A team of researchers in the United Kingdom has discovered ancient fossil forests believed to play a role in a massive climate shift on Earth during the Devonian period, about 400 million years past.

With their tree stumps intact and in place, the fossil forests were seen in the Norwegian archipelago of Svalbard by Dr. Chris Berry from Cardiff University and accurately dated to 380 million years by Professor John Marshall of Southampton University.

The fossil forest discovery is believed to help explain the 15-fold drop in atmospheric carbon dioxide levels during the late Devonian period, which was the time when the first big trees drew carbon dioxide out of the air through photosynthesis and soil formation.

"These fossil forests show us what the vegetation and landscape were like on the equator 380 million years ago, as the first trees were beginning to appear on Earth," explained Dr. Berry.

The emergence of big, tall trees, which are a far cry from the previous small plants of that era, initially absorbed more radiation from the sun. Eventually, however, temperatures dropped significantly to levels similar to today due to reduced atmospheric carbon dioxide reduction.

The researchers said that due to the high temperature levels and large rainfall amounts in the area, equatorial forests – Svalbard being one of them during that period, before tectonic plate movements led it to its present position in the Arctic Ocean – likely contributed greatly to carbon dioxide drawdown.

The Svalbard forests were primarily composed of lycopod trees, which grew millions of years afterwards in coal swamps turned coal deposits. The forests were characterized as highly dense with around 8-inch gaps between each tree, estimated to be about 13 feet tall.

Part of Dr. Berry’s previous work is a collaboration with U.S. researchers describing a slightly older forest located at New York’s Gilboa. This forest was situated at least 30 degrees south of the equator during that time, with the discovered tree stumps belonging to various plant types.

Dr. Berry added that the geographical diversity of the ecology and forest plants already existed soon after their evolution, to which he attributed the dramatic decrease in carbon dioxide levels.

“[T]he plants were absorbing carbon dioxide through photosynthesis to build their tissues, and also through the process of forming soils," Dr. Berry said.

Today freezing-cold Svalbard is among the most northernmost areas inhabited by man, home to about 2,500 and the so-called “Global Seed Vault,” an underground frozen seed bank containing a wide range of seeds for when a mass-scale crisis of diversity loss hits the planet.

The findings of the study were published in the journal Geology.