Sea Levels Spiked With Ancient Warming Event
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As climate negotiators continue their talks in Copenhagen, a massive rise in sea levels that resulted from global warming around 125,000 years ago is a reminder of what's at stake. (Credit: Getty Images)
Around 125,000 years ago, global warming drove sea levels to surge by more than 20 feet.
Sea levels were likely eight meters higher around 125,000 years ago when polar temperatures were 3-5 degrees Celsius (5.4-9 degrees Fahrenheit) warmer, says a new study published Wednesday to show the effects of global warming.
The research by Harvard University and Princeton University was released in the journal Nature as the world’s nations met in Denmark to forge a strategy to head off harmful effects of global warming blamed on greenhouse gases.
To understand the potential effects of a rise in temperature, the researchers reexamined data about the last interglacial stage — a warmer period within an ice age — which climaxed about 125,000 years ago, they said.
At the time, polar temperatures were 3-5 degrees Celsius higher than today, providing a comparison for current scenarios of future rises of 1-2 degrees Celsius (1.8-3.6 degrees Fahrenheit), they said.
“We find a 95 percent probability that global sea level peaked at least 6.6 meters (nearly 22 feet) higher than today during the last interglacial,” the study said.
“It is likely to have exceeded 8.0 meters (around 26 feet) but is unlikely to have exceeded 9.4 meters (nearly 31 feet),” it said.
Previous estimates of sea-level rises for the same period had been at a lower 4-6 meters (around 13-20 feet).
“The results highlight the long-term vulnerability of ice sheets to even relatively low levels of sustained global warming,” the scientists said.
The researchers also calculated that during the last interglacial period the average sea level rose six to nine millimeters a year compared to around two millimeters a year during the 20th century.
That may have accelerated to around three millimeters a year between 1993 and 2003, at least partly because of the melting of the Greenland and Antarctic ice sheets.
“If their results are correct, the sea-level rise over the coming century will be followed by many more meters of rise over the ensuing centuries,” they said in a commentary on the research also published in Nature.
