Cretaceous Thermal Maximum, also known as Cretaceous Thermal Optimum, was a period during Earth's history notable for its dramatic increase in global temperatures.

Characteristics

Carbon dioxide

Carbon dioxide

Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 levels reached astounding heights and the sea levels elevated. Plants such as plankton

Plankton

Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...

 became "glassy" and temperatures increased. Scientists predicted that the Cretaceous

Cretaceous

The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 Thermal Maximum occurred during the Cenomanian

Cenomanian

The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...

/Turonian

Turonian

The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...

transition based from the fact that there was a major downfall in global climate. It was also shown to be the most extreme carbon cycle recorded in the past 100 million years.

Impact

Although there was clearly an impact, the results of the Cretaceous Thermal Maximum are a little unclear. However, we do know that the average temperature was between 27 degrees Celsius and 29 degrees Celsius. Even worse, locations bordering the Atlantic Ocean rose to about 35 degrees Celsius to 36 degrees Celsius. In fact, it was extremely rare for the temperature to drop 4 degrees Celsius even in winter. The constant peak of high temperature was mostly because there were high carbon dioxide formulations. All of this implies that the mid-Cretaceous "super-greenhouse" climate was more unstable than we had thought before.