Scientists from Columbia University’s Lamont-Doherty Earth Observatory are examining coasts around the world to measure how high seas rose during past warm periods. Their aim: to refine estimates of sea-level rise in coming decades, during our current era of human-induced global warming. Recently, they visited the Caribbean island of Barbados. Made mostly of fossil coral reefs that have been slowly rising from the waves for hundreds of thousands of years, the island contains an exquisite record of how the ocean has risen and fallen. (All photos by Kevin Krajick) READ THE FULL SCIENTIFIC STORY
Shrouded by sea mist from giant waves, postdoctoral scientist Blake Dyer (left) and geochemist Steven Goldstein survey the geology along Barbados’s northern coast. The nearly 100-foot cliffs behind them are made entirely of fossil corals; offshore, new corals are constantly forming underwater, and probably also one day will be on dry land.
At a sheltered beach, the team inspects a feature known as Round Rock. According to previous studies, its top may be about 100,000 years old.
Team leader Maureen Raymo checks out corals, molluscs and other sea creatures embedded in a onetime sea cliff near the University of the West Indies. The site, exposed by a road cut, holds dozens of species.
Above the road cut is a broad, flat terrace, typical of the island’s stair-step topography. In the far background, another, older cliff juts up.
Near the town of Oistins, grad student Miranda Cashman inspects exposed small corals.
This brain coral is still frozen in “growth position,” meaning it rose straight out of the ocean intact, its head pointing skyward. Since it has not been broken or moved, it is valuable for measuring the exact age of the deposit. This one might be about 120,000 years old; lab analysis will tell more exactly.
At an older, higher-elevation site, the team dug out this exquisitely preserved brain coral. Current estimates say that the island’s most ancient corals are around 750,000 years old, but new analysis methods may change that.
Homeowner Sue Tryhane looks on as the team examines a fossil sea cliff in her back yard.
An apartment house backs up to what was once a sea cave.
Homeowner Ronald Blackmore (left) takes in grad student Michael Sandstrom’s explanation of the study. He generously gave permission for the researchers to sample the cliff in back of his house.
Sea-level modeler Jacqueline Austermann chisels out a sample.
The specimens will go back to the lab for analysis of chemical isotopes that can be used to measure age, and thus sea level at the time of formation.
At the modern shoreline, Blake Dyer fixes a tide gauge to a rock before planting it in the surf.
Mission accomplished, Dyer heads back to shore.
At a popular kite-surfing beach, the researchers set up a GPS station to produce high-precision readings of coral locations and elevations.
A washed-up sea fan is one of many species probably not preserved in the fossil deposits; it is too delicate. Scientists can rarely, if ever, get a 100 percent picture of the past.
About 15 percent of Barbados’s surface is made of sedimentary rocks like these. The island is rising because the seabed itself is rising, squeezing sediments to the surface.
This coral “mushroom” in the middle of cow pasture was probably a piece of a sea cliff, broken off into what was once the shallow surf zone, then eroded by waves. It is now a mile or so from shore.
A onetime sea arch is stranded on a hill about 750 feet above sea level, in the middle of a golf course. The rocks here might be among the oldest on the island.
Many of the island’s older buildings are made of coral blocks. Today, concrete prevails.
Seafood abounds here, but warming water temperatures may soon affect existing coral reefs, and the fish and other creatures that call them home. Here, a vendor opens for business at the Oistins Fish Market.
Barbados is rising, but almost certainly not fast enough to outpace ongoing rising of the sea. This fisherman’s spot could be permanently under water in coming decades.
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Claudia
7 years ago
What will happen to New Zealand if global temperatures rise to 2 degrees or more, say up to 4 degrees? Can anyone foretell? Is it possible that poles flip and NZ will be under snow? What is possible?
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What will happen to New Zealand if global temperatures rise to 2 degrees or more, say up to 4 degrees? Can anyone foretell? Is it possible that poles flip and NZ will be under snow? What is possible?