Sentences with phrase «by global glaciations»

Not exact matches

«In addition, this early phase of evolutionary divergence appears to have preceded the extreme climate changes that led to Snowball Earth, a period marked by severe long - term global glaciation that lasted from about 720 to 635 million years ago,» Dohrmann says.

The late Proterozoic — the time period beginning less than a billion years ago following this remarkable chapter of sustained low levels of oxygen — was strikingly different, marked by extreme climatic events manifest in global - scale glaciation, indications of at least intervals of modern - like oxygen abundances, and the emergence and diversification of the earliest animals.

Michael Mann, a meteorology professor at Penn State who was not involved with the study, said it's «speculative» but «plausible» that global climate models have been underestimating climate sensitivity by assuming too much cloud glaciation.

The current global cycle of glaciation dates to this period and might have been triggered by a transformation of the world's ocean currents, which a slender rib of land separating Atlantic and Pacific would naturally explain.

During glaciation, water was taken from the oceans to form the ice at high latitudes, thus global sea level drops by about 120 meters, exposing the continental shelves and forming land - bridges between land - masses for animals to migrate.

C: Datasets suggesting a drying environment at 2.5 Ma, shown by λ 18O from benthic foraminifera, a proxy for global temperature, smoothed with a Gaussian window of 200 ky; eustatic sea level; and magnetic susceptibility, a proxy for ice rafted debris and Northern Hemisphere glaciation.

Clarke et al.'s work is published in Nature Geoscience and uses a regional glaciation model driven by global climate model output to examine possible future changes to glaciers in western Canada.

In a paper «Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation», Shakun et al. (Nature 2012) contend that rising temperature at the end of the last Pleistocene glaciation were preceded by increasing atmospheric CO2.

As the ice sheets waxed and waned, global climate drifted steadily toward cooler conditions characterized by increasingly severe glaciations and increasingly cool interglacial phases.