Ancient “Pickled” Leaves Give a Glimpse of Global Greening

https://eos.org/articles/ancient-pickled-leaves-give-a-glimpse-of-global-greening

Source: By Kate Evans, Eos/AGU. 

Excerpt: From the surface, the fossil deposit of Foulden Maar looks like a typical New Zealand sheep paddock. But the ground beneath it contains both a world-class collection of leaf fossils and a 120,000-year record of Earth’s climate during the Miocene, 23 million years ago. Those features have allowed international researchers to show, for the first time, that carbon dioxide levels in the atmosphere during that period were relatively high and that some plants could harvest that atmospheric carbon more efficiently for photosynthesis, leading to increased growth and more drought tolerance. This insight has important implications for what we can expect later this century as the climate warms. Those features have allowed international researchers to show, for the first time, that carbon dioxide levels in the atmosphere during that period were relatively high and that some plants could harvest that atmospheric carbon more efficiently for photosynthesis, leading to increased growth and more drought tolerance. This insight has important implications for what we can expect later this century as the climate warms. ...Using a variety of different proxies, scientists estimate that average global temperatures during the Miocene were 5°C or 6°C warmer than today. The Antarctic ice sheet was larger, though, and then rapidly melted over a period of 100,000 years to about half of its current size. ... results indicated that in the early Miocene, atmospheric CO₂ shifted from 450 to 550 parts per million and then back to 450 parts per million over the 100,000 years represented in the Foulden Maar deposit. “That seems like a smoking gun to us: an increase in carbon dioxide that was responsible for a temperature increase that then led to the Antarctic deglaciation,” Reichgelt said....