Mangrove forests, once written off as one of the world’s most threatened ecosystems, have stopped shrinking and are now growing overall, with outright clearing and canopy thinning both easing since the 1980s. That is according to Zhen Zhang, a postdoctoral scholar at Tulane University’s School of Science and Engineering and lead author of research published in the journal Science, which finds the world’s mangroves have shifted from net loss to net gain since around 2010.
Four decades of satellite records put the losses at nearly 2,900 square kilometres between the 1980s and 2010, with gains over the 16 years since outpacing them. The net change across the whole period is a 0.5 per cent decline, a figure the authors bracket at 1.4 per cent, too small for the study to tell apart from no change at all.
“Our findings reveal the underestimated resilience of a highly threatened ecosystem,” the authors write, naming an end to deforestation as the fastest route to conservation targets through natural regrowth.
“After decades of loss, we’re finally seeing a global turning point for mangroves,” Zhang said, with the study crediting natural regrowth and seaward spread onto newly formed coastline, rather than planting schemes, for most of the turnaround.
Built from the Landsat archive run by NASA and the United States Geological Survey, the maps were checked against sharper imagery from the European Space Agency’s PlanetScope and stitched into annual records covering 1984 to 2023. Most earlier work used radar, which struggles to distinguish mangroves from other coastal vegetation, leaving the long-term trend poorly measured until now.
Southeast Asia Flips From Epicentre to Engine
Nowhere is the reversal sharper than in Southeast Asia, which drove nearly 60 per cent of the world’s mangrove losses between the 1980s and 2010 before supplying 43 per cent of global gains across the 13 years that followed. Heaviest clearing ran between 1990 and 2005, with two countries carrying most of the turnaround that came after.
Indonesia, the world’s most mangrove-rich nation, halted its steep decline after 2005 once farmland and fish ponds stopped eating into the coast, and the abandoned shrimp ponds of its Mahakam Delta are now filling with mangroves that seeded themselves. Myanmar, once the most heavily cleared major mangrove country, has added 10 per cent to its mangrove area since 2010.
Legal protections tightened across the region after the 2004 Indian Ocean tsunami drove home what the forests were worth as storm defence, Zhang said, with public awareness and the trees’ own knack for moving back in doing the rest.
“While there are still areas of concern where losses are ongoing,” said Thomas Worthington, head of the Global Coastal Wetlands Lab at the University of Cambridge and a co-author, who called the satellite record a way to find both the places that need protection and the places worth restoring.
In the forest carbon trade, canopy cover matters as much as area: closed-canopy stands hold the most carbon and blunt the most storm energy, spreading worldwide over the four decades, even as total extent barely moved. It comes as blue carbon markets scale up, with Pakistan’s Indus Delta project having sold US$40 million in credits into a market still arguing over whether young forests can bank what mature ones do.
Those gains sit on thin foundations, with young mangroves still carrying shallow roots, leaving them open to cyclones and heat extremes, as a 2021 freeze that killed off Texas mangroves showed. Much of the seaward spread also depends on rivers delivering the sediment that builds new mudflats, and the young stands need decades to match the carbon and the storm shelter of the old forests they replace.
“It may be challenging to maintain this trajectory in many places under climate change,” said Daniel Friess, Cochran Family Professor of Earth and Environmental Sciences at Tulane and director of The Mangrove Lab, who wants the money moving now rather than later.
Zhang says the fastest protection available is to stop clearing the forests, because cleared mangroves dump centuries of stored carbon while spared ones keep banking it. On the study’s own count, four decades of loss and recovery have left the world’s mangroves 0.5 per cent smaller than they were in the 1980s, and growing.
For more information: Zhang, Z., Murray, N. J., Song, X.-P., Bunting, P., Worthington, T. A., Fatoyinbo, L., Mao, D., Jia, M., Arifanti, V. B., Aung, T., Htay, S. S., & Friess, D. A. (2026). Unexpected expansion and regrowth in Earth’s mangrove forests over the past four decades. Science, 392(6802), 1082–1087. https://doi.org/10.1126/science.aec9773
