Coastal ecosystems are at risk from sea level rise

Coastal ecosystems such as reefs, mangroves and salt marshes, are facing significant threats due to rising global temperatures. These ecosystems play a critical role in island systems because they can reduce wave energy, protect shorelines, and provide habitats for diverse species. It is therefore important to take measures to preserve and protect these valuable ecosystems.

Coastal ecosystems are vital to millions of people around the world. However, if global warming exceeds pre-industrial levels by 2°C, many of these ecosystems and the communities that depend on them will be threatened by rapid sea level rise. It is important to take action to mitigate climate change and protect these valuable resources. This emerges from a study published in Natureled by Macquarie University (Australia).

Until now, it was not known with certainty how sea level rise would affect the vulnerability of coastal areas and which limits should not be exceeded. To assess this situation, the researchers collected data on the last glacial maximum, which occurred 19,000 years ago, as well as other more recent data from various coastal ecosystems. Paleorecords are records that contain information about past events, such as the flooding of mudflats and the formation of mangroves.

On the other hand, current recordings are accessed in real time via a global network of stations. This network includes 477 tidal marsh monitoring stations and 190 mangrove monitoring stations. The work also includes resizing 872 coral reef islands.

Coastal ecosystems as a protective line

Currently, the extensive mangrove and tidal swamps on the world’s coasts serve as a protective line against storm surges. The retreat and narrowing of these habitats will expose further areas to erosion, so that instability of the currently protected coasts would be one of the consequences.explains Neil Saintilan, a scientist at Macquarie University and lead author of the research.

Another important contribution of these wetlands is supporting fisheries, he adds. The fragmentation and loss of these ecosystems is likely to have some impact on wild fisheries.“.

The study considered different scenarios for predicting sea level rise. Estimates ranged from 4 mm to over 10 mm per year. Researchers estimate that a temperature of 2.0 °C could double the extent of tidal marshes, which would be subject to a sea level rise of 4 mm per year between 2080 and 2100.

Temperature forecasts and their impacts on coastal ecosystems

If the global temperature rises by 3.0°C, it would have serious consequences for mangroves, coral reefs and tidal marshes. Almost all of these ecosystems would be exposed to sea level rise of more than 7 mm per year, which could have significant impacts on biodiversity and coastal ecosystems.

Due to increasing coastal erosion and wave inundation, coral reefs are likely to be destabilized. In addition, salt marshes and mangroves are at risk of flooding and inundation.

There are several important island groups associated with coral reefs. These include the Solomon Islands, Tuvalu, Kiribati, Micronesia, French Polynesia and the Maldives.says Saintilan.

Some are already disappearing in parts of the world where sea levels are rising sharply. In the Solomon Islands group, tectonic movements have caused relatively rapid sea level rise in recent decades, and several of these have been lost. With a 2.0°C increase in temperature, a much larger proportion of coral islands will be exposed to these rates“, he emphasizes.

What should we do?

The results obtained indicate that the limits of an unsafe operating environment for coastal ecosystems are getting closer and depend on future emission trajectories.

In tidal swamps and mangroves, they form root systems that extend the swamp area upward. Coral reefs can also grow vertically, further protecting coral islands from wave attack. There are other coastal habitats (rock platforms or beaches), but they do not undergo a biological adaptation process to sea level rise. The fact that selected habitats can be adapted has sparked debate about the upper limits of this response“says the scientist.

This study highlights the importance of addressing environmental stressors in the local environment, such as pollution on coral reefs. It also highlights the need to restore cleared or degraded wetlands, as this will help increase resilience to climate change and mitigate the negative impacts of coastal recession.

Displaced by climate change

Unfortunately, in some places people are already leaving small island states due to the effects of climate change, particularly the salinization of drinking water. Coastal armoring (hard walls protecting property) is possible in some parts of the world, but can often make the problem worse by increasing erosion in other areas.“.

The authors suggest that meeting the Paris Agreement’s goals of achieving net-zero emissions by mid-century is the most effective way to minimize disruption to these important ecosystems.

It is also important that we do not cause the land to sink more quickly by withdrawing drinking water, which is contributing to rapid sea level rise in many Southeast Asian countries.“, concludes the expert.


Neil Saintilan et al. “Widespread coastal habitat retreat is likely at warming levels above 1.5°C,” Nature.

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