Sentences with phrase «glacial cycles did»

Evidently the hundred - thousand - year glacial cycles did follow a sawtooth pattern: each cycle showed a slow descent into a long - lasting cold state that ended with a mysteriously abrupt rise of temperature.

Not exact matches

The timing of this decline correlates with environmental changes associated with the onset of the last glacial cycle, the team reports, whereas archaeological evidence does not support the presence of large populations of humans in eastern Beringia until more than 15,000 years later.

Having briefly glanced at it, his main argument seems to come from overlaying the CO2 records at the same stage of different glacial cycles, and that seems quite hard to do, to me — William]

You don't get the minor changes in insolation from Milankovitch cycles causing glacial - interglacial cycles.

Having briefly glanced at it, his main argument seems to come from overlaying the CO2 records at the same stage of different glacial cycles, and that seems quite hard to do, to me — William]

Instead, it appears that the shift between glacials and interglacials is a change from one attractor to another, with the glacial attractor exhibiting (possibly) chaotic oscillations in the DO cycles.

I'd remind you that while humans have survived more than a full glacial cycle, we didn't yet exist as a species when temperatures last hit 3 C above our pre-Industrial levels, back in the Pliocene.

What this model shows is that if orbital variations in insolation impact ice sheets directly in any significant way (which evidence suggests they do Roe (2006)-RRB-, then the regression between CO2 and temperature over the glacial - interglacial cycles (which was used in Snyder (2016)-RRB- is a very biased (over) estimate of ESS.

Although the sensitivity of climate does change itself as the boundary conditions change, the past (PETM, glacial - interglacial cycles, etc) does not support sensitivities as low as 1 degree per doubling of CO2, and it doesn't support very high ones (like 10 degrees per doubling) either.

These differ from the glacial - interglacial cycles in that they probably do not involve large changes in global mean temperature: changes are not synchronous in Greenland and Antarctica, and they are in the opposite direction in the South and North Atlantic.

And another thing coby why doesn't the scientific evidence that i gave you say anything about Co2 setting glacial cycles in motion?

re: It's just like a natural change re: They said it was cooling 25 years ago re: CO2 does not cause the glacial cycles

Jose Rial clearly doesn't understand the glacial cycle or the Dansgaard - Oeschger cycle of which he writes about, and he appears to ignore crucial bibliography relevant to his work.

They do tend to occur in the coldest parts of the glacial cycles, when ice sheets extend out on to continental shelves.

Objection: The CO2 lags behind temperature by centuries in the glacial - interglacial cycles, so clearly CO2 does not cause temperatures to rise, temperatures cause CO2 to rise.

Okay, so now you suddenly agree that total energy received from the sun during the year does not change with the Milankovitch cycle and hence is not a factor in the glacial / interglacial transitions.

There are lots of pieces which don't quite fit together to give us a complete picture of why glacial cycles occur, but it seems that you think they do.

I'm not sure who you're referring to when you say it is thought that TSI has anything to do with glacial cycles.

Similarily, the significance of 100ppm rise from ~ 180 to ~ 280 in the glacial cycles is greater than the significance of 100ppm rise from 280 to 380 we have done now.

By over more than 20 times the amount (see Milankovitch cycles — recently improved in Wiki) starts the climate relevance: see glacial times...... To the point: I do not talk about ELLIPTICITY CHANGES, they stay constant on millenium scale.

Finally he does put a figure on the contribution of CO2 and others to the total glacial cycle at around half — the figure I have seen more recently is 40 %.

As Lindzen says IIRC, do we get big changes like the glacial cycles even with low sensitivity?

Lindzen was only able to keep the «iris» ball in the air for as long as he did because prior to the advent of AIRS the upper troposphere was an especially hard place to get accurate measurements, and by completely ignoring paleoclimate, e.g. the conflict between the «iris» and the Pleistocene glacial cycles, and the fact that prior to the Pleistocene higher CO2 levels led to temperatures that kept glaciers from existing at all (the latter having been firmed up only recently, to be fair).

Although even there we do have to ask ourselves what event caused the mid-Pleistocene 40 ky glacial cycle to suddenly step jump up to 100 ky?

If solar input has» no measurable» impact then why do you suggest that Milankovitch cycles cause glacials / interglacials

When Roy Spencer saw Wunsch's paper, he apparently glommed onto it as the last word on Milankovitch forcing — i.e., that we have no clue what caused the glacial - interglacial cycles, and we never will (even though Wunsch didn't go that far).

It does seem that the long - term cooling trend underlying the glacial / interglacial cycling flattened out at about the time that the 41 - to - 100 kyr shift occurred.

RealClimate and / or others should do a blog refuting the misinformation on the NC - 20 site, for instance the notion that CO2 is merely a dependent variable in the glacial cycles.

Actually, by the time you approach 200ppmv for CO2, you have already reached the break point in the curve, beyond which additional CO2 has much less impact on the RF — and this is close to the glacial value — suggesting that CO2 changes do not drive the glacial cycles (CO2 changes are supposed to amplify T rise during deglaciation, but there is scant evidence for this and the assumption that it did also underlay the IPCC belief — and a great many references in academic papers give a T degrees C per ppmv CO2 without stating over which range of concentrations this is meant to apply.