Mangrove trees won’t survive sea-level rise by 2050 unless greenhouse gas emissions are reduced

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Mangrove trees won’t survive sea-level rise by 2050 unless greenhouse gas emissions are reduced, study shows

  • Experts studied mangrove sediments dating back to around 10,000 years ago
  • During this time, sea-levels went from rising at 10 mm a year to being static
  • Researchers found that the mangroves struggled with rising rates of above 6 mm
  • Mangroves are key for protecting coastlines from erosion and as a habitat for life

Mangrove trees will not survive the sea-level rise projected by 2050 unless greenhouse gas emissions are reduced, a study has found.

These coastal forests — found in warm climates, like in Florida — help protect coastlines from erosion, provide a sheltered habitat and store carbon.

However, mangrove forests have previously struggled to outgrow sea level rise of more than six millimetres a year — leaving this vital ecosystem vulnerable.

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Mangrove trees will not survive the sea-level rise projected by 2050 unless greenhouse gas emissions are reduced, a study has found. Pictured, mangroves in the Caribbean

In their study, Erica Ashe of Rutgers University-New Brunswick in New Jersey and colleagues analysed sediments dating back as far as around 10,000 years ago.

This allowed the team to explore how mangrove ecosystems have responded to fluctuating sea levels in the past — and predict how they might react in the future.

Ten thousand years ago, sea-levels were rising at a rate of around 10 millimetres each year — but this had decreased to nearly stable conditions within 4,000 years.

At this, time the expansion of mangrove forests increased the amount of carbon they were capable of storing, helping to contribute to lower greenhouse gas levels. 

However, the researchers found that when the rate of sea-level rise exceeded six millimetres per year — as they are predicted to do by 2050 under a high-emissions scenario — the mangroves stopped being able to keep pace with the rising waters.

The forests are much more likely to be able to survive if sea-level rise can be kept under 5 millimetres each year — which is only projected by 2050 under low greenhouse gas emissions scenarios.

‘Under high-emissions scenarios, rates of sea-level rise on many tropical coastlines will exceed 7 millimetres per year, the rate at which we concluded there’s a 3.5 percent probability mangroves can sustain growth,’ said Dr Ashe.

‘The loss of these mangrove ecosystems could result in increased carbon dioxide in the atmosphere and fewer vital buffers against storm surges in the long run.’

These coastal forests — found in warm climates, like in Florida — help protect coastlines from erosion, provide a sheltered habitat and store carbon. Pictured, mangroves in the Caribbean

These coastal forests — found in warm climates, like in Florida — help protect coastlines from erosion, provide a sheltered habitat and store carbon. Pictured, mangroves in the Caribbean

In their study, Erica Ashe of Rutgers University-New Brunswick in New Jersey and colleagues analysed sediments dating back as far as around 10,000 years ago, pictured

In their study, Erica Ashe of Rutgers University-New Brunswick in New Jersey and colleagues analysed sediments dating back as far as around 10,000 years ago, pictured

If they are unable to build upwards, mangrove forest will naturally move inland, the researchers explained — but the coastal developments lining many shores act to impede such progress.

The findings highlight the importance of both mitigating emissions and the resulting sea-level rise, but also ensuring that mangroves have room to expand across coastal lowland. 

The full findings of the study were published in the journal Science.



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