Why do plants love CO2 but environmentalists don’t?
Yeah… late night sustainability discussions can take a weird turn
As the building block of all life on Earth, carbon is important to plants, animals, and fungi to survive and reproduce. All living organisms are part of the Carbon Cycle, which is the exchange of carbon molecules between Earth’s biological, hydrological, and geological spheres.
Carbon is not inherently bad. Yet excessive amounts of carbon in the atmosphere have played a large role in anthropogenic climate change. The global average atmospheric carbon dioxide level is over 400 parts per million. A number that is growing every day we continue to pollute.
One of the first things young environmentalists hear as a solution to climate change is to plant a tree. Trees sequester carbon from the air as they perform photosynthesis. It is a common misconception that we can plant enough trees to reduce our carbon emissions, which is untrue.
But, some individuals like to point out that increased carbon emissions in the atmosphere have benefited crop growth around the world through a process called carbon fertilization.
Carbon fertilization
A team of scientists from eight countries studied satellite imagery over a thirty-five-year period to see if the earth is becoming greener. Scientists found significant greening, which they could attribute to increased carbon levels.
About 70% of the effect was caused by carbon dioxide, and about 9% was from nitrogen. Increased carbon dioxide in the air facilitated more plant growth, both in number and in size. As carbon is an ingredient in photosynthesis, increasing the amount of carbon dioxide available to plants thus drives more growth.
Carbon fertilization is a term used by some to find a benefit to climate change. The carbon fertilization effect has contributed to increased agricultural productivity. Warming temperatures have increased growing seasons in higher latitudes.
What seems beneficial is actually naïve, as these “positive” effects are not guaranteed under climate change, and maybe rendered null as other effects come. There is also some evidence that plants may acclimate to the amount of carbon dioxide in their vicinity, negating the effects of carbon fertilization.
Carbon fertilization vs Climate change
Increased carbon can lead to increased plant growth, but this effect will not continue indefinitely. Both agricultural and wild plants will be affected by climate change in other ways, cancelling out any benefits of carbon fertilization.
Climate change affects plant growth in a wide range of ways. Increased floods, droughts, and wildfires can devastate natural habitats and cropland. As natural habitats are destroyed to create cropland, biodiversity is lost, creating unstable plant communities more susceptible to disease and blight. Increased temperatures and changes in weather patterns dictate where plants can grow in the future.
Desertification threatens millions of square kilometers around the world. The world’s most productive agricultural lands are suffering, and the carbon fertilization effect cannot offset that.
Different plants use carbon dioxide differently. C3 plants’ growth is limited by carbon availability, meaning these plants see the greatest effects of carbon fertilization. Other plants, called C4 plants, use atmospheric carbon dioxide more efficiently. Their growth is not as determined by carbon levels, and they are not as affected by carbon fertilization.
Maize, sugarcane, sorghum, and millet are C4 plants, so they do not reap the benefits of increased carbon levels in the same way other plants do. Carbon fertilization seems of significant benefit to plant life on earth, yet it is much more complicated than that.
Plants are carbon sinks because they can absorb and hold large amounts of carbon for extended periods. Forests, grasslands, and aquatic plants can remove carbon from the air at large rates, which helps mitigate the effects of anthropogenic carbon emissions.
However, plants cannot sequester all the carbon we emit. Estimates place forests as absorbing a net 7.6 billion metric tonnes of carbon dioxide per year. In 2019, humans emitted over 36 billion metric tons of carbon dioxide, meaning our forests only captured about 21% of those emissions.
We cannot rely on plants to capture our emissions, especially as we degrade and destroy forests for agriculture and human development. Destroying forests emits carbon too, and if we lose our most productive carbon sinks, we will only see the effects of climate change sooner.
Carbon fertilization technology
Some innovators have looked at carbon fertilization as a possible tool in food production. Instead of relying on natural carbon levels, some farmers have looked to direct carbon to their crops in hopes of increased productivity. GreenCap Solutions has created a Direct Air Capture (DAC) system that pulls carbon dioxide from the air and channels it into a greenhouse.
By increasing CO2 levels in the greenhouse, farmers can see increased growth in their plants while decreasing carbon levels in the surrounding air. Norway’s largest tomato producer, Lauvsnes Gartneri, has deployed the use of this technology at their farm. GreenCap Solutions claims that there will be a 40% increase in tomato production under this DAC system.
Systems like GreenCap’s allow plants to use carbon more efficiently, as they are doused in higher densities of carbon than they would be in normal circumstances.
Conclusion
Without carbon, life on earth would look much different. For millennia, a healthy carbon cycle has allowed plants and animals to thrive, but humans have thrown the cycle out of balance.
While it remains true that plants love carbon dioxide, as they need it to live, the excessive carbon in the atmosphere is not creating a paradise for plants. Carbon fertilization occurs with higher levels of carbon dioxide, but the negative effects of anthropogenic climate change are much more detrimental to plant life.
Plants are great carbon sinks, but as we force more carbon into the air, it will only continue to hurt the natural world.
References
- https://www.nasa.gov/feature/goddard/2016/carbon-dioxide-fertilization-greening-earth
- https://ageconsearch.umn.edu/record/179109/
- https://www.usda.gov/oce/energy-and-environment/food-security
- https://www.wri.org/insights/forests-absorb-twice-much-carbon-they-emit-each-year
- https://ourworldindata.org/co2-emissions
- https://greencap-solutions.com/norwegian-grower-first-to-apply-environment-control-system/
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