An international team of researchers has revealed that the global mean sea-level rise could exceed 1 metre by 2100 and 5 metres by 2300 if global targets on emissions are not achieved.

The study used projections by more than 100 international experts for the global mean sea-level changes under two climate scenarios – low and high emissions.

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By surveying a wide range of leaders in the field, the research, published in the journal Climate and Atmospheric Science, offers broader assurance about its projections for the ranges of future sea-level rise.

In a scenario where global warming is limited to 2 degree Celsius above pre-industrial levels, the experts estimated a rise of 0.5 metres by 2100 and 0.5 to 2 metres by 2300.

In a high-emissions scenario with 4.5 degree Celsius of warming, the experts estimated a larger rise of 0.6 to 1.3 metres by 2100 and 1.7 to 5.6 metres by 2300.

Professor Benjamin Horton from Nanyang Technological University in Singapore, who led the survey, said that sea-level rise projections and knowledge of their uncertainties are vital to make informed mitigation and adaptation decisions.

“We know that the planet will see an additional sea-level rise in the future,” said study co-author Dr Andra Garner, Assistant Professor at Rowan University in the US.

“But there are stark differences in the amount of sea-level rise experts project for low emissions compared to high emissions. This provides a great deal of hope for the future, as well as a strong motivation to act now to avoid the more severe impacts of rising sea levels,” Garner added.

This international study is based on the informed opinions of 106 sea-level experts and underlines the critical importance of pursuing a low emissions policy to limit sea-level rise.

The 106 experts who participated in the survey were chosen as they were among the most active publishers of scientific sea-level studies identified from a leading publication database.

In response to open-ended questions, the climate change experts identified the Greenland and Antarctic Ice Sheets as the greatest sources of uncertainty.

These ice sheets are an important indicator of climate change and driver of sea-level rise. Satellite-based measurements show the ice sheets are melting at an accelerating rate.

However, the experts also noted that the magnitude and impact of sea-level rise can be limited by successfully reducing emissions.