Carbon dioxide in Earth's atmosphere is increasing as climate change continues. Now, scientists have found that this excess carbon dioxide fertilization is actually greening our planet.
Green leaves use energy from sunlight through photosynthesis. More specifically, leaves combine carbon dioxide drawn in from the air with water and nutrients tapped from the ground to produce sugars with the help of sunlight. These sugars are the main food source for planets, and while previous studies have shown that more carbon dioxide can increase plant growth, researchers haven't looked at how excess carbon dioxide may be impacting the amount of plant growth globally.
In the latest study, the researchers used satellite data from NASA's Moderate Resolution Imaging Spectrometer and the National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer instruments in order to figure out the leaf area index, or amount of leaf cover, over the planet's vegetated regions. This, in particular, allowed them to see how "green" specific regions were.
So, what did they find? It turns out that carbon dioxide accounts for about 70 percent of the greening effect. Not only that, but about 85 percent of Earth's ice-free lands is covered by vegetation. In all, the area covered by all of the green leaves on Earth is equal to 32 percent of the planet's total surface area, which includes oceans, lands and permanent ice sheets.
Rising carbon dioxide concentrations in the air can be beneficial for plants. However, this is also the main reason for climate change. In addition, the beneficial impacts of the gas on plants may be limited.
The results show that carbon dioxide levels could be greening plants around Earth. Since 10 billion tons of carbon is emitted into the atmosphere every year from human activities, it's likely that we'll continue to see the gas' influence on plants globally.
With that said, it's important to note that there's only so many benefits from rising carbon dioxide levels. Instead, we're more likely to see a point at which the carbon dioxide ceases to cause more plant growth and the negatives of excess carbon dioxide outweigh the positives for plants.
The findings were published in the April 25 issue of the journal Nature Climate Change.