New paper predicts CO2 will decrease tropical cyclones by 19%

A paper published today in the Journal of Climate finds global cyclone frequency will substantially decrease by 19% due to a doubling of CO2 levels. The paper confirms many other papers finding, contrary to claims of climate alarmists, that global warming (if it resumes) will substantially decrease global cyclone and hurricane activity. Observational data also shows global hurricane frequency and cyclone energy have been on a declining trend since ~1994. 

According to the authors, 

"Globally, Tropical Cyclone frequency decreases (-19%) while the intensity [slightly] increases (+2.7%) in response to CO2 doubling, consistent with previous studies. The average Tropical Cyclone lifetime decreases by -4.6%, while the Tropical Cyclone size and rainfall increase by about 3% and 12%, respectively. These changes are generally reproduced across the different basins in terms of the sign of the change, although the percent changes vary from basin to basin and within individual basins. For the Atlantic basin, although there is an overall reduction in frequency from CO2 doubling, the warmed climate exhibits increased interannual hurricane frequency variability..."

Figures from Dr. Ryan Maue: Last 4-decades of Global and Northern Hemisphere Accumulated Cyclone Energy: 24 month running sums. Note that the year indicated represents the value of ACE through the previous 24-months for the Northern Hemisphere (bottom line/gray boxes) and the entire global (top line/blue boxes). The area in between represents the Southern Hemisphere total ACE.
1970- August 2013 monthly ACE Data File (Maue, 2010, 2011 GRL)
1970- Sept 2012 global tropical cyclone frequency monthly Data File

Figure: Global Hurricane Frequency (all & major) -- 12-month running sums. The top time series is the number of global tropical cyclones that reached at least hurricane-force (maximum lifetime wind speed exceeds 64-knots). The bottom time series is the number of global tropical cyclones that reached major hurricane strength (96-knots+). Adapted from Maue (2011) GRL.

Journal of Climate 2014 ; e-View

doi: http://dx.doi.org/10.1175/JCLI-D-13-00475.1

Tropical Cyclone Simulation and Response to CO₂ Doubling in the GFDL CM2.5 High-Resolution Coupled Climate Model

Hyeong-Seog Kim,^1,2,3,* Gabriel A. Vecchi,¹ Thomas R. Knutson,¹ Whit G. Anderson,¹ Thomas L. Delworth,¹Anthony Rosati,¹ Fanrong Zeng,¹ and Ming Zhao^1,4

¹ NOAA/Geophysical Fluid Dynamics Laboratory, Princeton, NJ

² Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ

³ Willis Research Network, London, UK

⁴ University Corporation for Atmospheric Research, Boulder, CO

Abstract

Global tropical cyclone (TC) activity is simulated by the Geophysical Fluid Dynamics Laboratory (GFDL) CM2.5, which is a fully coupled global climate model with horizontal resolution of about 50km for atmosphere and 25 km for ocean. The present climate simulation shows fairly realistic global TC frequency, seasonal cycle, and geographical distribution. The model has some notable biases in regional TC activity, including simulating too few TCs in the North Atlantic. The regional biases in TC activity are associated with simulation biases in the large-scale environment such as sea surface temperature, vertical wind shear, and vertical velocity. Despite these biases, the model simulates the large-scale variations of TC activity induced by El Nino/Southern Oscillation fairly realistically.

The response of TC activity in the model to global warming is investigated by comparing the present climate with a CO₂ doubling experiment. Globally, Tropical Cyclone frequency decreases (-19%) while the intensity increases (+2.7%) in response to CO ₂doubling, consistent with previous studies. The average Tropical Ccyclone lifetime decreases by -4.6%, while the Tropical Cyclone size and rainfall increase by about 3% and 12%, respectively. These changes are generally reproduced across the different basins in terms of the sign of the change, although the percent changes vary from basin to basin and within individual basins. For the Atlantic basin, although there is an overall reduction in frequency from CO₂ doubling, the warmed climate exhibits increased interannual hurricane frequency variability so that the simulated Atlantic TC activity is enhanced more during unusually warm years in the CO₂-warmed climate relative to that in unusually warm years in the control climate.

Full paper here

Also today:

Warmists now warn: global warming means fewer cyclones. Panic!

Andrew Bolt Blog

By Andrew Bolt

AUGUST 03, 2014
Global warming - dud predictions, Global warming - propaganda

Australia hasn’t had so few tropical cyclones for many centuries, says Jonathan Nott of James Cook University. But the strange thing is that Nott claims this was actually predicted by warmists all along:

Our CAI for Australia shows that seasonal Tropical Cyclone activity is at its lowest level since the year 500 AD in Western Australia and 1400 AD in Queensland and this decline in activity has been most pronounced since about 1960 AD. This reduction in activity reflects the forecasts of Tropical Cyclone behaviour for the Australian region from a suite of the most recent global climate models except this decrease appears to be occurring many decades earlier than expected.

Pardon? So global warming models actually predicted global warming would give us a decrease in tropical cyclones? Then why did the alarmists pretend the very opposite?

Here is Bob Brown in 2011 after Cyclone Yasi:

GREENS leader Bob Brown says the coal mining industry should foot the bill for the Queensland floods because it helped cause them…
“It’s the single biggest cause - burning coal - for climate change and it must take its major share of responsibility for the weather events we are seeing unfolding now,” he said in Hobart today.