•  Man made climate change could turn the Antarctica green as ice sheets shrink
• Carbon dioxide levels may have reached the same levels as the Pliocene period 
• This was three million years ago and could provide clues to what the future holds
• Scientists say there is likely to be a ‘lag’ before the true effects of hitting this threshold are felt

Man-made climate change could turn Antarctica green as ice sheets shrink and plants begin to colonise the land underneath once again, scientists have warned.

Current levels of carbon dioxide (CO²) in the atmosphere could lead to conditions comparable with the Pliocene period three million years ago, experts say.

The last time levels of the atmosphere were as high as today – at around 400 parts per million (ppm) – was during this geological epoch.

Studying evidence from this era may provide clues about the future of the planet and help humans understand the pressures they may face, researchers believe.

The Royal Meteorological Society and the Grantham Institute for Climate Change are holding a meeting on Wednesday to discuss the topic.

CO² levels in the atmosphere reached 400 ppm on average for the first time in 2015, World Meteorological Organisation figures show.

However, there is likely to be a ‘lag’ before the true effects of hitting this threshold are felt, according to Professor Martin Siegert, co-director of the Grantham Institute, Imperial College.

In the meantime, looking to the Pliocene era could offer clues as to how humans might deal with the challenges this creates, he said.

During this period, sea levels were around 15 metres higher and temperature estimated to be between 2C and 3.5C warmer than now.

‘(If) you put your oven on at home, and set it to 200C, the temperature doesn’t get to that immediately,’ he told reporters ahead of the meeting.

‘It takes a bit of time, and it’s the same with the climate.’

Professor Dame Jane Francis, director of the British Antarctic Survey, said remnants of the forests of Antarctica have been found, which are probably dated to the Pliocene age.

‘The really important significance of this is that we’ve got 400 ppm now, and if we had 400 ppm in the past, this is maybe where we are going back to,’ she said.

‘Which is the ice sheets are going to shrink at times, not all the time but at times… which may allow plants to colonise in Antarctic land again.’

Before the industrial revolution in 1850 carbon dioxide levels were about 280 ppm and since then the temperature has increased globally by around 1C, Proessor of Siegert said.

‘What it means is that by the end of this century, we might expect another 1C,’ he added.

If carbon dioxide emissions continue at current rates, levels could soar to 1000 ppm by 2100, he suggested.

This is the same as estimated levels around 100 million years ago, when dinosaurs roamed the earth and Antarctica was warmer and much greener.

‘If our mission was to put that carbon dioxide back into the atmosphere and recreate the Cretaceous period, 100 million years ago – if that was our mission, we are doing a pretty good job,’ Professor Siegert said.

He called for global action to reduce the amount of carbon dioxide in the atmosphere.

‘The consequences of what we have done over 150 years will continue into the future, so it’s up to us to do something,’ he said.

‘We will be judged in history on how well we respond to this issue, and at the moment we’re not doing a very good job.’