Presenting Juã and Rômulo, two young men who show that environmental services are the consequence of good agriculture.
It’s a simple question: how many trees are there on Earth? The answer required 421,529 measurements from fifty countries on six continents. Now this new data has been combined to produce a stunning visualisation of our planet as you’ve never seen it before. Find the full paper on mapping tree density here: http://www.nature.com/doifinder/10.10…
There are roughly 3 trillion trees on Earth — more than seven times the number previously estimated — according to a tally1 by an international team of scientists. The study also finds that human activity is detrimental to tree abundance worldwide. Around 15 billion trees are cut down each year, the researchers estimate; since the onset of agriculture about 12,000 years ago, the number of trees worldwide has dropped by 46%.
“The scale of human impact is astonishing,” says Thomas Crowther, an ecologist now at the Netherlands Institute of Ecology in Wageningen who led the study while at Yale University in New Haven, Connecticut. “Obviously we expected humans would have a prominent role, but I didn’t expect that it would come out as the as the strongest control on tree density.”
The previously accepted estimate of the world’s tree population, about 400 billion, was based mostly on satellite imagery. Although remote imaging reveals a lot about where forests are, it does not provide the same level of resolution that a person counting trunks would achieve.
Crowther and his colleagues merged these approaches by first gathering data for every continent except Antarctica from various existing ground-based counts covering about 430,000 hectares. These counts allowed them to improve tree-density estimates from satellite imagery. Then the researchers applied those density estimates to areas that lack good ground inventories. For example, survey data from forests in Canada and northern Europe were used to revise estimates from satellite imagery for similar forests in remote parts of Russia.
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Originally published on the Nature website.
The global extent and distribution of forest trees is central to our understanding of the terrestrial biosphere. We provide the first spatially continuous map of forest tree density at a global scale. This map reveals that the global number of trees is approximately 3.04 trillion, an order of magnitude higher than the previous estimate. Of these trees, approximately 1.30 trillion exist in tropical and subtropical forests, with 0.74 trillion in boreal regions and 0.66 trillion in temperate regions. Biome-level trends in tree density demonstrate the importance of climate and topography in controlling local tree densities at finer scales, as well as the overwhelming effect of humans across most of the world. Based on our projected tree densities, we estimate that over 15 billion trees are cut down each year, and the global number of trees has fallen by approximately 46% since the start of human civilization.
Click here to read the full paper.
Originally published on the Nature website.
Felix Finkbeiner is a young man in a hurry to get the world to plant trees. The 19-year-old from a small Bavarian village near Munich, now studying at a university in London, has founded a global youth movement, Plant For The Planet, which has spearheaded the planting of over 15 billion saplings, signed up 75,000 children as climate ambassadors.
Alongside setting up Change Chocolate, a successful fair-trade chocolate company to raise money, the tall, spectacled teenager has joined with three of the world’s biggest conservation charities to launch the most ambitious reforestation project in history.
Each mature tree absorbs about 22 pounds of carbon dioxide per year, Finkbeiner says, “so one trillion could capture 25 percent of all human-made CO2 emissions and help to keep global temperature rise below the crucial 2-degree C limit. It does not replace the need to avoid carbon emissions, as agreed in Paris, but is a necessary addition.”
Finkbeiner thinks big. He has spoken at the United Nations and European Parliament, and reels off numbers like the politicians, who he says have mostly failed to act.
No one paid him much attention back in 2008, when, at age 9 and inspired by Kenyan Nobel Peace Prize winner and tree-planter Wangari Maathai, he announced at his primary school assembly that he intended to get children to plant 1 million trees in every country.