A glaciation more than 80 million years ago in Barrika, Bizkaia, has put climate models in doubt

An international team of 16 researchers from Spain, the United Kingdom, France and the United States, led by Juan Pedro Rodriguez-Lopez of the University Institute for Environmental Science Research (IUCA) of theUniversity of Zaragoza (Unizar), has found that there was a glaciation in the cliffs of Barrika (Bizkaia) during the Cretaceous  – 82.8 million years ago and 80.96 million years ago – which has forced a rethinking of past climate patterns because they are "very low" latitudes.

This discovery would thus refute the idea that it is deeply rooted in the scientific community: that in the Cretaceous, and in general in the Mesozoic -- between 252 and 66 million years-the Earth lived in a state of 'super-greenhouse', with a very warm and ice-free climate, and reached one of the highest temperatures in history, according to Unesco.

TheBarrika Glaciation, identified on the cliffs of Bizkaia , shows irrefutable evidence of 'tidewater glacier' or 'tide glaciers' at very low latitudes, around 35 ° N, just during the period when it is one of the hottest Mesozoic models.
   
The ice fronts of these glaciers sailed directly into the ocean for 1.84 million years, and large icebergs were released directly from the front of the glaciers into the sea water. These blocks of ice and the dynamics of the glaciers themselves left glacial deposits between 82.8 and 80.96 million years in northern Iberia.

Paradigm shift

"300-255 million years ago, no evidence was found of glaciers reaching the sea from the icehouse of the Permic Carboniferous," explains Juan Pedro Rodriguez-López. In the case of Barrika, the discovery is "a paradigm shift that forces us to question the very basis of paleoclimatic models , at least in the Mesozoic. "

"The data documented in the barrel require a thorough assessment of the paleoclimatic indicators currently used, and the geochemical instruments used to reconstruct past temperatures suggest a systematic overestimation of Cretaceous paleotemarma, "the researcher said.

This is important, because understanding these past events depends on the accuracy of future projections of global climate change.

Thus, Barrika's research provides critical data for refining global paleoclimatic models and understanding the Earth's system's response to extreme global warming conditions.