Climate change wreaks havoc on microbial diversity

Many potential effects of climate change on humans, wildlife and plants are relatively well understood. Higher temperatures and extreme weather events can lead to food insecurity, habitat loss, and the decline or extinction of species of living things. However, it is also important to discuss how climate change can affect microorganisms or tiny living things found all over the planet that the naked eye cannot see.

Microorganisms are the earliest known life forms on Earth. They play a vital role in ecological processes such as organic matter decomposition, nutrient recycling, soil aggregation, and even pathogen control. Their abundance and diversity help maintain a stable and healthy global ecosystem. However, if microbial diversity were to change, the ability of other organisms to respond to climate change could also be affected.

A study published in Natural microbiology this month reported that long-term global warming is reducing microbial biodiversity in grassland soil. The authors conducted a seven-year experiment to observe changes in microbial communities in response to climate changes such as warming, changing precipitation, and annual biomass removal. They found that the richness of bacteria, fungi and protists decreased.

Microbial diversity is essential for maintaining soil health and quality and for achieving the function of soil as a living system that sustains biological productivity and sustains plant and animal health. Unfortunately, loss of microbial diversity is associated with loss of function. This bodes ill for humans, as it translates to reduced ability to grow crops, increased environmental damage, and reduced ability to fight off microbes and plant pathogens, says Henry Professor Martin J. Blaser Rutgers of the Human Microbiome at Rutgers University, which was not involved in the study.

To support food production for a growing human population, farmers need healthy soils. Climate change, through reduced microbial diversity, can not only affect our ability to grow food, but also cause the nutritional value of certain foods to decline, Blaser says. Indeed, microbial diversity is necessary to promote nutrient uptake and allow plants to more easily obtain essential minerals and micronutrients from the soil.

[Related: Bacteria wars are raging in soil, and it’s keeping ecosystems healthy.]

More than two billion people worldwide already suffer from micronutrient deficiencies, leading to various health problems such as cardiovascular disease, congenital disabilities and mental health problems. For example, many children in China suffer from iron and zinc deficiencies, which may stem from deficiencies of these elements in soils and foods. In 2007, about 40% of the total land area in China lacked iron and zinc.

“Human well-being is directly linked to microbes,” says Jay T. Lennon, a professor in the Department of Biology at Indiana University who was not involved in the study. “Of course, our health is intimately affected by the trillions of microbes that live on and within us. But, in nature, they also provide essential services, in terms of breaking down contaminants, purifying water and ensuring the fertility of the soil needed to feed a growing planet.

One of the essential roles of microbes is to reduce contaminant levels in crops, which is crucial because pathogen contamination of fresh produce poses a pressing threat to human health. For example, eating contaminated vegetables grown in soil amended with uncomposted animal manure can allow pathogens like Salmonella and E.coli enter the human body. Also, some plant defenses don’t work as effectively when temperatures get too high, making them more susceptible to pathogens. Overall, soil microbial diversity helps suppress soil pathogens due to the complex interactions that occur below the soil and potentially inhibit the development or persistence of pathogens.

“Scientists are concerned about how climate change will affect the distribution of diseases like cholera, but also the emergence of new pathogens,” says Lennon. “Plant and animal hosts form complex relationships with microbial symbionts. It is currently unclear how climate change will alter these relationships and what the consequences will be.

Ultimately, it is crucial to protect biological diversity — the variety of everything life on Earth – to maintain the stability of the global ecosystem. Biodiversity loss is driven by climate change, but this decline in biodiversity can also accelerate climate change, making it a positive feedback loop. For example, ecosystem instability due to biodiversity loss weakens the Earth’s ability to regulate greenhouse gas (GHG) emissions and prevent extreme weather events, which in turn alters the structures many ecosystems and makes species more vulnerable.

Since you can’t see the germs, it can be harder to protect them. Some studies show that the degree of understanding of microbial ecosystems and their services must increase to the same level of knowledge with plants and animals before they are taken seriously in conservation initiatives and policies. Yet protecting flora and fauna remains vital because as certain plants and animals disappear, the microbes associated with them may also disappear.

“In a certain way, [the] conserving plants and animals will also help maintain their associated microbiota,” says Lennon. “For example, a recent article discusses how ‘acoustic restoration’ – that is, working to restore natural soundscapes – contributes to conservation efforts, including the maintenance of ecosystems.”

Blaser says the loss of microbial diversity can also be due to the use of fertilizers, pesticides and monoculture practices. Specific solutions, such as reducing the use of chemical pesticides and crop diversification, are likely to reduce the negative impact on microbial diversity. The fight against climate change requires all kinds of attention, and the loss of biodiversity must be combated, including the living beings on which we depend and which almost never cross our minds.

Teresa H. Sadler