Global warming brought about by climate change may cause water levels to rise up to 20 feet. That's what scientists are saying in a study published in the journal Science on July 10.
Based on past climate patterns, sea levels increased to 20 feet at least twice in the last 3 million years when the global temperature reached the same level as it has today. In other words, the pattern shows that sea levels increased dramatically in the past when Earth was as warm as it is today.
"Modern atmospheric carbon dioxide levels are equivalent to those about 3 million years ago, when sea level was at least 6 meters higher because the ice sheets were greatly reduced," said Anders Carlson, co-author of the study and a glacial geologist and paleoclimatologist at Oregon State University, CBS News reports.
"It takes time for the warming to whittle down the ice sheets, but it doesn't take forever. There is evidence that we are likely seeing that transformation begin to take place now," he added.
The loss of ice mass from the Greenland and Antarctic ice sheets in the continuing climate change trends is expected to give the greatest contribution to the global mean sea level.
"Studies have shown that both the Greenland and Antarctic ice sheets contributed significantly to this sea level rise above modern levels," Carlson explained.
"Ice sheets as we see them today appear to be out of equilibrium with the present climate," said Andrea Dutton, lead author of the study and a geochemist at the University of Florida, The Guardian reports
Dutton also said said that limiting global warming to 2 degrees Celsius will not stop the sea levels from rising.
"Even if we meet that 2 degrees Celsius 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," Dutton said. "The decisions we make now about where we want to be in 2100 commit us on a pathway where we can't go back. Once these ice sheets start to melt, the changes become irreversible."
The study showed that sea levels increased 20 to 30 feet 125,000 years ago when the global average temperature reached 1 degree Celsius, and they rose 20 to 40 feet 400,000 years ago when the global average temperature was estimated to have reached 1 to 2 degrees Celsius.
The atmospheric carbon dioxide levels during those times were 280 parts per million. Today they are 400 parts per million, and they continue to rise, according to The Guardan.
If the sea levels should rise as the study predicts, millions of coastal residents will be put at risk of flooding and storm surges, according to CBS News.
"Understanding which are the most vulnerable sectors of polar ice sheets is critical to projecting future pattern of sea level rise regionally," said Dutton.
She also explained that recent models show that the melting Antarctic ice sheet alone can lead to sea levels rising several meters within a decade, which is faster than previously thought.
"There are some recent modeling efforts that now show you could get a section of the Antarctic ice sheet, several meters worth of sea level rise, to go in a decade. We used to think it was centuries," Dutton said.
The authors of the study acknowledged that the actual rate of sea level rise brought about by the loss of polar ice sheets is yet to be determined. Knowing which ice sheets were most susceptible and how fast they melted based on past records could help governments plan better for sea level change in their region, according to University of Florida news.
