Climate change: Why scientists are about to drill a kilometre-deep hole into the Antarctic ice

Kiwi scientists are planning to drill a kilometre down into the Antarctic ice to find out just what happened the last time the Earth warmed up.

If the West Antarctic Ice Sheet melts, it's estimated global sea levels could rise significantly - three metres thanks to the ice itself, and another metre as the ground beneath it springs up, no longer weighed down by ice, displacing the water above. 

Climate models suggest this could become inevitable if temperatures rise 1.5C to 2C above pre-industrial levels - we're already most of the way there, and on our way to blasting well past it on current trends. 

But rather than rely entirely on computer simulations, as accurate as they have been to date, scientists want to find out first-hand what happened in Antarctica's distant past. Since they can't go back in time, they're going to do the next-best thing - drill down to ice that's been untouched for eons. 

"We have formed a team of drillers, engineers, field experts and scientists who are up to the task," said Richard Levy, a paleoclimatologist at GNS Science. 

"Discoveries will show us how much the West Antarctic Ice Sheet could melt if we miss Paris Agreement targets.

The Paris Agreement, signed at the UN's COP21 meet in 2015, aims to keep the global temperature rise below 1.5C. COP26 is happening right now in the UK. 

The team will leave Scott Base later this month to a spot near the centre of the West Antarctic Ice Sheet, which scientists have deemed "unstable" and hard to predict when it comes to the effect of future warming. Much of its ice is below sea level, exposed to the warming ocean.

Tim Naish of Victoria University of Wellington says the project could reveal whether the West Antarctic Ice Sheet melted last time, and what triggered it. 

They'll dig through 800m of ice using "world-first" technology developed at the university's Antarctic Research Centre, scraping up sediment from 200m below that. 

Funding for the venture has come from around the world - including the US, Germany, Australia, the UK and Korea - and the team is just as diverse. 

"The fact that so many countries are joining us in this effort highlights the urgency to understand more about the West Antarctic Ice Sheet, which remains the largest uncertainty for sea level rise projections," said centre director Rob McKay.

"The climate records retrieved in this project will be critical to a much better understanding of how Antarctica will respond to a warming planet," said Antarctica New Zealand chief scientific advisor John Cottle.