Buffalo, N.Y. – The possibility that climate change might
simply be a natural variation like others that have occurred
throughout geologic time is dimming, according to evidence in a
Proceedings of the National Academy of Sciences paper published
The research reveals that sediments retrieved by University at
Buffalo geologists from a remote Arctic lake are unlike those seen
during previous warming episodes.
The UB researchers and their international colleagues were able
to pinpoint that dramatic changes began occurring in unprecedented
ways after the midpoint of the twentieth century.
"The sediments from the mid-20th century were not all that
different from previous warming intervals," said Jason P. Briner,
PhD, assistant professor of geology in the UB College of Arts and
Sciences. "But after that things really changed. And the change is
The sediments are considered unique because they contain rare
paleoclimate information about the past 200,000 years, providing a
far longer record than most other sediments in the glaciated
portion of the Arctic, which only reveals clues to the past 10,000
"Since much of the Arctic was covered by big ice sheets during
the Ice Age, with the most recent glaciations ending around 10,000
years ago, the lake sediment cores people get there only cover the
past 10,000 years," said Briner.
"What is unique about these sediment cores is that even though
glaciers covered this lake, for various reasons they did not erode
it," said Briner, who discovered the lake in the Canadian Arctic
while working on his doctoral dissertation. "The result is that we
have a really long sequence or archive of sediment that has
survived arctic glaciations, and the data it contains is
Working with Briner and colleagues at UB who retrieved and
analyzed the sediments, the paper's co-authors at the University of
Colorado and Queens University, experts in analyzing fossils of
bugs and algae, have pooled their expertise to develop the most
comprehensive picture to date of how warming variations throughout
the past 200,000 years have altered the lake's ecology.
"There are periods of time reflected in this sediment core that
demonstrate that the climate was as warm as today," said Briner,
"but that was due to natural causes, having to do with
well-understood patterns of the Earth's orbit around the sun. The
whole ecosystem has now shifted and the ecosystem we see during
just the last few decades is different from those seen during any
of the past warm intervals."
Yarrow Axford, a research associate at the University of
Colorado, and the paper's lead author, noted: "The 20th century is
the only period during the past 200 millennia in which aquatic
indicators reflect increased warming, despite the declining effect
of slow changes in the tilt of the Earth's axis which, under
natural conditions, would lead to climatic cooling."
Co-authors with Briner and Axford are Colin A. Cooke and
Alexander P. Wolfe of the University of Alberta; Donna R. Francis
of the University of Massachusetts; John P. Smol, Cheryl R. Wilson
and Neal Michelutti at Queens University; Gifford H. Miller of the
University of Colorado and Elizabeth K. Thomas, who did this work
at UB for her master's degree in geology.
The University at Buffalo is a premier research-intensive public
university, a flagship institution in the State University of New
York system and its largest and most comprehensive campus. UB's
more than 28,000 students pursue their academic interests through
more than 300 undergraduate, graduate and professional degree
programs. Founded in 1846, the University at Buffalo is a member of
the Association of American Universities.