Administravia: Cambrian and Precambrian papers

I have a bunch of them that are interesting.  However, some are a bit old.  How much do folks want to see?  I am planning on linking to one per day for the next few as to not cause a surfeit of very early bio/geo posts/links unless someone says otherwise.

New Map of Antarctica's Bedrock

Did Volcanos Cause the Little Ice Age?

In the winter of 1780, New York Harbor froze, allowing people to walk from Manhattan to Staten Island for the first time in recorded history. The deep freeze didn’t just occur in New York: For close to 500 years, beginning around the end of the Middle Ages and lasting into the early 19th century, unusually cold conditions blanketed much of the Northern Hemisphere.

Climate scientists now call this period of cooling the Little Ice Age. When exactly this period began, what triggered it and how it was sustained for so long are matters of much debate. But a new study, published in Geophysical Research Letters, may answer all three puzzles.

“Estimates regarding the onset of the Little Ice Age range from the 13th century to the 16th century,” says Gifford Miller, a climate scientist at the University of Colorado at Boulder and lead author of the new study. “More exact dates have been totally ambiguous and there is little consensus.”

To narrow the date of onset, Miller and colleagues radiocarbon dated dead vegetation emerging from ice caps on Baffin Island in the Canadian Arctic to determine when the plants died due to the initial encroachment of snow and ice. Most of the dates clustered at two periods of time: 1275 and 1450.

“Everybody tends to think of this as a gradual cooling, so we were quite surprised when we got the dates back,” Miller says. During both cold snaps, plants at lower elevations froze at approximately the same time as those at higher elevations, indicating a swift onset. Testing of sediment cores from glacial lakes in Iceland also indicated a change in erosion rates in the late 13th century and again in the 15th century.

Armed with more exact dates, Miller and colleagues pinpointed a likely culprit: a period of active volcanism, starting with an eruption in 1275 and continuing on and off through the early 1800s, with at least four major volcanic eruptions occurring during this time period.

Volcanism is often implicated in periods of abrupt cooling. After the 1991 eruption of Mount Pinatubo in the Philippines, for example, global temperatures dropped by half a degree Celsius due to airborne particulate matter blocking solar radiation. But the effects don’t usually last more than a few years, says David Schneider, a climate scientist at the National Center for Atmospheric Research in Boulder, Colo., who was not involved in the new study.

“Volcanism explains the abruptness but it can’t account for the longevity” of the Little Ice Age, Schneider says. “This has always been the problem with the volcanic explanation of the Little Ice Age. Volcanoes can make it cold but they can’t keep it cold.”

To account for the longevity issue, Miller and colleagues used computer modeling to determine how repeated short-lived episodes of volcanism might trigger a cooling period lasting several centuries. They found that the persistence of cold summers following the eruptions could be explained by a sea ice-ocean feedback originating in the North Atlantic Ocean.

Sustained cooling from repeated eruptions would have caused Arctic sea ice to expand southward until it eventually reached warmer waters and melted. Sea ice contains almost no salt, and when it melts it creates a less-dense freshwater cap over the salty seawater. This cap inhibits mixing and weakens heat transport from the tropics to the North Atlantic, creating a self-sustaining feedback system that could have lasted long after the effects of the volcanic aerosols subsided, Miller says.

Such a scenario is plausible, Schneider says. “This study is really the first to explain how a short-lived event like a volcanic eruption can trigger cooling that lasts for centuries.” However, there are still questions, he says. As of now, the weakest link in the study is the computer modeling, which depends on mere estimates of the size of the volcanic eruptions, Schneider says. There’s no accurate account of volcanic eruptions during this period.

The Little Ice Age is nominally  stated to run from ~1250 AD to ~1850.  That definition moves around a bit on the dates.  Some make it start later (1550).  However, the ending is generally agreed to be around the same time frame.  The most common hypothesis is that the LIA was caused by the variation in solar activity (re Maunder Minimum, but not exclusively).

Link to article.

Younger Dryas Impactor Hypothesis Crashes and Burns

It seemed like such an elegant answer to an age-old mystery: the disappearance of what are arguably North America’s first people. A speeding comet nearly 13,000 years ago was the culprit, the theory goes, spraying ice and rocks across the continent, killing the Clovis people and the mammoths they fed on, and plunging the region into a deep chill. The idea so captivated the public that three movies describing the catastrophe were produced.

But now, four years after the purportedly supportive evidence was reported, a host of scientific authorities systematically have made the case that the comet theory is “bogus.” Researchers from multiple scientific fields are calling the theory one of the most misguided ideas in the history of modern archaeology, which begs for an independent review so an accurate record is reflected in the literature.

“It is an impossible scenario,” says Mark Boslough, a physicist at Sandia Laboratory in Albuquerque, N.M., where he taps the world’s fastest computers for nuclear bomb experiments to study such impacts. His computations show the debris from such a comet couldn’t cover the proposed impact field. In March, a “requiem” for the theory even was published by a group that included leading specialists from archaeology to botany.

Yet, the scientists who described the alleged impact in a hallowed U.S. scientific journal refuse to consider the critics’ evidence — insisting they are correct, even though no one can replicate their work: the hallmark of credibility in the scientific world.

[...]

A new look at the comet claim suggests all of these phenomena may be in play, apparently creating a peculiar bond of desperation as the theory came under increasing attack. Indeed, the team’s established scientists are so wedded to the theory they have opted to ignore the fact their colleague “Allen West” isn’t exactly who he says he is.

West is Allen Whitt — who, in 2002, was fined by California and convicted for masquerading as a state-licensed geologist when he charged small-town officials fat fees for water studies. After completing probation in 2003 in San Bernardino County, he began work on the comet theory, legally adopting his new name in 2006 as he promoted it in a popular book. Only when questioned by this reporter last year did his co-authors learn his original identity and legal history. Since then, they have not disclosed it to the scientific community.

West’s history — and new concerns about study results he was integrally involved in — raise intriguing questions about the veracity of the comet claim. His background is likely to create more doubts about the theory. And the controversy — because it involves the politically sensitive issue of a climate shift — is potentially more broadly damaging, authorities suggest.

[...]

West has no formal appointment at an academic institution. He has said he obtained a doctorate from a Bible college, but he won’t describe it further. Firestone said West has told him he has no scientific doctorate but is self-taught. West’s Arizona attorney refers to him in writing as: “A retired geophysicist who has had a long and distinguished career.”

In the early 1990s, a new-age business West was involved in Sedona, Ariz., failed, and his well-drilling company went bankrupt. Then he ran afoul of California law in small Mojave Desert towns in a scheme with two other men, with court records saying they collected fees up to $39,500 for questionable groundwater reports.

He originally was charged with two felonies for falsely representing himself as a state-licensed geologist but agreed to a no contest plea to a single misdemeanor of false advertising as part of plea bargain in which state records say he was fined $4,500. Two other men in the scam also were sanctioned.

Acknowledging he made a mistake, West has sought to downplay the 9-year-old conviction. And last September, after his impact theory colleagues learned of it, he went back to court in Victorville, Calif., convincing a judge to void the old plea.

After earlier denying any impropriety with his Younger Dryas work, West declined a recent interview request. Last month, he wrote a letter charging it was “highly prejudicial and distorted” to bring up his legal past in the context of his current studies. He is a member of “a group of two dozen dedicated scientists performing cutting-edge, although controversial, research,” he wrote.

...

ouch.

Homo confisio strikes again? Or ought that be Homo audacia?

NOAA Graphics of the Tsunami Wave Height

Thoughts and prayers with the survivors. The bits I have had time to read have been devastating emotionally.

Dear Readers: What Do You Want To See First?

I accomplished some major milestones last week and this cleared off my plate some serious stress and time consumption. It will be replaced with more in the very near future. However, I have a window of time that I can work on other things. I have promised that I would return to doing some paleo posts here.

I have a number of half or three quarters finished posts. I'm considering which ones to finish up and bring online. I'd like to get some feedback from my readers to see what they would like to have first. IDK if I will get to two posts, but I will try. Here are the lists of the ones that are in production that you all can vote on:

1. Not Your Father's Archean: This is about the new research that indicates that the archaen was not what we had thought it was.

2. A Fully Functional Mass Extinction: Talks about the definitions of a mass extinction, its misuse, how they 'work' and some annoying things that scientists and nonscientists ought to avoid when discussing them.

3. The Great Harrowing: The Sixth Mass Extinction: Talking about the mass extinction(s) that are combined into what is being called the Sixth. This clarifies the extinctions that took place at the Pliocene-Pleistocene boundary, the Pleistocene-Holocene, and the ongoing one.

4. An unnamed therocephalian post: This would return to talking about the nonmammalian therapsids like I did with the gorgonopsids and the dicynodonts.

5. An unnamed Xenopermian post: This talks about the environments of the places that we will be highlighting in the ongoing xenopermian alternate paleohistory project.

Pick two please.

One for your first choice that I will get done.

A second for what you'd like me to get to after if I have time.