{"id":32382,"date":"2023-08-10T17:00:00","date_gmt":"2023-08-10T15:00:00","guid":{"rendered":"http:\/\/c02caa3c-108f-41a2-86c6-61f6b74e898f"},"modified":"2023-08-10T17:38:26","modified_gmt":"2023-08-10T15:38:26","slug":"scientists-dont-actually-have-a-clue-how-the-himalayas-got-so-tall-study-reveals","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/rss_feed\/scientists-dont-actually-have-a-clue-how-the-himalayas-got-so-tall-study-reveals\/","title":{"rendered":"Scientists don\u2019t actually have a clue how the Himalayas got so tall, study reveals"},"content":{"rendered":"

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By Noa Leach\n <\/p>

Published: Thursday, 10 August 2023 at 15:00 PM<\/p>

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Think you know the Himalayas? Well, it turns out leading scientists don\u2019t either, as a new study reveals that the iconic mountains<\/a> did not reach their dizzying heights in the way we previously thought they did.<\/p>

Considered the tallest point on Earth, Mount Everest \u2013 the tallest in the Asian mountain range \u2013 sits at 8,849m high (29,032 feet).<\/p>

But scientists have worked out the height of the mountains before the tectonic collision previously thought to have caused their sudden surge upwards. They found that, while the collision made them taller, the Himalayas were already tall \u2013 and no-one knows why.<\/p>

\u201cExperts have long thought that it takes a massive tectonic collision, on the order of continent-to-continent scale, to produce the sort of uplift required to produce Himalaya-scale elevations,\u201d said the study\u2019s first author Daniel Ibarra<\/a>, now assistant professor at Brown University, USA.<\/p>

\u201cThis study disproves that and sends the field in some interesting new directions.\u201d<\/p>

Published in the journal Nature Geoscience<\/em>, the study describes how scientists at Stanford Doerr School of Sustainability, USA, collaborated with scientists from China University of Geosciences.<\/p>

Together, they discovered a new way to measure the past altitudes of sedimentary rocks \u2013 inspired by an existing technique used to examine meteorites.<\/p>

What they found was that the Himalayan mountains, sitting at the edges of tectonic plates, were already high before the collision happened \u2013 at around 3.5km tall (2.2 miles). This means they were a lot higher than previously thought \u2013 already more than 60 per cent of their present-day height, in fact.<\/p>

\u201cThis new understanding could reshape theories about past climate and biodiversity,\u201d said Ibarra.<\/p>

The researchers took what they knew about the processes that change the climate around mountains, and applied this knowledge to measure the mountains\u2019 altitude.<\/p>

On the leeward (or downwind) side of mountains warm air rises and cools, condensing into rain and snow. This means the other side is dry \u2013 often known as the \u2018rain shadow\u2019 \u2013 making deserts common here.<\/p>

But as the warm air rises, the chemical composition of its rain changes. Heavier isotopes (variations of elements like oxygen that contain more neutrons) drop out of the clouds first. The rain sheds lighter isotopes, meanwhile, nearer the mountaintops.<\/p>

The clues lie in the rocks: the scientists measured the Himalayan rocks\u2019 isotopic composition to determine their ancient altitude in an analysis that took three years.<\/p>

\u201cThere are maybe eight labs in the world that can do this analysis,\u201d said Page Chamberlain<\/a>, professor of Earth and planetary sciences and senior author of the study.<\/p>

The findings are of high interest to climate modellers. The study of mountains is interlinked with climate studies, as weather and the plants and animals that live there shift according to the mountains\u2019 formation and structure.<\/p>

The results mean that ancient climate models around the Himalayas will need to be recalibrated \u2013 perhaps leading to new theories on the ancient climate of Southern Tibet.<\/p>

Other well-known mountain ranges like the Andes and the Sierra Nevada will likely be re-assessed too.<\/p>

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