The study suggests that Antarctica at that time was yet to develop extensive ice sheets. Back then, New Zealand was about 1100 km further south, at the same latitude as the southern tip of South America – so was closer to Antarctica – but the researchers found that the water temperature was 23-25°C at the sea surface and 11-13°C at the bottom.
“This is too warm to be the Antarctic water we know today,” said Dr Catherine (Cat) Burgess from Cardiff University and lead-author of the paper. “And the seawater chemistry shows there was little or no ice on the planet.”
These new insights come from the chemical analysis of exceptionally well preserved fossils of marine micro-organisms called foraminifers, discovered in marine rocks from New Zealand. The researchers tested the calcium carbonate shells from these fossils, which were found in 40 million-year-old sediments on a cliff face at Hampden Beach, South Island.
“Because the fossils are so well preserved, they provide more accurate temperature records.” added Dr Burgess. “Our findings demonstrate that the water temperature these creatures lived in was much warmer than previous records have shown.”
“Although we did not measure carbon dioxide, several studies suggest that greenhouse gases forty million years ago were similar to those levels that are forecast for the end of this century and beyond.
Our work provides another piece of evidence that, in a time period with relatively high carbon dioxide levels, temperatures were higher and ice sheets were much smaller and likely to have been completely absent.”
The rock sequence from the cliff face covers a time span of 70,000 years and shows cyclical temperature variations with a period of about 18,000 years. The temperature oscillation is likely to be related to the Earth’s orbital patterns.
The research was funded by the Natural Environment Research Council, the Netherlands Organisation for Scientific Research (NOW) and GNS Science, New Zealand.
Issued jointly by the Natural Environment Research Council and Cardiff University.
Marion O'Sullivan | alfa
"Flight recorder" of rocks within the Earth’s crust
16.04.2019 | Universität Bern
More than 90% of glacier volume in the Alps could be lost by 2100
09.04.2019 | European Geosciences Union
A stellar flare 10 times more powerful than anything seen on our sun has burst from an ultracool star almost the same size as Jupiter
A localization phenomenon boosts the accuracy of solving quantum many-body problems with quantum computers which are otherwise challenging for conventional computers. This brings such digital quantum simulation within reach on quantum devices available today.
Quantum computers promise to solve certain computational problems exponentially faster than any classical machine. “A particularly promising application is the...
The technology could revolutionize how information travels through data centers and artificial intelligence networks
Engineers at the University of California, Berkeley have built a new photonic switch that can control the direction of light passing through optical fibers...
Physicists observe how electron-hole pairs drift apart at ultrafast speed, but still remain strongly bound.
Modern electronics relies on ultrafast charge motion on ever shorter length scales. Physicists from Regensburg and Gothenburg have now succeeded in resolving a...
Engineers create novel optical devices, including a moth eye-inspired omnidirectional microwave antenna
A team of engineers at Tufts University has developed a series of 3D printed metamaterials with unique microwave or optical properties that go beyond what is...
17.04.2019 | Event News
15.04.2019 | Event News
09.04.2019 | Event News
18.04.2019 | Life Sciences
18.04.2019 | Physics and Astronomy
18.04.2019 | Life Sciences