Sentences with phrase «kyr cycle»
Pulsing of seafloor volcanic activity may feed back into climate cycles, possibly contributing to glacial / inter-glacial cycles, the abrupt end of ice ages, and dominance of the 100 kyr cycle.
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FYI: Michael, for the past million years the general warming and cooling cycle revolves around 100 kyr cycles
Not exact matches
Ice core records are rich archives of the climate history during glacial - interglacial cycles over timescales of up to ~ 800 kyr before the current age.
Ice core records show that atmospheric CO2 varied in the range of 180 to 300 ppm over the glacial - interglacial cycles of the last 650 kyr (Figure 6.3; Petit et al., 1999; Siegenthaler et al., 2005a).
It would be odd if there just happened to be a solar cycle on exactly the 100 kyr timescale — William]
The CaCO3 cycle was able to keep up with the 10 - kyr CO2 rise as the ice sheets melted, but it won't be able to keep up with the 100 - yr anthropogenic CO2 rise.
Over very long time periods such that the carbon cycle is in equilibrium with the climate, one gets a sensitivity to global temperature of about 20 ppm CO2 / deg C, or 75 ppb CH4 / deg C. On shorter timescales, the sensitivity for CO2 must be less (since there is no time for the deep ocean to come into balance), and variations over the last 1000 years or so (which are less than 10 ppm), indicate that even if Moberg is correct, the maximum sensitivity is around 15 ppm CO2 / deg C. CH4 reacts faster, but even for short term excursions (such as the 8.2 kyr event) has a similar sensitivity.
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.
Older ice is required to test hypotheses about any consistent long - term CO2 trend and a probable connection with the 500 - kyr variations of the Quaternary carbon cycle found in marine records15.
The strongest is at frequency 0.024 cycles / kyr, period about 41,000 years.
Figure 2 shows our data together with earlier results from the Dome C (650 — 390 kyr bp4 and 22 — 0 kyr bp5), Vostok1, 2,3 (440 — 0 kyr bp) and Taylor Dome6 (60 — 20 kyr bp) ice cores resulting in a composite CO2 record over eight glacial cycles.
The movies (after the first two) show four 100 - kyr sawtooth - shaped glacial / interglacial cycles (62 - 62.4 Myr) followed by 100 kyr of a global warming scenario (62.4 - 62.5 Myr).
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.
Marine and terrestrial sediment sequences demonstrate that subtropical African climate periodically oscillated between markedly wetter and drier conditions, paced by earth orbital precession cycles recurring roughly every 20 kyr (Lourens et al., 1996).
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.
Seafloor spreading is considered a small but steady contributor of CO2 to climate cycles on the 100 kyr time scale, however this assumes a consistent short - term eruption rate.
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.
The LR04 age model establishes that MIS 11 spans two precession cycles, with 18O values below 3.6 o / oo for 20 kyr, from 398 - 418 ka.
E.g., Pisias and Shackleton (1984); «The existence of the 100 - kyr [kiloyear] cycle and the synchronism between Northern and Southern Hemisphere climates may have their origin in the large glacial - interglacial CO2 changes.»
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.
A Fourier analysis of each 4 kyr interval can then be used to produce a local «prediction» for the subsequent 1 ka, based on the putative cycles in the preceding 4 kyr.
The average is more like 14 - 15 kyr (a precessional cycle, BTW, since you know all about Milankovich cycles), but the standard deviation is about 10,000 years.
The interglacial thus lasts an additional precessional cycle, yielding a total duration of 28 kyr.
[1] Also, Archer and Ganopolski (2005) report that probable future CO2 emissions may be enough to suppress the glacial cycle for the next 500 kyr.»
During the Early Triassic, Milankovitch cycles were dominated by 405 kyr, 125 kyr, and 95 kyr eccentricity cycles, 33 kyr obliquity cycles, and 21 kyr, 20 kyr, and 17 kyr precession cycles19, 31,49.