How Many Trees Do We Actually Need On Earth?

Various sources publish data on deforestation rates, and also the potential impact deforestation might have.

But, there might be less information available on exactly how many trees we actually need on Earth in order to sustainably support humans, animals and the environment.

Some people might say as many as possible, but that answer might be too simplistic, & might miss important & nuanced points that need to be considered.

In this guide, we discuss how many trees we might need on Earth, and attempt to provide some numbers and context behind potential estimates.

 

Summary – How Many Trees Do We Actually Need On Earth?

Measuring The Amount Of Trees Already On Earth

There’s various ways we can measure the amount of trees on Earth:

– Total number of individual trees

– The total area of land with trees on it

– Tree cover density (number of trees per square area of land)

– Tree size, species identity, and tree qualities

+ other measurements such as the type of trees, and whether they are just trees, or forested tree areas (especially rainforest and tropical tree cover areas)

 

Estimates Of Trees Currently On Earth

Earlier estimates of total trees on Earth (in about 2005) put the total number of trees on Earth at about 400 million trees.

Some of the latest estimates as of around 2015 suggest there are 3.04 trillion trees on Earth

 

Regions With The Densest Tree Cover, & Most Total Trees On Earth

The Arctic has the densest tree cover on Earth, but the tropics and subtropics (warmer climates) support 43% of all trees on Earth

 

Tree Loss Rates, Tree Replanting Rates, & Net Tree Gain/Loss Rates

It is estimated about 15 billion trees are being cut down or lost every year

It is estimated only about 5 billion new trees are being replanted every year

The net loss of total trees is about 10 billion trees a year

Tree cover, and tree loss or replacement rates can differ from region to region around the world

There can also be a difference between the loss of man made trees, trees planted by humans, and non rainforest trees, and the loss of tropical rainforests and their trees

Some estimates indicate that the rate of tropical canopy cover specifically has doubled over the last decade or so

 

How Many Trees We Might Need To Plant Each Year

We might want to plant at least 10 billion more trees a year than we are now so we are running at a net neutral for annual tree numbers, and not a loss.

This number likely needs to be higher as more developed countries progress economically (and need more resources), and world population numbers increase.

So, there’s got to be consideration about net annual tree numbers, population growth, consumption rate, and so on

 

The Type Of Tree & Tree Cover Matters

Man made forests can easily be re-planted and are less valuable.

However, primary tropical forests and savannas are almost impossible to replace (or take a very long time to replenish and restore), and are incredibly valuable for the biodiversity they have.

We might want to protect these types of forests and trees as a first priority.

Also, the tree species, tree qualities, tree size, the types of trees a local area can support, and other characteristics of the tree may matter

 

Trees Provide Several Benefits That Address Several Problems

Just as one example, along with soil and the ocean, trees and the world’s vegetation are responsible for being major carbon sinks.

Trees also produce oxygen, help with water and air quality, and help with nutrient cycling and soil health.

We may want to identify the problems that are most important to solve, and manage tree numbers based on solving these specific problems.

With this approach, the number of trees and the amount of tree cover we may need in different regions on Earth may vary.

 

Some of these specific problems that trees help solve, and how many more trees we might need to address the problems might include:

 

– Trees & Climate Change – Absorbing Carbon From The Atmosphere

Some studies estimate 1.2 trillion more trees on Earth would absorb enough carbon dioxide to remove the last 10 years worth of human carbon dioxide emissions

 

– Trees & Cycling Nutrients, & Soil Health

Dependent on local conditions – different soils are degraded to different extents, so soils which are most unhealthy or most degraded may need more trees

 

– Trees & Water Quality

Dependent on local conditions – water sources in different areas are of different qualities, so water which has the most severe quality problems may benefit from more trees

 

– Trees & Oxygen Production

Plankton, and on-land vegetation like seaweed, trees and land based plant life produce all of the world’s oxygen. We discuss these organisms and plants further in our guides on the most important animals to humans and society, and the most important plant life to humans and society

Every year, we might need one tree on Earth to provide enough oxygen for 10 people.

The actual number of trees might be less when you consider that plankton and land based vegetation also provide oxygen to breathe

There’s currently almost 8 billion people on Earth, and that number could be up to 10 to 13 billion by the year 2100.

 

– Trees & Air Quality and Air Pollution (Absorbing Air Contaminants)

Different cities and countries in the world have different levels of air pollution and air quality.

Those with the poorest air pollution and air quality might consider planting more trees and vegetation to absorb some of these air contaminants

Some cities have already added vegetation to do this.

 

– Trees For Human Products & Services

Trees are used all over the world for different products and services.

Big cities and small rural and local communities/population rely on trees for not only good and services, but their livelihood.

Obviously, trees need to be replenished at a rate that allows humans to sustainably consume and use the products and services we need to live, or to actually live in their local area

 

– Tress & Biodiversity, Wildlife & Ecosystems

Along with soils and the world’s oceans, primary forests, tropical forests and savannas have heavy concentrations of biodiversity.

There might be reason to protect them as a priority over man made tree cover.

It’s sometimes impossible to replace or restore natural forests and natural tree cover.

Whereas, with human made tree cover, these tree areas can be replenished (but trees still take time and resources to grow, and we lose the benefits that trees provide once they are cut down and take their time to grow).

 

So, How Many Trees Do We Need On Earth In The Future?

Only estimates can be made about this number, and there can be several variables that impact estimates.

But, above we’ve give estimates on how many trees we currently have on Earth, and how many trees need to be replanted each year to make up for net tree gain/loss rates from deforestation and re-afforestation.

These numbers may be used as a baseline, and then specific considerations like how many trees we need for individual functions like carbon sequestration, oxygen production, wood supplies, and so on can be taken into account.

Right now for example, we might have billions to trillions of trees on Earth, and we might be losing about 10 billion trees a year.

We might combine those numbers with an estimate for oxygen production for example that we need one tree for every 10 people, and also take into consideration current and projected population sizes for society.

This might give us a rough guide of how many trees we need for any one end use or function.

 

Other notes on how many trees we might need …

The theoretical number of trees we need on Earth could decrease in some instances if we are able to address a problem at it’s root cause e.g. stopping air pollution in the first place, reducing emissions in the first place, recycling more paper and wood based products so we need less trees etc.

The number of trees needed in a particular geographic region, such as a State or province within a country, may differ from place to place.

So, each local area should be assessed individually

 

Other Potential Options Other Than Planting More Trees

Trees might not be the only option to address some problems that arise as a result of tree and forest loss

Other plants like bamboo provide some of the same benefits of trees (like carbon sequestration), but grow much quicker.

So, it may be worth us planting more bamboo in some areas compared to trees if it helps us achieve objectives quicker and easier than trees would.

But, bamboo and other vegetation might not be able to provide the biodiversity or some of the other benefits that rainforests with trees for example might.

 

Potential Challenges With Mass Tree Planting

The mass planting of trees is not without it’s challenges – we’ve mentioned some of those challenges in this guide on deforestation.

There can also be challenges when using trees as part of land restoration and re-greening

 

How Many Trees Are Currently On Earth?

The number of trees globally might be in the trillions, but, the number might vary between regions and countries

 

One global estimate in 2015 was:

[As of 2015 there were previous estimates of 400 billion total trees on Earth, but that estimate increased with a new study to 3.04 trillion trees on Earth, or around 422 for each person on the planet]

However, stats can differ country by country (as opposed to a global level):

[There were] three billion trees in the UK, or around 47 for every Briton [in 2015]

– independent.co.uk

 

How Many Trees Are Cut Down/Lost Per Year? (Deforestation Rates)

The number of trees lost each year might currently be in the billions, but, this number can vary from year to year

Non-forest tree loss may also be different to forested or tropical rainforest tree loss

 

Around 15 billion [trees] are lost every year due to deforestation, forest management and changes in land use (independent.co.uk)

 

How Many Trees Has Earth Lost Since The Beginning Of Human Civilisation?

… since the start of human civilisation, around 11,700 years ago, the total number of trees has fallen by around 46 per cent (independent.co.uk)

 

What About More Recently – Have We Gained Or Lost Tree Cover Over The Last Century?

Tree cover is the total area of trees, rather than total number of individual trees.

Some reports indicate we have gained tree cover in the last 40 to 50 years.

 

Recent estimates suggest Earth has more tree cover today than it did 35 years ago:

… research suggests an area covering 2.24 million square kilometers – roughly the combined land surface of Texas and Alaska, two sizeable US states – has been added to global tree cover since 1982.

This equates to 7% of the Earth’s surface covered by new trees.

– weforum.org, nature.com

 

Also, note that there are different tree cover gain and loss rates in different regions of the world, such as Oceania, South America, North America, Europe, Asia and Africa.

Places like South America might experience large losses, while Asia might experience large gains.

 

Type Of Tree Cover Loss/Gain – Tree Cover vs Forested Tree Cover

Also note that the types of trees matter (there is a distinction between tree cover and forest cover.)

Forests are probably more valuable than man made trees.

And in the above numbers, man made trees are being planted to replace natural forest area. 

 

As noted by weforum.org:

[Tree cover and forest cover] are not equal in biodiversity.

Primary tropical forests and savannas harbour a wealth of flora and fauna which is lost when these areas are cleared.

And man-made forests do not compensate for the damage and degradation done to ecosystems through land clearance.

The research attributes 60% of all land-use change throughout the study period directly to human activity, with the remaining 40% caused by indirect factors like climate change

 

So, when we look at deforestation and new trees being planted, we have to look at the types of trees being removed.

Tropical forest cover and savanna areas might be far more worrying to lose compared to man made and woodland tree cover (such as industrial timber plantations, mature oil palm estates and other specifically planted forests).

Some estimates indicate that tropical canopy cover loss has doubled over the last decade or so.

 

Tree Density In Different Regions In The World

Tree density is the number of trees per square area of land and some regions have denser tree coverage than others.

 

From sciencemag.org:

The densest areas of tree coverage are the boreal forests of the Arctic, whereas deserts support the fewest trees per hectare.

Even so, cold places have just 24% of the trees, whereas the tropics and subtropics support almost 43%.

The rest are distributed throughout other places, including temperate zones.

 

How Else Can We Measure Trees On Earth Other Than Number, Cover & Density?

There can be be other ways to measure trees other than what is outlined above and elsewhere in this guide.

 

From sciencemag.org:

Tree size, species identity, and tree qualities matter hugely in accounting for the importance of forests and trees outside of forests

… particularly the sizes of trees, because that determines how much biomass—and consequently carbon storage—in each one

 

How Many Trees Are Replanted Or Re-Grown Per Year?

[It is thought] about 5 billion new trees are planted or sprout annually, yielding a net loss of 10 billion (sciencemag.org)

 

What Are The Benefits Of Trees & Forests For The Earth, Humans, Animals & The Environment?

We listed the benefits of trees and forests in the summary above and also in the sections below.

But, specifically, trees might offer some of the following benefits:

 

Store huge amounts of carbon

Are essential for the cycling of nutrients

Are essential for water and air quality

And, are used for countless human services

– independent.co.uk

 

Trees provide food, energy and income to help communities achieve long-term economic and environmental sustainability.

Trees also filter the air and help reverse the impacts of climate change.

In just one year, a mature leafy tree produces as much oxygen as 10 people inhale

– earthday.org

 

Forests are important to humans, not just for their products, but also for their ability to foster biodiversity, store carbon, preserve water quality, and perform other ecosystem services.

Up to 45% of the carbon stored on land may be tied up in forests.

– sciencemag.org

 

Trees & Reversing Climate Change/Carbon Dioxide Absorption – How Much Carbon Do Trees Sequester & Store?

A tree can absorb as much as 48 pounds of carbon dioxide per year and can sequester 1 ton of carbon dioxide by the time it reaches 40 years old (projects.ncsu.edu)

 

… much of human CO2 emissions are being absorbed by natural sinks [like the ocean and vegetation like trees] (skepticalscience.com)

 

From treehugger.com:

[A very rough estimate of how many additional trees we would need to combat climate change is] 1.2 trillion new trees

There’s 400 gigatons [of carbon] now, in the 3 trillion trees [on Earth], and if you were to scale that up by another trillion trees that’s in the order of hundreds of gigatons captured from the atmosphere – at least 10 years of anthropogenic emissions completely wiped out

 

Trees & Oxygen Production

One large tree can provide a day’s supply of oxygen for up to four people (projects.ncsu.edu)

 

Trees, Cycling Nutrients & Soil Health

From mdocs.skidmore.edu:

A nutrient cycle (or ecological recycling) is the movement and exchange of organic and inorganic matter back into the production of matter.

In forest environments, there is an exchange of nutrient elements such as hydrogen, nitrogen and oxygen among the soil, plants and animals living within the environment.

Trees and other plants take up mineral and non-mineral nutrients from the soil through their roots.

These nutrients are stored in the leaves, flowers and other parts of plants.

The nutrients are either transferred to animals when animals eat the plants or they are transferred back into the soil.

 

Trees & Air Quality and Air Pollution

From thepresenttree.com:

[Trees absorb] Toxins such as nitrogen oxides, ammonia and sulphur dioxide through their leaves, bark and roots.

This improves the air quality in the microclimate around the trees and contributes to a healthier and cleaner environment overall.

 

Trees & Biodiversity, Wildlife & Ecosystems

Read more about the biodiversity in forests and rainforests in this guide.

 

Trees & Services/Products For Humans (& Supporting Human Livelihood) 

From projects.ncsu.edu:

Hundreds of food products (fruit, coffee, nuts, etc.) and food additives (for ice cream, chewing gum, etc.) come from trees.

Each year, one person uses wood and paper products equivalent to a 100 foot tree 18 inches in diameter.

Over 5,000 products are made from trees.

 

Trees & Water Quality

From articles.extension.org:

Trees and vegetation can help reduce water quality problems in communities by decreasing stormwater runoff and soil erosion. 

Trees also absorb some of the nutrients in the soil that would otherwise be washed away

 

 

Sources

1. https://www.independent.co.uk/environment/how-many-trees-are-there-on-earth-10483553.html

2. https://www.earthday.org/campaigns/reforestation/

3. https://www.weforum.org/agenda/2018/08/planet-earth-has-more-trees-than-it-did-35-years-ago/

4. https://www.nature.com/articles/s41586-018-0411-9

5. https://www.sciencemag.org/news/2015/09/earth-home-3-trillion-trees-half-many-when-human-civilization-arose

6. https://projects.ncsu.edu/project/treesofstrength/treefact.htm

7. https://skepticalscience.com/human-co2-smaller-than-natural-emissions-intermediate.htm

8. https://www.carbonbrief.org/doha-infographic-gets-the-numbers-wrong-underestimates-human-emissions

9. https://www.treehugger.com/climate-change/heres-how-many-trees-it-would-take-cancel-out-climate-change.html

10. https://articles.extension.org/pages/67763/urban-forests-improve-water-quality

11. http://mdocs.skidmore.edu/crandallparktrees/ecosystem/nutrient-cycling/

12.  https://thepresenttree.com/blogs/news/how-trees-reduce-air-pollution

13. http://greenwave.cbd.int/en/resources/tree-biodiversity

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