![]() |
||
![]() |
![]() |
|
![]() |
![]() |
![]()
January
18, 2007 How severe will
global warming get? Jason P. Briner is
looking for an answer buried deep in mud
dozens of feet below the surface of lakes in the frigid Canadian
Arctic. His group is
gathering the first quantitative temperature
data over the last millennium from areas in extreme northeastern
sections of
the Canadian Arctic, such as Every spring,
Briner, Ph.D., assistant professor of geology
in the "As
paleoclimatologists, we want to study Earth under
conditions similar to those we have today, what we call 'climate
analogues,'
which might tell us what to expect in the future," he said. The Arctic as a
region is an excellent harbinger of future
change, Briner said, because the signals or clues that signify climate
change
are so much stronger in the "Yet, even when we
take that phenomenon into
account," he noted, "the signals we're finding on For example, during
the 'Holocene thermal maximum,' the
warmest period of the past 10,000 years, the Arctic average temperature
was two
to three degrees warmer than it is today, while the global average was
only a
degree or so warmer. "But based on lake
sediments from Baffin Island, our
data show that this area of the Briner and his
co-authors published these results last May
in Quaternary Research (Vol. 65,
pp.
431-442). The co-authors were N. Michelutti, formerly of the Because Arctic
regions show such strong seasonality, Briner
explained, it's relatively easy to correlate climate changes with very
fine
layers in the sediments. In some lakes, each layer represents one year,
with
thicker sediment layers generally signaling warmer summers. Like other
paleoclimatologists, he also is finding that the
warming trend that began in the 20th century is more pronounced in the "The magnitude of
warmth over the past 100 years seems
pretty exceptional in the context of the past 1,000 years," he said. "Whereas maybe an
average of all of the instrument data
from the globe shows just a half a degree increase in this century, in
the The rapidity of the
change also is exceptional, he added. "If we look at the
temperature graphs that we've
generated for the past 1,000 years for this region, the temperatures
wiggle
back and forth, so there is a little variability in there," he said.
"However, in the past 100 years, both the magnitude and the rate of
temperature increase exceed all the variations of the past 1,000 years." To do the research,
Briner and his graduate students and
post-doctoral associates travel to Baffin Island and other areas in
extreme
northeast Canada each May, while it is still winter there. They fly to remote
Eskimo villages, and then drive
snowmobiles, dragging their gear behind them on sleds, for hours across
the
tundra and sea ice. Once they reach a good sampling site, they set up
camp
nearby and get to work, drilling through the ice and the water below
until
their equipment reaches sediments. "The beauty of lake
sediments is that they're being
deposited continuously right up until yesterday," Briner said, "so by
looking at them, we get clues into past climates, which we can then
overlap
with records from weather stations, which only cover the past 50 to 75
years." They then send their
samples -- long tubes full of mud --
back to UB, where Briner and his team analyze them. Among the clues in
the cores are isotopes, fossils and
increases in organic material from the accumulation of dead organisms
and
algae. "Generally, the more
organic matter in sediments, the
warmer the climate," said Briner. A primary goal of
the research is to account for spatial
variability when reconstructing past climate records. "Everyone knows the
climate is extremely variable,
spatially," said Briner. "For example, earlier this year, Reconstructing this
spatial variability will help develop a
more precise view of how past changes in climate have affected the
planet,
Briner says, providing a guide for how the current global warming trend
may
unfold. "We can use these
patterns to test climate
models," said Briner. "Once models can adequately predict past
climates and their spatial patterns, then we have confidence that they
work and
so can be used to predict the future." Briner and members
of his team will present some of their
data May 2-5 at the 37th Annual International Arctic Workshop in The research is
funded by the National Science Foundation. The University at
This
text derived from: Recommend this Article to a Friend Back to: News |
Subscribe to the Earth Observatory About the Earth Observatory Contact Us Privacy Policy and Important Notices Responsible NASA Official: Lorraine A. Remer Webmaster: Goran Halusa We're a part of the Science Mission Directorate |