There are a lot of trees to hug on planet Earth, if you are so inclined. In fact new research has estimated there are currently 3 trillion all up, significantly more than previously thought. Source: Sydney Morning Herald
But despite the seemingly high numbers, researchers behind the new estimate have also found that humans are removing 15 billion trees a year from the planet.
And overall the study – which was published in the journal Nature – also concludes that since the start of human civilisation the total number of trees on Earth has crashed by 46%.
Scientists who collaborated on the new global tree estimate spanned 15 countries, and were led by researchers at Yale University in the US.
“[Trees] store huge amounts of carbon, are essential for the cycling of nutrients, for water and air quality, and for countless human services,” said lead researcher, Thomas Crowther, in a statement released by Yale.
“Yet you ask people to estimate, within an order of magnitude, how many trees there are and they don’t know where to begin.
“I don’t know what I would have guessed, but I was certainly surprised to find that we were talking about trillions.”
The paper says the previous estimate of total global tree numbers had been about 400 billion, a figure generated in 2008 using satellite imagery and global estimates of forest coverage.
But that number was later thrown into doubt after further work in 2013 found almost the same number of trees in the Amazon basin alone.
The new research came to the much higher estimate of 3.04 trillion by also incorporating information from 430,000 global on-ground surveys measuring tree density in different types of forests into modelling, along with satellite and other data.
The paper’s findings mean whereas previously it was thought there were 61 trees for each of the 7.2 billion humans on the planet, it could actually be more like 422.
The boreal forests in sub-artic regions of Russia, Scandinavia and North America were found to be the most tree-dense.
But the tropics were home to the most trees – 43%.
By making what the researchers describe as the most comprehensive assessment global trees numbers, they were also able to make an estimate of what has being lost.
“We’ve nearly halved the number of trees on the planet, and we’ve seen the impacts on climate and human health as a result,” Dr Crowther said.
“This study highlights how much more effort is needed if we are to restore healthy forests worldwide.”
Global deforestation has long been a major concern of conservationists due to the impacts it has on animal species, land and water quality.
Those concerns have been emphasised in recent decades because of the contribution the problem makes to climate change, with deforestation responsible for about 15% of global emissions on some estimates, though these can be highly uncertain.
Global Forest Watch project, lead by the World Resources Institute, released new data finding that the world lost more than 18 million hectares of forest cover in 2014, an area twice the size of Portugal. Over half of this occurred in tropical countries.
