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'Time travel' study reveals the fate of coastal marshes 

Scientists from Tulane University have unveiled findings that could significantly alter our understanding of the future impact of climate change on coastal wetlands. 

This research, described as a “time travel” study, provides a glimpse into the potential future of coastal marshes under the threat of rising sea levels.

Unexpected opportunity 

Traditionally, the scientific community has relied on computer models to forecast the long-term effects of climate change, particularly sea-level rise. However, an unexpected opportunity arose along the Gulf Coast, following the devastation caused by hurricanes Katrina and Rita. 

In response to these natural disasters, an extensive network of nearly 400 monitoring sites was established along the Louisiana coast. This network was primarily intended to monitor the recovery and changes in the coastal landscape post-hurricanes. 

Extreme sea-level rise 

After the monitoring network was established, the Gulf Coast region experienced a dramatic increase in the rate of sea-level rise, exceeding more than 10 millimeters (half an inch) per year. This is at least three times the global average. 

This accelerated rate of sea-level rise subjected the area to conditions not expected until around 2070, providing a unique, real-world laboratory for scientists to study the potential impacts of future climate change on coastal wetlands.

Looking into the future

“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,” said Torbjörn Törnqvist, a professor in the Tulane Department of Earth and Environmental Sciences.

The researchers utilized innovative techniques developed by European scientists, which allowed for the measurement of sea-level rise directly off the coast using satellite data. This approach was previously unavailable, marking a significant advancement in the study of climate impacts. 

Unprecedented climate impact experiment 

By comparing the rate of water-level rise at each monitoring site with the rate of wetland elevation change, the researchers discovered that almost 90% of the sites were experiencing a deficit, indicating that the wetlands were not keeping pace with the rising sea levels.

“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,” said  PhD candidate Guandong Li, who led the study. “This has also allowed us to study the climate impact on a heavily human-influenced landscape, rather than a more resilient pristine ecosystem.”

Alarming results

The results show that if the current climate scenario persists, by 2070, approximately 75% of wetland sites will be in deficit, potentially leading to a rate of wetland loss much higher than what has been observed over the past century. 

This prediction underscores the urgency of addressing climate change to mitigate its impacts on coastal ecosystems.

Glimmer of hope 

The researchers also offer a glimmer of hope, suggesting that immediate action to meet the targets set by the Paris Agreement and reduce carbon emissions could lead to a more sustainable climate trajectory. 

This proactive approach could significantly reduce the rate of wetland loss, preserving these critical ecosystems for future generations.

The study is published in the journal Nature Communications.

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