New paper predicts a decrease of Atlantic hurricanes in the future

A paper published today in the Journal of Climate finds climate models predict a significant decrease of 18 - 24% in the number of Atlantic hurricanes in the future. According to the authors, "An ensemble of high-resolution simulations project reductions in ensemble-average tropical cyclone counts between 18 and 24%, consistent with previous studies." Contrary to the claims of climate alarmists, the paper adds to many other peer-reviewed publications demonstrating that warming decreases the frequency and intensity of hurricanes and tropical cyclones.

Journal of Climate 2013 ; e-View

doi: http://dx.doi.org/10.1175/JCLI-D-12-00183.1

Atlantic Hurricanes and Climate Change. Part II: Role of Thermodynamic Changes in Decreased Hurricane Frequency

Megan S. Mallard,¹ Gary M. Lackmann, and Anantha Aiyyer

North Carolina State University

Abstract

A method of downscaling which isolates the effect of temperature and moisture changes on tropical cyclone (TC) activity was presented in Part I of this study. By applying thermodynamic modifications to analyzed initial and boundary conditions from past TC seasons, initial disturbances and the strength of synoptic-scale vertical wind shear are preserved in future simulations. This experimental design allows comparison of TC genesis events in the same synoptic setting, but in current and future thermodynamic environments. Simulations of both an active (September 2005) and inactive (September 2009) portion of past hurricane seasons are presented.

An ensemble of high-resolution simulations project reductions in ensemble-average TC [tropical cyclone] counts between 18 and 24%, consistent with previous studies. Robust decreases in TC and hurricane counts are simulated with 18- and 6-km grid lengths, for both active and inactive periods. Physical processes responsible for reduced activity are examined through comparison of monthly- and spatially-averaged genesis-relevant parameters, as well as case studies of development of corresponding initial disturbances in current and future thermodynamic conditions. These case studies show that reductions in TC counts are due to the presence of incipient disturbances in marginal moisture environments, where increases in the moist entropy saturation deficits in future conditions preclude genesis for some disturbances. Increased convective inhibition and reduced vertical velocity are also found in the future environment. It is concluded that a robust decrease in TC frequency can result from thermodynamic changes alone, without modification of vertical wind shear or the number of incipient disturbances.