Discovering the secret past of Antarctica
The first human to ever visit the Ross Sea might have been Ui-te-Rangiora, who travelled there from Rarotonga in the 7th century. The first New Zealander to see Antarctica was a Māori sailor named Tuati. He was on a famous expedition to the Southern Ocean led by Charles Wilkes in 1838.
Now in 2018, Aotearoa is taking part in another international ocean voyage of discovery. On Expedition 374, JOIDES Resolution, a scientific research ship, is journeying to the Ross Sea to discover more about the history of the ice sheets around Antarctica. It will be crossing the Antarctic circle to explore under the seafloor in the world’s southernmost waters and is carrying 31 scientists on board. The expedition was organised by the International Ocean Discovery Program (IODP). Read more about other IODP expeditions in Voyages of discovery.
JOIDES Resolution in Lyttelton Harbour
JOIDES Resolution is a seagoing research vessel that drills core samples and collects measurements from under the ocean floor. Here, the vessel is in Lyttelton Harbour, near Christchurch.
In the past, the ice sheets and glaciers around Antarctica have grown and retreated in natural cycles. These cycles were related to changes to the Earth’s rotation around the Sun, causing more or less sunlight at the polar regions of the Earth. However, the amount of greenhouse gases humans are emitting is causing a very fast rise in the temperature of the sea, which will cause big changes to the ice in the polar regions.
Penguins on sea ice in the Ross Sea
Penguins are often seen on floating sea ice. These were seen from the research vessel JOIDES Resolution on a voyage to the Ross Sea in 2018.
The Ross Ice Shelf
The Ross Ice Shelf is the biggest ice shelf in Antarctica. It is almost twice as large as Aotearoa. Ice shelves are floating islands of ice and are several hundreds of metres thick. Scientists on JOIDES Resolution want to know what happened to the Ross Ice Shelf in the distant past to help us understand what will happen to Antarctica as climate change makes the sea warmer.
The scientists on board JOIDES Resolution use clues from the sediment (a mix of mud, sand and stone) from beneath the seafloor to help them understand what happened to the ice millions of years ago. For example, they look for stones that would have been dragged to the seafloor by glaciers to tell if the glaciers were growing larger or smaller in the past.
We’re looking at the middle Miocene because it’s the period in time when the Earth is warmest over the past 16 million years, and we’re trying to understand how Antarctica’s ice sheets behaved during that time.
Amelia Shevenell, scientist on board
Scientists on JOIDES Resolution are particularly interested in a time period called the mid-Miocene, around 15 million years ago. Antarctica was particularly warm at that time, so learning more about the mid-Miocene will give scientists clues about what could happen to Antarctica’s ice sheets as the world warms. To get to sediment from mid-Miocene times, the ship has to drill down hundreds of metres below the seafloor.
The sediment is brought up out of the ocean in long thin cores for the scientists to measure and test in all kinds of ways, using geology, chemistry, physics and biology. There are many laboratories on board the ship to undertake these important tests.
A scientist on board JOIDES Resolution
Sedimentologist Isabela Cordeiro de Sousa looking at microfossils from millions of years ago. Scientists like Isabela have access to a wide range of scientific equipment on board the research vessel JOIDES Resolution. This means scientists can collect samples and then analyse them on board.
Dating sediment
To understand how old the sediment is, scientists use tiny microfossils, which are smaller than grains of sand. Different kinds of microorganisms lived in different times, so the scientists can tell how many millions of years old the sediment is by the kinds of fossils it holds. The fossils can also tell us about the water temperature and depth, because some microorganisms only like to live in warm water, some in shallow water and some only where there are icebergs in the water. For example, if a scientist looks in a microscope and sees fossils of creatures that lived 15 million years ago and some that liked warm water, they can assume that the water around Antarctica was warmer 15 million years ago. Learn more about the process of dating sediment using fossils in Relative dating.
Everybody’s happy and everybody’s working hard. We are a team.
Laura de Santis, co-chief scientist on the ship
By working together, these scientists from 13 different nations including New Zealand are discovering more about Antarctica’s future by looking at the distant past. They are helping us to understand why we should prevent too much climate change and how we can adapt when it does happen.
Useful links
Watch this YouTube clip about Expedition 374.
Read stories about the expedition on the JOIDES Resolution ship log.
Get more information on the IODP.
Returning to a green Antarctica is a comic by Simone Giovanardi and Bella Duncan. It explains why Antarctica once looked more like South Island’s West Coast beech forests than the frozen continent we know today.
See our Pinterest board full of useful related resources.
Acknowledgement
This article was written by Rosa Hughes-Currie, an outreach educator on board the JOIDES Resolution, expedition 374, a voyage to the Ross Sea in 2018.
ANZIC logo
ANZIC is the Australian and New Zealand IODP Consortium, part of the 23-nation team engaged in deploying state-of-the-art drilling technologies. IODP advances the scientific understanding of the Earth and unifies the international research community to explore Earth’s last frontiers.
