Sentences with phrase «several glacial cycles»

Not exact matches

The archaeological record suggested that very roughly 150,000 individuals spanned Europe and Asia, living in small groups of 15 to 25 — and that their total numbers fluctuated greatly during the several climate cycles (which included harsh glacial periods) that occurred during the half a million years they inhabited Earth, before going extinct 40,000 years ago.

However, several «feedbacks» are known to have amplified the magnitude of the glacial cycles.

Together with the long - term decrease of 15 p.p.m.v. during the past four glacial cycles, we suggest significant slow fluctuations in the atmospheric CO2 concentration on timescales of several 105 years, probably influenced by changes in the weathering14 or by major reorganizations in the carbon reservoir of the global ocean15.

In 1999, the year after the high temperatures of the 1998 El Nino, I became convinced that geologic data of recurring climatic cycles (ice core isotopes, glacial advances and retreats, and sun spot minima) showed conclusively that we were headed for several decades of global cooling and presented a paper to that effect (Fig. 5).

It was a surprise when evidence turned up, around the end of the 19th century, that the recent glacial epoch had been made up of several cycles of advance and retreat of ice sheets — not a uniform Ice Age but a series of ice ages.

Over the past 450,000 years there have been several major glacial / interglacial (ice age / current climate) cycles.