Hurricanes, natural variability, and global warming
On the Record
Mar 23, 2010 - by Staff
Kevin Trenberth
Winter 2004, updated June 2006
Kevin Trenberth is head of the Climate
Analysis Section in the Climate and Global Dynamics Division of NCAR's Earth System Laboratory.
Please note: This page provided for archival purposes; for current research, please see
Atlantic hurricanes and global warming (2004–2006)
Research Article
Trenberth, K. E., and D. J. Shea (2006), "Atlantic hurricanes
and natural variability in 2005," Geophysical
Research Letters,
27 June, 33, L12704.
Perspective Article
Trenberth, Kevin (2005), "Climate: Uncertainty
in Hurricanes and Global Warming, Science, 17 June,
vol. 308, no. 5729, pp. 1753–1754.
News Releases
Global
Warming Surpassed Natural Cycles in Fueling 2005 Hurricane
Season, NCAR Scientists Conclude (June
22, 2006)
Hurricanes
To Intensify as Earth Warms (June 16, 2005)
News conference, October 21, 2004
Center for Health and Global Environment
Harvard Medical School, Cambridge, Massachusetts
Written statement distributed at news conference
Human
activities are changing the composition of the atmosphere and global
warming is happening as a result. Global warming is manifested in
unexpected ways. Sea level has risen 1.25 inches in the past 10 years
as a result of warming of the oceans and glacier melting. The
environment in which hurricanes form is changing. The result was a
hurricane in late March 2004 in the South Atlantic, off the coast of
Brazil: the first and only such hurricane in that region. Several
factors go into forming hurricanes and where they track. But the
evidence strongly suggests more intense storms and risk of greater
flooding events, so that the North Atlantic hurricane season of 2004
may well be a harbinger of the future.
Opening statement excerpts
Global
sea level has risen about an inch and a quarter in the past 10 years.
This is good information—the first time we've had global information
from satellites using a process called altimetry. Now most of this rise
in sea level is due to expansion of the ocean as it warms up, and maybe
20 to 35% is from melting of glaciers. So the sea surface temperature
is rising globally. It's been about 1 degree Fahrenheit over the 20th
century and it's risen in particular in recent times in the Atlantic
and other regions, of course, that affect hurricanes.
. . .And of course this is the fuel for the hurricanes and it also means
that the hurricanes end up dropping a lot more precipitation and
rainfall as a result. And so the environment in which these hurricanes
form is changing and it's changing in ways that provide more fuel for
them through the water vapor and the changes in sea surface
temperature.. . .
What we can say is that the high sea surface temperatures of water
vapor make for more intense storms, and so this is consistent with the
evidence that we're seeing. And so this is the main link with global
warming that we can establish at the current time.
And so this is supported also by the modeling evidence and the
theoretical evidence. There was a certain amount of activity regarding
a paper that came out recently by a group headed by Tom Knutson at the Geophysical Fluid Dynamics Laboratory—laboratory
for those of you, if I say it in American. And that supports the idea
that indeed hurricanes are apt to become more intense in the future. So
a key consequence, I think, is certainly perhaps increased damage from
winds, but I think the biggest consequence is likely to be more heavy
rains and flooding.
Other news conference participants
- Paul Epstein, M.D.
Associate Director, Center for Health and the Global Environment (now Department of Global Health and Social Medicine), Harvard Medical School - Jim McCarthy
Professor of Biological Oceanography, Harvard University - Matthias Weber
Senior Vice President and Chief Property Underwriter, U.S. Direct Americas Division, Swiss Re
Transcript
Download transcript of news conference (PDF)
Related Links
Backgrounder: Hurricanes,
Typhoons, and Cyclones