————————————————————————-
” … 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.”
” … the seawater chemistry shows there was little or no ice on the planet.”
————————————————————————-
Public release date: 28-Jul-2008
Cardiff University
Contact: Dr. Cat Burgess
catherine_burgess99@hotmail.com
07-740-500-722
A snapshot of New Zealand’s climate 40 million
years ago reveals a greenhouse Earth, with warmer
seas and little or no ice in Antarctica,
according to research published this week in the
journal Geology.
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’s School of Earth and Ocean
Sciences, 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.
Notes for editors
1. “Middle Eocene climate cyclicity in the
Southern Pacific: Implications for global ice
volume” is published in the August issue of
Geology. (vol.36, no.8, p.651-654;
doi:10.1130/G24762A.1)
The authors are:
Catherine E. Burgess, School of Earth and Ocean
Sciences, Cardiff University (lead author)
Paul N. Pearson and Caroline H. Lear, School of
Earth and Ocean Sciences, Cardiff University
Hugh E.G. Morgans, GNS Science New Zealand
Luke Handley and Richard D. Pancost, University of Bristol
Stefan Schouten, Royal Netherlands Institute for Sea Research
————————————————————————————