One of the reasons we’ve never been troubled by the prospect of a less-cold world – a broader tropical belt with temperate zones to the poles just isn’t that frightening a prospect.
New research published in Science points to the significant role of oceans in ancient global cooling
Research led by Rensselaer Polytechnic Institute scientist finds evidence that early antarctic circumpolar current development impacted global climate
Troy, N.Y. – Thirty-eight million years ago, tropical jungles thrived in what are now the cornfields of the American Midwest and furry marsupials wandered temperate forests in what is now the frozen Antarctic. The temperature differences of that era, known as the late Eocene, between the equator and Antarctica were only half of what they are today. A debate has long been raging in the scientific community on what changes in our global climate system led to such a major shift from the more tropical, greenhouse climate of the Eocene to the modern and much cooler climates of today. (EurekAlert)
“A debate has long been raging in the scientific community on what changes in our global climate system led to such a major shift from the more tropical, greenhouse climate of the Eocene to the modern and much cooler climates of today.”
I can think of two events that may have contributed to climatic shifts observed in the fossil record of the early Cenozoic era. First was the thermal isolation of Antarctica by the newly formed Antarctic Circumpolar Current which was itself created when South America continued to drift northward, leaving a gap between itself and Antarctica wide enough to allow the ACC to form for the first time. This occurred near the end of the Eocene and is thought to be largely responsible for the minor mass extinction that ushered in the Oligocene where global temps were cooler overall and conditions were more seasonal than during the Paleocene/Eocene ages. The formation of the ACC also reconnected Earths’ oceans and resulted in the formation of the thermohaline circulation, which likely contributed further to the climatic shifts observed.
Another event that possibly contributed to the climatic changes was the uplifting of the Tibetan Plateau caused by the collision of the Indian subcontinent with Eurasia that began 55 million years ago and continues today.
These events were among the most significant to occur during the Cenozoic era and were almost certain to have contributed significantly to climate change at the time.