New paper predicts a decrease in tropical cyclones in the future

A paper published today in the Journal of Climate finds climate models predict a decrease in tropical cyclones due to alleged warming from CO2, the opposite of claims by climate alarmists. According to the paper, "Tropical cyclones are shown to decrease in frequency globally by 9% in the [doubled CO2 simulation] and 26% in the [quadrupled CO2 simulation]." The paper corroborates many other peer-reviewed papers projecting a decrease of the frequency and intensity of tropical cyclones and hurricanes in the future. Multiple observational studies also find that tropical cyclones decrease with warming. 

Journal of Climate 2013 ; e-View

doi: http://dx.doi.org/10.1175/JCLI-D-12-00749.1

Response of tropical cyclones to idealized climate change experiments in a global high resolution coupled general circulation model

Ray Bell*

Department of Meteorology, University of Reading, Reading, United Kingdom

Jane Strachan and Pier Luigi Vidale

National Centre for Atmospheric Science, Department of Meteorology, University of Reading, Reading, United Kingdom

Kevin Hodges

NERC Centre for Earth Observation, University of Reading, Reading, United Kingdom

Malcolm Roberts

Met Office, Hadley Centre, Exeter, United Kingdom

Abstract

We present an assessment of how tropical cyclone activity might change due to the influence of increased atmospheric carbon dioxide concentrations, using the UK’s High Resolution Global Environment Model (HiGEM) with N144 resolution (~90 km in the atmosphere and ~40 km in the ocean). Tropical cyclones are identified using a feature tracking algorithm applied to model output. Tropical cyclones from idealized 30-year 2×CO₂ (2CO2) and 4×CO₂ (4CO2) simulations are compared to those identified in a 150-year present-day simulation, which is separated into a 5-member ensemble of 30-year integrations. Tropical cyclones are shown to decrease in frequency globally by 9% in the 2CO2 and 26% in the 4CO2. Tropical cyclones only become more intese in the 4CO2, however uncoupled time slice experiments reveal an increase in intensity in the 2CO2. An investigation into the large-scale environmental conditions, known to influence tropical cyclone activity in the main development regions, is used to determine the response of tropical cyclone activity to increased atmospheric CO₂. A weaker Walker circulation and a reduction in zonally averaged regions of updrafts lead to a shift in the location of tropical cyclones in the northern hemisphere. A decrease in mean ascent at 500 hPa contributes to the reduction of tropical cyclones in the 2CO2 in most basins. The larger reduction of tropical cyclones in the 4CO2 arises from further reduction of mean ascent at 500 hPa and a large enhancement of vertical wind shear, especially in the southern hemisphere, North Atlantic and North East Pacific.