First plants caused ice ages: research

Feb 01, 2012

New research reveals how the arrival of the first plants 470 million years ago triggered a series of ice ages. Led by the Universities of Exeter and Oxford, the study is published today (February 1, 2012) in Nature Geoscience.

The team set out to identify the effects that the first had on the climate during the , which ended 444 million years ago. During this period the climate gradually cooled, leading to a series of 'ice ages'. This was caused by a dramatic reduction in atmospheric carbon, which this research now suggests was triggered by the arrival of plants.

Among the first plants to grow on land were the ancestors of mosses that grow today. This study shows that they extracted minerals such as calcium, magnesium, phosphorus and iron from rocks in order to grow. In so doing, they caused chemical weathering of the Earth's surface. This had a dramatic impact on the and subsequently on the climate. It could also have led to a mass extinction of marine life.

The research suggests that the first plants caused the weathering of calcium and magnesium ions from silicate rocks, such as granite, in a process that removed carbon dioxide from the atmosphere, forming new in the ocean. This cooled by around five degrees Celsius.

In addition, by weathering the nutrients phosphorus and iron from rocks, the first plants increased the quantities of both these nutrients going into the oceans, fuelling productivity there and causing burial. This removed yet more carbon from the atmosphere, further cooling the climate by another two to three degrees Celsius. It could also have had a devastating impact on marine life, leading to a that has puzzled scientists.

The team used the modern moss, Physcomitrella patens for their study. They placed a number of rocks, with or without moss growing on them, into incubators. Over three months they were able to measure the effects the moss had on the chemical weathering of the rocks.

They then used an Earth system model to establish what difference plants could have made to climate change during the Ordovician Period.

One of the lead researchers, Professor Tim Lenton of the University of Exeter said: "This study demonstrates the powerful effects that plants have on our climate. Although plants are still cooling the Earth's climate by reducing levels, they cannot keep up with the speed of today's human-induced climate change. In fact, it would take millions of years for plants to remove current carbon emissions from the atmosphere."

Professor Liam Dolan of Oxford University, one of the lead researchers, said: "For me the most important take-home message is that the invasion of the land by plants – a pivotal time in the history of the planet – brought about huge climate changes. Our discovery emphasises that plants have a central regulatory role in the control of climate: they did yesterday, they do today and they certainly will in the future."

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User comments : 12

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1 / 5 (13) Feb 01, 2012
so basically the whole 'global warming' thing is just another planetry phase we go through. As far as i can tell, the earth is just reverting to how it was. I think we're gonna see another lizard age, in the sense that lizards have most of the same properties as plants... cut a plant head off it grows 2.. same with most lizards.. cut another 1, another 2 grow.
1 / 5 (7) Feb 01, 2012
p.s. i'm not refering to the lizard age as an actual age.. but just refering to what i think it'll be like.... & lizards get eaten by a lot of birds so if my theory is right, with the degeneration of plant life, birds & lizards should bloom as they eat each other.. more so carniverous birds like owls & will probably be lower moving lizards like snakes, crocs, turtles etc
5 / 5 (13) Feb 01, 2012
the "whole global warming thing" is occurring within the span of a hundred years, the changes that caused this ice age took millions of years.
1.5 / 5 (12) Feb 01, 2012
Returning to the "lizard age" would not cause plant life to degenerate. If anything, it would bloom and new jungles would spring up.

The mini ice age came on quickly and took a few hundred years to dissipate. Not all ice ages come and go over millions of years. Just sayin.
5 / 5 (6) Feb 01, 2012
how after reading that someone could surmise that the whole global warming thing is another planetary phase?
1 / 5 (6) Feb 01, 2012
In science classrooms all across this country, kids are trained to memorize science in factual chunks. The methodology rarely involves actually asking a kid what he thinks of the science: The idea is that, rather than train a kid to ask good questions in science, we instead train them to answer good answers. What do you think happens to all of our innate abilities to think for ourselves, over time? Since it doesn't get used, it atrophies. Increasingly, "thinking like a scientist" is treated as though it's simply a matter of knowing the correct textbook answer.

When I look at the articles which appear on physorg, and the various responses which they evoke, I am stunned. Do you all truly accept the assumption that the Earth is a self-contained system? If there are any critical thinkers out there who are willing to question assumptions in science, go back to the old Kristian Birkeland debates about the source for the aurora, and revisit the old Velikovsky-Sagan debates.
1.1 / 5 (10) Feb 01, 2012
This notion that we can rewind time and get a reliable answer is built upon a weak foundation. Not only do we see evidence that there exists an astronomical component to radioactive decay, calling into question the authenticity of our timekeeper, but there also exists this absolutely enormous and detailed recounting by all of the cultures of the world of a human history which exhibits peculiar similarities from one culture to the next. This reductionist approach to reconstructing the Earth's history -- where we try to nail down one tiny piece of information, one bit at a time -- completely ignores the written word and petroglyphs which come from every portion of our world. It won't work. We see the same reductionist approach failing in other scientific disciplines as well. The only true approach to solving these riddles involves a process of interdisciplinary synthesis, and a willingness to question the underlying assumptions of science.
5 / 5 (6) Feb 01, 2012
@Hannes your views on radioactive decay are fascinating, but unfortunately does not stand up to scrutiny. But science does.
4 / 5 (4) Feb 01, 2012
the "whole global warming thing" is occurring within the span of a hundred years, the changes that caused this ice age took millions of years.

Not only that, but we'll be seeing the global population grow to 9 billion inhabitants by 2050. Most of the present population growth happened relatively recently in relation to man's beginning. Humans share some traits with rabbits.
2 / 5 (4) Feb 01, 2012
@Hannes your views on radioactive decay are fascinating, but unfortunately does not stand up to scrutiny. But science does.
Actually the science on this very site says you're wrong. Proton decay varies with neutrino emissions, which are non-isotropic.
Humans share some traits with rabbits.
So up to a billion new bunnies? Hugh should be having fun if he can hold out that long.
1 / 5 (2) Feb 02, 2012
Hannes is right, there is interaction among ALL componenets of our visible universe, as well as what ISN'T visible. I think what he is overlooking is that each new "bit" of info adds to the agregate (can't see the forest for the trees analogy) so that someday we actually WILL know the bigger picture.
Unfortunately, the thing about the big picture is that there is ALWAYS a bigger picture.
Feb 02, 2012
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not rated yet Feb 05, 2012
New research reveals how the arrival of the first plants 470 million years ago triggered a series of ice ages. Led by the Universities of Exeter and Oxford, the study is published today (February 1, 2012) in Nature Geoscience.

I have been saying this very thing to my friends for the last 30 years. Whenever we are just bangin on about stuff. My stance has always been that photosynthesis occurred then the climate changed dramatically. To the point the even ice age earth may well have been caused by the imbalance between plant and animal. Animals that needed oxygen had to wait until the plants produced enough to make it worth their while.

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