Production: Pablo Cantudo
Mangrove trees or mangroves, very valuable coastal ecosystems found in warm climates, will not survive sea level rise by 2050 if greenhouse gas emissions are not reduced, according to a study published by the journal Science .
Mangroves store large amounts of carbon dioxide, help protect coasts, and provide habitat for fish and other species.
Using sediment data from the past 10,000 years, an international team led by Macquarie University in Australia estimated the survival chances of mangroves based on rates of sea level rise.
When rates exceeded 6 millimeters per year, similar to estimates under high-emission scenarios for 2050, the scientists found that mangroves were very likely to stop keeping up with rising water levels. Instead, mangroves are more likely to survive when sea level rise is less than 5 millimeters per year, something that is projected for low-emission scenarios this century.
In the world there are about 80 species of mangroves , which grow in tropical and subtropical areas. Mangroves stabilize the shoreline, reducing erosion caused by storm surges, currents, waves and tides, according to the National Oceanic and Atmospheric Administration (NOOA). The intricate root system of mangroves makes forests attractive to fish and other organisms that seek food and shelter from predators.
This study covered 78 locations and explored how mangroves responded as the rate of sea level rise decreased by more than 10 millimeters annually 10,000 years ago to nearly stable conditions 4,000 years later. Carbon storage as mangrove forests expanded during that period contributed to reducing greenhouse gas levels.
Mangroves will naturally move inland if they cannot build vertically, but the constructions of civilization along many coasts already greatly impede such movement . The results highlight the importance of mitigating the magnitude of rapid sea level rise and ensuring that coastal adaptation measures allow mangroves to expand through the coastal lowlands.
Video images: M. Goddard
N. Saintilan at Macquarie University in Macquarie Park, NSW, Australia el al., ‘Thresholds of mangrove survival under rapid sea level rise’, Science (2020). DOI: 10.1126 / science.aba2656
