planetary changes,” said Gemma Reguera, Ph.D., Academy fellow and editor-in-chief of Applied and Environmental Microbiology. “Something that amazes me is that microbes always figure out a way to adapt. And despite all the changes that we are introducing in our planet, microbes persist and even manage to grow.”

While some microbes are beneficial to curbing climate change—serving as major drivers of elemental cycles (i.e. carbon, nitrogen and phosphorus) or consuming greenhouse gases, like methane and carbon dioxide—others may contribute to rises in methane, carbon dioxide or nitrous oxide in the environment. Even less desirable, some pathogenic bacteria, fungi and viruses are finding ways to thrive in new environments under changing climate conditions.

Reguera said she hopes the lessons learned from both beneficial and harmful microbes may serve as hope for the future. “Learning about how they grow is very important because the collective activity of these microbes is actually transforming the Earth,” she said. “By learning [from them], we can harness those activities to address sustainability issues.”

“The new Academy colloquium report reiterates that in the quest to find solutions for climate change, humans have new opportunities to use microbes to their benefit,” said Nguyen K. Nguyen, Ph.D., Director of the American Academy of Microbiology, the honorific leadership group and scientific think tank of ASM.

We Can Explore Alternative Fuel Sources

Microbes are adept at utilizing various compounds and methods as energy sources. In fact, microbes are responsible for the majority of photosynthesis on Earth, a process that removes carbon from the atmosphere and generates oxygen as a byproduct. Studying chemoautotrophs that utilize methane, and other harmful greenhouse gases, as energy sources may also provide insight into how humanity can imitate these processes to find alternative uses for carbon emissions.

Microorganisms have been harnessed to produce biofuels like bioethanol, biodiesel and methane, from waste byproducts of agricultural and industry sectors. Through microbial energy conversion technology, microorganisms convert chemical energy in the biomass of raw organic materials to chemical energy in the form of ethanol or hydrogen. In addition, microbes can convert solar energy to hydrogen, which can be burned to make electrical energy or, in the case of internal combustion engines, kinetic energy to power a car.

Another technology that falls under the heading of microbial energy conversion is the microbial fuel cell, a bioreactor in which bacteria transform the chemical energy in biomass directly to electrical energy. For example, scientists have engaged in numerous collaborations that resulted in Saccharomyces cerevisiae yeast that can effectively produce cellulosic ethanol. Similarly, research has shown Arctic algae, grown in cold temperatures, using only light, carbon dioxide and a few minerals, can be broken down to produce biodiesel and bioethanol for use as fuel in many different internal combustion engines. “Microbe-driven energy sources can provide a greener and more sustainable alternative to fossil fuels,” the Academy report states.

We Can Take a Global Approach

Some of the most common disease-causing microbes are successful because they have adapted to thrive at human body or host temperatures. As the climate warms, areas once too cold to support these microbes, or their vectors, become hospitable alternatives. Warmer environments may also select for pathogens that can better survive at normal and elevated body temperatures, making them more difficult for the host to clear, as is the case with warm-adapted Candida auris. Animal and plant pathogens can also be devastating to wildlife or crop species that lack acquired immune responses to foreign microbes. For example, dengue virus, the causative agent of dengue fever, a mosquito-borne disease usually seen only in tropical areas, has been observed north of its usual range, including in the United States. Similarly, extreme weather events like hurricanes, floods and wildfires may further affect microbial distribution by disturbing and transporting organisms previously dormant in the soil or ice.

Climate changes affect multiple types of habitats and associated ecosystem functions. Changes in seasonality have resulted in more frequent and longer harmful algae bloom “red tide” events in coastal communities during the summer months, as well as an increase in reported vibriosis cases, caused by the marine bacterium Vibrio spp. The overgrowth of cyanobacteria, photosynthetic bacteria found in warm, nutrient-rich environments, including freshwater sources of drinking water, results in concentrations of toxins that are harmful to the environment and people. Even in cold, glacial environments, increased microbial activity may further contribute to feedback loops that trap solar radiation and allow increased microbial growth.

We Can Work Together

Climate change further impacts communities and ecosystems by creating conditions intolerable for native microbes. Coral reefs, which are important sources of food, income and coastal protection for millions of people worldwide, rely on symbiotic microbial communities composed in part of photosynthetic algae. Corals tend to eject their symbionts under warming temperature and increased ocean acidification, triggering a change in the coral microbiome, making the organism less resilient to disease and leading to coral bleaching. Ongoing research suggests transplanting symbionts from more heat-resistant corals could transfer heat resistance to more vulnerable individuals. Understanding the factors that make one coral microbiome more resilient than another could provide clues into saving these ecosystems.

The soil microbiome is an integral determinant of the impact climate change will have on agriculture and feeding a growing global population. Microbes in the soil decompose decayed organic plant matter into fuel and carbon for the below rhizosphere, in which many plant roots derive their essential nutrients. The Food and Agriculture Organization (FAO) predicts that due to human activity and climate change, soil erosion could result in between 20-80% losses in agricultural yields. To address this, scientists are making use of the natural ability of some microbes to sequester carbon and investigating the use of microbial interventions to regenerate soil or provide enhanced resilience to plants. When applied to soil, for instance, some fungi can help plants enhance their drought resistance, which is important in a time of increasing aridification. Bacterial treatments were also able to increase plant tolerance to heat stress by reducing reactive oxygen species, boosting plant immunity and assisting with drought stress.

Seed coating is an effective delivery method for many beneficial microbes and has been shown to boost plant health. Some research indicates can adapt to warming temperatures and provide plants more nutrients as plants increase the rate of photosynthesis because of rising carbon concentrations (though only to a limited extent). Plant growth–promoting rhizobacteria, nitrogen-fixing bacteria and mycorrhizal fungi are valuable facilitators of ecosystem change and may help to restore degraded lands.

We Can Clean Up After Ourselves

Microbes play important roles in agriculture and the environment by breaking down organic waste. For centuries, microbial communities have cleaned water in wastewater treatment facilities. Recent research has demonstrated that these decomposition abilities extend to toxic substances, explosive materials and even plastics. Many microbes have the similar abilities to “fix” carbon or nitrogen, transforming the unusable substances into a usable form.

The ocean and the soil, both home to vast microbial communities, are by no coincidence where most carbon transformations on Earth take place. Low-oxygen zones in the ocean inhabit methane-producing archaea that generate energy by transforming methane and sulfate to carbonate and sulfide. Other anaerobic microbes in the surrounding environment consume much of this methane, preventing it from reaching the atmosphere. On land, scientists from the U.K. recently developed a way to convert atmospheric CO₂ using engineered Escherichia coli. Likewise, a study following the Deepwater Horizon oil spill suggested the promising potential of “oil-eating” microbial communities to degrade the complex hydrocarbon mixture petroleum.

The Climate Future

Many experts working with microbes share a similar outlook: regardless of how the climate changes, microbes are nearly guaranteed to adapt to survive. Although humans do not have the same capabilities as microbes with regards to physiology, replication rate and adaptability, society can learn from their example and adapt to the changing environment. The scientific community is working to understand microbes’ methods of survival and adaptation to prepare all life on the planet for inevitable climate change impacts.

Over the next 5 years, the Academy will focus on promoting the understanding of the relationship between microbes and climate change and building a scientific framework to inform climate change policies and market innovations. “Calculus was invented out of necessity to help address complex physics problems and transform our lives. For a complex problem like climate change, we need to think different. We may need novel approaches, new tools, and unconventional mindsets,” said Arturo Casadevall, M.D., Ph.D., Chair of Academy Governors and a member of the steering committee that organized the colloquium.

The microbial sciences can provide valuable insight in various areas where adaptation will be required, from developing alternative fuels to preventing the spread of pathogens. "By working together with microbes, humans can learn how to adapt to a changing climate and build a healthier, more sustainable and resilient future," the report concluded.