A high level of carbon dioxide in the atmosphere poses a double risk to food safety and to the global climate. A study coordinated by the Catalonia Centre for Ecological Research and Forestry Practices (CREAF) found that elevated CO2 reduces the availability of soil phosphorus by more than 20 percent, which can limit nutrient supply to crops such as rice.
The findings come from two pioneering experiments that examined rice fields under elevated CO2 conditions. The research, published in Nature Geoscience, involved scientists from Australia, Spain, Canada, the United States, France and China.
The article warns of a potential widespread drop in rice yields, a scenario that would disproportionately affect low income nations and exacerbate global economic inequality through both CO2 emissions and shifts in geochemical processes.
The results indicate that 55 percent of large paddy fields in China and India could face higher yield risk due to phosphorus limitations. In comparison, many low income countries beyond these giants, especially in Southeast Asia, Central America, South America, Africa, and the Middle East, may experience more acute impacts. About 70 percent of paddy fields could face increased harvest risk, versus 52 percent in higher income regions.
The researchers note a paradox: while atmospheric CO2 provides carbon for crop growth in the short term, its sustained elevation eventually reduces soil phosphorus availability, limiting plant metabolism over time.
Phosphorus remains a critical mineral for plant growth in agricultural soils. CREAF and CSIC scientist Josep Peñuelas remarked that crops may benefit briefly from higher CO2, but in the long run rice plants suffer as phosphorus becomes scarcer and soils poorer, ultimately hindering growth.
This dynamic threatens global food security as world population rises and rice plays a central role in many diets.
A global challenge
Phosphorus fertilizer is unevenly distributed and largely derived from rock phosphate, a non-renewable resource. About 70 percent of the world’s reserves are located in Morocco and Western Sahara, with many nations relying on imports to meet demand. If the deficit persists, agricultural yields in several regions may be restricted. The situation could worsen as atmospheric CO2 advances and continues to limit phosphorus availability.
This situation represents a significant international sociopolitical challenge for access to a mineral with fertilizing power. Peñuelas notes that the difficulty of supplying phosphorus to farms in lower income countries is evident and worrying. During the 2007–2008 global food crisis, phosphate rock and fertilizer prices surged by roughly 400 percent within 14 months, a pattern echoed in 2022, underscoring the link between price volatility and instability in vulnerable economies.
As a way forward, the scientific team recommends urgent planning of international phosphorus management strategies that anticipate future global changes.
Intensive fertilization, a questioned alternative
Pushing for heavy fertilizer use to compensate for long term phosphorus declines may seem appealing to boost production, but it carries drawbacks that must be weighed.
Over-fertilization tends to concentrate in wealthier regions that can absorb the costs, especially parts of Europe, North America, and portions of Southeast Asia.
In addition, excess phosphorus in soils can be washed away by rain, eroding soil nutrients and contributing to eutrophication. Elevated levels in rivers and coastal waters fuel harmful algal blooms, fish dieoffs, and the creation of dead zones in estuaries.
Two long term rice-focused experiments used Free Air CO2 Enrichment technology to raise atmospheric CO2 and observe biosphere responses. FACE experiments are costly and challenging to maintain, making decade-long studies rare and highly valuable for understanding real-world impacts.
Reference work: Nature Geoscience article cited by researchers in the United States, Europe, and Asia.
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The environmental department notes that the situation calls for coordinated action and open dialogue among researchers, policymakers, and communities to manage phosphorus resources responsibly.