CO2 Sustains Greenhouse Farming Revolution

By Vijay Jayaraj

The world would be safer if industrial emissions of carbon dioxide (CO₂) were stopped, according to the teachings of many schools, the regulatory schemes of some governments and the hyperbolic public relations campaigns of a climate industrial complex. But the truth is happier: CO₂ is an irreplaceable plant food that is increasing.

Carbon dioxide – the gas branded as public enemy number one – is not destroying the planet. It’s enhancing life on it. Across the globe, elevated CO₂ levels are supercharging plant growth and delivering bountiful crop harvests at unprecedented rates. 

Why does this matter? Because future generations could benefit from rejecting the hysteria and embracing common sense and well-established facts.

Since the start of the 20th century, atmospheric CO₂ has risen from around 300 parts per million (ppm) to over 420 ppm. If you believe some headlines, this is tantamount to a death sentence. But if you’re a farmer – or a scientist focused on plant physiology – this increase looks like a gift. 

Studies show that crops such as tomatoes, cucumbers, lettuce and grains grow faster and yield more under higher CO₂ concentrations. This phenomena has been verified by observations of plants in the world at large and in controlled environments over many decades. 

People taking advantage of this knowledge have contributed to an agricultural revolution. From Israel’s Negev Desert to Kenya’s Rift Valley, farmers are proving that CO₂ is not a villain but an ally in feeding a growing population. 

Greenhouse Boom: Food Where There Was None 

Greenhouse farming employs tent-like structures with controlled environments to grow crops. Unlike open-field agriculture, which is susceptible to the risks of weather and pests, greenhouses provide stable ecosystems that extend growing seasons and manage lighting and temperature. In addition, greenhouses can artificially elevate CO₂ to levels two or three time higher than ambient atmospheric concentrations. 

These farmers achieve what nature cannot – predictable, abundant harvests in deserts, tundra and urban sprawl. The benefits include lower water use, reduced reliance on pesticides, year-round production and higher yields.

In a study, researchers assessed the proliferation of greenhouse farming in 119 countries, including 22 in Africa. Greenhouses now cover more than 5,000 square miles of land worldwide, 40 times the agricultural area under cover four decades ago.

China has 60% of the world’s greenhouse farms. Some of the largest are in Weifang, China, (82,155 hectares) and Almeria, Spain (35,117 hectares). 

CO₂-enriched greenhouses now supply a significant portion of urban vegetable demand in China, a country once plagued by food shortages and famine. “Rice, cucumbers, eggplants, and tomatoes provide off-season supply to the whole country,” says Chinese researcher Xiaoye Tong.

In the Hotan Prefecture of the Xinjiang desert, farmers grow tomatoes, cucumbers, and melons in greenhouses having CO₂ levels up to 1,200 ppm, triple the outdoor concentration. 

Greenhouses in this region have enabled the development of fast-breeding rice, reducing the growth cycle to just 75 days by leveraging vertical soil-less cultivation and artificial light control. The Desert Greenhouse Project in Xinjiang’s Shawan Oasis has over 2,100 units that can produce annually about 19,000 tons of vegetables and fruits in more than 30 varieties. 

“The rate of expansion is the most dramatic in China, but the increase is a global phenomenon,” says Tong. For example, India’s greenhouse horticultural sector is growing by more than 6% annually. India’s government is fueling this growth through subsidies under the National Horticulture Mission, which covers up to 50% of setup costs. 

The Metrolina Greenhouses in Huntersville, North Carolina, consists of 8 million square feet of heated indoor growing space, making it the largest single-site, heated greenhouse in the U.S.

In Spain, Novagric built the largest single-module greenhouses that cultivate high-yield tomato plants. Production rose from 21 kilograms of tomatoes per square meter to a record 30 kilograms of cherry tomatoes, and the yield is expected to continue rising. 

You don’t need a Ph.D. to see through the haze. Ask yourself: If CO₂ is so harmful, why do farmers pump it into greenhouses? Why are crop yields breaking records as CO₂ levels rise? The answers are in biology, not ideology.

Plants evolved when CO₂ levels were five times higher than today. CO₂ emissions from the burning of fossil fuels are restoring the carbon dioxide that was removed from the atmosphere when coal, oil and natural gas were formed from the remains of flora and fauna in swamps and seas millions of years ago. A deficiency of atmospheric carbon dioxide is being rectified.

In the meantime, greenhouse farming, fueled by this life-giving molecule, will be part of a promising future free of hunger.

Vijay Jayaraj is a Science and Research Associate at the CO₂ Coalition, Fairfax, Virginia. He holds an M.S. in environmental sciences from the University of East Anglia and a postgraduate degree in energy management from Robert Gordon University, both in the U.K., and a bachelor’s in engineering from Anna University, India.