Around 400,000 years ago when temperature was around 1C warmer than present, ocean levels have gained between six and 13 metres.
As reported by Andrea Dutton, a geochemist at the university of Florida and one of the study’s authors, “Even if we meet that 2C target, in the past with those types of temperatures, we may be committing ourselves to this level of sea level rise in the long term…”
At the recent United Nations panel on climate change (in 2013) scientists said that global warming could bring sea levels up between 26 and 82 cm (as many as 32 inches) by the late 21st century.
And in a heat interval three million years in the past, sea ranges have been additionally a minimum of six metres greater than now.
“It takes time for the warming to whittle down the ice sheets”, added Carlson, who is in OSU’s College of Earth, Ocean and Atmospheric Sciences, “but it doesn’t take forever”.
Icebergs near Timiamuit, SE Greenland (left) and modern reef in the Seychelles (right) where fossil corals record global mean sea level 7.5 m higher than present during a previous warm period 125,000 years ago. It is not going to take place soon. It shows that changes in Earth’s climate and sea level are closely linked, with only small amounts of warming needed to have a significant effect on seal levels.
“The ominous aspect to this is that Carbon dioxide levels are continuing to rise, so we are entering uncharted territory”, Clark said. “While this amount of sea-level rise will not happen overnight, it is sobering to realize how sensitive the polar ice sheets are to temperatures that we are on path to reach within decades”.
When past temperatures were similar to or slightly higher than the present global average, sea levels rose at least 20 feet, suggesting a similar outcome could be in store century unless there is a substantial reduction in greenhouse gas emissions.
Sea levels have risen already by eight inches in comparison to industrial times. Miami, which has an average elevation of about 6 feet, would probably be completely underwater. That rise has helped boost the surge and flooding damage from storms like Sandy and Typhoon Haiyan, and dramatically increased the occurrence of everyday flooding during high tide in cities from Baltimore to Honolulu. Dhaka in Bangladesh is one of the world’s 10 most populous cities with 14.4 million inhabitants, all living in low-lying areas.
“For the Antarctic ice sheet, the key challenge involves determining which marine-based sectors of the ice sheet are most vulnerable to collapse and identifying the forcing (atmospheric or oceanic) that would trigger such events”, DeConto and colleagues add. He clarifies that this applies to the parts of the ice sheet resting on bedrock below sea level. Recent observations show accelerating retreat of a few major outlet glaciers, especially in West Antarctica where the bed of the ice sheet lies hundreds of meters below sea level, hinting that a massive runaway ice-retreat may be already underway.