Researchers have found that the pause in the rate at which atmospheric carbon dioxide is growing and which the planet has been enjoying is due to plants on Earth absorbing more carbon from the air than they previously did in the last few decades.
In a study published in the journal Nature Communications, researchers led by a Lawrence Berkeley National Laboratory scientist came to the conclusion after analyzing extensive atmospheric and terrestrial carbon dioxide observations, computer modeling and satellite measurements of vegetation.
However, they want to reiterate that carbon dioxide emissions are still increasing. Atmospheric concentrations of carbon dioxide are still on the rise as well but the rate at which carbon dioxide levels increased in the atmosphere has remained steady at around 1.9 parts per million every year from 2002 to 2014.
The researchers saw that annual carbon dioxide emissions from human activity have dropped by about 20 percent but the slowdown in atmospheric carbon dioxide growth still can't keep up with the emissions' pace so overall carbon dioxide levels attributed to humans were still recorded as increasing, although not as quickly.
The study results point to plants as the reason behind the pause in the growth of atmospheric carbon dioxide, and Trevor Keenan, the study's corresponding author, said this highlights the need to not only identify ecosystems where carbon sinks are growing rapidly but to protect them as well.
Plants vs. Atmospheric Carbon Dioxide Growth
The researchers attributed the pause to a rise in land-based photosynthetic activity which rising carbon dioxide levels from fossil fuel emissions influenced. And the effects snowballed, with carbon dioxide emissions on the rise, they promoted photosynthesis, leading to plants taking in more carbon. This paved the way for more plant growth, which led to more photosynthetic activity and, consequently, more carbon uptake.
Additionally, they found that plant respiration, the process where plants produce carbon dioxide by using oxygen, also helped. Plant respiration didn't increase as fast as photosynthetic activity did in recent years, which may have been caused by the global warming slowdown recently experienced across vegetated lands.
This means that while plants did take in more carbon dioxide from 2002 to 2014 via photosynthesis, they didn't produce more carbon dioxide during respiration, which would've contributed to levels of the greenhouse gas in the atmosphere.
Climate Change Still A Problem
"Unfortunately, this increase [in carbon uptake] is nowhere near enough to stop climate change," said Keenan.
While the study offered answers, it also led to new questions, like which carbon sink is absorbing carbon dioxide the most, how long the increased uptake will last and how increased carbon uptake will affect the planet's climate in the future.