Fossil Corals Show Catastrophic Sea-Level Rise?

[Tiffany Bell]

Fossil Corals Show Catastrophic Sea-Level Rise?
Brian Handwerk
for National Geographic News

April 15, 2009
Fossil coral reefs at a Mexican theme park "confirm" that sea levels rose rapidly about 121,000 years ago, according to a controversial new study.

Previous research on fossil reefs had shown that sea levels surged by 13 to 19 feet (4 to 6 meters) near the end of the last time period between ice ages, known as an interglacial period. But researchers have been unsure whether this sea-level rise happened quickly or gradually.

By mapping the ages and locations of ancient corals at Xcaret, an eco-park in the Yucatán Peninsula, Paul Blanchon of the National Autonomous University of Mexico, and colleagues, were able to chart when the reefs died and were replaced by others on higher ground.

Their data suggest that sea levels rose by about 10 feet (3 meters) in 50 years—much faster than the current annual rate of 0.08 to 0.1 inch (2 to 3 millimeters).

Because this event happened during an interglacial period—similar to the one we're in currently—the find boosts the chances that today's melting ice sheets could trigger rapid sea-level rise, the study authors say.

But not all experts on corals and climate are convinced by the new study.

Tad Pfeffer, of the University of Colorado at Boulder, noted that Blanchon's team couldn't directly measure the rate of sea level change around the Mexican corals, because the age estimates aren't accurate enough.

Instead the study authors compared changes seen in Xcaret to those seen in reefs with well-established ages in the Bahamas.

"It's an interesting idea, but one that for me is only suggestive and not compelling," Pfeffer said.

"I'd want to see something more solid than this if I'm going to buy the idea of such rapid sea level rise at the time [of the last interglacial]."


Even if the new study is confirmed, Pfeffer added, more research would be needed to determine if rapid sea-level rise 121,000 years ago provides evidence that similar changes can happen now.

"And of course, when would 'now' be?" he asked.

"'In the next few decades' vs. 'the next few thousand years' are both 'now' on the time scales at which glacial and interglacial periods are defined, but are very different situations in terms of how we determine responses."

Mike Kearney, of the University of Maryland, said it's "within the realm of possibility" that global warming will trigger a sudden collapse of the West Antarctic ice sheet, which could lead to a rapid increase in sea levels like that predicted by the new study.

(Related: "PHOTOS: Jamaica-Size Ice Shelf Breaks Free")

"But the big unknown is whether any of the things we think we know about the Antarctic ice sheet prove to be true," Kearney cautioned.

"One camp says [rapid sea-level rise] could happen, another camp says it would take thousands of years. I'm not sure what the conventional wisdom is right now. It depends on who you talk to."

Findings appear in this week's issue of the journal Nature.

http://news.nationalgeographic.com/news/2009/04/090415-sea-levels-catastrophic.html

[Tiffany Bell]

A split-level view shows corals growing in the shallow waters around American Samoa.

Odd growth patterns in ancient reefs in Mexico show that sea levels rose rapidly about 121,000 years ago, according to a controversial study published in April 2009.

Photograph by Randy Olson

[BlueHue]

Dear    Tiffany

 in the " BlueHue " Theory- rules -of- Thumb  series:

mean-SEA LEVEL RISE  AXIOMA is thus:

from: 10.000 till 855 bc one Hundred meters,( in 9.000 years time-lapse ( ! )
from: 855 till 755 bc 'only' 50 meters ( in a hundred years time-lapse.}

Dead coralreef beds with minoan shipwrecks everywhere are proof of this" rapid sea level rise "

[Bianca]

                                       Mystery Undersea Extinction Cycle Discovered






John Roach
for National Geographic News
March 9, 2005

Robert Rohde and Richard Muller are vexed. For the past 542 million years the number of animal species living in the world's oceans has risen and fallen in a repeating pattern, and the scientists haven't the foggiest idea why.

"I wish I knew what it all meant," said Muller, who is a professor of physics at the University of California, Berkeley.

The pattern includes a rise and fall of marine animal diversity every 62 million years and a weaker cycle of rising and falling marine diversity, which repeats every 140 million years. The researchers think that expanding and retreating glaciers may explain the 140-million-year cycle, but they are stumped over what drives the 62-million-year cycle.

The declines in the 62-million-year cycle correspond with some of the best known mass extinctions on Earth.

Among them are the die-off caused by the asteroid or comet widely believed to have doomed the dinosaurs 65 million years ago and the "Great Dying" of 250 million years ago. During the Great Dying, some unknown cause wiped out most life on Earth.

The patterns found in the new study identify five additional declines in marine-animal diversity. Muller and his graduate student Rohde say the pattern is too regular to occur by chance. But they have failed to find a plausible explanation for its existence.

The pair looked for a pattern of asteroid and comet impacts, global climate shifts, volcanic eruptions, fluctuating sea levels, changes in the total amount of plant and animal life, and the reshuffling of the continents. None fit.

Muller went so far as to purchase a lava lamp, plug it in, and studiously gaze at how often the blobs rose to the surface. He thought perhaps magma bubbles from the Earth's core rise in a cyclical pattern. "It's not regular enough," he said.

The researchers' report will appear in tomorrow's issue of the science journal Nature.

[Bianca]

Computer Analysis



Rohde and Muller started with Sepkoski's compendium, a database of every marine-animal fossil ever found. Then they correlated this database with the dates of when the species appeared and disappeared from the fossil record. The dates were gleaned from the International Commission on Stratigraphy's 2004 timescale.

"We took all the best data and put it with the best timescale. It's not what we were looking for, but [Rohde] plotted it up and there it was. We've been wrestling with it ever since," Muller said.

Wolfgang Kiessling is a paleontologist with the Museum of Natural History at Humboldt University in Berlin, Germany. He said Rohde and Muller's statistical analysis is robust and that the 62-million-year cycle is distinct in the data—but its finding comes as a surprise.

"Looking at my own analysis of Sepkoski's compendium, I do see a similar pattern, although I have resolved the data more coarsely," he said. "Perhaps the periodicity did not strike my eye because so many previous analyses on regularities in extinctions and diversity have proved erroneous in the past."

John Alroy coordinates the Paleobiology Database at the National Center for Ecological Analysis and Synthesis in Santa Barbara, California. He is skeptical about the accuracy of Rohde and Muller's statistical analysis. He does, however, applaud their exhaustive search for the cycle's cause.

"Nice of them to argue in detail that there is no known mechanism, out of many considered that could possibly explain this pattern," he said.

Muller invites the scientific community at large to help find an answer and is working to make publicly available their computerized database of Sepkoski's compendium correlated with the International Commission on Stratigraphy's 2004 timescale.

[Bianca]

Shrinking Habitat



Wolfgang Kiessling, a paleontologist at Humboldt University in Berlin, Germany, is an expert on mass-extinction events.

While he doubts that changing sea levels alone drive mass die-offs, he said the study is important because it shows that habitat size is relevant to species diversity.

"The bigger habitat you have, the more species you can sustain—and when habitat shrinks, you get increased risk of extinction," said Kiessling, who was not involved in the study.

However, he added, changes in sea level alone are insufficient to explain the magnitude of mass-extinction events such as the one 65 million years ago, which wiped out the dinosaurs. (See "Volcano Theory of Dino Die-Off Gets New Support" [November 5, 2007].)

"There's got to be more," he said, "something like supervolcanoes, asteroid impacts. … "

[BlueHue]

dear Tiffany/ Bianca,

Sealevel rise is caused by the Moon's eratic orbit
 around 1.000 bc when the sea was 50 meters lower
after the moon hit earth briefly  the mountain lakes were poured out and hightened the sea level by 50 meters inbetween 855 / 755 bc

in paleo geology this event was named the quarternary lake( dams-)burst. in this case climate change was not caused by global warming but by seismic shocks and seafloorspreading

Dear    Tiffany

 in the " BlueHue " Theory- rules -of- Thumb  series:

mean-SEA LEVEL RISE  AXIOMA is thus:

from: 10.000 till 855 bc one Hundred meters,( in 9.000 years time-lapse ( ! )
from: 855 till 755 bc 'only' 50 meters ( in a hundred years time-lapse.}

Dead coralreef beds with minoan shipwrecks everywhere are proof of this" rapid sea level rise "

[Bianca]

                                        P R O V E   IT ,   A S I N O !!!





NO REFERENCES, NO LINK -


                                                          NO PROOF!!!