Hurricanes
A compendium of hurricane information

Hurricanes & Climate Change

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Hurricanes & Climate Change

About the past
There is observational evidence for an increase of intense tropical cyclone activity in the North Atlantic since about 1970, correlated with increases of tropical sea surface temperatures. There are also suggestions of increased intense tropical cyclone activity in some other regions where concerns over data quality are greater.  Multi-decadal variability and the quality of the tropical cyclone records prior to routine satellite observations in about 1970 complicate the detection of long-term trends in tropical cyclone activity. There is no clear trend in the annual numbers of tropical cyclones."

CCSP Reports:

Weather and Climate Extremes in a Changing Climate. Regions of Focus: North America, Hawaii, Caribbean, and U.S. Pacific Islands. Final Report of Synthesis and Assessment Product 3.3

• Atlantic tropical cyclone (hurricane) activity, as measured by both frequency and the Power Dissipation Index (which combines storm intensity, duration, and frequency) has increased. The increases are substantial since about 1970, and are likely substantial since the 1950s and 60s, in association with warming Atlantic sea surface temperatures. There is less confidence in data prior to about 1950.
• There have been fluctuations in the number of tropical storms and hurricanes from decade to decade, and data uncertainty is larger in the early part of the record compared to the satellite era beginning in 1965. Even taking these factors into account, it is likely that the annual numbers of tropical storms, hurricanes, and major hurricanes in the North Atlantic have increased over the past 100 years, a time in which Atlantic sea surface temperatures also increased.
• The evidence is less compelling for significant trends beginning in the late 1800s. The existing data for hurricane counts and one adjusted record of tropical storm counts both indicate no significant linear trends beginning from the mid- to late 1800s through 2005. In general, there is increasing uncertainty in the data as one proceeds back in time.
• There is no evidence for a long-term increase in North American mainland land-falling hurricanes.
• The hurricane Power Dissipation Index in the eastern Pacific, affecting the Mexican west coast and shipping lanes, has decreased since 1980, but rainfall from near-coastal hurricanes has increased since 1949.
• It is very likely that the human-induced increase in greenhouse gases has contributed to the increase in sea surface temperatures in the hurricane formation regions. Over the past 50 years there has been a strong statistical connection between tropical Atlantic sea surface temperatures and Atlantic hurricane activity as measured by the Power Dissipation Index (which combines storm intensity, duration, and frequency). This evidence suggests a human contribution to recent hurricane activity. However, a confident assessment of human influence on hurricanes will require further studies using models and observations, with emphasis on distinguishing natural from human-induced changes in hurricane activity through their influence on factors such as historical sea surface temperatures, wind shear, and atmospheric vertical stability
• It is likely that hurricane/typhoon wind speeds and core rainfall rates will increase in response to human-caused warming. Analyses of model simulations suggest that for each 1°C increase in tropical sea surface temperatures, hurricane surface wind speeds will increase by 1 to 8% and core rainfall rates by 6 to 18%.
• Frequency changes are currently too uncertain for confident projections.
• The spatial distribution of hurricanes/typhoons will likely change.
• Storm surge levels are likely to increase due to projected sea level rise, though the degree of projected increase has not been adequately studied.

Effects of Climate Change on Energy Production and Use in the United States. Final Report of Synthesis and Assessment Product 4.5.

This report includes a discussion of the implications of changes in hurricane severity on the energy infrastructure of the U.S.  See especially the section on extreme events starting on page 59 of Chapter 3.  In addition, see the box below, a brief “case study” on Hurricane Katrina.

 “Impacts of Climate Variability and Change on Transportation Systems and Infrastructure -- Gulf Coast Study”. Final Report of Synthesis and Assessment Product 4.7.

Chapter 6 of the report says:   

• Climate change appears to worsen the region’s vulnerability to hurricanes, as warming seas give rise to more energetic storms. The literature indicates that the intensity of major storms may increase 5 to 20 percent. This indicates that Category 3 storms and higher may return more frequently to the central Gulf Coast and thus cause more disruptions of transportation services.  The impacts of such storms need to be examined in greater detail; storms may cause even greater damage under future conditions not considered here. If the barrier islands and shorelines continue to be lost at historical rates and as relative sea level rises, the destructive potential of tropical storms is likely to increase.
• While further study is needed to examine in more detail the impacts on specific transportation facilities, such as individual airports or rail terminals, this preliminary assessment finds that the potential impacts on infrastructure are so important that transportation decision makers should begin immediately to assess them in the development of transportation investment strategies

Other Links:

Scientists examine African dust link to hurricanes. Reuters, 9 Aug 2007. Storm scientists are taking a closer look  at whether giant dust clouds from the Sahara could join the El Nino phenomenon as a leading indicator of the ferocity of Atlantic hurricane seasons.

Frequency of Atlantic hurricanes doubled over last century, climate change suspected. Press release (dtd 29 July 2007) from NCAR. About twice as many Atlantic hurricanes form each year on average than a century ago, according to a new statistical analysis. The study concludes that warmer sea surface temperatures and altered wind patterns associated with global climate change are fueling much of the increase.  See also:

• Frequency of Atlantic Hurricanes Doubled During Last Century - US. Press release (30 July 2007) from NSF.
• Atlantic Hurricane Frequency Doubles. Media alert (dtd July 29, 2007) from NASA's Earth Observatory.

A change in the wind. Press release (dtd 17 Apr 2007) from University of Miami Rosentiel School of Marine & Atmospheric Science. Climate model simulations for the 21st century indicate a robust increase in wind shear in the tropical Atlantic due to global warming, which may inhibit hurricane development and intensification. Historically, increased wind shear has been associated with reduced hurricane activity and intensity. This new finding is reported in a study in the April 18 Geophysical Research Letters.
Hurricane Spin. RealClimate » 24 April 2007

LSU professor uncovers prehistoric hurricane activity. Press release (dtd 20 Mar 2007) from Lousiana State University. Hurricanes Katrina and Rita focused the international spotlight on the vulnerability of the US coastline. Fears that a "super-hurricane" could make a direct hit on a major city and cause even more staggering losses of life, land and economy triggered an outpouring of studies directed at every facet of this ferocious weather phenomenon. Now, an LSU professor takes us one step closer to predicting the future by drilling holes into the past.

New evidence that global warming fuels stronger Atlantic hurricanes. Press release (28 Feb 2007) from Univ of Wisconsin-Madison. Atmospheric scientists have uncovered fresh evidence to support the hotly debated theory that global warming has contributed to the emergence of stronger hurricanes in the Atlantic Ocean.
 
Dust Dampens Hurricane Formation
Posting (circa 2007) from NASA’s Earth Observatory.

FAQ / State of the Science: Atlantic Hurricanes & Climate [PDF].  Two page document (dtd 12 Dec 2006) from the U.S. National Oceanic and Atmospheric Administration.

Link Between Climate Change and Tropical Cyclone Activity: More Research Necessary [MS Word].  Press release (dtd 11 Dec 2006) from the World Meteorological Society (WMO).

NASA'S live tropical sea surface temperature Web site gives climate, hurricane clues Press release (dtd 12 Oct 2006) from NASA/Goddard. Sea surface temperatures give scientists information about ocean currents, climate, climate change and how a hurricane may evolve. Now, NASA has a Web page that provides frequent updates on changing ocean temperatures.

Answers to frequently-asked questions on “Forced and unforced ocean temperature
changes in Atlantic and Pacific tropical cyclogenesis regions”, by B.D. Santer et al [PDF].  By Ben Santer and Tom Wigley, August 29th, 2006.

U.S. Study Links Global Warming, Hurricane Intensity. Article (dtd 16 Aug 2006) from U.S. Department of State.

Mixing Politics and Science in Testing the Hypothesis That Greenhouse Warming Is Causing a Global Increase in Hurricane Intensity.   Article by J.A. Curry, P.J. Webster and G.J. Holland in the Bull. Amer. Met. Soc., 87 (8), 1025-1037 (August 2006).

Establishing a Connection Between Global Warming and Hurricane Intensity. Press release (dtd 15 Aug 2006) from the American Geophysical Union (AGU).

Statement on the U.S. Hurricane Problem.  Statement (dtd 25 July 2006) by Kerry Emanuel, Richard Anthes, Judith Curry, James Elsner, Greg Holland, Phil Klotzbach, Tom Knutson, Chris Landsea, Max Mayfield, and Peter Webster.

Hurricanes: Global Warming Surpassed Natural Cycles in Fueling 2005 Season, NCAR Scientists Conclude. Press release (dtd 22 June 2006) from National Center for Atmospheric Research.

Hurricanes and the US Gulf Coast. Press release (dtd 19 Jun 2006) from the American Geophysical Union today published the report of a Conference of Experts, intended to guide policy makers charged with rebuilding areas affected by Hurricanes Katrina and Rita. The 20 scientists who participated in the conference looked at seven major areas: hurricanes, storm surge and flooding, subsidence, climate change, hydrology, infrastructure, and disaster preparedness and response. For each topic, they assessed current understanding of the phenomenon, near-term scientific needs, and longer-term directions.  Includes section on Climate Change.

Atlantic hurricane trends linked to climate change. Article by M.E. Mann and K. A. Emanuel in EOS, 87, 233-244 (13 June 2006).  Online supplement also available.

Are Category 4 and 5 hurricanes increasing in number?. Article (undated, circa 2006) by Jeff Masters.

Climate change responsible for increased hurricanes. Press release (dtd 30 May 2006) from Penn State. Human induced climate change, rather than naturally occurring ocean cycles, may be responsible for the recent increases in frequency and strength of North Atlantic hurricanes, according to Penn State and Massachusetts Institute of Technology researchers. "Anthropogenic factors are likely responsible for long-term trends in tropical Atlantic warmth and tropical cyclone activity," the researchers report in an upcoming issue of the American Geophysical Society's Eos.

Hurricanes and Global Warming— Potential Linkages and Consequences.  H  Article by R.A. Anthes, R.W. Corell, G. Holland, J.W. Hurell, M. MacCracken, and Kevin E. Trenberth in BAMS (May 2006).

Area Where Hurricanes Develop Is Warmer, Say NOAA Scientists Press release (dtd 1 May 2006) from NOAA.

Deconvolution of the factors contributing to the increase in global hurricane intensity.  Article by C.D. Hoyos, P.A. Agudelo, P.J. Webster, and J.A. Curry in Science, 312 (5770), 94-97 (7 April 2006).

Response to comment on "Changes in tropical cyclone number, duration, and intensity in a warming environment." Article  by P.J. Webster, J.A. Curry, J. Liu, and G. J. Holland in Science, 311 (5768), 1713c (24 March 2006).

Reactions to Tighter Hurricane Intensity / SST link.  Article (dtd 20 March 2006) from RealClimate.

Research re-examines strong hurricane studies Press release (dtd 16 March 2006) from Georgia Institute of Technology.

Climate and Hurricanes: An Idea With a History Posting (dtd 28 Feb 2006) from The Intersection (Chris Mooney).

Major New Paper on Hurricanes and Global Warming.  Article (dtd 16 Feb 2006) from The Intersection (Chris Mooney).

Atlantic hurricane trends linked to climate change.[PDF]  Article (dtd 2006) by M.E. Mann and K. A. Emanuel published in EOS (87: pp 233-244).  Online supplement available here.

Anthropogenic Effects on Tropical Cyclone Activity.  Page (revised January 2006) maintained by Kerry Emanuel (Massachusetts Institute of Technology).  Includes "Frequently Asked Questions about Global Warming and Hurricanes." (link posted 12 Feb 2007).

Are There Trends in Hurricane Destruction?.  Letters published in the 22/29 December 2005 issue of Nature.  The letters were in response to the following article:  [Kerry Emanuel,436, 686–688 (2005)]

Storm season ends: Are potent hurricanes linked to global warming?. Article (dtd 30 Nov 2005) from Christian Science Monitor.

NOAA Reviews Record-Setting 2005 Atlantic Hurricane Season. Article (dtd 29 Nov 2005) from NOAA Magazine.

NOAA Attributes Recent Increase in Hurricane Activity to Naturally Occurring Multi-Decadal Climate Variability.  Article (dtd 29 Nov 2005) from NOAA Magazine.

Hurricane Science.  Segment (dtd 18 October 2006) from the NewsHour with Jim Lehrer, produced by the non-profit media enterprise, PBS.  Includes transcript, video and audio.  The 2005 hurricane season raises "questions about why so many hurricanes and, especially, why so many very powerful hurricanes?  We explore that now with two experts in the field: Christopher Landsea is a meteorologist with the hurricane research division at NOAA, the National Oceanic and Atmospheric Administration; Judith Curry is a climate scientist and chair of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology. She recently co-authored a study on this subject in the journal Science." (link posted 19 October 2005)

Gulf Warm-Water Eddies Intensify Hurricane Changes. Press release (dtd 3 October 2005) from the National Science Foundation (NSF).

Is there a link between the Arctic and hurricanes?  Questions and answers (dtd 28 September 2005) from the National Snow and Ice Data Center (NSIDC). (link posted 7 October 2005)

Hurricanes and Global Warming - Q&A.  Posting (undated, circa early 2005) from the Pew Center on Global Climate Change.  (link posted 28 Sep 2005). 

Tip Sheet: What Do We Know About Hurricane Prediction, Behavior, and Impacts?  Press release (dtd 7 Sep 2005) from the National Center for Atmospheric Research and the University Corporation for Atmospheric Research.  (link posted 22 Sep 2005). 

The 2005 Hurricane Season.  First hour of The Diane Rehm Show from National Public Radio (NPR), originally broadcast on 21 September 2005. Includes extensive discussion of relationship between hurricanes and climate change. (link posted 21 Sept 2005)  Guests include:

• Dr. Anthony Busalacchi, director of the Earth System Science Interdisciplinary Center at the University of Maryland
• Dr. Judith Curry, chair of the School of Earth and Atmospheric Sciences at Georgia Tech
• Dr. William Gray, professor of atmospheric science at Colorado State University

Climate Change, Hurricanes, and Extreme Weather.  Collection of articles, freely available to the public, from Science Online.   This is part of a larger collection, Hurricanes, Climate, and Katrina: Research, Reviews, and Articles from Science Online.  (link posted 21 Sept 2005). 

• Is Katrina a Harbinger of Still More Powerful Hurricanes?  Article by Richard A. Kerr in Science (16 September 2005). 
• Hurricanes Are Getting Stronger, Study Says.  Press release (dtd 15 Sep 2005) from National Center for Atmospheric Research (NCAR).  See similar press release from Georgia Institute of Technology (dtd 15 Sep 2005). 
• Storms get fewer but fiercer.  "Satellite images agree with study of hurricane costs."  Article (dtd 15 September 2005) from news@nature.com.
• Study: Severe Hurricanes Increasingly Common. Segment from National Public Radio's Morning Edition (originally broadcast 16 September 2005).

Hurricanes: A Global Warming Connection?  Article (dtd 8 September 2005) from The Why Files.  (link posted 8 September 2005).

Stronger Hurricanes? Researchers Debate Whether Global Warming Will Make Storms More Destructive.  Article (dtd 8 September 2005) by Richard Monasterky published by The Chronicle of Higher Education.  (link posted 8 September 2005).

Hurricanes and Global Warming - Is There a Connection?   Posting (dtd 2 September 2005) by Stefan Rahmstorf, Michael Mann, Rasmus Benestad, Gavin Schmidt, and William Connolley on RealClimate.org. (link posted 2 September 2005).

Hurricanes & Climate Change. Segment (9:00 minutes) from the radio program, Living on Earth (originally broadcast 2 September 2005). "MIT Professor Kerry Emanuel talks about his book "Divine Wind: the History and Science of Hurricanes." Emanuel's latest research, published in Nature Magazine, shows a startling global increase in hurricane strength and duration, which he correlates to rising sea temperatures linked to global warming." (link posted 4 September 2005).

Increasing destructiveness of tropical cyclones over the past 30 years. Article by K.A. Emanuel in Nature, 436, 686-688 (4 August 2005). See also Online supplement to this paper.

FAQ: Hurricanes and global warming.  Page (updated 31 July 2005) from USA Today.  (link posted 1 September 2005)

Increasing destructiveness of tropical cyclones over the past 30 years [PDF]. Letter by K. A. Emanuel, Nature advance online publication, posted online 31 July 2005.  See also online supplement[PDF]. (links posted 1 August 2005)

New Orleans, Hurricanes and Climate Change: A Question of Resiliency. Four-page flyer from a 20 June 2005 seminar in Washington, DC, sponsored by the American Meteorological Society.  Also available online in PDF format:

• Presentation by Thomas Knutson, Research Scientist, NOAA Geophysical Fluid Dynamics Laboratory, Princeton, NJ.
• Presentation Shirley Laska. Director of the Center for Hazards Assessment, Response and Technology (CHART)
  and Professor of Sociology at the University of New Orleans.

NCAR Climate Expert: Hurricanes To Intensify as Earth Warms.  Press release (dtd 16 June 2005) from the National Center for Atmospheric Research (NCAR). (posted 17 June 2005).

Hurricanes and global warming [PDF].  Article by R.A. Pielke, Jr., C. Landsea, M. Mayfield, J. Laver and R. Pasch (in press,2005), Bulletin of the American Meteorological Society.

Earth & Sky.  Daily science radio series, currently funded by a grant from the National Science Foundation and National Oceanic and Atmospheric Administration. Both transcripts & audio files are provided. (link posted 31 May 2005)

Hurricanes and climate change: Is there a connection? Article (dtd October 2004) in Staff Notes Monthly, from the University Corporation for Atmospherice Research. 

Impact of CO2-Induced Warming on Simulated Hurricane Intensity and Precipitation: Sensitivity to the Choice of Climate Model and Convective Parameterization. [PDF] Article by Thomas R. Knutson (NOAA/Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey) and Robert E. Tuleya (Center for Coastal Physical Oceanography, Old Dominion University, Norfolk, Virginia), published in Journal of Climate, 17(18), 15 September 2004.

Global Warming & Hurricanes.  Page (updated 7 May 2004) maintained by the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory.

FAQ: Hurricanes and Global Warming.  Series of questions & answers (dated 27 Oct 2003) from USA Today's "Ask Jack" feature.

Published in Science magazine, 20 July 2001 (Volume 293, Number 5529):

• Bengtsson, Lennart, "Hurricane Threats," pp 440-441.

• Goldenberg, Stanley B., Christopher W. Landsea, Alberto M. Mestas-Nuñez, and William M. Gray, "The Recent Increase in Atlantic Hurricane Activity: Causes and Implications,"  pp 474-479.

Anthropogenic Effects on Tropical Cyclone Activity.  Article (undated, circa late 1990s) by Kerry Emanuel (Center for Meteorology and Physical Oceanography, Massachusetts Institute of Technology).

National Public Radio (NPR),   All Things Considered. September 2, 1998. RealAudio: Hurricanes and Global Warming -- "NPR's Richard Harris reports that hurricanes and tropical storms may do much more than stir up the weather. A study in the journal Nature finds they draw enormous quantities of carbon dioxide out of the ocean and put it into the air. Carbon dioxide in the atmosphere contributes to global warming. But in the long run, severe storms may paradoxically slow climate change." (3:45)

Articles from the "Popular Science" series published by US National Aeronautics and Space Administration (NASA), Goddard Institute for Space Studies (GISS):

• How Will the Frequency of Hurricanes be Affected by Climate Change? (dated Apr 1997)
  
• Will Climate Change Cause More Atlantic Hurricanes? (dated Jan 1998)

Backgrounders for USGCRP Seminars:

• El Niño/La Niña and Hurricanes: Was 1999 a Preview of the Near Future? (held 16 December 1999)

• Hurricanes! (held 11 December 1995)

• Climate Change Impacts  on the United States.  The Potential Consequences of  Climate Variability and Change: Foundation (2000)
  • Southeast  [PDF] (Chapter 5)
  • Northeast [PDF].  (Chapter 4)
  • Coastal Areas and Marine Resources.[PDF] (Chapter 16).    See section on "Hurricanes and Non-Tropical Storms."
• Assessing the Vulnerability of the Alabama Gulf Coast to Intense Hurricane Strikes and Forest Fires in the Light of Long-term Climatic Changes [654 KB PDF].  Chapter 13 of Integrated Assessment of the Climate Change Impacts on the Gulf Coast Region.  Detailed report (236 pages; dtd June 2003) by Z. H. Ning, R. E.Turner, T. Doyle and K.K. Abdollahi (lead authors), published by the Gulf Coast Climate Change Assessment Council (GCRCC) and Louisiana State University (LSU) Graphic Services.
• Effects and Outcomes of Caribbean Hurricanes in a Climate Change Scenario (PDF file), by Ariel E. Lugo. Published in special issue of The Science of the Total Environment (vol. 262, no.3, 2000) on Climate Change, Forests and Disturbances, edited by V.H. Dale.
• The Potential Consequences of Climate Variability and Change on Coastal Areas and Marine Resources. [PDF] (dtd October 2000, released 19  January 2001).

Coasts [PDF] . Chapter 4, Volume 1 of Preparing for an Uncertain Climate, report (dtd October 1993) from the US Congress, Office of Technology Assessment.