reply to Russell, and all, a colleague of mine in network security circles, Doug McKenna, is the son of another McKenna, who conjectured another killing mechanism for the Dino-Killer of 65 MYa: The senior McKenna proposed decades ago that ejecta from the Chixulub impact (which is known to reached the antipodes, as shown by the throw of tektites) emitted enough IR during re-entry, for long enough (hours or days) to have turned the surface of the Earth into an oven set on "broil". The thermal energy deposited was enough to set every forest on fire (denoted by the worldwide layer of carbon), and kill every non-burrowing, non-swimming creature in the open. I've heard tell that this hypothesis explains the peculiar peaks and gaps in mortality that are observed in the fossil record.
Since the original subject of the post begins with "SRM", I felt this topic about radiation from space would be on-point. PS. I regret I will miss the pleasure of all y'all's company at the Gordon Conference. On my last geothermal trip to East Africa, from whence I've just returned, I contracted some respiratory bug (unknown primary) and pneumonia (known secondary). So probably more prudent that I don't expose you to that at close range for days and days. -- Robert G Kennedy III, PE 1994 AAAS/ASME Congressional Fellow U.S. House Subcommittee on Space www.ultimax.com On Monday, July 10, 2017 at 1:48:48 PM UTC-4, Russell Seitz / Bright Water wrote: > > " Today, the primary sources of mercury are coalburning power plants and > other anthropocentric activitiesÍž " > > Just barely- more atmospheric mercury arises from hydrothermal > emissions - hot springs , than high temperature volcanic euptions , and > deliberate mercury mining for industrial use in batteries , fluorescent > lamps and gold mining exceeds the flux from fossil fuel burning. > > It is notable that the natural emissions are concentrated along active > subduction zones and in accretionary terranes including California . > > > On Wednesday, May 31, 2017 at 10:51:10 AM UTC-4, Renaud de_Richter wrote: >> >> *Anyone concerned by the idea that people might try to combat global >> warming by injecting tons of sulfate aerosols* >> *into Earth's atmosphere may want to read an article in the May 1, 2017 >> issue of the journal Geology.* >> >> https://www.sciencedaily.com/releases/2017/05/170530082345.htm >> http://geology.gsapubs.org/content/early/2017/05/01/G38940.1.full.pdf >> >> In the article, a Washington University scientist and his colleagues >> describe what happened when pulses of >> atmospheric carbon dioxide and sulfate aerosols were intermixed at the >> end of the Ordivician geological period more than 440 million years ago. >> The counterpart of the tumult in the skies was death in the seas. At a >> time when most of the planet north of the >> tropics was covered by an ocean and most complex multicellular organisms >> lived in the sea, 85 percent of marine >> animal species disappeared forever. The end Ordivician extinction, as >> this event was called, was one of the five >> largest mass extinctions in Earth's history. >> Although the gases were injected into the atmosphere by massive volcanism >> rather than prodigious burning of fossil >> fuels and under circumstances that will never be exactly repeated, they >> provide a worrying case history that reveals >> the potential instability of planetaryscale climate dynamics. >> Figuring out what caused the end Ordivician extinction or any of the >> other mass extinctions in Earth's history is >> notoriously difficult, said David Fike, associate professor of earth and >> planetary sciences in Arts & Sciences and a coauthor on the paper. >> Because the ancient atmospheres and oceans have long since been altered >> beyond recognition, scientists have to >> work from proxies, such as variations in oxygen isotopes in ancient rock, >> to learn about climates long past. The >> trouble with most proxies, said Fike, who specializes in interpreting the >> chemical signatures of biological and >> geological activity in the rock record, is that most elements in rock >> participate in so many chemical reactions that a >> signal can often be interpreted in more than one way. >> But a team led by David Jones, an earth scientist at Amherst College, was >> able to bypass this problem by >> measuring the abundance of mercury. Today, the primary sources of mercury >> are coalburning power plants and >> other anthropocentric activitiesÍž during the Ordivician, however, the >> main source was volcanism. >> Volcanism coincides with mass extinctions with suspicious frequency, Fike >> said. He is speaking not about an >> isolated volcano but rather about massive eruptions that covered >> thousands of square kilometers with thick lava >> flows, creating large igneous provinces (LIPs). The most famous U.S. >> example of a LIP is the Columbia River Basalt >> province, which covers most of the southeastern part of the state of >> Washington and extends to the Pacific and into Oregon. >> Volcanoes are plausible climate forcers, or change agents, because they >> release both carbon dioxide that can produce longterm >> greenhouse warming and sulfur dioxide that can cause shortterm reflective >> cooling. In addition, >> the weathering of vast plains of newly exposed rock can draw down >> atmospheric carbon dioxide and bury it as >> limestone minerals in the oceans, also causing cooling. >> When Jones analyzed samples of rock of Ordivician age from south China >> and the Monitor Range in Nevada, he >> found anomalously high mercury concentrations. Some samples held 500 >> times more mercury than the background >> concentration. The mercury arrived in three pulses, before and during the >> mass extinction. >> But what happened? It had to have been an unusual sequence of events >> because the extinction (atypically) >> coincided with glaciation and also happened in two pulses. >> As the scientists began to piece together the story, they began to wonder >> if the first wave of eruptions didn't push >> Earth's climate into a particularly vulnerable state, setting it up for a >> climate catastrophe triggered by later eruptions. >> The first wave of eruptions laid down a LIP whose weathering then drew >> down atmospheric carbon dioxide. The >> climate cooled and glaciers formed on the supercontinent of Gondwana, >> which was then located in the southern hemisphere. >> The cooling might have lowered the tropopause, the boundary between two >> layers of the atmosphere with different >> temperature gradients. The second wave of volcanic eruptions then >> injected prodigious amounts of sulfur dioxide >> above the tropopause, abruptly increasing Earth's albedo, or the amount >> of sunlight it reflected. >> This led to the first and largest pulse of extinctions. As ice sheets >> grew, sea level dropped and the seas became >> colder, causing many species to perish. >> During the second wave of volcanism, the greenhouse warming from carbon >> dioxide overtook the cooling caused by >> sulfur dioxide and the climate warmed, the ice melted and sea levels >> rose. Many of the survivors of the first pulse of >> extinctions died in the ensuing flooding of habitat with warmer, oxygen >> poor waters. >> The takehome, said Fike, is that the different factors that affect >> Earth's climate can interact in unanticipated ways >> and it is possible that events that might not seem extreme in themselves >> can put the climate system into a >> precarious state where additional perturbations have catastrophic >> consequences. >> *"It's something to keep in mind when we contemplate geoengineering >> schemes to mitigate global warming," said* >> *Fike, who teaches a course where students examine such schemes and then >> evaluate their willingness to deploy them.* >> >> Story Source: >> Materials provided by Washington University in St. Louis. Original >> written by Diana Lutz. Note: Content may be >> edited for style and length. >> >> Journal Reference: >> 1. David S. Jones, Anna M. Martini, David A. Fike, Kunio Kaiho. A >> volcanic trigger for the Late Ordovician >> mass extinction? Mercury data from south China and Laurentia. Geology, >> 2017Íž G38940.1 DOI: 10.1130/G38940.1 >> *http://geology.gsapubs.org/content/early/2017/05/01/G38940.1.full.pdf >> <http://geology.gsapubs.org/content/early/2017/05/01/G38940.1.full.pdf> * >> > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
