Late Cenozoic Ice Age
The Cenozoic Era is part of the Phanerozoic Eon which started ~538.8 million years ago.
The Late Cenozoic Ice Age,[5][6] or Antarctic Glaciation,[7][8] began 34 million years ago at the Eocene-Oligocene Boundary and is ongoing.
It commenced with Greenland becoming increasingly covered by an ice sheet in late Pliocene (2.9-2.58 Ma ago)[11] During the Pleistocene Epoch (starting 2.58 Ma ago), the Quaternary glaciation developed with decreasing mean temperatures and increasing amplitudes between glacials and interglacials.
[citation needed] The concept that the Earth is currently in an ice age that began around 30 million years ago can be dated back to at least 1966.
The hottest part of the last greenhouse earth was the Late Paleocene - Early Eocene.
The hottest part of this torrid age was the Paleocene–Eocene Thermal Maximum, 55.5 million years ago.
53 million years ago during the Eocene Epoch, summer high temperatures in Antarctica were around 25 °C (77 °F).
[10] This current still exists today, and is a major reason for why Antarctica has such an exceptionally cold climate.
[15] The Eocene-Oligocene Boundary 33.9 million years ago was the transition from the last greenhouse period to the present icehouse climate.
[10] By 28.7 million years ago, the Gamburtsev ice cap was now much larger due to the colder climate.
[9] About 15 million years ago was the warmest part of the Late Cenozoic Ice Age, with average global temperatures around 18.4 °C (65.1 °F).
By 14 million years ago, the Antarctic ice sheets were similar in size and volume to present times.
[5] The glaciation of the Arctic in the Northern Hemisphere commenced with Greenland becoming increasingly covered by an ice sheet in late Pliocene (2.9-2.58 Ma ago).
As a result the North East part or Atlantic Ocean underwent harsher winters.
This time period saw the great advancement of polar ice sheets into the middle latitudes of the Northern Hemisphere.
According to Blue Marble 3000 (a video by the Zurich University of Applied Sciences), the average global temperature around 19,000 BCE (about 21,000 years ago) was 9.0 °C (48.2 °F).
According to the IPCC, average global temperatures increased by 5.5 ± 1.5 °C (9.9 ± 2.7 °F) since the last glacial maximum, and the rate of warming was about 10 times slower than that of the 20th century.
According to the United States Geographical Survey (USGS), permanent summer ice covered about 8% of Earth's surface and 25% of the land area during the last glacial maximum.
Currently (as of 2012), about 3.1% of Earth's surface and 10.7% of the land area is covered in year-round ice according to the USGS.
[30] The current sea level (as of 2009) is 70 m (230 ft) lower than it would be without the ice sheets of Antarctica and Greenland.
[17] Based on the Milankovitch cycles, the current interglacial period is predicted to be unusually long, continuing for another 25,000 to 50,000 years beyond present times.
[24] There are also high concentrations of greenhouse gases in the atmosphere from human activity, and it is almost certain to get higher in the coming decades.
However, the high levels of greenhouse gases are predicted to keep it from getting cold enough to build up enough ice to meet the criteria of a glacial period.
Hypothetical runaway greenhouse state Tropical temperatures may reach poles Global climate during an ice age Earth's surface entirely or nearly frozen over
