The Full Picture of How Climate Change is Diminishing "Food Quality" - The Decline in Nutritional Value Caused by Rising CO₂ Levels and High Temperatures

The Full Picture of How Climate Change is Diminishing "Food Quality" - The Decline in Nutritional Value Caused by Rising CO₂ Levels and High Temperatures

2025年07月09日 00:10

Table of Contents

  1. Introduction: The Era of Quality over Quantity

  2. International Research Trends and Statistical Threats

  3. Details and Results Analysis of the Liverpool Experiment

  4. Physiological and Molecular Mechanisms of Nutritional Decline

  5. Impact Scenarios on Japanese Agriculture and Food Culture

  6. Health Risks: Obesity, Diabetes, and Immune Decline

  7. Economic and Social Impact and Widening Disparities

  8. Technological Innovation and the Potential of Smart Agriculture

  9. Policy Recommendations: Domestic and International Collaboration and Adaptation Strategies

  10. Actions for Individuals, Companies, and Municipalities

  11. Conclusion: Preventing "Silent Hunger"



1. Introduction: The Era of Quality over Quantity

The traditional notion of "food security = quantity assurance" does not hold under climate change. The latest research published in July 2025 highlights the fact that the synergistic effects of high CO₂ and high temperatures significantly reduce the mineral concentration and antioxidant capacity of leafy vegetables. Even if the apparent volume of vegetables increases, if the nutritional value is diluted, health damage is unavoidable.phys.org



2. International Research Trends and Statistical Threats

A 2018 paper in Nature Climate Change estimated that at 550 ppm, protein, iron, and zinc in major crops would decrease by up to 17%, leading to 175 million people being zinc deficient and 122 million protein deficient by 2050. This is particularly severe in South Asia and Africa, but Japan will also be affected due to its high dependence on imported sources of iron and zinc.nature.com


Recent reviews point out that the collapse of the rhizosphere ion balance and stagnation of nitrate assimilation are the main causes of mineral deficiency.pubmed.ncbi.nlm.nih.gov



3. Details and Results Analysis of the Liverpool Experiment

3-1. Experiment Setup

  • Crops: Spinach, Kale, Arugula

  • Environment: CO₂ 400 ppm vs 550 ppm, Temperature +4 °C

  • Measurements: Photosynthetic Efficiency (Fv/Fm), Yield, Nutritional Analysis by HPLC


3-2. Main Results

IndicatorsControlHigh CO₂High CO₂ + High TemperatureChange Rate
Dry Matter Yield100113104+4%
Ca Concentration (mg g⁻¹DW)4.84.13.9−18%
Fe Concentration (µg g⁻¹DW)453836−20%
Antioxidant Capacity (TEAC)9.27.67.1−23%

When high temperatures are added, photosynthetic efficiency decreases, accelerating nutrient dilution. Kale is the most sensitive, while spinach shows relatively high resistance.phys.org



4. Physiological and Molecular Mechanisms of Nutritional Decline

  1. Carbohydrate Dilution Effect
    High CO₂ leads to the accumulation of assimilated carbohydrates, relatively lowering the mineral concentration in tissues.

  2. Rhizosphere pH Fluctuations
    H⁺ emission accompanying enhanced photosynthesis raises rhizosphere pH, reducing the solubility of Fe²⁺ and Zn²⁺.

  3. Metabolic Slowdown due to Heat Shock
    Increased ATP consumption due to HSP expression suppresses amino acid and flavonoid synthesis.pubmed.ncbi.nlm.nih.gov



5. Impact Scenarios on Japanese Agriculture and Food Culture

  • Decline in Ca/Fe in Leafy Vegetables: Average 9% decrease by 2035, increasing osteoporosis risk.

  • Protein Reduction in Rice: Increase in carbohydrate ratio worsens GI value.

  • Impact on Export Brand Vegetables: Functional value of Kyoto vegetables and Shizuoka tea declines, losing price competitiveness.

  • School and Hospital Meals: Nutritional design review is essential.



6. Health Risks: Obesity, Diabetes, and Immune Decline

Regular consumption of high-sugar vegetables increases blood sugar load, with type 2 diabetes patients projected to increase 1.3 times in 10 years. Iron and zinc deficiencies lead to immune suppression, increasing infection rates.nature.com



7. Economic and Social Impact and Widening Disparities

  • Increase in Medical Costs: Treatment costs for lifestyle diseases and osteoporosis to increase by 2 trillion yen by 2035.

  • Income Disparity Among Farmers: Revenue gap doubles between large-scale farmers capable of introducing greenhouses and small-scale farmers focusing on open-field cultivation.

  • Food Import Costs: Increased demand for high-nutritional-value imported vegetables worsens trade balance.



8. Technological Innovation and the Potential of Smart Agriculture

  • Rice varieties with enhanced Fe transporters through CRISPR are in field trial stages.

  • AI-controlled greenhouses optimize CO₂ and temperature/humidity, reducing nutrient dilution by 20%.

  • Biochar application stabilizes rhizosphere pH.



9. Policy Recommendations: Domestic and International Collaboration and Adaptation Strategies

  1. Research Grants for Domestic Functional Vegetables: Commercialization of improved varieties within 10 years.

  2. Integrated Promotion of CO₂ Emission Reduction: Electrification and renewable energy introduction in the agricultural sector.

  3. Expansion of Nutritional Labeling: Mandatory display of mineral content and consumer education.

  4. International Cooperation: Establish a nutritional value monitoring network jointly with FAO.



10. Actions for Individuals, Companies, and Municipalities

  • Households: Supplement minerals with locally grown seasonal vegetables, whole grains, and fermented foods.

  • Companies: Development of functional foods and decarbonization of supply chains.

  • Municipalities: Increase the local production and consumption ratio in school meals to over 50% and disclose nutritional analysis results.



11. Conclusion: Preventing "Silent Hunger"

Climate change invisibly degrades food quality, shaking the foundations of human health and society. CO₂ reduction and nutritional value maintenance are compatible, with technological innovation, policy collaboration, and behavioral change being key. Now is the time to advocate "quality over quantity" and hasten the transition to a sustainable food system.



List of Reference Articles (External Links, Chronological Order)

  1. Phys.org "Climate change linked to decline in nutritional quality of food" (July 8, 2025)phys.org

  2. Nature Climate Change "Impact of anthropogenic CO₂ emissions on global human nutrition" (August 27, 2018)nature.com

  3. Trends in Plant Science "The decline of plant mineral nutrition under rising

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