Super @RKunzig “whatdunnit” on competing camps and Younger Dryas cool spell. Check this lede:
Why did mammoths, mastodons, and other mega-beasts vanish from North America?
Was it because:
1) humans killed them;
2) they couldn’t hack the climate after the Ice Age ended; or
3) an exploding comet ignited continent-wide wildfires, sent hundred-mile-an-hour winds and tornadoes howling across the land, and shattered the North American ice sheet, while also maybe gouging out the Great Lakes?
Let’s talk about option number three. READ ON!
In contrast to work in PA, Duke/USGS study finds no groundwater issues in Arkansas #fracking regions. Main conclusions:
• Methane in groundwater is low and likely associated with shallow aquifer processes.
• No relationship between methane and salinity in groundwater and shale-gas wells.
• δ13CCH4 and δ13CDIC suggest biogenic origin for dissolved methane.
• Water- aquifer rock interaction controls majority of water chemistry.
More from Duke U. news release:
Previous peer-reviewed studies by Duke scientists found direct evidence of methane contamination in drinking water wells near shale-gas drilling sites in the Marcellus Shale basin of northeastern Pennsylvania, as well as possible connectivity between deep brines and shallow aquifers, but no evidence of contamination from fracking fluids.
"The hydrogeology of Arkansas’s Fayetteville Shale basin is very different from Pennsylvania’s Marcellus Shale," [Avner] Vengosh noted. Far from contradicting the earlier studies, the Arkansas study "suggests that variations in local and regional geology play major roles in determining the possible risk of groundwater impacts from shale gas development. As such, they must be taken into consideration before drilling begins."
Human factors — such as the drilling techniques used and the integrity of the wellbores – also likely play a role in preventing, or allowing, gas leakage from drilling sites to shallow aquifers, Vengosh said.
Jim Hansen of NASA has sent a fresh warning to his e-mail list (details below) concluding in a draft paper that past warm spells between ice ages were barely warmer than the present, with a host of implications. I’m sending a query around to a batch of paleoclimatologists and geologists to get reactions. Here’s the Hansen note with links to this paper and another:
Robert J. Geller of the University of Tokyo calls on seismologists in Japan to stop making long-term earthquake forecasts using flawed methodology, to scrap futile efforts at short-term earthquake prediction, and to stop treating the hypothetical ‘Tokai earthquake’ as if it were real. Geller writes in a Comment piece published online in advance of print this week in Nature. (This is from the journal’s news summary, just released when embargo lifted on the forthcoming issue.) More:
"We don’t think that large, global earthquake clusters are anything more than coincidence."
Tom Parsons, a veteran earthquake researcher for the U.S. Geological Survey, comments on his new work concluding that global clusters of powerful earthquakes are statistical flukes, with no apparent relationship:
No Evidence for Large Triggered Earthquakes Across the Globe
MENLO PARK, Calif. — New scientific research concludes that large earthquakes do not increase the global seismic hazard for more damaging earthquakes far from the mainshock. Although large aftershocks close to the mainshock remain highly probable following an earthquake, and small earthquakes less than magnitude 5 can be triggered at great distances, scientists at the U.S. Geological Survey and the University of Texas at El Paso found no significant increase in the rate of large earthquakes happening farther away than two to three times the length of the ruptured fault that caused the mainshock.
“Based on the evidence we’ve seen in our research, we don’t think that large, global earthquake clusters are anything more than coincidence,” says Tom Parsons, USGS geophysicist and author of the new study that appears in this month’s journal, “Nature Geoscience.”
The study looked at all M5 or greater earthquakes worldwide potentially associated with a M7 or greater event over the past 30 years. Using these data, scientists compared the timing of seismic wave arrivals and the occurrence of large earthquakes worldwide and found no correlation.
The study, “Absence of remotely triggered large earthquakes beyond the mainshock region,” appears in a current edition of “Nature Geoscience.” The research was conducted by Tom Parsons, U.S. Geological Survey and Aaron A. Velasco, University of Texas, El Paso.