Kiwi scientists just returned from an ambitious drilling expedition in Antarctica broke more than ice on the frozen continent.
The 30-strong research team also broke two records: the highest-ever recovery rate from a deep drill core they sent below the vast West Antarctic Ice Sheet, and the longest-ever piston core.
That yielded a pristine geological record of change in the ocean over a much longer time period than expected – several million years.
The two-month voyage aboard the international drilling vessel JOIDES Resolution sought to uncover valuable new insights into past changes in the ice sheet, which contains about 10 per cent of the wider Antarctic ice sheet's 25.4 million sq km volume.
According to satellite data, the West Antarctic Ice Sheet is losing around 150 cu km of ice each year.
If it were to melt — as it has in the past — the global sea level would rise about three metres.
The impact from the collapse of the Eastern Antarctic Ice Sheet would be even more dramatic, because it contains enough ice to cause an estimated 20m rise in sea levels.
The research team, led by Victoria University's Associate Professor Rob McKay and Italy's Dr Laura De Santis, this week returned with rock cores from up to 700m below the sea floor collected from five different sites on the ice sheets.
Not only did these records tell us what had happened far back in the past, but what could happen as the effects of climate change began to be felt around this vulnerable area of Antarctica.
By drilling down so deeply into the sea floor, the team sought to gain a glimpse into so-called "greenhouse worlds" that contained the same level of carbon dioxide as that now in our atmosphere.
"We think the modern melting of the West Antarctic Ice Sheet is due to ocean warming, but we are not sure exactly how much warming is required to cause a major loss of the West Antarctic Ice Sheet," McKay said.
"Because of this expedition we now have records that will document the magnitude of ocean warming during major ice sheet collapse events in the geological past.
"It is this direct link between large changes in ice sheet size and the associated change in the oceans directly offshore that is unique to this expedition."
This expedition was only the second ship-based deep geological drilling expedition to travel to the Ross Sea.
The first expedition on the GLOMAR Challenger in 1973 showed that the Antarctic Ice Sheet was more than 25 million years old - much older than the two million years researchers had expected.
This was followed by another expedition aboard the Challenger to the Southern Ocean that provided the first ocean temperature history for the last 50 million years through pioneering studies on microfossil geochemistry.
The work completed by the JOIDES Resolution and GLOMAR Challenger teams is part of a 50-year history of expeditions that began with the Deep Sea Drilling Project in 1968.
Since then, 23 countries have taken part in over 300 expeditions, culminating in the International Ocean Discovery Programme, which will run until 2023.
"There's no way one single country could afford to do research at this scale," McKay said.
"Working in close proximity with a diverse group of scientists from a range of different cultures and scientific approaches, every single day for two months, means everyone emerges from these cruises a better-rounded scientist."