The arrival of the first plants cooled the planet so much that it triggered a series of ice ages


  • Mosses first grew on land 470 million years ago
  • Arrival caused temperature to drop up to 8 degrees
  • Plants have 'central role' in regulating climate


Glacier face, Antarctica: Scientists believe that the arrival of the first plants caused a sharp drop in the planet's temperature, cooling Earth by up to eight degrees

Glacier face, Antarctica: Scientists believe that the arrival of the first plants caused a sharp drop in the planet's temperature, cooling Earth by up to eight degrees

The arrival of the first plants 470 million years ago triggered a series of ice ages, according to a study.

The plants caused a dramatic reduction in atmospheric carbon, which lowered temperatures by up to eight degrees centigrade.

A team from Oxford University set out to identify the effects that the first primitive mosses had on the climate during the Ordovician Period, which ended 444 million years ago.

During this period the climate gradually cooled, leading to a series of 'ice ages'.

The researchers analysed the effects of primitive mosses growing on rocks to simulate the conditions.

They found that the way mosses reacted with the rocks they clung to led to drastic climate change.

Professor Liam Dolan, 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.’

This study shows that the first mosses extracted minerals such as calcium, magnesium, phosphorus and iron from rocks in order to grow.

This had a dramatic impact on the global carbon cycle and subsequently on the climate. It could also have led to a mass extinction of marine life.

The research suggests that the chemical change to the make-up of the Earth's surface that was brought about by moss led to a process that removed carbon dioxide from the atmosphere, forming new carbonate rocks in the ocean.

This cooled global temperatures by around five degrees Celsius. Minerals washing into the ocean could have caused carbon to become 'locked' in the ocean, reducing the temperature by a further two to three degrees.

Professor Dolan said: 'Before this experiment we knew plants had a dramatic effect on the climate about 350 milllion years ago.'

'But this takes the clock much further back to when the first mosses began appearing. We believe they probably looked similar to the same non-vascular plants we see today although we don't really have any fossil records of them.'

At this time, our ancestors were jawless fish and the land was ruled by insects, Earth was being pounded by a series of enormous meteorites.

The traces of that hammering still survive today in ancient rocks in southern Sweden and central China, where scientists have found exotic mineral grains from meteorites.

Mosses first grew on land 470 million years ago

Mosses first grew on land 470 million years ago: The team used the modern moss, Physcomitrella patens for their study. They placed a number of rocks into incubators and watched the effects on the rocks beneath

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 atmospheric carbon 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.’