"Some like it hot": Exploring Earth’s thermal maximum by reconstructing the spatial distributions of atmospheric temperature and moisture content throughout the Phanerozoic.

Anthropogenic carbon dioxide emissions rapidly warm Earth’s
climate. However, a good understanding of the atmospheric
manifestation of Earth’s warmest possible climate state is lacking.
The geological record shows the Earth’s climate sensitivity to a high
concentration of atmospheric carbon dioxide (pCO2). Yet, the most
commonly studied Cenozoic period has obviously not witnessed
Earth’s warmest climate states. To investigate the terrestrial “hot
limit” – in the past and in a possible future – this project reconstructs
the warmest climates of the Phanerozoic. To do so, the isotope
compositions of pedogenic siderites from locations all around the
world are analyzed using state of the art methods: clumped and
oxygen isotope (∆47 and δ18O) and triple oxygen composition
(∆'17O and δ'18O) measured on the siderite respectively at the VUB
and the University of New Mexico. These siderites formed in the soils
of moist floodplains that covered large regions during Earth’s
warmest periods. The siderite isotope signatures provide a measure
of the temperature and humidity of the atmosphere at their time of
formation. These parameters document fundamental constraints on
Earth’s climate system, illustrate what a hot world feels like, and
document how life on Earth may be impacted. The obtained results
improve the predictive power of climate models used to simulate
Earth’s future.