A scientific report shows that planting billions of trees across the world is by far the biggest and cheapest way to tackle the climate crisis. Researchers have finalized their first calculations of how many more trees could be planted without encroaching on cropland or urban areas, as well as how much carbon they’ll absorb, plus much more, and published the study in the journal Science.
Prof Tom Crowther at the Swiss university ETH Zürich, who led the research, said:
This new quantitative evaluation shows [forest] restoration isn’t just one of our climate change solutions, it is overwhelmingly the top one. What blows my mind is the scale. I thought restoration would be in the top 10, but it is overwhelmingly more powerful than all of the other climate change solutions proposed.
Carbon dioxide emissions, which are driving global warming, are absorbed and stored in a tree as it grows. If a worldwide tree planting program was executed, it could potentially remove (a “mind-blowing”) two-thirds of all the emissions that have been pumped into the atmosphere by human activities.
René Castro, assistant-director general at the UN Food and Agriculture Organization, said:
We now have definitive evidence of the potential land area for re-growing forests, where they could exist and how much carbon they could store.
The Analysis Zoning Figures
- About 8.7 billion hectares (two-thirds of all land) could support forest.
- 5.5 billion hectares already have trees.
- 3.2 billion hectares is treeless land.
- 1.5 billion hectares of treeless land is used for growing food.
- So, the remaining 1.7 billion hectares of treeless land is potential forest land.
- Of these 1.7 billion hectares of treeless land, 1.2 trillion native tree saplings would naturally grow. To illustrate, that area is about 11% of all land and equivalent to the size of the US and China combined.
- Tropical areas could have 100% tree cover.
- Other areas would be more sparsely covered, meaning about half the area would be under the tree canopy.
- All fields used to grow crops and urban areas are excluded. However, with the exception of grazing land, on which a few trees can also benefit sheep and cattle.
The research is based on the measurement of the tree cover calculated by hundreds of people. 80,000 high-resolution satellite images from Google Earth were used. Then, artificial intelligence computing combined all the data with 10 key soil, topography, and climate factors to create a global map of where trees could grow.
Christiana Figueres, former UN climate chief and founder of the Global Optimism group, said:
Finally we have an authoritative assessment of how much land we can and should cover with trees without impinging on food production or living areas. This is hugely important blueprint for governments and private sector.
Crowther emphasized that this is not a replacement solution to the elimination of greenhouse gas emissions from fossil fuel burning that still needs to be brought down to zero. Furthermore, it is envisaged that it will take 50-100 years before the trees will be effectively removing 200 billion tons of carbon. Which is also all the more reason to act now!
Crowther said:
Tree planting is a climate change solution that doesn’t require President Trump to immediately start believing in climate change, or scientists to come up with technological solutions to draw carbon dioxide out of the atmosphere. It is available now, it is the cheapest one possible and every one of us can get involved. Individuals could make a tangible impact by growing trees themselves, donating to forest restoration organizations and avoiding irresponsible companies.
Other scientists have already warned that technological solutions will not work on the vast scale needed. They agree that carbon will need to be removed from the atmosphere to avoid catastrophic climate impacts and planting more trees is a smart solution.
Jean-François Bastin, also at ETH Zürich, said: “Governments must now factor [tree restoration] into their national strategies.”
There is one thing missing from the research paper: addressing how a global tree planting program would be paid for and delivered. However, it does calculate how much it would cost to plant 1 trillion trees and the answer is shockingly lower than any other carbon capture solution available or proposed.
Crowther said:
The most effective projects are doing restoration for 30 US cents a tree. That means we could restore the 1tn trees for $300bn [£240bn], though obviously that means immense efficiency and effectiveness. But it is by far the cheapest solution that has ever been proposed. Financial incentives to land owners for tree planting are the only way I sees it happening, but I think $300bn would be within reach of a coalition of billionaire philanthropists and the public.
The potential is literally everywhere – the entire globe. In terms of carbon capture, you get by far your biggest bang for your buck in the tropics [where canopy cover is 100%] but every one of us can get involved. The world’s six biggest nations, Russia, Canada, China, the US, Brazil and Australia, contain half the potential restoration sites.
For more information, you can visit the Crowther Lab website for a tool that enables users to look at particular places and identify the areas for restoration and which tree species are native there.
