Sentences with phrase «kyr at»

The causes of the age differences at MIS 5 were proposed to occur from (i) an overestimation of the surface mass balance at around MIS 5d - 6 in the glaciological model, and (ii) an error in one of the age constraints by ~ 3 kyr at MIS 5b.

The DF core produced ages that were older than the EDC core, with peak values in the age difference of 4.5 kyr at MIS 5d (ca. 120 kya) and 3.1 kyr at MIS 5b (ca. 90 kya).

Not exact matches

Obviously, Figure 9 shows that 40 kyrs ago the earth's magnetic field intensity was 75 % less (2 × 10 ^ 22Am ^ 2) than the geomagnetic field's current intensity (8 × 10 ^ 22Am ^ 2) and that the earth's magnetic field intensity peaked at around (12 × 10 ^ 22Am ^ 2) and has dropped 30 % in the last 1000 years and that the geomagnetic field intensity is now dropping at the rate of 5 % / 100 yrs.

East African hominin diversity at each 100 kyrs interval were estimated using first (FAD) and last appearance dates (FAD) from the literature [2], [35]--[36], [46].

The emerging timeline is as follows (Unit II): (1) a gradual rise of the chemocline over a period of ∼ 2 kyr following the onset of anoxia at ca. 7.6 kyr B.P., (2) fully developed euxinic conditions with an ascent of the chemocline onto the shelf at ca. 5.3 kyr B.P., (3) a subsequent descent of the chemocline, and (Unit I)(4) establishment of the chemocline in its present - day position at the shelf break from 2.7 kyr B.P. onward.

In other words, it is only in the last glacial (100 kyr) that we see any change in tropical temperature corresponding to that at the poles.

The resulting record shows a CO2 concentration of about 270 ppmv at 11,300 yr BP, a sharp increase to about 330 ppmv at 11,260 yr BP, and (with the exception of a dip to 300 ppmv at about 11 kyr BP) a rather constant CO2 concentration at the high level of about 330 ppmv over the next 500 years.

There's also a cluster of small peaks in the range 0.042 to 0.045 cycles / kyr (periods 22,000 to 24,000 years) and a small peak at 0.053 cycles / kyr (period 19,000 years) that are all coincident with periods in the changes of precession, the orientation of earth's spin axis relative to the longitude of perihelion (closest approach to the sun) of earth's orbit.

The strongest is at frequency 0.024 cycles / kyr, period about 41,000 years.

During this period, CO2 falls to its lowest value ever found in ice cores, 172 p.p.m.v. (667 kyr bp), redefining the natural range of CO2 of the late Quaternary to about 170 to 300 p.p.m.v., before it rises at a rate of 8 p.p.m.v. kyr — 1 to 190 p.p.m.v. at 665 kyr bp.

At the beginning of MIS 16, CO2 remains below 180 p.p.m.v. for 3 kyr, most probably reflecting more pronounced glacial carbon storage in the ocean.

Starting at a glacial level of 188 p.p.m.v. in MIS 20, the CO2 concentration rises by about 70 p.p.m.v. within 9 kyr.

later, «For ODP 1218 the estimated autocorrelation coefficient is ϕ = 0.87 and the variance of the ∈ disturbances is 0.41 at a time step of 4.3 kyr.»

Archer's work covers 300 Gtn (what we've already released) up to 5000 Gtn (which would require considerable permafrost and clathrate feedbacks)-- and with 300 GTn (by his numbers) we'll still have 14 - 17 % of that carbon in the atmosphere at 1 kyr.

Archer's work points to 17 - 33 % of fossil fuel carbon remaining in the atmosphere after 1000 years (1 kyr), 10 - 15 % at 10 kyr, 7 % at 100 kyr.

This issue, known as the 100 - kyr problem, is compounded by a lack of explanation for the transition of the length of the cycles from 41,000 to 100,000 years at the mid-Pleistocene transition 1.2 million years ago.

To quote «Proof is obtained by considering the contrary: ice sheet forcing approximately 3W / m ^ 2 and a 5 kyr timing gap between forcing and response, as appears to be the case at Termination IV (figure 2c), is 15,000 W yr / m ^ 2, enough to warm the upper kilometre of the ocean by approximately 160 C» (pdf page 7) This is his justification for modifying the data - not my «characterization» of what he said.

«An examination of the fossil record indicates that the key junctures in hominin evolution reported nowadays at 2.6, 1.8 and 1 Ma coincide with 400 kyr eccentricity maxima, which suggests that periods with enhanced speciation and extinction events coincided with periods of maximum climate variability on high moisture levels.»

In the case of the 100 kyr ice age cycles, that forcing is high northern latitude summer insolation driven by predictable changes in Earth's orbital and rotational parameters — aka, Milankovitch theory — which has the intial effect of melting glaciers, thereby reducing albedo at those latitudes.

Atmospheric CO2 concentration was about 260 ppm at its Holocene minimum around 8 kyr BP and increased towards about 280 ppm in the pre-industrial period.

Seafloor eruption rates, and mantle melting fueling eruptions, may be influenced by sea - level and crustal loading cycles at scales from fortnightly to 100 kyr.

Roger Bray identified cooling episodes at 0.3, 2.8, 5.5, 8.2 and 10.2 kyr BP over 45 years ago (figure 46).

That your model requires an Arctic free of ice during the build up of the continental ice - sheets ~ 100 kyr ago, doesn't mean that the Arctic was free of ice at that time.

Dongge cave stalagmite D shows at 8.2 kyr the usual Asian monsoon weakening that takes place during periods of low solar activity.

And what if the final drainage event of Lake Agassiz was actually at 8.4 kyr BP (or 8.475 kyr from some sources), where GISP2 has a warm spike?

In my opinion the unique methane downward spike at 8.2 kyr BP in Antarctic records is likely to be tied to the other unique event that we know at the time, the outbreak of Lake Agassiz.

Yes you have posted that before, and the comment I made was the Aegean sea and Craig cave show warm spikes centered at 8.2 kyr BP, and more importantly, intensified trade winds, which is the wrong sign to associate with a cold period.

With Rohling, E. J., & Pälike, H. (2005) showing a well timed increase in trade wind speed at 8.2 kyr, the event obviously involves global teleconnections, and of the wrong sign to be a global cold event.

A comprehensive global compilation of archeomagnetic data of the past 50 kyrs is provided by the GEOMAGIA.v2 database (Donadini et al. 2006; Korhonen et al. 2008) at http://geomagia.ucsd.edu/.

I noted that we haven't published on the data set that Phil used in 1998 and didn't wish to archive it publicly as it was a very early product that might have been state of the art at that time, but which was superseded by data coming on line in subequent years: noteably the LD2.1 kyr data set and the Schneider and Steig data sets (both archived).

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.

Given that current low orbital eccentricity will persist over the next tens of thousand years, the effects of precession are minimised, and extremely cold northern summer orbital configurations like that of the last glacial initiation at 116 ka will not take place for at least 30 kyr (Box 6.1).

On the evidence of the previous and four new reconstructions that reach back more than 1 kyr, it is likely that the 20th century was the warmest in at least the past 1.3 kyr.

Obviously, Figure 9 shows that 40 kyrs ago the earth's magnetic field intensity was 75 % less (2 × 10 ^ 22Am ^ 2) than the geomagnetic field's current intensity (8 × 10 ^ 22Am ^ 2) and that the earth's magnetic field intensity peaked at around (12 × 10 ^ 22Am ^ 2) and has dropped 30 % in the last 1000 years and that the geomagnetic field intensity is now dropping at the rate of 5 % / 100 yrs.

However, such a break up of the Laurentide would raise sea level and sea level rise slowed down at 12.9 kyr BP and during the Younger Dryas.

In Actuality, air sampling surveys over ESAS yield a calculated annual flux to the atmosphere of 8 Tg C - CH ₄ (Shakhova et al., 2010), a figure 200 x higher than the model estimate (at Year - 1 of this 100 - kyr - scale warming) and equivalent to the methane emissions of the entire world's oceans.