Plants Are Absorbing 30% More CO2 Than Expected- Here’s What It Means for Climate Change

Of all the elements cataloged in the periodic table, carbon is the fourth most abundant element found in the universe. This is unsurprising given that carbon is essential for life on Earth, particularly due to its life-sustaining property of catenation. From the food humans eat to the DNA and proteins in their bodies, carbon is all-pervasive. Till the last century, carbon was primarily released by natural sources like venting volcanoes, decomposing vegetation, outgassing from oceans, forest wildfires, and even from the belches and poop of animals. With these sources, the balance of carbon happily stayed at or below 300 parts per million (ppm) for millions of years. However, the rising human population has led to an abrupt uptake in the carbon that has now reached close to 410 ppm.

If it weren’t for activities like burning fossil fuels, generating electricity, cattle herding, and deforestation, it would have taken thousands of years for carbon emissions to reach this level. Thankfully, nature already has a magic formula that can dramatically reduce the escalating carbon fumes in the atmosphere. In a study published in the journal Nature, researchers share how forests are remarkable “carbon sinks” that slurp down immense quantities of carbon and play a critical role in soothing global warming by lowering greenhouse gas emissions. Plus, the research showed that terrestrial plants are absorbing 31% more carbon dioxide than previously estimated.

The amount of carbon dioxide that plants absorb and wipe from the atmosphere is called “Terrestrial Gross Primary Production (GPP).” GPP is typically measured in petagrams of carbon per year, where one petagram equals one billion metric tons. During the 1980s, scientists estimated that the GPP was around 120 petagrams per year. However, in the new research, led by researchers at Cornell University with support from the Department of Energy (DOE)’s Oak Ridge National Laboratory (ORNL), researchers found that the latest estimate is about 157 petagrams per year, equivalent to the emissions of 37.36 billion international combustion vehicles. This means plants around the world are absorbing 37 billion more metric tons of carbon than previously thought.

To estimate this updated GPP, researchers employed two key approaches. Instead of monitoring satellite images which could interfere with the cloud cover, they used high-resolution data from environmental monitoring towers. Another approach they used was to measure the photosynthesis in plants by tracing the path of the molecule carbonyl sulfide (OCS). OCS follows a process similar to carbon dioxide as it travels from the air, enters the leaf tissues, and makes its way inside chloroplasts, the factories where photosynthesis happens. The researchers assured that OCS is a reliable indicator of worldwide GPP.

The team also collected data from the LeafWeb database, which contains data about photosynthesis traits observed by scientists around the world. The purpose of analyzing all this data was a better understanding and representation of “mesophyll diffusion,” the process in which OCS and CO2 move from the leaf tissues into the chloroplasts where carbon fixation occurs. “Figuring out how much CO2 plants fix each year is a conundrum that scientists have been working on for a while,” Lianhong Gu, co-author of the study and a photosynthesis expert at ORNL, said in a press release. “It’s important that we get a good handle on global GPP since that initial land carbon uptake affects the rest of our representations of Earth’s carbon cycle.”

Apart from a detailed understanding of mesophyll diffusion and carbon sequestration, the study revealed that pan-tropical forests play a significant role in guzzling down more carbon than they release into the atmosphere. Researchers believe that this refined knowledge will enable them to better predict, understand, and control climate change, while also illuminating how natural ecosystems can be cultivated as marvelous “land sinks” that sop up carbon dioxide from the air and store it in biomass or wood.