Evaporation and ongoing destruction of world wetlands, which hold a volume of carbon similar to that in the atmosphere today, could cause them to exhale billows of greenhouse gases, according to scientists attending the 8th INTECOL International Wetlands Conference in the Brazilian city of Cuiaba on the edge of South America’s vast Pantanal wetland region.

They called for urgent action to better understand and manage these vibrant ecosystems, ranked among the planet’s most threatened, and slow their decline and loss. Warming world temperatures are speeding both rates of decomposition of trapped organic material and evaporation, while threatening critical sources of wetlands recharge by melting glaciers and reducing precipitation. Covering just 6% of Earth’s land surface, wetlands (including marshes, peat bogs, swamps, river deltas, mangroves, tundra, lagoons and river floodplains) store 10-20% of its terrestrial carbon. Wetlands slow the decay of organic material trapped and locked away over the ages in low oxygen conditions. These waterlogged areas contain an estimated 771 billion tonnes of greenhouse gases ・both CO_2 and more potent methane ・an amount in CO2 equivalent comparable to the carbon content of today’s atmosphere.

The Pantanal wetlands of Brazil. (Photo by Phillie Casablanca/Creative Commons Attibution License)

“Humanity in many parts of the world needs a wake-up call to fully appreciate the vital environmental, social and economic services wetlands provide absorbing and holding carbon, moderating water levels, supporting biodiversity and countless others,” said conference co-chair Paulo Teixeira, co-ordinator of the Cuiaba-based Pantanal Regional Environmental Programme, a joint effort
of United Nations University and Brazil’s Federal University of Mato Grasso (UFMT).

Said UNU Rector Konrad Osterwalder: “Too often in the past, people have unwittingly considered wetlands to be problems in need of a solution. Yet wetlands are essential to the planet’s health ・and with hindsight, the problems in reality have turned out to be the draining of wetlands and other ’solutions’ we humans devised.”

If the decline of wetlands continues through human and climate change-related causes, scientists fear the release of carbon from these traditional sinks could compound the global warming problem significantly, said UFMT Rector Prof. Paulo Speller. Drained tropical swamp forests release an estimated 40 tonnes of carbon per hectare per year. Drained peat bogs release 2.5 to 10 tonnes.

German expert Wolfgang Junk, of the Max Planck Institute for Evolutionary Biology, said that reducing the stress on wetlands caused by pollution and other human assaults will improve their resiliency and represents an important climate change adaptation strategy. “Wetland rehabilitation, meanwhile, represents a viable alternative to artificial flood control and dredging efforts that may be needed to cope with the larger, more frequent floods predicted in a hotter world.”