by EARTH INSTITUTE AT COLUMBIA UNIVERSITY, August 20, 2020 in WUWT

Scientists studying leaves from a 23-million-year-old forest have for the first time linked high levels of atmospheric carbon dioxide with increased plant growth, and the hot climate off the time. The finding adds to the understanding of how rising CO₂ heats the earth, and how the dynamics of plant life could shift within decades, when CO₂ levels may closely mirror those of the distant past.

Scientists retrieved the leaves from a unique onetime New Zealand lake bed that holds the remains of plants, algae, spiders, beetle, flies, fungi and other living things from a warm period known as the early Miocene. Scientists have long postulated that CO₂ was high then, and some plants could harvest it more efficiently for photosynthesis. This is the first study to show that those things actually happened in tandem. The findings were published this week in the journal Climate of the Past.

“The amazing thing is that these leaves are basically mummified, so we have their original chemical compositions, and can see all their fine features under a microscope,” said lead author Tammo Reichgelt, an adjunct scientist at Columbia University’s Lamont-Doherty Earth Observatory and assistant professor of geosciences at the University of Connecticut. “Evidence has been building that CO₂ was high then, but there have been paradoxes.”

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IMAGE: A 23-MILLION-YEAR-OLD LEAF PRESERVED IN A ONETIME NEW ZEALAND LAKE BED, KEY TO PAST ATMOSPHERIC CONDITIONS. ONE CAN SEE VEINS, GLANDS ALONG THE TEETH, AND HOLES GNAWED BY INSECTS, WITH… view more CREDIT: JENNIFER BANNISTER/UNIVERSITY OF OTAGO

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