Mangrove forests, once considered one of the world's most threatened coastal ecosystems, are showing signs of recovery worldwide, according to new research from Tulane University that finds decades of losses largely offset by regrowth and expansion.
The study , based on four decades of satellite data and published in the journal Science, finds that mangrove forests worldwide are no longer in net decline and are now growing overall. After decades of loss driven by deforestation and coastal development, mangroves are expanding in many regions, largely through natural regeneration and expansion into newly formed coastal areas.
The findings suggest a more hopeful trajectory for these ecosystems, which play a critical role in protecting coastlines, supporting fisheries and storing climate-warming carbon.
"After decades of loss, we're finally seeing a global turning point for mangroves," said Zhen Zhang, a postdoctoral scholar at Tulane University School of Science and Engineering and lead author of the study. "This highlights their strong resilience and their potential as a powerful nature-based solution for climate mitigation and coastal protection."
Mangrove forests declined through much of the late 20th century, losing nearly 2,900 square kilometers between the 1980s and 2010. During the past 16 years, gains have outpaced losses. By 2023, mangrove areas had rebounded, resulting in only about a 1% net decline over the entire four-decade period – a much smaller loss than previously estimated.
"What we're seeing now is a real shift. Mangroves are now showing a net increase globally, and the rate of degradation is slowing," said Daniel Friess, Cochran Family Professor of Earth and Environmental Sciences at Tulane and director of The Mangrove Lab .
"While some mangroves are still being lost, this could make them a rare conservation success story and an important source of optimism for climate action," said Friess, who also serves as director for the Center for Public Policy Research at the Murphy Institute .
The recovery is being driven by a combination of restoration efforts and natural processes. In many regions, mangroves are recolonizing abandoned aquaculture ponds and expanding into newly formed coastal mudflats, especially in river deltas where sediment creates ideal growing conditions.
Along the U.S. Gulf Coast, mangrove trends reflect a different but related process. In the Mississippi River Delta, mangrove area declined slightly from the 1980s through the late 1990s, then began to increase, with more pronounced expansion after 2012. Researchers attribute this growth primarily to warming temperatures, which allow mangroves typically found in tropical and subtropical climates – to expand into higher-latitude regions.
Louisiana has also seen an overall increase in mangroves over the past four decades, underscoring the broader regional shift.
Beyond increases in area, the research highlights another encouraging trend: many existing mangrove forests are becoming denser and healthier. Closed-canopy mangrove forests, which store more carbon and provide stronger coastal protection, have expanded globally over the past four decades. Rates of degradation have dropped significantly since the 1980s, reflecting the growing impact of conservation policies and restoration programs worldwide.
That growth suggests that mangroves may be capturing more carbon than previously recognized. At the same time, the study shows how vulnerable these gains can be. In Texas, for example, mangroves have expanded in recent decades but experienced a sharp decline in 2021 due to an extreme freeze event, highlighting how climate extremes can quickly reverse progress.
Still, researchers caution that the recovery is not complete. Newly established mangrove forests are often young and less capable of providing the full ecological benefits of mature systems. And deforestation remains a threat in some regions, particularly where coastal land is converted for agriculture or development.
The study underscores that continued protection is key to sustaining the rebound.
"The most immediate and effective way to protect mangroves is to stop deforestation," Zhang said. "When mangroves are cleared, large amounts of long-stored carbon are released into the atmosphere. But when deforestation stops, mangroves can continue to accumulate carbon naturally over time, so there's a major climate benefit in both avoiding emissions now and allowing future carbon storage."
Protecting the natural processes that support mangrove growth is equally important, he said.
"Much of mangrove expansion happens on newly formed mudflats, which depend on a steady supply of river sediment," Zhang said. "Maintaining that sediment flow is critical for creating the conditions mangroves need to establish and spread."
The findings also suggest that conservation strategies should look beyond simply measuring total area.
"As countries invest in nature-based solutions to climate change, mangroves stand out as a rare example of an ecosystem where global trends are beginning to move in the right direction," Zhang said.
