Climate Change Fraud - Because the debate is not over - The Lack of Recent Hurricane Activity?

The Lack of Recent Hurricane Activity?

Written by worldclimatereport.com

Monday, 14 April 2008

This hurricane issue never goes away and new websites appear every day warning us of more hurricanes in the immediate future. We cover this issue over and over, and no fewer than three more articles on hurricane activity have appeared in the scientific literature recently of interest to us at World Climate Report:

1. A team of scientists from Florida State University of Louisiana State University examined sediment deposits from Lake Shelby in Alabama. The lake provides an opportunity to engage in a little paleotempestology, which if you don’t know, is the study of storms from geological evidence. Elsner et al. note “Coastal wetlands and lakes are episodically subjected to overwash processes during catastrophic hurricane strikes when barrier sand dunes are overtopped by storm surge.

1. continued... The frequency of overwash sand layers in lake and wetland cores provides an estimate of their return period.” Over the past 3,240 years, it seems that Lake Shelby has experienced 11 hurricanes sufficient to produce significant sediment layers in the lake. The date, in years before present (and the convention is to make 1950 AD “present”), are 770, 1,360, 2,190, 2,240, 2,450, 2,650, 2,960, 3,000, 3,110, 3,160, and 3,240. In other words, over the past three plus millennium, nine of the 11 large hurricanes occurred more that two thousand years ago, one occurred around 1,500 years ago, and one occurred over 700 years ago. None has occurred in the past 700 years – for whatever reason, Lake Shelby’s hurricane activity has been remarkably low for the past 1,000 years!

2. Our second feature paper was published in the prestigious Proceedings of the Royal Society by Johnny Chan of the University of Hong Kong. In discussing whether tropical cyclones (TCs) are becoming more frequent in recent years, Chan notes “Because all such studies generally focused on the data after 1970, others have pointed out that if the time series of intense TC occurrence is extended backwards to earlier years, such an upward trend in intense TC occurrence frequency is actually part of a multi-decadal oscillation in the frequency of TC occurrence.” To test his idea of oscillations rather than trends, Chan collected data on intense (category 4 and 5, aka NCat45) storms in the western North Pacific from 1960 – 2005. The solid line on Figure 1 shows the number of category 4 and 5 storms in the study area over that time period, and Chan shows that the time series contains a distinctive oscillation, but no trend. He concludes “A major conclusion from the results of this study is that the frequency of intense typhoon occurrence undergoes a strong multi-decadal (16–32 years) variation due to similar variations in the planetary scale oceanographic and atmospheric conditions that govern the formation, intensification and movement of TCs.” Furthermore, we learn “Based on the reconstructed 16–32 year series of NCat45, the period 1960–2005 is divided into three sub-periods according to whether the reconstructed values on this time scale are positive or negative, i.e. above or below normal: 1960–1970 (period A1, above normal), 1971–1986 (period B, below normal) and 1987–1997 (period A2, above normal). As the values from 1998 to 2000 are nearly zero, and the period from 2001 to 2005 is too short, these years are ignored in the subsequent analyses.” With respect to global warming and intense activity in the Western North Pacific (WNP), Chan firmly states “Thus, at least for the WNP, it is not possible to conclude that the variations in intense typhoon activity are attributable to the effect of global warming.” Read rest...