Greenhouse gas emissions up to the present day have triggered an irreversible warming that will cause sea levels to rise for thousands of years, scientists have warned.
A study, published in Environmental Research Letters, found that the world could already be committed to a sea level rise of 1.1 metres by the year 3000.
It is one of the first times a studied has considered the impacts of glaciers, ice caps, the Greenland and Antarctic ice sheets and the expansion of oceans as they warm.
It is still difficult for scientists to model how the polar ice sheets might react to climate change. Accounting for approximately 200,000 individual glaciers worldwide can also be complicated.
It remains difficult for scientists to model how the Antarctic ice sheet will react to climate change and how this could impact sea levels (Source: Mark 217/Creative Commons)
The Intergovernmental Panel on Climate Change’s (IPCC) Fourth Assessment Report predicted sea-levels would rise between 18 and 59 cm by 2100. This assessment did not include the impact of the Greenland or Antarctic ice sheets.
In 2009, however, two years after the IPCC report, scientists at the climate change congress in Copenhagen said changes to these ice sheets could put sea level rises at a metre or more by 2100.
The latest study found that if the world was to follow the high emissions scenario adopted by the IPPC an 8.6 metre sea-level rise could be expected in the next thousand years.
In the other scenarios (B1 and A1B), sea-level rises of 2.1 and 4.1 metres were seen respectively.
In all their models researchers found the Greenland ice sheet to be responsible for more than half of the sea level rise, with an expansion of warming oceans as the second highest contributor.
It found the contributions of glacier melt to be small.
“Ice sheets are very slow components in the climate system; they respond on time scales of thousands of years,” said Professor Philippe Huybrechts, co-author of the study.
“Together with the long life-time of greenhouse gases in the atmosphere, this inertia is the real poison on the climate system: anything we do now that changes the forcing in the climate system will necessarily have long consequences for the ice sheets and sea level.”
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