Most people have no idea how many trees there are in our planet, but a new study decided to solve this mystery, revealing an estimated 3.04 trillion trees. This means there is about 400 trees for every person on Earth.
While this may sound a lot, this number doesn't necessarily translate to good news. According to the study's researchers, Earth had as twice as many trees before humans started clearing forests.
"The number of trees cut down is almost 3 trillion since the start of human civilization" according to the head of the study, Thomas Crowther, who is a postdoctoral fellow at the Yale School of Forestry & Environmental Studies. "That is an astronomical figure."
A previous estimate which was based on satellite images says that there are about 400 billion trees on the planet. A good 61 trees for every person, as compared to the 400 per person revealed in the recent study. However, this estimate had reportedly been tricky since satellites are not able to see individual trees.
According to NEPR, doubts were added as a recent estimate, which this time was based on ground-truthed measurements, revealed ther are approximately 390 billion trees just in the Amazon alone.
"Satellite images can tell you a lot about the forest area and canopy cover, but what we provide is a more detailed understanding of what is going on beneath the surface," said Crowther.
The new study was published in the journal "Nature." To come up with the estimates, the researchers incorporated satellite imagery with 429,775 tree density ground-based measurements, in which a person counts the number of trees per area, according to The Los Angeles Times.
National forest inventories were mostly the basis for the ground based data, which allowed the study's authors to track trees down from every continent, except Antarctica.
According to Crowther however, the study simply sheds light on the fact that there are half as many trees as compared to before human civilization began.
Using the same technique as when they counted the trees, the researchers also estimated how much trees the planet has lost, and is losing. They found that the Earth is losing an estimate of 15 billion trees a year, with only 5 billion being replaced.
"If you do the math the net loss is about 1/3 of a percent of all trees globally," according to Harry Glick, a post-doctoral student at Yale. "That's not insignificant."
Crowther added that another important theme discovered in the study is how humans have largely affected tree population on the planet.
"Human activity came out as the strongest control on tree density across all biomes," he said. "It really highlights how big of an impact humans are having on the Earth on a global scale."
Trees have long been used by humans for survival - for cooking, clothes-making, timber and construction, to name a few. However, it has been proven that what is more important is the indirect value of trees, which means their value while alive.
When uncut, trees are able to stabilise slopes, preventing erosion and floods. Natural dead wood debris creates dams, which in turn create other bodies of water such as ponds and lakes. As well as changing water on the ground, trees are able to alter water in the air.
Massive forests also have the ability to affect global climate. While burning fossil fuels reportedly releases approximately 32 billion tons of carbon dioxide into Earth's atmosphere per annum, trees absorb these high concentrations of CO2, which leads to quicker photosynthesis and plant growth.
The Amazon rainforest, for example, reportedly absorbs an approximate of two billion tons of carbon dioxide each year, making it an important solution to the growing problem of anthropogenic climate change.
However, it appears as if tree growth in the Amazon is halting due to progressing climate change. According to Science Codex, the mortality rates of trees in the Amazon have been predicted to climb higher largely as extreme weather ensues. This problem in the Amazon means more carbon dioxide in the atmosphere unabsorbed.
Because of the new study in the journal "Nature," perhaps the public will be provided of an improved understanding in the role that trees play for the planet's future welfare. Apart from helping create better management practices for remaining forests, perhaps the greater impact of the study would be a comprehension of how humans have great impact on the natural world.
On a lighter note, the "Nature" study has also led the "Plant for the Planet" movement to plant even more trees. From a billion trees, the group now reportedly wants to plant a trillion.
"Based on this, they really want to upscale their efforts hugely," said Crowther. "Their goal is now to plant a trillion trees."
There is hope yet.
