Jest Streams Shifting Poleward

Carnegie Institution
Public release date: 16-Apr-2008

Contact: Cristina Archer
lozej@stanford.edu
650-462-1047 x232

Changing jet streams may alter paths of storms and hurricanes

Stanford, CA-The Earth’s jet streams, the
high-altitude bands of fast winds that strongly
influence the paths of storms and other weather
systems, are shifting-possibly in response to
global warming. Scientists at the Carnegie
Institution determined that over a 23-year span
from 1979 to 2001 the jet streams in both
hemispheres have risen in altitude and shifted
toward the poles. The jet stream in the northern
hemisphere has also weakened. These changes fit
the predictions of global warming models and have
implications for the frequency and intensity of
future storms, including hurricanes.

Cristina Archer and Ken Caldeira of the Carnegie
Institution’s Department of Global Ecology
tracked changes in the average position and
strength of jet streams using records compiled by
the European Centre for Medium-Range Weather
Forecasts, the National Centers for Environmental
Protection, and the National Center for
Atmospheric Research. The data included outputs
from weather prediction models, conventional
observations from weather balloons and surface
instruments, and remote observations from
satellites. The results are published in the
April 18 Geophysical Research Letters.

Jet streams twist and turn in a wide swath that
changes from day to day. The poleward shift in
their average location discovered by the
researchers is small, about 19 kilometers (12
miles) per decade in the northern hemisphere, but
if the trend continues the impact could be
significant. “The jet streams are the driving
factor for weather in half of the globe,” says
Archer. “So, as you can imagine, changes in the
jets have the potential to affect large
populations and major climate systems.”

Storm paths in North America are likely to shift
northward as a result of the jet stream changes.
Hurricanes, whose development tends to be
inhibited by jet streams, may become more
powerful and more frequent as the jet streams
move away from the sub-tropical zones where
hurricanes are born.

The observed changes are consistent with numerous
other signals of global warming found in previous
studies, such as the widening of the tropical
belt, the cooling of the stratosphere, and the
poleward shift of storm tracks. This is the first
study to use observation-based datasets to
examine trends in all the jet stream parameters,
however.

“At this point we can’t say for sure that this is
the result of global warming, but I think it is,”
says Caldeira. “I would bet that the trend in the
jet streams’ positions will continue. It is
something I’d put my money on.”

###

Contact Ken Caldeira at 650-704-7212, kcaldeira@stanford.edu

For copies of the paper contact the authors

The Carnegie Institution (www.CIW.edu) has been a
pioneering force in basic scientific research
since 1902. It is a private, nonprofit
organization with six research departments
throughout the U.S. Carnegie scientists are
leaders in plant biology, developmental biology,
astronomy, materials science, global ecology, and
Earth and planetary science. The Department of
Global Ecology, located in Stanford, California,
was established in 2002 to help build the
scientific foundations for a sustainable future.
Its scientists conduct basic research on a wide
range of large-scale environmental issues,
including climate change, ocean acidification,
biological invasions, and changes in biodiversity.

————————————————————————————

Bookmark the permalink.

Comments are closed