‘Time travel’ study shows climate change impact on coastal wetlands

A new study highlights the possible impact of climate change on coastal wetlands 50 years or longer into the future. Usually, researchers have to depend on computer models to show the long-term effects of rising seas.

However, unexpected circumstances made it possible for researchers to see what the future might look like for these marshes.

For the study, researchers from Tulane University set up an extensive network of nearly 400 monitoring sites along the Louisiana coast after hurricanes Katrina and Rita. The rate of sea-level rise in the region increased to more than 10 millimetres (half an inch) annually, which is at least three times the global average. This exposed the region to the kind of ocean rise not expected until around 2070, a press release explains.

According to the researchers, rapid rise presented a unique opportunity to determine whether the marshes can survive that pace of coastal flooding. “It is the dream of every field researcher who does experiments – we can basically travel 50 years into the future to get a peek at what’s in store,” study author Torbjörn Törnqvist said in a statement.

For the study, new techniques developed by European scientists were used to measure sea-level rise right off the coast with satellite data. The researchers then compared the rate of water-level rise at each monitoring site with the rate of wetland elevation change determined by other instruments, the statement explained. The findings showed that almost 90% of the sites were in deficit.

“To our knowledge, this is the first time that a climate impact experiment has been carried out over a region this large, based on hundreds of monitoring stations that have collected data for about 15 years,” lead author Guandong Li said in the statement. This has also enabled them to study the impact of climate change on a human-influenced landscape, rather than a more resilient pristine ecosystem, Li added.

The findings showed that if the current climate scenario persists, the rate of sea-level rise by 2070 will be about 7 millimetres (one-quarter inch) every year. Notably, about 75% of wetland sites will be in deficit by then. This could result in a rate of wetland loss much higher than what has already occurred in the last 100 years.

In the last 300 years, several wetlands have been destroyed to build towns and farms. According to a major study published in the journal Nature in February 2023, 21% of wetlands have been wiped out. Losing more wetlands to climate change could severely affect the species that made a home there and people whose livelihoods depend on them.

According to the scientists, taking immediate action such as meeting the target set by the Paris Agreement and reducing carbon emissions could decrease the rate of wetland loss.