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As Antarctic ice melts, a warning emerges from the past

By Marshall Connolly, Catholic Online (NEWS CONSORTIUM)
July 22nd, 2013
Catholic Online (www.catholic.org)

A study published in Nature Geoscience reveals that global warming that occurred some five million years ago causing sea levels to rise dramatically, possibly as much as by 20 meters. Scientists suggest that Antarctic ice may be more susceptible to warming than previously thought.

LOS ANGELES, CA (Catholic Online) - According to a study published in Nature Geoscience, global warming led to the melting of the East Antarctic ice sheets, contributing to a worldwide sea level rise of about ten to twenty meters.

Researchers from the Imperial College London examined mud samples and discovered there were multiple episodes of warming which officered during the Pliocene epoch, between five and three million years ago. During these episodes of warming, massive amounts of Antarctic and Greenland ice melted raising worldwide sea levels by as much as 20 meters. As ice melted, it cast off mud into the oceans where it now bears witness to climate change in sediment cores studied by researchers.

The conclusion is significant because during the Pliocene epoch, world carbon dioxide levels are similar to what they are now, about 400 parts per million.

 Dr Tina Van De Flierdt, co-author from the Department of Earth Science and Engineering at Imperial College London said, "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."

Later in the Pliocene epoch, temperatures dropped and ice sheets returned. However, the warm period found in the middle of the epoch is the time most similar to Earth's climate today. In fact, it was even warmer with temperatures at high latitudes as much as 10 to 20 degrees higher than present average. Temperatures in the tropics remained about the same.

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Scientists have blamed the high temperatures on CO2 concentrations in the atmosphere, and possibly on the rotation of the Earth around the sun. Many suggest the conditions are now comparable to the present day and use the period as a cautionary tale of what we can expect in the near-future.

At this time, many scientists agree that much of the CO2 in the atmosphere has been produced by human activity and that it can be a major contributing factor to future temperature increases and melting ice. Indeed, the change is about us. The Arctic ice cap is expected to disappear, at least during the summer months, within the next several decades.

However, Arctic ice mostly floats upon the sea and will not contribute significantly to seal level rise. What is more problematic is the melting of the ice sheets in Antarctica and Greenland.

If all that ice melts, scientists say we could see another 20 meters or more of sea-level rise. Naturally, that would be incredibly catastrophic.

Incidentally, there were no humans to cause global warming during the Pliocene, although our primitive ancestors, Australopithecus, did exist in the open tropical woodlands of Africa.

It remains a matter of some dispute, the level of human involvement in global climate change, and if CO2 levels matching that of the Pliocene epoch will also produce the same result. It is also of great debate if humans can do anything other than adapt.

Our knowledge of the Pliocene era is incomplete and sweeping conclusions based on data from that era is certainly premature, including major policy shifts. However, the latest research provides a cautionary note that if our planet continues to warm, for whatever reason, we may see a much different, more watery world in the centuries to come.

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