While there are millions of trees on our planet an accurate estimate of the precise number has never been known. That is until a recent study published in Nature revealed that there are currently over three trillion trees on Earth, which is more than seven times greater than previous estimates.
With this more accurate picture of the world’s forests, scientists will be able to improve climate research, as well as deforestation tracking.
Thomas Crowther of Yale’s School of Forestry & Environmental Studies, who was lead author of the study, was able to arrive at the new estimate by establishing a relationship between satellite imagery and first-hand tallies of trees in the areas where such records existed. From there it was simply a matter of applying this relationship to the satellite imagery for areas that have no first-hand data.
The highest areas of tree density are those of North America and Eurasia, whereas the tropics have the largest overall forested area, containing some 43% of the world’s trees. Scientists state that there are currently 46% fewer trees than when human civilization occurred, with numbers continuing to drop at a rapid rate.
The research has great potential for improved education on deforestation, which may eventually lead to better efforts to reverse it. The phenomenon has many impacts, from wildlife habitat destruction, to its effect on the water cycle. For example, the rainforests of the tropics provide about 30% of the world’s fresh water by the method of transpiration, which is the movement of water from a tree’s leaves to the atmosphere. This same mechanism also removes heat from forested areas, and transports it via the resulting water vapor.
One other effect of forests as it relates to climate change, is their function as a carbon sink, storing over two billion tons of carbon each year, according to a US Forest Service study. This is equivalent to one third of global carbon emissions. The forests may not be able to maintain their current rate of carbon absorption, however, which would cause an increase in the rate of global warming.