Tropical Cyclones and Global Warming: Science, Communication, and Politics

In 2004 Peter, Judy Curry, Hai-Ru Chang and myself embarked on a relatively straightforward study to see if there had been any observable changes in tropical cyclone characteristics over the previous few decades. To our surprise, we found a substantial increase in the proportion of Cat 4-5 hurricanes amongst an otherwise generally static or decreasing frequency of tropical cyclones in general – an increase that was well beyond what could reasonably be attributed to improving observing systems. Submitted to Science in October, the paper was published with impeccable timing in August 2005, right between Hurricanes Katrina and Rita (Webster et al 2005). Similar findings were made in parallel by Emanuel (2005). Both papers subsequently were listed in the Discover Magazine Top 100 Stories for 2005, with a ranking of #1 for hurricanes and global warming.

Follow up studies (see, e.g., the reviews in Anthes et al 2006 and Walsh et al, 2015) have provided further evidence of there being a real trend. In particular, Holland and Bruyere (2014) quantified the observing changes and climate change components and noted that substantial global and regional trends remained.

Rather than focus on the science, this talk addresses the communication and political issues that arose from the superheated societal environment on global warming around that time. We found ourselves swamped by press and other enquiries, and some particularly nasty attacks. It rapidly became obvious that this was not your normal scientific debate and that we needed to recalibrate our communication approaches. The outcome of the initial learning process has been summarised in Curry et al (2006) and this, plus Mooney (2007) and subsequent lessons learnt, will form the basis of my presentation.

References Cited (in temporal order):

Webster, P.J., G.J. Holland, J.A. Curry and H-R. Chang, 2005: Changes in tropical cyclone number, duration and intensity in a warming environment. Science, 309, 1844-1846.

Emanuel, K., 2005: Increasing destructiveness of tropical cyclones over the past 30 years. Nature, 436, 686–688.

Anthes, R.A, R.W. Corell, G.J Holland, J.W. Hurrell, M. MacCracken, and K.E. Trenberth, 2006: Hurricanes and Global Warming – Potential Linkages and Consequences. Bull. Amer. Meteor. Soc., 87, 623-628.

Curry, J., P.J. Webster and G.J. Holland, 2006: Mixing Politics and Science in Testing the Hypothesis that Greenhouse Warming is Causing a Global Increase in Hurricane Intensity. Bull. Amer. Met. Soc., 87, 1025–1037.

Mooney, C., 2007: Storm World: Hurricanes, Politics, and the Battle Over Global Warming. Harcourt, Orlando, 392 pp. ISBN 9780151012879.

Holland, G.J. and C. Bruyere, 2014: Recent Intense Hurricane Response to Global Climate Change. Clim. Dyn., 42, 617-627. DOI: 10.1007/s00382-013-1713-0.

Walsh, K.J.E., J.L. McBride, P.J. Klotzbach, Balachandran, S.J. Camargo, G. Holland, T.R. Knutson, J. Kossin, T.-C. Lee, A. Sobel, and M. Sugi, 2015: Tropical cyclones and climate change. WIRES Climate Change, 7, 65–89. doi:10.1002/wcc.371.