A study published in Nature Geoscience on the similarities between the Pliocene Epoch and today’s temperature, CO2 concentration, and sea level rise, may provide evidence of the impending fate of low-lying states like Florida and Louisiana.

The study was conducted by researchers from Imperial College London, along with other partners. Scientists analyzed the chemical content of mud from marine sediment samples, which allowed them to understand the activity of the East Antarctic ice sheet in times of climatic warmth during the Pliocene Epoch.

“Warm intervals within the Pliocene Epoch (5.33 – 2.58 million years ago) were characterized by global temperatures comparable to those predicted for the end of this century and atmospheric CO2 concentrations similar to today,”according to this and prior studies.

During the Pliocene, melting of the East Antarctic ice sheet led to a sea level rise of as much as 65 feet (20 meters). If such a rise were to occur today, Louisiana and the majority of Florida would be under water, not to mention New York, San Francisco, Washington, D.C., the Nile Delta, the Netherlands, Venice, and more.

Dr. Tina Van De Flierdt, a co-author from the Department of Earth Science and Engineering at Imperial College London told Phys.org, “The Pliocene Epoch had temperatures that were two or three degrees higher than today and similar atmospheric carbon dioxide levels to today. Our study underlines that these conditions have led to a large loss of ice and significant rises in global sea level in the past. Scientists predict that global temperatures of a similar level may be reached by the end of this century, so it is very important for us to understand what the possible consequences might be.”

Today, CO2  levels have reached 400 parts per million (ppm) for the first time in 55 years of measurement, and in “probably more than 3 million years of Earth history,” National Geographic reports. Greenhouse gases are at their highest levels since the Pliocene, when Earth was in the final stage of a greenhouse gas era and levels were on their way down. Now levels are steadily rising due mainly to the release of CO2 from burning fossil fuels.

Co-author, Carys Cook, of the Grantham Institute for Climate Change at Imperial College, added that scientists had previously thought that the East Antarctic ice sheet was more stable than smaller ice sheets, yet the study indicates otherwise. “Our work now shows that the East Antarctic ice sheet has been much more sensitive to climate change in the past than previously realized. The finding is important for our understanding of what may happen to the Earth if we do not tackle the effects of climate change.”

Alisha is a writer and researcher for Ring of Fire.

Florida - sea level rise