Study: Ancient Forests Fueled Early Climate Change

Posted November 23rd, 2015 at 5:30 pm (UTC-4)
1 comment

Reconstructed drawing of fossil forest in Svalbard (Cardiff University)

Reconstructed drawing of fossil forest in Svalbard (Cardiff University)

A pair of scientists from the United Kingdom have found a fossilized tropical forest complete with tree stumps of one of Earth’s first forests in Svalbard, a Norwegian archipelago located between Norway and the North Pole.

They also say that primitive forests such as the one they found may be one of the reasons for an extraordinary climatic event nearly 400 million years ago.

The researchers, Chris Berry of Cardiff University, Wales and John Marshall of England’s Southampton University have dated this ancient forest and found it to about 380 million years old.

Back then, during the Devonian period what is now known as Norway was located near the equator, where high temperatures and large amounts of rain created ideal growing conditions for large forest trees.

It wasn’t until later after periods of continental drift that Norway eventually moved from the equator to its current icy location.

Scientists say that until the large trees that formed the ancient forests started to sprout up, vegetation on Earth mostly consisted of small plants, no taller than a meter high.

“These fossil forests shows us what the vegetation and landscape were like on the equator 380 million years ago, as the first trees were beginning to appear on the Earth,” said Berry in a University of Cardiff press release.

Animation of the continental rifting of Pangaea (USGS)

Animation of continental drift (USGS)

Between about 420 and 360 million years ago, scientists said that there was a significant drop in the levels of atmospheric carbon dioxide.  Before the decrease, CO2 levels were said to be about 15 time more than today.

That huge reduction in the level of CO2 also happened to coincide with the growth and spread of these very first forests, whose trees sucked the gas from the air to create food and tissue through the process of photosynthesis.

Scientists say that the large drop in atmospheric CO2 was also responsible for a remarkable reduction in Earth’s temperatures to levels that are similar to those we have today.

“The evolution of tree-sized vegetation is the most likely cause of this dramatic drop in carbon dioxide because the plants were absorbing carbon dioxide through photosynthesis to build their tissues, and also through the process of forming soils,” Berry said.

The UK research duo say most of the trees that made up the ancient fossil forest were lycopods, a species that reproduced by spreading spores produced in cones at their stem tips.

They also found that the primitive forest was extremely dense, with very small gaps, around 20cm, between each of the trees, which were probably around 4 meters high.

The pair’s findings were published in the journal Geology.

Rick Pantaleo
Rick Pantaleo maintains the Science World blog and writes stories for VOA’s web and radio on a variety of science, technology and health topics. He also occasionally appears on various VOA programs to talk about the latest scientific news. Rick joined VOA in 1992 after a 20 year career in commercial broadcasting.

One response to “Study: Ancient Forests Fueled Early Climate Change”

  1. Philip Haddad says:

    It is quite likely that the drop in temperature coinciding with the drop in CO2 concentration was caused because when CO2 is converted by photosynthesis to trees, 4800 btus of solar energy per pound of CO2 are removed that otherwise would become heat. This makes it controversial whether the temperature drop was caused because of a decrease in the greenhouse effect or the simple conversion of solar energy to trees, and therefore, by inference, does a rise in CO2 (without heat of combustion) cause a rise in temperature?