2016-10-10. Simulating the Climate 145 Million Years Ago.

posted Oct 15, 2016, 8:58 AM by Alan Gould
By Shannon Hall, Earth and Space Science News (EoS, AGU). For GSS Life and Climate chapter 8. Excerpt: A new model shows that the Intertropical Convergence Zone wasn't always a single band around the equator, which had drastic effects on climate. The United Kingdom was once a lush oasis. That can be read from sediments within the Kimmeridge Clay Formation, which were deposited around 160 to 145 million years ago on Dorset’s “Jurassic Coast.” ...the formation is rich in organic matter, which suggests that it likely formed when global greenhouse conditions were at least 4 times higher than present levels. ...Armstrong et al. used those black shales to build new climate simulations that better approximate the climate toward the end of the Jurassic period. The model simulated 1422 years of time that suggested a radically different Intertropical Convergence Zone—the region where the Northern and Southern Hemisphere trade winds meet—than the one today. The convergence of these trade winds produces a global belt of clouds near the equator and is responsible for most of the precipitation on Earth. ...Today the Intertropical Convergence Zone in the Atlantic strays, at most, 12° away from the equator. However, 145 million years ago, when the continents were still much closer together, the model showed that the zone split, like a fork in the road, where the Pacific Ocean met the western coast of the American continents. The zone was driven apart by the proto-Appalachian mountain range to the north and the North African mountains to the south. ...  https://eos.org/research-spotlights/simulating-the-climate-145-million-years-ago

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