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The Phanerozoic eon, encompassing the last 542 million years and almost the entire time since the origination of complex multi-cellular life, has more generally been a period of fluctuating temperature between ice ages, such as the current age, and "climate optima", similar to what occurred in the Cretaceous. Roughly 4 such cycles have occurred ...
The Jurassic North Atlantic Ocean was relatively narrow, while the South Atlantic did not open until the following Cretaceous Period, when Gondwana itself rifted apart. [46] The Tethys Sea closed, and the Neotethys basin appeared. Climates were warm, with no evidence of glaciation. As in the Triassic, there was apparently no land near either ...
The first eon in Earth's history, the Hadean, begins with the Earth's formation and is followed by the Archean eon at 3.8 Ga. [2]: 145 The oldest rocks found on Earth date to about 4.0 Ga, and the oldest detrital zircon crystals in rocks to about 4.4 Ga, [34] [35] [36] soon after the formation of the Earth's crust and the Earth itself.
Tropical reefs tend to show temperature increases of less than 1 °C. The tropical ocean surface at the Great Barrier Reef about 5350 years ago was 1 °C warmer and enriched in 18 O by 0.5 per mil relative to modern seawater. [9] Temperatures during the HCO were higher than in the present by around 6 °C in Svalbard, near the North Pole. [10]
Late Cenomanian sea surface temperatures (SSTs) in the equatorial Atlantic Ocean were substantially warmer than today (~27-29 °C). [2] Turonian equatorial SSTs are conservatively estimated based on δ18O and high p CO 2 estimates to have been ~32 °C, but may have been as high as 36 °C. [ 10 ]
The timing of changes in ocean circulation with respect to the shift in carbon isotope ratios has been argued to support the proposition that warmer deep water caused methane hydrate release. [211] However, a different study found no evidence of a change in deep water formation, instead suggesting that deepened subtropical subduction rather ...
The second is a shift in the tilt of Earth's axis, or obliquity. The third is the wobbling motion of Earth's axis, or precession. [1] In the Southern Hemisphere, warmer summers occur when the lower-half of Earth is tilted toward the Sun and the planet is nearest the Sun in its elliptical orbit. Cooler summers occur when Earth is farthest from ...
An examination of the average global temperature changes by decades reveals continuing climate change: each of the last four decades has been successively warmer at the Earth's surface than any preceding decade since 1850. The most recent decade (2011-2020) was warmer than any multi-centennial period in the past 11,700 years. [16]: 2–6