More inconvenient results for Al Gore and the mouthpiece of “Forecast the Facts” Brad Johnson who like to claim that tropical storms will increase due to global warming.
A paper published last week in the Journal of Climate projects a 3-15% decrease of tropical cyclones throughout the 21st century, which seems to be inline with what has been observed so far:
The figure is from Dr. Ryan Maue’s paper Recent historically low global tropical cyclone activity published June 2011 at Geophys. Res. Lett. in press PDF
The new paper is:
Projected changes in late 21st century tropical cyclone frequency in thirteen coupled climate models from the Coupled Model Intercomparison Project Phase 5
Journal of Climate 2013 ; e-Viewdoi: http://dx.doi.org/10.1175/JCLI-D-13-00010.1
Changes in tropical cyclone (TC) frequency under anthropogenic climate change are examined for thirteen global models from the Coupled Model Intercomparison Project Phase 5 (CMIP5), using the OWZP TC detection method developed by the authors in earlier papers. The method detects large-scale conditions within which TCs form. It was developed and tuned in atmospheric reanalysis data, and then applied without change to the climate models to ensure model and detector independence. Changes in TC frequency are determined by comparing TC detections in the CMIP5 historical runs (1970—2000) with high emission scenario (representative concentration pathway 8.5) future runs (2070—2100). A number of the models project increases in frequency of higher latitude tropical cyclones in the late 21st century. Inspection reveals these high latitude systems were subtropical in origin and are thus eliminated from the analysis using an objective classification technique.
TC detections in eight of the thirteen models reproduce observed TC formation numbers and geographic distributions reasonably well, with annual numbers within ±50% of observed. TC detections in the remaining five models are particularly low in number (9—27% of observed). The eight models with a reasonable TC climatology all project decreases in global TC [tropical cyclone] frequency varying between 3 and 15 %. Large inter-model and inter-basin variations in magnitude and sign are present, with the greatest variations in the Northern Hemisphere basins.
These results are consistent with results from earlier generation climate models, and thus confirm the robustness of coupled model projections of globally-reduced TC [tropical cyclone] frequency.