Scientists ‘find’ over two trillion new trees

There are likely to be eight times more trees in the world than we previously thought, according to a new study. When they can be so wrong, should we trust in the statistics we read?

The Taiga forest stretches across the northern hemisphere just south of the Arctic, through Alaska, Canada, Scandinavia and Russia. Within its vast bounds, there is a tree for every square metre: it has a denser population of trees than anywhere else in the world.

A new study from Yale University now suggests that they are part of a global population of just over three trillion, meaning there are more trees on earth than stars in the Milky Way. Almost half of the trees are in the tropical regions. Russia is the country with the highest tree population (642 billion), followed by Canada, Brazil and the United States.

The scientists who conducted the study did not count every tree in the world, but they did undertake a painstaking two-year process. They first counted the number of trees in some wooded areas and compared them with satellite images. They then used the comparison to make overall projections based on satellite pictures from around the world. It allowed them to create the first map which fully covers the tree density on the entire planet.

Their results suggest that there are 422 trees for each person. They also imply that the previous best estimate — that there were 400 billion trees — was wildly incorrect. But some experts have responded to the new study by suggesting that it also remains subject to a vast margin of error, saying that it is reliant upon information mainly gathered in Europe and North America. And scientists now face the challenge of finding out where particular species tend to be represented and how particular forest types evolve.

The study also provides the human race with some awkward reminders of our impact upon global tree numbers. Since man began using agriculture around 12,000 years ago, the tree population has fallen by 46%. The researchers say man now cuts down 15 billion trees per year, and may only plant five billion. Dr Thomas Crowther, the ecologist who led the research, says the scale of human impact on deforestation is ‘astonishing’.

And others attack the way statistics are interpreted. ‘Bad Science’ writer Ben Goldacre says that numbers are frequently abused by those wishing to prove themselves right. There are lies, damned lies and statistics.


Management consultancy firm McKinsey has the unofficial motto: ‘Everything can be measured, and what is measured can be managed’. We should seek to measure as many things as we can; doing so will inevitably bring progress.

But some commentators question our level of attachment to data. Margaret Wheatley calls measurement a ‘false god’ which now dominates our lives to an unhealthy extent. Finding out exactly how many trees exist in the world is not a priority.

You Decide

  1. Do you think this estimate is accurate?
  2. Are we too attached to measurable data?


  1. Estimate the number of trees in your school grounds (or in a similar area). Then count the number in a small area and make a new estimate of the total. Finally, count how many trees there really are in total.
  2. List the things which matter to you that are quantifiable (can be counted) and those that are not. Discuss with a partner: could you quantify the items in the second list? Would you want to?

Some People Say...

“All statistics are lies.”

What do you think?

Q & A

Are trees useful?
Trees are vital to our planet’s ecosystems — many animals use them as habitats. They also convert carbon dioxide into oxygen, making them a crucial factor in the fight against climate change, and provide material for products such as paper, furniture and housing. They also have lesser-known benefits: for example, they are a source of L-Dopa, a chemical which helps to treat Parkinson’s Disease.
How can I help to tackle deforestation?
The Woodland Trust is keen to encourage people to plant trees, and there is information about them in the links under Become An Expert. Otherwise you can help to deal with the problem by limiting the amount of rubbish you throw away. The average UK family throws away six trees’ worth of paper in their household bin each year.

Word Watch

Three trillion
A trillion is one thousand billion. The number contains twelve zeroes when written out.
Tropical regions
The scientists said that 1.39 trillion trees are in the tropics and sub-tropics. They believe that 0.61 trillion are in temperate regions (between the tropics and the poles) and 0.74 trillion in the boreal forests of the Taiga.
Margin of error
Dr Martin Lukac of the University of Reading says ‘the real number could be anything between two and even 10 times higher’ than three trillion trees.
Ecology is the combination of biology (the study of living things) and earth science (the study of the earth and its atmosphere). Ecologists therefore study the way in which living things relate to each other and their physical surroundings.
Dr Crowther says: ‘Europe used to be almost covered by one giant forest and now it’s almost entirely fields and grasslands.’ Campaigning groups such as WWF and Greenpeace are concerned: they say deforestation is responsible for around one-fifth of global carbon dioxide emissions, making climate change worse.


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