What are wetlands?

The world's kidneys, nature's sponge, and biodiversity superheroes — these waterlogged soils have a host of accolades and come in many shapes and sizes. 

Wetlands describes a range of ecosystems on land that are wet either permanently or seasonally. They can be found on all continents except Antarctica. 

They come in many forms — from mossy, peat-filled bogs to marshes strewn with rushes and swamps dominated by trees. Some are in freshwater floodplains and low-lying inland areas. Others are coastal, such as tropical mangrove forests made up of trees that can survive in saltwater. 

Wetlands can be thought of as biological supermarkets, because the combination of shallow water with high levels of nutrients and biomass makes them a feast for a wide variety of plant and animal species. 

They are among the most productive ecosystems in the world. Despite occupying just 6% of the world's land surface they host an astonishing 40% of global biodiversity. 

Why do they matter? 

Wetlands were long overlooked — seen as unproductive wasteland best drained and turned into fuel and farmland or filled-in with sediment to make solid ground for buildings and roads.

Now they are recognized not only as biodiversity hotspots but as vital carbon sinks, absorbing millions of tons of carbon every year.

Wetlands hold around a third of the world's carbon locked in living vegetation, as well as soil, sediment and peat that has built up over thousands of years. Peatlands alone store twice as much carbon as all the world's forests.

When wetlands are damaged, they become a potent source of global emissions by releasing carbon dioxide, methane and nitrous oxide — all powerful greenhouse gases driving global temperature increases. Drained and burned peatlands account for 4% of human-induced emissions every year. 

Wetlands can also be thought of as the world's kidneys. The plants, fungi and algae in these ecosystems help to filter and purify water of chemicals, heavy metals and other pollutants. They are also natural defences against floods — by acting as sponges that soak up heavy rain — and protect coasts from erosion during storms. 

What does the future hold for them? 

Wetlands are the world's most threatened ecosystem and are disappearing three times faster than forests. A third of all wetland areas have been lost in the last fifty years, largely due to draining them for agricultural use and construction. In Europe, the US, India, Japan and China, over half of all wetland areas have disappeared since 1700. 

But restoring and conserving wetlands has now been recognized as an important nature-based solution on the road to limiting goal temperature rises to 1.5 Celsius (2.7 Fahrenheit), as set out in the Paris Agreement. 

Almost 70% of countries signed up to the climate agreement now include a type of wetland in their national climate commitments. In 2022, a landmark global commitment to protect nature also stated provisions to restore at least 30% of inland water bodies and freshwater ecosystems. 

Many countries are striving to bring wetlands back from the brink. Argentina has an ambitious conservation project to restore thousands of kilometers of its Ibera wetlands. In Indonesia measures to rewet peatlands have helped stopped the spread of wildfires.

Some scientists now argue wetlands are so important to supporting human well-being and life on earth that they should even be granted legal rights.

Edited by: Sarah Steffen