Detecting the Footprint of Man in Tropical Cyclone Damage Data
Crompton, R.P., Pielke, Jr., R.A. and McAneney, K.J. 2011. Emergence timescales for detection of anthropogenic climate change in US tropical cyclone loss data. Environmental Research Letters 6: 10.1088/1748-9326/6/1/014003.
In an attempt to determine the odds of breaking through this detection barrier, Crompton et al. focused their attention upon US tropical cyclone loss data. Knowing, however, that Chen et al. (2009) and Knutson et al. (2010) had failed to find a clear signal of man's impact on Atlantic hurricanes, they asked a somewhat more tractable question: "if changes in storm characteristics in fact occur as projected, then on what timescale might we expect to detect the effects of those changes in damage data?"
Employing the ensemble projection of 18 global climate models derived from the World Climate Research Programme's Coupled Model Intercomparison Project 3 (CMIP3, based on the IPCC's A1B emissions scenario), plus individual projections obtained from four of the CMIP3 models -- (1) the Geophysical Fluid Dynamics Laboratory GFDL-CM2.1, (2) the Japanese Meteorological Research Institute MRI-CGCM, (3) the Max Planck Institute MPI-ECHAM5, and (4) the Hadley Centre UK Meteorological Office UKMO-HadCM3 -- the three researchers estimated "the time that it would take for anthropogenic signals to emerge in a time series of normalized US tropical cyclone losses." So just how long is it?
Crompton et al. determined that "depending on the global climate model(s) underpinning the projection, emergence timescales range between 120 and 550 years, reflecting a large uncertainty." And they report that "it takes 260 years for an 18-model ensemble-based signal to emerge."
Based on their results, the US and Australian scientists "urge extreme caution in attributing short term trends (i.e., over many decades and longer) in normalized US tropical cyclone losses to anthropogenic climate change," suggesting that "anthropogenic climate change signals are very unlikely to emerge in US tropical cyclone losses at timescales of less than a century."
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