Why could wetlands save us from the climate crisis?

Did you know that the world's wetlands are disappearing three times faster than forests? And that although they only cover 6% of the Earth's land surface, they harbor 40% of the world's biodiversity? This and much more is what is highlighted every February 2nd, World Wetlands Day. This date also reminds us of the urgent need to protect these fragile and often overlooked ecosystems. "People are guided by aesthetics, and a forest is more attractive than a wetland, which is often considered just a source of mosquitoes and bad smells," warns Margarita Menéndez, professor of ecology at the Faculty of Biology of the University of Barcelona. This lack of "attractive" animals in our country—unlike the hippos we might find on a safari in Kenya—means we ignore a hidden biodiversity of amphibians, reptiles, and macroinvertebrates that are the true driving force of the global food web.

Despite their bad reputation, you should know that these ecosystems purify the water that irrigates our crops and the water that ends up in rivers and seas. "Through complex biochemical reactions, the plants and microorganisms in wetlands retain dissolved nutrients and suspended matter, thus preventing eutrophication and improving the quality of the final discharge," explains Menéndez. But their most important role is that of a climate "safe." "Thanks to the anoxia—lack of oxygen—in their sediments, organic matter takes millennia to decompose and sequesters carbon from the atmosphere," explains the professor. Specifically, marshes and, above all, peatlands and bogs are the great champions of CO₂ sequestration.

Marshes, mangroves, deltas, or peatlands: the variety of wetlands is as great as their state of emergency. On the Iberian Peninsula, we have lost more than 50% of these areas since the 1950s due to urbanization and intensive agriculture. "They are very resilient ecosystems; if we give them the right conditions, they colonize quickly, but the problem is that the land is already occupied," laments Menéndez. To illustrate the importance of these invisible services they provide—which include water purification, carbon sequestration, and flood mitigation—we looked at the United Nations Ramsar Convention and selected 10 wetlands from around the world that exemplify why we must save these havens.

It is the world's largest freshwater wetland and is considered the water engine of the South American continent, boasting a biodiversity reserve that is home to the highest concentration of jaguars and hyacinth macaws on the planet. Despite its vastness, the UN warns that the area faces threats such as deforestation, deliberately set forest fires, and the expansion of intensive livestock farming, which jeopardize this great reserve of life and its capacity to regulate the water cycle throughout the Paraguay River basin.

This inland delta, which doesn't flow into the sea but evaporates into the Kalahari Desert, is one of the most unique ecosystems on the planet and is recognized by the UN as a World Heritage Site. It covers a labyrinthine system of permanent swamps and seasonal floodplains that support more than a thousand plant species and one of the largest concentrations of large mammals in Africa. The survival of 650 bird species depends on it, and it requires joint management through a tripartite commission between Botswana, Namibia, and Angola, essential to ensure that tourism and subsistence farming do not degrade this vital oasis in a semi-arid region.

Located at the confluence of the Ganges and Brahmaputra rivers, it encompasses the world's largest contiguous mangrove forest. A UNESCO World Heritage Site, this network of hundreds of islands and waterways is the only mangrove forest in the world that supports a significant population of Bengal tigers, adapted to aquatic hunting. Beyond its importance for wildlife, the UN also defines it as an irreplaceable human shield: its roots act as a natural barrier protecting millions of people from cyclones, although rising sea levels and salinity threaten its delicate balance.

Located at the southern tip of Vietnam, it is the last stronghold of mangroves on a peninsula that lost almost all its bounty during the war. A Biosphere Reserve, it is now the only place in the country where two different tidal regimes interact, creating breeding habitats for endangered species such as the four-toed turtle and the black-faced heron, while the delta struggles to recover from the pressures of intensive shrimp farming.

Located in western Lapland, it is home to the largest and most intact peat bog in the region and is one of the most important in the world for climate regulation. The anoxic (oxygen-deprived) state of the flooded sediment slows the decomposition of organic matter, making this area a colossal carbon sink that stores millennia' worth of greenhouse gases beneath the mud. In addition to being a CO₂ reservoir, it is a breeding ground for endangered birds, such as the Lapland snipe, and a cornerstone of traditional reindeer herding. Currently, the site is the subject of European Union restoration projects to reverse its drying and ensure that this carbon is not released into the atmosphere.

Shared by Chad, Cameroon, Niger, and Nigeria, it is the only body of water of this magnitude in the heart of the Sahara Desert, making it a vital resource for the survival of the entire region. The Chadian portion alone supports more than 150 species of fish and is the only place where the kouri bull, an endangered endemic species, lives. The UN identifies it as one of the world's most critical hotspots: the loss of 90% of its surface area, due to desiccation and the advance of the dunes, has generated an unprecedented humanitarian and migration crisis.

Everglades National Park in Florida is one of the world's most famous wetlands and one of its most complex water filtration systems. Designated a World Heritage Site and Biosphere Reserve, it combines freshwater meadows with mangroves and brackish estuaries that are home to more than a thousand plant species and hundreds of bird species. After decades of degradation caused by the sugar industry, it is currently the site of the most ambitious hydrological restoration project on the planet to recover its natural flow.

This delta at the mouth of the Rhône River represents one of the most emblematic groups of wetlands on the Mediterranean coast. With some 356 bird species (more than 75% of the aquatic species recorded in France) and the largest population of European pond turtles on the entire French Mediterranean coast, the United Nations highlights it as a model of coexistence—often tense—between the conservation of natural spaces, tourism, and the environment.

Located in Andalusia, Doñana is a mosaic of marshes, dunes, and pine forests that constitutes one of Europe's most important wetlands for migratory birds traveling between the continent and Africa. Despite its international protection as a World Heritage Site, Doñana is in a state of emergency: the UN has maintained strict monitoring of the area since 1990 due to mass tourism and the overexploitation of aquifers for intensive strawberry irrigation, which threatens to permanently dry up its marshes.

It is one of the most important wetlands in the western Mediterranean, vital for the nesting of 30,000 pairs of birds. According to official UN information, the Ebro Delta is a regulated ecosystem where rice cultivation and coastal lagoons coexist in an artificial but necessary balance for biodiversity and commercial fishing. However, the Delta is now the ultimate symbol of vulnerability to climate change, threatened by the lack of sediment, retained in reservoirs, and by rising sea levels that jeopardize its existence as a natural barrier.