The Wall Made
of Trees
In 2007, Africa set out to plant a living barrier along the southern edge of the Sahara, from Dakar on the Atlantic to Djibouti on the Gulf of Aden. On the map it is one green line. On the ground it is still mostly a plan.
The planned length of the Great Green Wall, a band of restored land crossing 11 countries in the Sahel. By the UN’s 2020 count, about 4% of its 100-million-hectare goal had been restored inside the Wall’s own zone.
A belt drawn along a rainfall line
The Sahel is the strip where yearly rain falls from roughly 600 mm to 200 mm. The Wall follows the middle of it, where land is most at risk of tipping into desert.
+10% SaharaThe desert’s area grew about 10% between 1920 and 2013, and about 16% in summer (Thomas & Nigam, 2018).
Thirteen years, four million hectares
Reaching 100 million hectares by 2030 means restoring 8.2 million hectares a year. From 2007 to 2020 the in-zone average was about 0.3 million.
≈0.3 M ha / yrthe average achieved inside the zone, 2007–2020 (derived: 4 M ÷ 13 years).
The farmers outgrew the wall
Southern Niger’s farmers began protecting tree stumps on their fields in the 1980s, well before the Wall existed. That regrowth covers more ground than the official in-zone total.
Pledged is not planted
Donors pledged US$14.3 billion in 2021. Two years later about a sixth of it had been paid out, less than one year of the estimated need.
What a finished wall would hold
The 2030 goals are large. The early field evidence suggests that planting trees alone does not get there.
of carbon the restored land is meant to sequester by 2030.
rural green jobs targeted across the 11 countries.
planted sites studied in Senegal came out greener than it would have been naturally.
Read the line, then read the land around it
- The Wall follows rainfall, not borders. Its route runs between the 200 mm and 600 mm rain lines, the zone where a few dry years can turn grassland into dune.
- The hatched oval in Niger is the real success story. It is farmer-managed regrowth of about 5 M ha. It sits right on the route but did not come from planting campaigns.
- The line is a promise, not a forest. On the ground the Wall is a scatter of projects about 15 km wide. Inside that zone, about 4% of the target had been restored by 2020.
- Two big rivers cross the band. The Niger and the Nile carry water through the Sahel, and settlements cluster along them.
Sources & notes
- African Union / UNCCD — Great Green Wall for the Sahara and the Sahel Initiative, launched 2007: ≈8,000 km from Senegal to Djibouti across 11 core countries.
- UNCCD (2020) — The Great Green Wall: Implementation Status and Way Ahead to 2030. ≈4 M ha restored inside the intervention zone (≈4% of target); ≈18 M ha incl. wider national areas; 8.2 M ha/yr and US$4.3 bn/yr needed to reach 2030.
- UNCCD (2021) — Great Green Wall Accelerator, One Planet Summit, 11 Jan 2021: US$14.3 bn pledged; 2030 goals of 100 M ha, 250 Mt carbon sequestered, 10 M rural jobs.
- UNCCD GGW Accelerator, as reported (2023–25) — ≈US$2.5 bn of the 2021 pledge disbursed by March 2023.
- Thomas & Nigam (2018), Journal of Climate — The Sahara grew ≈10% (annual) and ≈16% (summer) in area, 1920–2013.
- NOAA Physical Sciences Laboratory (2005) — “The Great Drying of Africa”: roughly 30% less rain in the Sahel during the 1970s–80s droughts than in the 1950s.
- Reij, Tappan & Smale (2009), IFPRI — Farmer-managed natural regeneration on ≈5 M ha of southern Niger; ≈200 M trees (derived from ≈40 extra trees/ha).
- Zhu & Ndiaye (2025), Land Use Policy; via Yale e360 — In Senegal, only 1 of 36 planted sites studied was greener than it would have been naturally.
NOTE · The 200 mm and 600 mm rainfall lines are approximate. They follow a common definition of the Sahel, not a specific survey dataset.
NOTE · *Derived: 4 M ha over 2007–2020 averages ≈0.3 M ha/yr; carried on to 2030 that gives ≈7 M ha. The 2007–2020 segment is a straight line between two reported endpoints, not annual data.
NOTE · Hectare figures are self-reported by national governments and mix tree planting, assisted regeneration and land management. Niger’s farmer regrowth largely predates the Wall and is counted separately.