New Soil Warming Study Challenges Climate Change Predictions

For decades, scientists have studied how rising temperatures might influence the amount of carbon dioxide emitted from soil. Soil stores a large amount of carbon, and understanding this process is essential for predicting future climate changes. A recent study has found that warming soil alone does not always lead to increased CO₂ emissions. Instead, higher emissions occur only when warming happens alongside more carbon and nutrients and phosphorous in the soil.

The study explores how nature manages the balance between carbon stored in soil and carbon released into the atmosphere. It was published in the journal Biogeochemistry.

Why Soil Matters for Carbon

Soil contains tiny living organisms such as bacteria, fungi, viruses, and others that release carbon dioxide through their metabolic processes, similar to how humans breathe. These microbes break down dead plants and organic matter, producing carbon dioxide as part of their life activities.

Dr Debjani Sihi, the lead researcher from North Carolina State University, and her team found that warming the soil by itself did not automatically cause high CO₂ emissions. If the soil lacked carbon and nutrients that microbes could easily use, the extra heat had little impact.

More Than Just Heat

The researchers also tested adding nutrients and warming the soil at the same time. Surprisingly, this still did not increase CO₂ emissions. The critical factor was the presence of“available carbon,” i.e., simple forms of carbon that microbes can quickly process. Only when the soil was warmed and had this accessible carbon, did CO₂ levels rise significantly.

This means that microbes require both energy and nutrients to grow and release more carbon dioxide when temperatures increase. Without these, warming the soil alone will not lead to higher emissions of carbon dioxide.

A Different Climate, A Different Story

Previous studies focused on colder regions, such as the Arctic or northern forests. Scientists believed that small temperature increases in these cold areas might lead to significant changes in carbon release. But this study examined soil from a subtropical region: Athens, Georgia. This site has one of the longest-running soil-warming experiments in the world. The land was once used for cotton farming but has since transformed into a forest.

Cotton farming tends to deplete the soil of nutrients and organic carbon, making it less fertile. The soil is considered unhealthy due to this lack of nutrients and carbon. The researchers collected this soil and warmed it by up to 2.5 degrees Celsius in a lab. They then studied how carbon moved through different parts of the soil, such as plant remains and microbes.

How Microbes Use Carbon

Microbes need carbon not only for energy but also to build their cells and enzymes. Dr Sihi compared their needs to our own. She explained that microbes need a balanced diet with energy, protein, and fibre, the same way humans need a balanced diet. They need carbon for energy and nutrients for growth.

When microbes consume carbon, some of it is used to build their cells, some to create enzymes that help break down complex materials, and the rest is released as carbon dioxide.

Since nature both releases and absorbs carbon, understanding how much CO₂ comes from soil helps scientists track the overall carbon cycle. This knowledge is important for figuring out how much human activities and industries need to reduce their emissions.

Why This Matters

Understanding how soil response to warming is crucial for scientists to predict the future of climate change. If warming alone does not cause soil to release more CO₂ without enough carbon and nutrients, then maintaining healthy soil with plenty of organic matter could be an important strategy for controlling carbon emissions.

MENAFN18092025007385015968ID1110078173