It’s hard to talk about carbon without ultimately including plants in the conversation. Even as we worry over carbon dioxide emissions from burning coal, we’re calling up the ghosts of plants that lived in the Carboniferous, whose long-fossilized remains are the materials for coal. And, given that coal energy has the “highest carbon footprint of all energy types,” which is broken down HERE, plants take center stage in figuring out how to generate the energy we want while stemming climate change.
As natural reservoirs and conduits for carbon, plants are, in fact, the problem as well as the solution. Although, from the lofty perspective of NASA’s Earth Observatory, we see most of Earth’s carbon stored in rocks, it’s the carbon moving through plants that travels on a more human timescale. The geologic erosion of rocks is the “slow cycle,” compared to the “fast cycle” of carbon taken up by plants during photosynthesis and released when plants die and decompose.
More plants means more carbon uptake and storage, thus the oversized role of tropical forests in global carbon cycles. A recent study analyzed the decline of the old-growth tropical forest “carbon sinks” (taking up more atmosphere carbon than they release). By modeling Amazon Forest regrowth after deforestation, burning, and other human disturbances, researchers found that the renewal counterbalanced only about a quarter of the carbon emitted from degradation.
"Countries have repeatedly made pledges to reduce deforestation and forest degradation and restore deforested areas… the most cost-effective and immediately available way to remove carbon from the atmosphere… Yet targets are repeatedly missed," says study author Jo House.
Deforestation not only robs valuable carbon sinks, but also affects cycling through rivers, a pathway geochemists describe as “Earth’s circulatory system,” that flushes carbon from land as plant materials are carried by wind and rain.
On the up side, this riverine pathway removes decaying debris from the forest floor, where decomposition would add carbon back to the atmosphere. On the down side, the decaying material in rivers gets eaten by microbes, emitting carbon dioxide and methane from the water surfaces.
A new study of rivers in the Andes Mountains pegged them as culprits for these two climate-warming gases. Says study author, Gonzalo Chiriboga, "We found that mountain rivers in the Andes… are hot spots for CO2 and CH4 emissions, with significantly higher flux intensities than in the lowland rivers of the central Amazon."
So, plants are central to carbon considerations, with plant scientists eager to give plants the credit they deserve at the table. A new report of “One hundred important questions facing plant science: an international perspective,” shares priorities in plant science for tackling climate change, among other topics.
In the research questions identified by panelists ranging from researchers to plant enthusiasts, climate rose to the top. Study author Sanna Sevanto emphasizes that the results offer up the, “myriad questions and technical challenges that, if solved, could sustainably support the increasing human population on a planet under climate change.”