It did, and now we do know. Exactly. Which is why deniers are so often scorned by scientists. They don't care what the science is - they only care that their political agendas are met.
"...We do know..." You think you know? OK: Please: Enlighten the rest of us as to the significant causal factors of: What triggered this current ice age? Was(were) the trigger(s?) the same for the previous ice ages? What triggers periods of glaciation and interglacials within this and/or other ice ages? How does this trigger/these triggers differ for "normal" interglacials, and superinterglacials?
That is what most debates are for, "maintaining confusion". Knowing, suspecting and believing are three different things. But when the consequences can be catastrophic and irreparable we have a serious situation. We do not have a spare planet. There is more than enough evidence for AGW but who decides what constitutes PROOF. So confusion will be maintained and and almost nothing of use will be done. psik
This is the same game played by people who want to smoke without responsibility. "Oh so you think you know that smoking causes cancer, because Big Pharma told you that? Well, then please enlighten us. Which carcinogen, exactly, deactivates the oncogene that causes lung cancer? Which one oncogene causes lung cancer anyway? No? You can't answer that? Well, I guess you don't know that smoking causes cancer, do you?"
billvon Just in case this escaped your notice: (during your rant into carcinogens) You still haven't shared your knowledge as/re: What triggered this current ice age? Was(were) the trigger(s?) the same for the previous ice ages? What triggers periods of glaciation and interglacials within this and/or other ice ages? How does this trigger/these triggers differ for "normal" interglacials, and superinterglacials? and yet, you claimed: "...We do know..." I submit that: We do not know. This is a thread about climate. If, indeed, YOU do know the answers to the above, then this is something worth sharing. Do so now, please.
Wouldn't it be terrible if we worked towards cleaning up the atmosphere and the environment and it all turned out that we made the world a better place for nothing?
No one is certain* (instruments not there to measure) but this is a generally accepted explaination, with original calculations now confirmed by computers: This orbital perturbation of Earth's tilt mainly, but eccentricity too, was first proposed about 100 years ago by Serbian mathematician, Milutin Milankovitch. Please Register or Log in to view the hidden image! Computers did not exist back in 1911; So: In his honor, we still call the some what more accurate computation done with modern computers: The "Milankovitch Cycles." * Our confidence level on this is perhaps greater than that smoking causes cancer. Certainty is found only in tautologies (Math mainly).
Milankovitch cycles fall way short of the mark in explaining or predicting the recently discovered superinterglacials.
I was not aware of that. Can you tell in a little more than an assertion how they fail? At least what "superinterglacial" is inconsistent with this cycles driven by planetary perturbations. If there is one, my first guess would be that an unbound massive object passed near the solar system. - prehaps a small black hole, like the one I invented for my book Dark Visitor It only gave an impulse of a few weeks duration to the Earth (and other planets) that increased Earth's eccentricity such that summers of the Northern Hemisphere were a little cooler and winters there slightly warmer. Initially that seemed nice - a cosmic gift; but not so when the warmer winters let heavy snow falls occur, not just in spring as they do now, but almost all of the winter and then the cooler summers failed to melt all that snow. I.e. each year Earth's albedo increased (less solar heating as the permanent snow /ice cover moved further South). In about a decade, the Dark Visitor's effects had stored so much water as solids on land that not only was a new ice-age beginning but also all the world's existing ports were left "high and dry" - imports were possible only by airplanes, and significant amounts of fossil fuel imported that way is impossible. That "cosmic gift" was really world's worst ever disaster. Unfortunately it all could happen and we would not know it was about to as the Dark Visitor's approach is not visible (Black holes do not reflect light for telescopes to see.) Also their gravitation lens effect is very small, but worse, it is very brief as the Dark Visitor is too close. - I.e. Any distant star it transits in front of has a small lensing effect measured in hours, not months. So is not found in sky surveys that periodically measure stellar intensities. Eventually as the Dark Visitor gets into the very diluted by expansion solar wind, there might possibly be some radiation as it is compressed while falling into the event horizon.
superinterglacials marine isotope stages (mis) 11, 31, 49, 55, 77,89,91,93 Look to the lake el'gygytgyn studies. Prof. julie brigham grette commented that they were surprised by their findings because the findings were outside of current knowledge about climate modeling, including milankovitch cycles. When new field evidence flies in the face of conventional wisdom, like the gobekli tepe dig forcing a rethinking of the v gordon childe neolithic/agricultural revolution and monumental architecture. Then it is prudent to re-examine one's adherence to conventional wisdom. In a very real sense: Lake el'gygytgyn was paleoclimate's gobekli tepe.
Here is what Wiki tells: Lake El'gygytgyn (Chukchi: Эльгыгытгын) is an impact crater lake located in the Chukotka Autonomous Okrug in northeast Siberia, about 150 km southeast of Chaunskaya Bay. It is drained to the southeast by the Enmybaam branch of the Belaya River. It is approximately 12 km in diameter and has a maximum depth of 174 m +/- 2m. The lake is centered within an impact crater with a rim diameter of 18 km that formed 3.6 million years ago during the Pliocene).[1] The lake is of particular interest to scientists because it has never been covered by glaciers. This has allowed the uninterrupted build-up of 400 m of sediment at the bottom of the lake, recording information on prehistoric climate change. That it has not become ice covered does not even seem very strange to me. A great deal of heat was deposited deep during a collision with asteroid that made a hole 12km in diameter at lake level and with 18 km diameter rim and 400 +174 meter deep. Also it seems possible the crustal cover was at least cracked so deep earth heat is flowing upwards too. SUMMARY: Nothing here inconsistent with Milnkovitch Cycles and certainly the asteroid might have some what differnent isotopes than the surface earth there does, if that is what you are referring to. (I did not see any discussion of that at wiki.) WTF are you speaking of as inconsistent with Milnkovitch Cycles climatic effects? No one expects Milnkovitch Cycles to include earth based events, like excessive CO2 release, volcano and asteroid impact induced "winters." Normally these last two don't last long enough to be called a "climate change," but unfortunately the CO2 will last at least 1000 years even if the increasing rate of release were reversed - fat chance of that, so only most will die, if the human species is lucky. More probably all that cool by perspiration will die as humans do in less than an hour with wet bulb of 35C.
OK. I'm willing to do that, give me some link(s) but also tell what you think is inconsistent with the Milnkovitch Cycles other than the earth based events I mentioned. Also since you referred to a very local event, are you claiming it triggered some global climate change. That is what I would expect for that large asteroid impact.
no triggers Lake El'gygytgyn is up on the continental divide and therefore has a continuous record of sediment for the entire northern portion of this ice age because it was not scoured by glaciers. So, we have a window into the climate during periods of glaciation and interglacials for the past 3 million years. Julie went out of her way to explain that they were seeing approximately the same climate changes reflected in antarctic cores. Not just a local event is her claim. A good starting place would be her presentation before the NSF
I listened to her entire talk. At 13:10 until 13:25 into it is the only time she even briefly mentions the Milnkovitch Cycles and that is to tell the unusually conditions she locally observed in her lake studies are supported by - IN FULL AGREEMENT with - the Milnkovitch Cycles! The main points she makes are two; (1) That several times the Arctic temperatures have been 6 to 8 degree higher than present as the Lake El'gygytgyn record shows. and (2) That, sort of as now, the west Antarctic ice sheet extent is correlated well* with that - i.e. reduced in size when the Arctic is exceptionally warm. (Much of earth was warmer then, but as now, warming in Arctic was greater.) NONE OF THIS is in conflict with the Milnkovitch Cycles. Her ONLY comments indicate AGREEMENT between her studies of the lake and the Milnkovitch Cycles. So, again: WTF are your speaking of (as in disagreement)? Don't give me more links to read (especially not more like this one agreeing with the Milnkovitch Cycles). Tell me in words what is the disagreement. (and give link stating that). * In fact between 10:05 & 10:15 she shows graphs of records form several globally different location and notes that their changes are accurately reflected in the Lake's change too! - I. e. she thinks, and several times states, that the lake is very long term "global climate record" (not in those exact words) - Thus if gives information not otherwise available. (more warm Artic periods than previously known, etc.)
We heard the same thing differently I heard "there was a milankovitch or orbital forcing part to this". subtle? (I've read much more on the subject-----always from an anthropological/archaeological perspective) more to the point: http://frontierscientists.com/tag/coring/ and as/re mis 31 Climate simulations have difficulty in producing such a degree of warmth with the then greenhouse gas and orbital (Milankovitch) forcings alone, suggesting there must be some other factor at work, such as amplifying feedbacks. The fact that the sheer amount of Arctic warming that occurred exceeds that simulated by climate models is both interesting and somewhat worrying what I posted was: "surprised by their findings because the findings were outside of current knowledge about climate modeling, including milankovitch cycles." What I meant was that orbital forcing and atmospheric gasses did not seem to account for all of the warming observed.
Billy T Here's another of Julie's(more recent), wherein she talks about the potential for low--extremely low eccentricity as a potential causal factor in West Antarctic Ice Sheet(wais) collapse leading to arctic warming and super interglacials. Work underway by Rob DeConto and Rajarshi Roychowdhury. good stuff accurate? informative? interesting-------fersure. --------------- why am I interested? It has to do with 7ft heidelbergensis during mis 11, etc..... Limited food supplies tend to shorten descendants(epigenetics) does the opposite hold true? I would love to know more about our ancestors circa 1.1 million years ago during mis 31. Was it a good time to be alive?
