Sentences with phrase «start of a glacial period»
Not exact matches
Instead, the fossil record indicates they vanished during the Earth's glacial - interglacial transition, which occurred about 12,000 years ago and led to much warmer conditions and the start of the current Holocene period.
https://www.sciencedaily.com/
The MIS 5a palaeosol is overlain by massive sands, representing a major change in the depositional regime, which we interpret as evidence for climatic desiccation at the start of the last glacial period (MIS 4), which would be consistent with other dated records for the region [13], [16], [18], [30].
It is very unlikely that the Milankovitch cycles can start or end an ice age (series of glacial periods):
There is a new glacial period every approximately 11,500 years after the start of an interglacial period.
What is known is that during the period called Little Ice Age, global glacial were advancing, and starting around 1850, instead advancing global glacier became retreating, this trend of glacial retreat continues to the present time, but not all glaciers adding during the Little Ice Age have not yet melted.
Kent points out that according to the Milankovitch theory, we should be at the peak of a 20,000 - some year warming trend that ended the last glacial period; the Earth may eventually start cooling again over thousands of years, and possibly head for another glaciation.
Similarly, in a study of air temperature and CO2 data obtained from Dome Concordia, Antarctica for the period 22,000 - 9,000 BP — which time interval includes the most recent glacial - to - interglacial transition — Monnin et al. (2001) found that the start of the CO2 increase lagged the start of the temperature increase by 800 years.
However I have found another with a CO2 level in the range we have experienced since the 1940's http://www.pnas.org/content/99/20/12567.full At 379 ppm within 35 ppm, the start of the Namurian period, 330 million years ago, should be deep in an glacial period if CO2 was the answer to the faint sun paradox.
This also explains the shape of the historical global temperature plots (straight up to start an interglacial, but then following natural cooling curve downwards over much longer periods back to glacial equilibrium).