Sea levels could rise by a “catastrophic” 10 feet by the end of the century – putting millions of people at risk of flooding with coastal cities such as London, New York, Tokyo and Calcutta submerged, according to a new study. The findings confirm the potential that continuing rapid ice loss could cause disastrous sea-level rise by 2100.
by Richard Alleyne
The Daily Telegraph (April 15, 2009) — The melting of the vast ice sheets in Antarctica and Greenland caused water to pour into the world’s oceans at an alarming rate at the end of the last period of global warming, the study shows.
Analysis of fossilised coral reefs off the Gulf of Mexico found many died during this time – known to climatologists as an “interglacial” – and were replaced by new reefs on higher ground.
This happened over a long-term ecological timescale and was caused by a rapid jump in sea level of between 6.5ft and 9.8ft (two to three metres) that occurred around 121,000 years ago, say the researchers.
The findings published in Nature raise concerns that current climate change could yield similar quick ice loss and disastrous sea-level rise in the near future.
Dr Paul Blanchon, a marine scientist of the National University of Mexico in Cancun, said his study shows there was a spell of swift melting during the warmest part of the last interglacial.
With growing evidence for contributions from the Antarctic and Greenland ice sheets to sea-level rise, the findings confirm the potential that continuing rapid ice loss could cause disastrous sea-level rise by 2100.
Dr Blanchon said this is also bad news for modern coral reefs which are already suffering because of human activity.
He said: “Knowing the rate at which sea level reached its high-stand during the last interglacial period is fundamental in assessing if such rapid ice-loss processes could lead to future catastrophic sea-level rise.
“The best direct record of sea level during this high-stand comes from well-dated fossil reefs in stable areas.
“Here we present a complete reef-crest sequence for the last interglacial high-stand from the stable north-east Yucatan peninsula in Mexico.
“The abrupt demise of the lower-reef crest allows us to infer that this occurred on an ecological timescale and was triggered by a two-to-three metre jump in sea level.
“We constrain this jump to have occurred 121,000 years ago and conclude it supports an episode of ice-sheet instability during the terminal phase of the last interglacial period.”
The prediction is not as high as those from some scientists who have warned sea levels may rise as much as 16 feet (five metres) by the end of the century.
But a rise of even a metre could have major implications for low-lying countries whose economies are not geared up to build sophisticated sea defence systems, such as Bangladesh.