World's first animals caused global warming

July 2, 2018, University of Exeter
Credit: CC0 Public Domain

The evolution of Earth's first animals more than 500 million years ago caused global warming, new research shows.

Some 520-540 million years ago, animal life evolved in the ocean and began breaking down organic material on the seafloor, leading to more carbon dioxide and less oxygen in the atmosphere.

In the 100 million years that followed, conditions for these earliest became much harsher, as ocean oxygen levels fell and carbon dioxide caused .

The research, published in Nature Communications, is from the Universities of Exeter, Leeds and Antwerp, and the Vrije Universiteit Brussel.

"Like worms in a garden, tiny creatures on the seabed disturb, mix and recycle dead organic material—a process known as bioturbation," said Professor Tim Lenton, from the University of Exeter.

"Because the effect of animals burrowing is so big, you would expect to see big changes in the environment when the whole ocean floor changes from an undisturbed state to a bioturbated state."

"We did indeed see a decrease in oxygen levels in the ocean around 520 million years ago," said Professor Filip Meysman, from the University of Antwerp.

"But evidence from the rock record showed sediment was only a little disturbed."

Professor Simon Poulton, from the University of Leeds, said: "This meant that the animals living in the seafloor at that time were not very active, and did not move very deep into the seabed.

"At first sight, these two observations did not seem to add up."

Lead author Dr. Sebastiaan van de Velde, of the Vrije Universiteit Brussel, explained: "The critical factor was to realise that the biggest changes happen at the lowest levels of animal activity.

"This meant that the first bioturbators had a massive impact."

The researchers said this realisation was the "missing piece of the puzzle", and allowed them to construct a mathematical model of Earth around that time to look to the changes caused by these early life forms.

Dr. Benjamin Mills, also from the University of Leeds, who led this part of the research, said: "When we ran our model, we were surprised by what we saw.

"The evolution of these small animals did indeed decrease the oxygen in the ocean and atmosphere, but also increased atmospheric levels to such an extent that it caused a global warming event.

"We knew that warming occurred at this point in Earth history, but did not realise it could be driven by animals."

This process made conditions worse for these animals, which possibly contributed to a number of mass extinction events during the first 100 million years of animal evolution.

"There is an interesting parallel between the earliest animals changing their world in a way that was bad for them, and what we human animals are doing to the planet now," said Professor Lenton, director of Exeter's new Global Systems Institute, which aims to develop transformative solutions to the challenges facing the world today.

"We are creating a hotter world with expanding anoxia (oxygen deficiency) which is bad for us and a lot of other creatures we share the planet with."

Explore further: What caused the mass extinction of Earth's first animals?

More information: Sebastiaan van de Velde et al, Early Palaeozoic ocean anoxia and global warming driven by the evolution of shallow burrowing, Nature Communications (2018). DOI: 10.1038/s41467-018-04973-4

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8 comments

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Benni
2 / 5 (8) Jul 02, 2018
The planet needs to be vacated of all animal (human too) so that the normal pristine order of the environment can be re-established............ but then there will be no AGWs around WHO WILL EVEN CARE?
granville583762
2.7 / 5 (7) Jul 02, 2018
The evolution of Earth's first animals more than 500 million years ago caused global warming?
What can one say, now nature caused global warming so we do not exist were just a mirage!
rrwillsj
3 / 5 (2) Jul 02, 2018
Yes gv5m you finally got something right!

Humanity is but an ephemeral mirage. Shimmering far off in the distance. Across the cruelly plundered desolation we are making of this world.
granville583762
4 / 5 (4) Jul 02, 2018
Fermi's Paradox was true all this time; we are the cause of all the environmental damage in the universe
Bennie > The planet needs to be vacated of all animal (human too) so that the normal pristine order of the environment can be re-established............ but then there will be no AGWs around WHO WILL EVEN CARE?

The irony Bennie, is we will never know because we never exited and you will not have been able to tell the world "The planet needs to be vacated of all animal (human too)". Nature is causing global warming as the solution is nature to go extinct is as almost as sad as Fermi's Paradox that were the only life in the entire Universe, well now we know the truth, Fermi's Paradox was true all the time!
Da Schneib
4 / 5 (4) Jul 02, 2018
Amusing to find that supposedly intelligent humans are as stupid as bacteria.
rrwillsj
3 / 5 (2) Jul 02, 2018
Oh DS, what have Bacteria ever done to you?

Hhmm??

I hope you apologize to the little critters... Soon! I hear them muttering about denying us pickles and cider and trumptweets.
Benni
2.3 / 5 (6) Jul 02, 2018
I hope you apologize to the little critters... Soon! I hear them muttering about denying us pickles and cider and trumptweets.


OMG, no pickles? Only cukes? Glad that got fixed in a hurry.......
Joker23
1 / 5 (1) Jul 09, 2018
Too bad there were no politicians to tax them! You know, never let a crisis go to waste.

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