Younger Dryas cooling period (stadial) — is now persuasively linked to a cosmic impact that occurred within a 100 year period — between 12,835 and 12,735 years before present

© 2015 Peter Free

Citation — to study

James P. Kennetta, Douglas J. Kennett, Brendan J. Culleton, J. Emili Aura Tortosa, James L. Bischoff, Ted E. Bunch, I. Randolph Daniel, Jr., Jon M. Erlandson, David Ferraro, Richard B. Firestone, Albert C. Goodyear, Isabel Israde-Alcántara, John R. Johnson, Jesús F. Jordá Pardo, David R. Kimbel, Malcolm A. LeCompte, Neal H. Lopinot, William C. Mahaney, Andrew M. T. Moore, Christopher R. Moore, Jack H. Ray, Thomas W. Stafford, Jr., Kenneth Barnett Tankersley, James H. Wittke, Wendy S. Wolbach, and Allen West, Bayesian chronological analyses consistent with synchronous age of 12,835–12,735 Cal B.P. for Younger Dryas boundary on four continents, Proceedings of the National Academy of Sciences [PNAS], DOI: 10.1073/pnas.1507146112 (online before print, 27 July 2015)

Citation — to press release

Julie Cohen, A Cataclysmic Event of a Certain Age, University of California – Santa Barbara (27 July 2015)

Cause and date of Younger Dryas stadial now appears to have been reasonably well proven

From the abstract:

The Younger Dryas [see here] impact hypothesis posits that a cosmic impact across much of the Northern Hemisphere deposited the Younger Dryas boundary (YDB) layer, containing peak abundances in a variable assemblage of proxies, including magnetic and glassy impact-related spherules, high-temperature minerals and melt glass, nanodiamonds, carbon spherules, aciniform carbon, platinum, and osmium.

Bayesian chronological modeling was applied to 354 dates from 23 stratigraphic sections in 12 countries on four continents to establish a modeled YDB age range for this event of 12,835–12,735 Cal B.P. [term explained here] at 95% probability.

This range overlaps that of a peak in extraterrestrial platinum in the Greenland Ice Sheet and of the earliest age of the Younger Dryas climate episode in six proxy records, suggesting a causal connection between the YDB impact event and the Younger Dryas.

Two statistical tests indicate that both modeled and unmodeled ages in the 30 records are consistent with synchronous deposition of the YDB layer within the limits of dating uncertainty (∼100 y).

The widespread distribution of the YDB layer suggests that it may serve as a datum layer.

© 2015 James P. Kennetta, Douglas J. Kennett, Brendan J. Culleton, J. Emili Aura Tortosa, James L. Bischoff, Ted E. Bunch, I. Randolph Daniel, Jr., Jon M. Erlandson, David Ferraro, Richard B. Firestone, Albert C. Goodyear, Isabel Israde-Alcántara, John R. Johnson, Jesús F. Jordá Pardo, David R. Kimbel, Malcolm A. LeCompte, Neal H. Lopinot, William C. Mahaney, Andrew M. T. Moore, Christopher R. Moore, Jack H. Ray, Thomas W. Stafford, Jr., Kenneth Barnett Tankersley, James H. Wittke, Wendy S. Wolbach, and Allen West, Bayesian chronological analyses consistent with synchronous age of 12,835–12,735 Cal B.P. for Younger Dryas boundary on four continents, Proceedings of the National Academy of Sciences [PNAS], DOI: 10.1073/pnas.1507146112 (online before print, 27 July 2015) (paragraph split)

Following the investigative tracks

Good science arguably requires determination and sound reasoning:

In a previous paper, Kennett and colleagues conclusively identified a thin layer called the Younger Dryas Boundary (YDB) that contains a rich assemblage of high-temperature spherules, melt-glass and nanodiamonds, the production of which can be explained only by cosmic impact.

[I]n order for the major impact theory to be possible, the YDB layer would have to be the same age globally, which is what this latest paper reports.

“We tested this to determine if the dates for the layer in all of these sites are in the same window and statistically whether they come from the same event,” Kennett said. “Our analysis shows with 95 percent probability that the dates are consistent with a single cosmic impact event.”

All together, the locations cover a huge range of distribution, reaching from northern Syria to California and from Venezuela to Canada. Two California sites are on the Channel Islands off Santa Barbara.

However, Kennett and his team didn’t rely solely on their own data, which mostly used radiocarbon dating to determine date ranges for each site. They also examined six instances of independently derived age data that used other dating methods, in most cases counting annual layers in ice and lake sediments.

Two core studies taken from the Greenland ice sheet revealed an anomalous platinum layer, a marker for the YDB. A study of tree rings in Germany also showed evidence of the YDB, as did freshwater and marine varves [see explanation here], the annual laminations that occur in bodies of water. Even stalagmites in China displayed signs of abrupt climate change around the time of the Younger Dryas cooling event.

“The important takeaway is that these proxy records suggest a causal connection between the YDB cosmic impact event and the Younger Dryas cooling event,” Kennett said.

“In other words, the impact event triggered this abrupt cooling.”

© 2015 Julie Cohen, A Cataclysmic Event of a Certain Age, University of California – Santa Barbara (27 July 2015) (extracts)

The moral? — Diligence and technique can pay off in satisfying ways

This team should be justifiably proud of its work.

Low level of brain-derived neurotrophic factor (BDNF) in the blood —sampled within the first 24 hours post-trauma — appears to predict the severity of subsequent brain injury symptoms — says Johns Hopkins

© 2015 Peter Free

Citation — to study

Frederick Kofi Korley, Ramon Diaz-Arrastia, Alan H.B. Wu, John K. Yue, Geoffrey T. Manley, Haris I. Sair, Jennifer Van Eyk, Allen D. Everett, David O Okonkwo, Alex Valadka, Wayne A Gordon, Andrew Maas, Pratik Mukherjee, Esther Lim Yuh, Hester Lingsma, Ava M. Puccio, and David M. Schnyer, Circulating Brain Derived Neurotrophic Factor (BDNF) Has Diagnostic and Prognostic Value in Traumatic Brain Injury, Journal of Neurotrauma, doi:10.1089/neu.2015.3949 (ahead of print, 10 July 2015)

Citation — to press release

Shawna Williams and Helen Jones, Blood Test Predicts Prognosis for Traumatic Brain Injuries, Johns Hopkins Medicine (30 July 2015)

The gist — should we test blood levels of brain-derived neurotrophic factor post-head injury?

From the abstract:

Day-of-injury serum BDNF [brain-derived neurotrophic factor] is associated with TBI diagnosis and also provides 6-month prognostic information regarding recovery from TBI.

Incomplete recovery was defined as having either post-concussive syndrome (PCS) [see here] or a Glasgow Outcome Scale Extended (GOSE) [see here] score<8 at 6 months.

Thus, day-of-injury BDNF values may aid in TBI risk stratification.

© 2015 Frederick Kofi Korley, Ramon Diaz-Arrastia, Alan H.B. Wu, John K. Yue, Geoffrey T. Manley, Haris I. Sair, Jennifer Van Eyk, Allen D. Everett, David O Okonkwo, Alex Valadka, Wayne A Gordon, Andrew Maas, Pratik Mukherjee, Esther Lim Yuh, Hester Lingsma, Ava M. Puccio, and David M. Schnyer, Circulating Brain Derived Neurotrophic Factor (BDNF) Has Diagnostic and Prognostic Value in Traumatic Brain Injury, Journal of Neurotrauma, doi:10.1089/neu.2015.3949 (ahead of print, 10 July 2015) (at Abstract) (reordered extracts)

Arguably a prognostic advance over what we do now

From Johns Hopkins Medicine:

TBIs [traumatic brain injuries] can range from mild concussions — causing only a headache or temporary blurred vision — to much more severe injuries — causing seizures, confusion, memory and attention problems, muscle weakness, or coma for many months. These symptoms, whether mild or more severe, are generally caused by damaged brain cells.

Until now, most physicians have relied on CT scans and patients’ symptoms to determine whether to send them home and have them resume their usual activities or take extra precautions. However, CT scans can only detect bleeding in the brain, not damage to brain cells, which can happen without bleeding.

“A typical situation is that someone comes to the emergency department with a suspected TBI, we get a CT scan, and if the scan shows no bleeding, we send the patient home,” says [Frederick] Korley.

“However, these patients go home and continue having headaches, difficulty concentrating and memory problems, and they can’t figure out why they are having these symptoms after doctors told them everything was fine.”

Korley and collaborators around the country wanted to know if a blood test could better predict which patients would have ongoing brain injury-related problems, to provide better treatment for them. So they measured the levels of three proteins that they suspected play a role in brain cell activity in more than 300 patients with a TBI and 150 patients without brain injuries. Then, they followed those with a TBI for the next six months.

Levels of one protein, called brain-derived neurotrophic factor (BDNF), taken within 24 hours of someone’s head injury, could predict the severity of a TBI and how a patient would fare, they found.

While healthy people averaged 60 nanograms per milliliter of BDNF in their bloodstreams, patients with brain injuries had less than one-third of that amount, averaging less than 20 nanograms per milliliter, and those with the most severe TBIs had even lower levels, around 4 nanograms per milliliter.

Moreover, patients with high levels of BDNF had mostly recovered from their injuries six months later. But in patients with the lowest levels of BDNF, symptoms still lingered at follow-up. The results suggest that a test for BDNF levels, administered in the emergency room, could help stratify patients.

“The advantage of being able to predict prognosis early on is that you can advise patients on what to do, recommend whether they need to take time off work or school, and decide whether they need to follow up with a rehab doctor or neurologist,” Korley says.

In addition, it could help decide which patients to enroll in clinical trials for new drugs or therapies targeting severe TBIs.

“We looked at that very first blood sample obtained within 24 hours of an injury,” he says.

“But for BDNF to be used as a surrogate outcome, we’ll have to see what happens to BDNF blood levels down the line, at one, three or six months after the injury.” He and his collaborators have already started collecting data for those prospective studies, he adds.

Korley would like to follow up with more research on why, at a molecular level, brain injuries lower levels of BDNF in the blood and whether things known to increase BDNF levels — including exercise and omega-3 fatty acids — could help treat TBIs. He also wants to know whether changes in BDNF levels over time can be a proxy for recovery and if they could be used to gauge the effectiveness of an intervention.

© 2015 Shawna Williams and Helen Jones, Blood Test Predicts Prognosis for Traumatic Brain Injuries, Johns Hopkins Medicine (30 July 2015) (partially resequenced extracts)

The moral? — This finding suggests fertile research opportunities

What mechanism causes such a presumably abrupt drop in brain-derived neurotrophic factor? Or is the perceived drop a misimpression, meaning that those with noticeable head injury symptoms were already predisposed to suffering bad consequences?

Sorting this out will be physiologically and statistically challenging.

Hubble Space Telescope — sees cosmic wind stripping a spiral galaxy — of the gas required for new star formation

© 2015 Peter Free

30 July 2015

Citation — to study

Jeffrey D. P. Kenney, Anne Abramson, and Hector Bravo-Alfaro, Hubble Space Telescope and Hi Imaging of Strong Ram Pressure Stripping in the Coma Spiral NGC 4921: Dense Cloud Decoupling and Evidence for Magnetic Binding in the ISM, Astronomical Journal 150(2): 59, DOI: 10.1088/0004-6256/150/2/59 (August 2015)

Citation — to press release

Jim Shelton, Dust pillars of destruction reveal impact of cosmic wind on galaxy evolution, YaleNews – Yale University (27 July 2015)

A picture is worth a thousand words and suppositions?

From the press release:

Astronomers have long known that powerful cosmic winds can sometimes blow through galaxies, sweeping out interstellar material and stopping future star formation. Now they have a clearer snapshot of how it happens.

Yale astronomer Jeffrey Kenney looked at the way the cosmic wind is eroding the gas and dust at the leading edge of the galaxy.

[His] analysis is based on Hubble images of a spiral galaxy in the Coma cluster, located 300 million light years from Earth.

[W]ind, or ram pressure, is caused by the galaxy’s orbital motion through hot gas in the cluster.

“On the leading side of the galaxy, all the gas and dust appears to be piled up in one long ridge, or dust front. But you see remarkable, fine scale structure in the dust front,” Kenney explained.

“There are head-tail filaments protruding from the dust front. We think these are caused by dense gas clouds becoming separated from lower density gas.”

“We’re seeing this decoupling, clearly, for the first time.”

Cosmic wind can easily push low-density clouds of interstellar gas and dust, but not high-density clouds. As the wind blows, denser gas lumps start to separate from the surrounding lower density gas which gets blown downstream. But apparently, the high and low-density lumps are partially bound together, most likely by magnetic fields linking distant clouds of gas and dust.

Because gas is the raw material for star formation, its removal stops the creation of new stars and planets.

© 2015 Jim Shelton, Dust pillars of destruction reveal impact of cosmic wind on galaxy evolution, YaleNews – Yale University (27 July 2015) (resequenced extracts)

The moral? — We never outgrown the utility of the book’s pictures

Astronomer Jeffrey Kennedy’s reasoning makes sense to me.

Chesapeake Bay area “forebulge collapse” — and its implications for Washington DC’s date with rising salt water — plus one geologist’s sardonic poke at the United States’ arguably brain dead Congress

© 2015 Peter Free

Citation — to study

Benjamin D. DeJong, Paul R. Bierman, Wayne L. Newell, Tammy M. Rittenour, Shannon A. Mahan, Greg Balco, and Dylan H. Rood, Pleistocene relative sea levels in the Chesapeake Bay region and their implications for the next century, GSA Today 25(8): 4-10, DOI: 10.1130/GSATG223A.1 (August 2015)

Citation — to press release

Joshua E. Brown, Washington, D.C., Sinking Fast, Adding to Threat of Sea-Level Rise, University of Vermont (28 July 2015)

“Oops, we’re sinking!”

From Joshua Brown’s University of Vermont press release:

New research confirms that the land under the Chesapeake Bay is sinking rapidly and projects that Washington, D.C., could drop by six or more inches in the next century—adding to the problems of sea-level rise.

For sixty years, tide gauges have shown that sea level in the Chesapeake is rising at twice the global average rate and faster than elsewhere on the East Coast. And geologists have hypothesized for several decades that land in this area, pushed up by the weight of a pre-historic ice sheet to the north, has been settling back down since the ice melted.

The new study—based on extensive drilling in the coastal plain of Maryland—confirms this hypothesis, and provides a firm estimate of how quickly this drop is happening.

Washington’s woes come from what geologists call “forebulge collapse.”

During the last ice age, a mile-high North American ice sheet, that stretched as far south as Long Island, N.Y., piled so much weight on the Earth that underlying mantle rock flowed slowly outward, away from the ice. In response, the land surface to the south, under the Chesapeake Bay region, bulged up.

Then, about 20,000 years ago, the ice sheet began melting away, allowing the forebulge to sink again.

© 2015 Joshua E. Brown, Washington, D.C., Sinking Fast, Adding to Threat of Sea-Level Rise, University of Vermont (28 July 2015) (paragraphs split)

The research team’s logic and forecast

From the abstract:

[W]e applied a suite of dating methods to the stratigraphy of the Blackwater National Wildlife Refuge, one of the most rapidly subsiding and lowest-elevation surfaces bordering Chesapeake Bay.

Data indicate that the region was submerged at least for portions of marine isotope stage (MIS) 3 (ca. 60–30 ka) [—see definitions here—], although multiple proxies suggest that global sea level was 40–80 m lower than present.

Today MIS 3 deposits are above sea level because they were raised by the Last Glacial Maximum forebulge, but decay of that same forebulge is causing ongoing subsidence.

These results suggest that glacio-isostasy controlled relative sea level in the mid-Atlantic region for tens of thousands of years following retreat of the Laurentide Ice Sheet [see here] and continues to influence relative sea level in the region.

Thus, isostatically [see explanation here] driven subsidence of the Chesapeake Bay region will continue for millennia, exacerbating the effects of global sea-level rise and impacting the region’s large population centers and valuable coastal natural resources.

© 2015 Benjamin D. DeJong, Paul R. Bierman, Wayne L. Newell, Tammy M. Rittenour, Shannon A. Mahan, Greg Balco, and Dylan H. Rood, Pleistocene relative sea levels in the Chesapeake Bay region and their implications for the next century, GSA Today 25(8): 4-10, DOI: 10.1130/GSATG223A.1 (August 2015) (at Abstract) (paragraph split)

The practical implication — waders in the District of Columbia

From the press release:

“Right now is the time to start making preparations,” said [Benjamin] DeJong.

“Six extra inches of water really matters in this part of the world,” he says—adding urgency to the models of the Intergovernmental Panel on Climate Change that project roughly one to three or more feet of global sea-level rise by 2100 from global warming.

© 2015 Joshua E. Brown, Washington, D.C., Sinking Fast, Adding to Threat of Sea-Level Rise, University of Vermont (28 July 2015) (paragraph split)

Tellin’ it like it is

Geologist Paul Bierman took a (legitimate) poke at Congress:

“It’s ironic that the nation’s capital—the place least responsive to the dangers of climate change—is sitting in one of the worst spots it could be in terms of this land subsidence.

“Will the Congress just sit there with their feet getting ever wetter?

“What’s next, forebulge denial?”

© 2015 Joshua E. Brown, Washington, D.C., Sinking Fast, Adding to Threat of Sea-Level Rise, University of Vermont (28 July 2015) (extracts)

The moral? — Science raises issues that government institutions often do not want to deal with

“Forebulge denial.”

I love the phrase. Thank you, Dr. Bierman.

In 2013, 73 percent of Massachusetts honey bee pollen contained neonicotinoid pesticides — and 72 percent of their honey did

© 2015 Peter Free

Citation — to study

Chensheng (Alex) Lu, Chi-Hsuan Chang, Lin Tao, and Mei Chen, Distributions of neonicotinoid insecticides in the Commonwealth of Massachusetts: a temporal and spatial variation analysis for pollen and honey samples, Environmental Chemistry, DOI: 10.1071/EN15064 (online early, 24 July 2015)

Citation — to press release

Marge Dwyer, Pesticides found in most pollen collected from foraging bees in Massachusetts, Harvard School of Public Health (23 July 2015)

Honing in on a main cause of European honeybee colony collapse disorder?

I have addressed this environmental problem a few times before. See here.

This study tosses neonicotinoid pesticides firmly into the picture in Massachusetts

From the paper’s stated “environmental context” and abstract:

Neonicotinoids are a group of widely used insecticides that have been implicated in the deterioration of honeybee health and the declining number of honeybee colonies worldwide. We wanted to find out whether neonicotinoids are commonly present in pollen and honey, which are the main food sources for bees.

In this study, we aimed to assess temporal and spatial variations of neonicotinoids in pollen collected across the Commonwealth of Massachusetts.

Monthly pollen samples and a honey sample were collected between April and August 2013 from 62 volunteered hives and analysed for eight neonicotinoids.

We utilised the relative potency factor (RPF) method to integrate individual neonicotinoids into a single measurement of imidaclopridRPF. We then analysed the spatial and temporal variations of imidaclopridRPF in pollen using the response profile analysis.

Overall, 73 % of pollen and 72 % of honey samples contained at least one detectable neonicotinoid.

We found that 49, 20 and 4 % of pollen samples contained one, two and three neonicotinoids respectively.

In honey, we detected that 57 and 15 % of samples contained one and two neonicotinoids respectively.

Considering the ubiquitous [use] of neonicotinoids in the environment and their effects on bees at the sub-lethal levels, it is prudent to identify ways to minimise the uses of neonicotinoids in order to reduce the risk of neonicotinoid exposure to honeybees.

© 2015 Chensheng (Alex) Lu, Chi-Hsuan Chang, Lin Tao, and Mei Chen, Distributions of neonicotinoid insecticides in the Commonwealth of Massachusetts: a temporal and spatial variation analysis for pollen and honey samples, Environmental Chemistry, DOI: 10.1071/EN15064 (online early, 24 July 2015) (at environmental context and abstract) (paragraphs split)

In more detail

From Harvard’s School of Public Health:

Previous studies analyzed either stored pollen collected from hives or pollen samples collected from bees at a single point in time.

In this study, the Harvard Chan School researchers looked at pollen samples collected over time—during spring and summer months when bees forage—from the same set of hives across Massachusetts.

Collecting pollen samples in this way enabled the researchers to determine variations in the levels of eight neonicotinoids and to identify high-risk locations or months for neonicotinoid exposure for bees. To do so, the researchers worked with 62 Massachusetts beekeepers who volunteered to collect monthly samples of pollen and honey from foraging bees, from April through August 2013, using pollen traps on the landings of beehives. The beekeepers then sent the samples to the researchers.

The researchers analyzed 219 pollen and 53 honey samples from 62 hives, from 10 out of 14 counties in Massachusetts.

They found neonicotinoids in pollen and honey for each month collected, in each location—suggesting that bees are at risk of neonicotinoid exposure any time they are foraging anywhere in Massachusetts.

The most commonly detected neonicotinoid was imidacloprid, followed by dinotefuran.

Particularly high concentrations of neonicotinoids were found in Worcester County in April, in Hampshire County in May, in Suffolk County in July, and in Essex County in June, suggesting that, in these counties, certain months pose significant risks to bees.

The new findings suggest that neonicotinoids are being used throughout Massachusetts.

Not only do these pesticides pose a significant risk for the survival of honey bees, but they also may pose health risks for people inhaling neonicotinoid-contaminated pollen, [Chensheng “Alex”] Lu said.

“The data presented in this study should serve as a basis for public policy that aims to reduce neonicotinoid exposure,” he said.

© 2015 Marge Dwyer, Pesticides found in most pollen collected from foraging bees in Massachusetts, Harvard School of Public Health (23 July 2015)

The moral? — “may also pose health risks for people inhaling neonicotinoid-contaminated pollen”

Cynically speaking, if our frequently lackadaisical agricultural policies — regarding the use of environmental poisons — kill off bunches of pollen breathing people, bees might eventually get a break.