Donate Bitcoin

Donate Paypal


PeakOil is You

PeakOil is You

Paleoclimate Thread

Re: Paleoclimate Thread

Unread postby dohboi » Mon 18 Jan 2016, 16:11:04

Thanks for the update. The last I looked, we were acidifying the oceans at the fastest rate for 200 million years, iirc. So now it's 300 m. That's some kind of 'progress' I guess! :) :x :cry: :twisted:
User avatar
dohboi
Harmless Drudge
Harmless Drudge
 
Posts: 19990
Joined: Mon 05 Dec 2005, 04:00:00

Re: Paleoclimate Thread

Unread postby onlooker » Mon 18 Jan 2016, 16:19:00

Dohboi, check out the link I posted on the thread about Human extinction and how it offers the shocking possibility that the epoch of habitability on Earth may be drawing to a close.
"We are mortal beings doomed to die
User avatar
onlooker
Fission
Fission
 
Posts: 10957
Joined: Sun 10 Nov 2013, 13:49:04
Location: NY, USA

Re: Paleoclimate Thread

Unread postby vox_mundi » Tue 16 Feb 2016, 20:53:03

Well, now we know where the methane for the PETM event came from...

Research offers new evidence about the Gulf of Mexico's past

Image

Geologists studying a region in the Mexican state of Veracruz have discovered evidence to explain the origin of the Wilcox Formation, one of Mexico's most productive oil plays, as well as support for the theory that water levels in the Gulf of Mexico dropped dramatically as it was separated from the rest of the world's oceans and the earth entered a period of extreme warming.

The drop in water levels and the warming, known as the Paleocene-Eocene thermal maximum (PETM), occurred around 55.8 million years ago. The Gulf refilled about 850,000 years later.

The researchers said waters in the Gulf dropped at least 650 feet, leaving an exposed area that refilled less than a million years later - the blink of an eye in geologic time.

They conclude the dropping sea levels reduced pressure on hydrate-rich sediments, resulting in a massive methane release.
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late.
User avatar
vox_mundi
Intermediate Crude
Intermediate Crude
 
Posts: 3939
Joined: Wed 27 Sep 2006, 03:00:00

paleoclimatology

Unread postby Whitefang » Sun 04 Feb 2018, 13:31:15

https://en.wikipedia.org/wiki/Paleoclimatology

Paleoclimatology (in British spelling, palaeoclimatology) is the study of changes in climate taken on the scale of the entire history of Earth. It uses a variety of proxy methods from the Earth and life sciences to obtain data previously preserved within things such as rocks, sediments, ice sheets, tree rings, corals, shells, and microfossils. It then uses the records to determine the past states of the Earth's various climate regions and its atmospheric system. Studies of past changes in the environment and biodiversity often reflect on the current situation, specifically the impact of climate on mass extinctions and biotic recovery.[1]


https://en.wikipedia.org/wiki/Early_anthropocene

The Early Anthropocene Hypothesis (sometimes called Early Anthropogenic) was proposed by William Ruddiman.[1] It posits that the Anthropocene era, as some scientists call the most recent period in Earth's history when the activities of the human race first began to have a significant global impact on Earth's climate and ecosystems, did not begin in the eighteenth century with advent of coal-burning factories and power plants of the industrial era, as was commonly assumed, but dates back to 8,000 years ago, triggered by intense farming activities after agriculture became widespread. It was at that time that atmospheric greenhouse gas concentrations stopped following the periodic pattern of rises and falls that had accurately characterized their past long-term behavior, a pattern that is explained by natural variations in Earth's orbit known as Milankovitch cycles.


http://www.realclimate.org/index.php/ar ... an-update/

For over a decade, paleoclimate scientists have argued whether the warmth of the last several thousand years was natural or anthropogenic. This brief comment updates that debate, also discussed earlier at RC: Debate over the Early Anthropogenic Hypothesis (2005) and An Emerging View on Early Land Use (2011). The graph below outlines the evolution of that debate through 4 phases.
Realclimate, update on Early Anthropocene Hypothesis, EAH.


Phase 4 (2009-2016) has seen a major shift in viewpoint of published papers: 30 papers favor aspects of the EAH, 6 papers oppose it, and 5 are in the middle. Most of the phase 4 papers that oppose the hypothesis or are ‘in the middle’ are based on modeling studies. Many of the 30 supporting papers are broad-scale compilations of archaeological and paleoecological evidence:
* The average GHG trends from 7 previous interglaciations show CO2 and CH4 decreases, in contrast to the late Holocene increases;
* Interglacial stage 19, the closest Holocene analog, shows decreases in CH4 and CO2, and the CO2 decrease closely matches the 2003 EAH prediction;
* CH4 emissions from Asian rice paddies account for 70% of the observed CH4 rise from 5000 to 1000 years ago
* historical data show that early per-capita land use was at least 4 times larger than assumed in several phase-3 land use simulations
* a recent land use simulation based on historical evidence accounts for more than half the CO2 anomaly originally proposed in the EAH;
* pollen evidence shows nearly complete deforestation in north-central Europe before the industrial era began;
* δD and δ18O trends show anomalous late Holocene warmth compared to cooling trends in prior interglaciations, in agreement with A-OGCM simulations of the warming effect of the anthropogenic CO2 and CH4 trends.


I think it's pretty safe to say that we, humans, started or lighted the fuse on abrupt climate change that we are experiencing now. After Eden, expelled from Paradise..........into the dark that will likely follow once we, Earth gears up and we are all in the midst of a cold to heathouse flipflop.
User avatar
Whitefang
Tar Sands
Tar Sands
 
Posts: 896
Joined: Fri 12 May 2006, 03:00:00

Re: paleoclimatology

Unread postby Newfie » Sun 04 Feb 2018, 14:15:07

Not thought of that connection. Sort of interesting.
User avatar
Newfie
Forum Moderator
Forum Moderator
 
Posts: 18458
Joined: Thu 15 Nov 2007, 04:00:00
Location: Between Canada and Carribean

Re: paleoclimatology

Unread postby rockdoc123 » Sun 04 Feb 2018, 14:16:38

a recent paper (part 1 of 2) speaking to abrupt climate change as a consequenc of the earth's collision with particles of a comet back during Younger Dryas.

Wolbach, W.S. et al, 2018. Extraordinary biomass burning episode and impact winter triggerd by the younger dryas cosmic impact ~12,800 years ago. 1. Ice cores and glaciers. Jour of Geol, https://doi.org/10.1086/695703

The Younger Dryas boundary (YDB) cosmic-impact hypothesis is based on considerable evidence that Earth collided with fragments of a disintegrating ≥100-km-diameter comet, the remnants of which persist within the inner solar system ∼12,800 y later. Evidence suggests that the YDB cosmic impact triggered an “impact winter” and the subsequent Younger Dryas (YD) climate episode, biomass burning, late Pleistocene megafaunal extinctions, and human cultural shifts and population declines. The cosmic impact deposited anomalously high concentrations of platinum over much of the Northern Hemisphere, as recorded at 26 YDB sites at the YD onset, including the Greenland Ice Sheet Project 2 ice core, in which platinum deposition spans ∼21 y (∼12,836–12,815 cal BP). The YD onset also exhibits increased dust concentrations, synchronous with the onset of a remarkably high peak in ammonium, a biomass-burning aerosol. In four ice-core sequences from Greenland, Antarctica, and Russia, similar anomalous peaks in other combustion aerosols occur, including nitrate, oxalate, acetate, and formate, reflecting one of the largest biomass-burning episodes in more than 120,000 y. In support of widespread wildfires, the perturbations in CO2 records from Taylor Glacier, Antarctica, suggest that biomass burning at the YD onset may have consumed ∼10 million km2, or ∼9% of Earth’s terrestrial biomass. The ice record is consistent with YDB impact theory that extensive impact-related biomass burning triggered the abrupt onset of an impact winter, which led, through climatic feedbacks, to the anomalous YD climate episode.
User avatar
rockdoc123
Expert
Expert
 
Posts: 7685
Joined: Mon 16 May 2005, 03:00:00

Meteor madness

Unread postby Whitefang » Sun 04 Feb 2018, 14:51:47

Thanks for the link Rock D, bit like the past discussion on what caused the great past 5 mass extinctions, ET impacts or abrupt CC by various mechanisms.......CC rules!

Meteor impact, then lot of soot in atmosphere and winter for years, decades?
A blib and I think shortlived as the atmosphere gets clean again.
The methane monster/CO2 wears out in millenia or longer, after all those feedbacks played out, worst case wiping out complex life until a fresh start, I read 30 million years after the great dying, 250 million years ago.

Paper is behind paywall, have not read it except the summary.
User avatar
Whitefang
Tar Sands
Tar Sands
 
Posts: 896
Joined: Fri 12 May 2006, 03:00:00

Re: paleoclimatology

Unread postby onlooker » Sun 04 Feb 2018, 15:16:13

https://www.airspacemag.com/daily-plane ... 180963910/

Nearly 20 extinction events in Earth’s natural history have been analyzed in a new study by David Bond from the University of Hull in the U.K. and Stephen Grasby from the University of Calgary in Canada. They found that most of the events seen in the geologic record, starting about 500 million years ago and extending until today, can be linked to periods of massive volcanic activity, which caused global warming of the atmosphere together with acidification and oxygen depletion in Earth’s oceans.
"We are mortal beings doomed to die
User avatar
onlooker
Fission
Fission
 
Posts: 10957
Joined: Sun 10 Nov 2013, 13:49:04
Location: NY, USA

Re: Paleoclimate Thread

Unread postby rockdoc123 » Sun 04 Feb 2018, 16:11:33

Thanks for the link Rock D, bit like the past discussion on what caused the great past 5 mass extinctions, ET impacts or abrupt CC by various mechanisms.......CC rules!


You need to read the paper. Their proposal is the amount of aerosols tossed up into the atmosphere from the sudden impact and the huge amount of biomass burned over a short period resulted in the cooling event referred to as Younger Dryas.
User avatar
rockdoc123
Expert
Expert
 
Posts: 7685
Joined: Mon 16 May 2005, 03:00:00

Re: Paleoclimate Thread

Unread postby dohboi » Mon 05 Feb 2018, 00:03:40

https://sciencealert.com/13000-years-ag ... ng-ice-age

A Recent Ice Age Was Triggered by a Firestorm Bigger Than The One That Killed The Dinosaurs

In a hugely detailed and comprehensive new study, researchers have painted a picture of how around a tenth of Earth’s surface suddenly became covered in roaring fires at a point some 12,800 years ago.
The firestorm rivals the one that wiped out the dinosaurs, and it was caused by fragments of a comet that would have measured around 100 kilometres (62 miles) across.
As dust clouds smothered the Earth, it kicked off a mini ice age that kept the planet cool for another thousand years, just as it was emerging from 100,000 years of being covered in glaciers. Once the fires burned out, life could start again, according to the international team of scientists.
“The hypothesis is that a large comet fragmented and the chunks impacted the Earth, causing this disaster,” says one of the team, Adrian Melott from the University of Kansas.
“A number of different chemical signatures – carbon dioxide, nitrate, ammonia and others – all seem to indicate that an astonishing 10 percent of the Earth’s land surface, or about 10 million square kilometres [3.86 million square miles], was consumed by fires.”
To peer back into the burning fires and shock waves of this major event, a large number of geochemical and isotopic markers were measured from more than 170 sites across the world, involving a team of 24 scientists.
One of the pieces of analysis carried out was on patterns in pollen levels, which suggested pine forests were suddenly burned off to be replaced by poplar trees – a species specialising in covering barren ground, as you might get when your planet has been hit by a series of massive fireballs.
In fact parts of the comet that disintegrated in space are still likely to be floating around parts of our Solar System 13,000 years later.
High concentrations of platinum – often found in asteroids and comets – and high levels of dust were also noted in the samples analysed by the researchers, alongside increased concentrations of combustion aerosols you would expect to see if a lot of biomass was burning: ammonium, nitrate, and others.
Plants died off, food sources would have been scarce, and the previously retreating glaciers began to advance again, say the researchers. Human culture would have had to adapt to the harsher conditions, with populations declining as a result.
“Computations suggest that the impact would have depleted the ozone layer, causing increases in skin cancer and other negative health effects,” says Melott.
The team thinks such a widespread impact of comet fragments, and the ensuing firestorm, is responsible for that extra bit of cooling known as the Younger Dryas period. This relatively brief blip in the planet’s temperature has sometimes been put down to changing ocean currents.


Kinda interesting, but it seems to still be in the ... hypothesis stage. I'd like to hear or see some critical analysis on this by some folks in the field of paleo-climatology (who aren't already one of the many co-authors of the study).
User avatar
dohboi
Harmless Drudge
Harmless Drudge
 
Posts: 19990
Joined: Mon 05 Dec 2005, 04:00:00

Re: Paleoclimate Thread

Unread postby rockdoc123 » Mon 05 Feb 2018, 01:08:24

Kinda interesting, but it seems to still be in the ... hypothesis stage. I'd like to hear or see some critical analysis on this by some folks in the field of paleo-climatology (who aren't already one of the many co-authors of the study).


already posted above. And being published as two papers in this journal (one of the oldest ones out there) means it has undergone some pretty significant peer review.
User avatar
rockdoc123
Expert
Expert
 
Posts: 7685
Joined: Mon 16 May 2005, 03:00:00

Re: Paleoclimate Thread

Unread postby dohboi » Mon 05 Feb 2018, 08:04:33

But...it seems to be...faulty science, at best, as it turns out. Sorry I posted it before checking more thoroughly:

”(this whole ‘Younger Dryas Impact’ hypothesis [external link] actually is disputed itself [external link], so making Göbekli Tepe a ‘smoking gun’ in this argument should absolutely ask for a closer look).

….as of yet no convincing proof for an actual celestial orientation or observation of such phenomena could have been put forward. We always were and still are open to consider these discussions. So, of course we were looking into the new study with quite some interest, too. After all it is a new and fascinating interpretation. However, upon closer inspection we as excavators of this important site would like to raise a few points which may challenge this interpretation in our point of view:”


https://tepetelegrams.wordpress.com/201 ... e-aurochs/
User avatar
dohboi
Harmless Drudge
Harmless Drudge
 
Posts: 19990
Joined: Mon 05 Dec 2005, 04:00:00

Re: Paleoclimate Thread

Unread postby rockdoc123 » Mon 05 Feb 2018, 14:28:54

But...it seems to be...faulty science, at best, as it turns out. Sorry I posted it before checking more thoroughly:


Perhaps you should read the paper before linking to an article that has absolutely nothing whatsoever to do with the premise that the paper in question is putting forth?

Studies of 140 sedimentary sequences distributed across North and South America, western Europe, and western Asia document peaks in exotic YDB materials, including high-temperature iron-rich spher- ules; silica-rich glassy spherules; meltglass; and nano- diamonds, iridium, platinum (fig. A1; figs. A1 and A2 are available online), and osmium (tables A1, A2; ta- bles A1–A4 are available online). Independent groups have confirmed much of the YDB impact evidence, but others have not or have offered alternate expla- nations. It is not the intent of this contribution to review and discuss previous publications concerning the YDB impact proxies, and so a comprehensive bib- liography is provided in table A3.


From ice-sheet and ice-core records in Greenland, Antarctica, and Russia, the evidence reported in this study supports the co-occurrence of (1) the YDB im- pact event, represented by elevated Pt concentrations and many other impact-related proxies; (2) the YD cool episode, represented by a temperature decrease reflected by changes in d18O and elevated concentra- tions of Cl, Ca, Na, Mg, and K, reflecting increased atmospheric dustiness and changes in atmospheric circulation; and (3) a major episode of biomass burn- ing, represented by anomalously high coeval peaks in NH4, NO3, acetate, oxalate, and formate.
For the GISP2 core, all of these proxies overlap in the same Pt-enriched, 21-y-long section of ice that peaks at 12,822 cal BP (range: 12,836–12,815 cal BP), a span that overlaps the Bayesian-calculated age for the YDB impact event of 12,835–12,735 cal BP (Kennett et al. 2015). Multiple lines of ice-core evidence appear syn- chronous, and this synchroneity of multiple events makes the YD interval one of the most unusual climate episodes in the entire Quaternary record. Because a cosmic impact is the only known event capable of simultaneously producing the collective evidence discussed in the two parts of this study, a cause-and-effect relationship among these events is supported, as proposed by YDB theory.


What precisely does this have anything whatsoever to do with whether there was an ancient space observatory? Answer...Nada
User avatar
rockdoc123
Expert
Expert
 
Posts: 7685
Joined: Mon 16 May 2005, 03:00:00

Re: Paleoclimate Thread

Unread postby dohboi » Mon 05 Feb 2018, 22:39:44

Sorry, I should have bolded the first clause for you, since that was the relevant part I was referring to.

For a summary of some of the scientific skepticism about the 'Younger Dryas Impact' hypothesis, see:

A study of Paleoindian demography found no evidence of a population decline among the Paleoindians at 12,900 ± 100 BP, which was inconsistent with predictions of an impact event.[29] They suggested that the hypothesis would probably need to be revised.[30][31] There is also no evidence of continent-wide wildfires at any time during terminal Pleistocene deglaciation,[32] though there is evidence that most larger wildfires had a human origin,[32] which calls into question the origin of the "black mat."[33] Iridium, magnetic minerals, microspherules, carbon, and nanodiamonds are all subject to differing interpretations as to their nature and origin, and may be explained in many cases by purely terrestrial or non-catastrophic factors.[34]

If it is assumed that the hypothesis supposes that all effects of the putative impact on Earth's biota would have been brief, all extinctions caused by the impact should have occurred simultaneously. However, there is much evidence that the megafaunal extinctions that occurred across northern Eurasia, North America and South America at the end of the Pleistocene were not synchronous. The extinctions in South America appear to have occurred at least 400 years after the extinctions in North America.[35][36][37] The extinction of woolly mammoths in Siberia also appears to have occurred later than in North America.[35] A greater disparity in extinction timings is apparent in island megafaunal extinctions that lagged nearby continental extinctions by thousands of years; examples include the survival of woolly mammoths on Wrangel Island, Russia, until 3700 BP,[35][36][38] and the survival of ground sloths in the Antilles,[39] the Caribbean, until 4700 cal BP.[35] The Australian megafaunal extinctions occurred approximately 30,000 years earlier than the hypothetical Younger Dryas event.[40]

The megafaunal extinction pattern observed in North America poses a problem for the bolide impact scenario, since it raises the question why large mammals should be preferentially exterminated over small mammals or other vertebrates.[41] Additionally, some extant megafaunal species such as bison and Brown bear seem to have been little affected by the extinction event, while the environmental devastation caused by a bolide impact would not be expected to discriminate.[35] Also, it appears that there was collapse in North American megafaunal population from 14,800 to 13,700 BP, well before the date of the hypothetical extraterrestrial impact,[42] possibly from anthropogenic activities, including hunting.[17]

Scientists have asserted that the carbon spherules originated as fungal structures and/or insect fecal pellets, and contained modern contaminants[7][24] and that the claimed nanodiamonds are actually misidentified graphene and graphene/graphane oxide aggregates.[23][43] An analysis of a similar Younger Dryas boundary layer in Belgium yielded carbon crystalline structures such as nanodiamonds, but the authors concluded that also did not show unique evidence for a bolide impact.[44] Researchers have also have not found any extraterrestrial platinum group metals in the boundary layer which would be inconsistent with the hypothesized impact event.[45] Further independent analysis was unable to confirm prior claims of magnetic particles and microspherules, concluding that there was no evidence for a Younger Dryas impact event.[46]

Other research has shown no support for the impact hypothesis. One group examined carbon-14 dates for charcoal particles that showed wildfires occurred well after the proposed impact date, and the glass-like carbon was produced by wildfires and no lonsdaleite was found.[47] Analysis of fluvial sediments on Santa Rosa Island by another group also found no evidence of lonsdaleite, impact-induced fires, or extraterrestrial impact.[28]

Research published in 2012 has shown that the so-called "black mats" are easily explained by typical earth processes in wetland environments.[6] The study of black mats, that are common in prehistorical wetland deposits which represent shallow marshlands, that were from 6000 to 40,000 years ago in the southwestern USA and Atacama Desert in Chile, showed elevated concentrations of iridium and magnetic sediments, magnetic spherules and titanomagnetite grains. It was suggested that because these markers are found within or at the base of black mats, irrespective of age or location, suggests that these markers arise from processes common to wetland systems, and probably not as a result of catastrophic bolide impacts.[6]

A 2013 study found a spike in platinum in Greenland ice. The authors of that study conclude that such a small impact of an iron meteorite is “unlikely to result in an airburst or trigger wide wildfires proposed by the YDB impact hypothesis."[15]

Finally, researchers have criticized the conclusions of various studies for incorrect age-dating of the sediments,[48] contamination by modern carbon, inconsistent hypothesis that made it difficult to predict the type and size of bolide,[49] lack of proper identification of lonsdaleite,[50] confusing an extraterrestrial impact with other causes such as fire,[51] and for inconsistent use of the carbon spherule "proxy".[52] Naturally occurring lonsdaleite has also been identified in non-bolide diamond placer deposits in the Sakha Republic.[13]


And links there given...

https://en.wikipedia.org/wiki/Younger_D ... hypothesis
User avatar
dohboi
Harmless Drudge
Harmless Drudge
 
Posts: 19990
Joined: Mon 05 Dec 2005, 04:00:00

Previous

Return to Environment, Weather & Climate

Who is online

Users browsing this forum: No registered users and 69 guests