Climate change is quietly rewriting the world’s nitrogen cycle, with high stakes for food and the environment

(Press-News.org)  

Climate change is not only warming the planet and disrupting rainfall, it is also quietly rewiring the way nitrogen moves through the world’s croplands, forests, and grasslands. This hidden shift in the global nitrogen cycle carries major consequences for food security, water quality, biodiversity, and climate policy.

Nitrogen is a basic building block of proteins and DNA, and healthy terrestrial ecosystems depend on a steady but balanced flow of nitrogen through soils, plants, and microbes. When that balance is disturbed, harvests can fall, rivers can turn green with algae, and more greenhouse gases can escape into the atmosphere.​

“In a warming world, nitrogen is becoming a make or break factor for both food security and environmental health,” said lead author Miao Zheng of Zhejiang University. “Our study shows that climate change is reshaping nitrogen cycles in ways that can either support sustainable development or push ecosystems beyond critical thresholds.”​

What the study did The new review pulls together 30 years of field experiments and global model simulations to examine how three key climate forces affect nitrogen: rising carbon dioxide, higher temperatures, and shifting rainfall patterns. It compares their impacts across croplands, forests, and grasslands worldwide, and links these changes to human goals such as ending hunger and protecting clean water.​

By translating hundreds of site level studies into a global picture, the authors quantify how nitrogen inputs, plant uptake, harvest, losses, and long term storage respond under different climate conditions. They also highlight large regional inequalities, showing that some areas may gain productivity while others face deepening risks of crop failure and pollution.​

When higher CO₂ helps and hurts The review finds that elevated atmospheric carbon dioxide can act like a double edged sword for nitrogen. On one side, higher CO₂ tends to boost plant growth and crop yields by around 10 to 27 percent in forests and grasslands, and about 21 percent for major crops such as wheat, rice, maize, and soybean.​

At the same time, plants often dilute their nitrogen content under high CO₂, which can lower the protein quality of grains and leaves. “More calories do not automatically mean better nutrition,” said co author Baojing Gu. “We may be harvesting more biomass but with less nitrogen per unit, which matters for both human diets and livestock feed.”​

Warming drives losses and inequality Rising temperatures tell a more troubling story, especially for agriculture. The study shows that warming generally reduces yields in key crops, with maize particularly vulnerable in tropical and arid regions, while also accelerating losses of reactive nitrogen compounds to the air and water.​

Warmer conditions stimulate soil microbes, speeding the breakdown of organic matter and increasing emissions of ammonia, nitrous oxide, and nitrogen oxides, as well as nitrate leaching into groundwater and rivers. These losses can worsen air pollution, fuel climate warming, and degrade water quality, while disproportionately harming developing regions in Africa, Latin America, and Asia.​

Too little or too much rain Changes in rainfall patterns further complicate the picture. In dry regions, modest increases in precipitation can strongly boost plant growth and nitrogen uptake, while in wetter regions, droughts can cause large drops in productivity and nitrogen harvest.​

The review reports that decreased rainfall tends to suppress microbial activity and reduce many nitrogen losses, effectively trapping more nitrogen in soils. In contrast, heavy and frequent rainfall can flush nitrate into waterways and enhance gaseous nitrogen emissions, raising the risk of algal blooms and greenhouse gas release.​

A call for integrated nitrogen management Overall, the study concludes that climate change is amplifying spatial inequalities in how nitrogen cycles operate and in who bears the risks. Regions already facing food insecurity and weak environmental protections are likely to experience the most damaging combinations of yield loss, nutrient stress, and pollution.​

To respond, the authors call for integrated nitrogen management that links fertilizer practices, water management, climate policy, and biodiversity goals. Promising examples include pairing rainwater harvesting with organic amendments in African smallholder systems, and planting nitrogen fixing tree species in tropical forests to maintain natural nitrogen inputs.​

“We need to move beyond treating nitrogen as just a farm input and start governing it as a global commons,” said Zheng. “If we manage nitrogen wisely under climate change, we can support zero hunger, protect clean water, and limit greenhouse gas emissions at the same time.”​

The authors argue that nitrogen must be more fully integrated into international climate and sustainability frameworks, including the Paris Agreement and national climate pledges. With climate change accelerating, they stress that coordinated global action on nitrogen is essential to keep both people and ecosystems within safe operating limits.​

 

=== 

Journal Reference: Zheng M, Huang Q, Cui J, Gu B. 2025. Impacts of climate change on global terrestrial nitrogen cycles. Nitrogen Cycling 1: e012  

https://www.maxapress.com/article/doi/10.48130/nc-0025-0012  

=== 

About Nitrogen Cycling:
Nitrogen Cycling (e-ISSN 3069-8111) is a multidisciplinary platform for communicating advances in fundamental and applied research on the nitrogen cycle. It is dedicated to serving as an innovative, efficient, and professional platform for researchers in the field of nitrogen cycling worldwide to deliver findings from this rapidly expanding field of science.

Follow us on Facebook, X, and Bluesky. 

END