PDF | 2 MB - Australian Building Codes Board

More documents

Recommendations

Info

IWTC (2006) ‘The scientific debate … is not as to whether global warming can cause a trend in tropical cyclone intensities. The more relevant question is how large a trend: a relatively small one decades into the future or large changes occurring today. Currently published theory and numerical modeling results suggest the former, which is inconsistent with the observational studies of … Webster et al (2005) by a factor of 5… .’ (McBride et al, 2006). IPCC (2007) ‘There is observational evidence for an increase in intense tropical cyclone activity in the North Atlantic since about 1970, correlated with increases in sea surface temperatures. There are also suggestions of increased intense tropical cyclone activity in some other regions where concerns over data quality are greater. … There is no clear trend in the annual numbers of tropical cyclones.’ 6.7 Summary and Conclusions There has been some speculation that the frequency of severe tropical cyclones worldwide has already been increasing as a result of global warming. This view has been promoted by two well-known publications in 2005. The main problem appears to be observational errors, in both the numbers of tropical cyclones observed and their intensity, prior to about 1980. Before the advent of regular satellite observations in about 1970, many storms that did not cross a coastline were not observed or not recorded. It is only since 1980 that satellite observations have been regular enough and of sufficient quality to produce reasonable and consistent estimates of storm strengths. Currently it is only in the North Atlantic basin, that the strengths of hurricanes are being regularly observed by means of aircraft penetration flights and then only for those storms that potentially may cross the coastline of the United States. In other parts of the world where frequent tropical cyclones occur a technique based on a qualitative interpretation of satellite images has been used. This may have resulted in some mis-classification of tropical cyclones. References K. Emanuel (2005), Increasing destructiveness of tropical cyclones over the past thirty years, Nature, Vol. 436, pp686-688. P.J. Webster, G.J. Holland, J.A. Curry and H.R. Chang (2005), Changes in tropical cyclone number, duration and intensity in a warming environment, Science, Vol. 309, pp1844-1846. CSIRO (2007). Climate change in Australia. Technical Report. CSIRO. P.J. Klotzbach (2006), Trends in global tropical cyclone activity in the last twenty years (1986-2005), Geophysical Research Letters, Vol. 33, L10805 36
J.P. Kossin, K.R. Knapp, D.J. Vimont, R.J. Murnane, B.A. Harper (2007), A globally consistent reanalysis of hurricane variability and trends, Geophysical Research Letters, Vol. 34, L04815. J. McBride, J. Kepert, J. Chen, J. Heming, G. Holland, K. Emanuel, T. Knutson, H. Willoughby and C. Landsea (2006), Statement on tropical cyclones and climate change, 6 th WMO International Workshop on Tropical Cyclones (IWTC-VI), Costa Rica, November. 37
Page 2 and 3: IMPACT OF CLIMATE CHANGE ON DESIGN
Page 4 and 5: Executive Summary The objective of
Page 6 and 7: 1. Introduction 1.1 Project scope B
Page 8 and 9: Figure 1.1. Average number of days
Page 10 and 11: 2. History of cyclonic design wind
Page 12 and 13: The ratios of the current (2002) va
Page 14 and 15: Station Table 2.3. Comparison of de
Page 16 and 17: 2.3 Summary and Discussion The chan
Page 18 and 19: 3. Simulation methods for predictio
Page 20 and 21: with the hurricane. An imposed pres
Page 22 and 23: C.M.L. Dorman (1984), Tropical cycl
Page 24 and 25: In the absence of other comparable
Page 26 and 27: averaging of many individual normal
Page 28 and 29: T.F. Hock and J.L. Franklin (1999),
Page 30 and 31: A road-sign failure near the eye wa
Page 32 and 33: α β = cav (5.6) where c av is an
Page 34 and 35: References G.N. Boughton and D. Fal
Page 36 and 37: 6.3 Interpretations by Emanuel (200
Page 40 and 41: 7. Observed trends in tropical cycl
Page 42 and 43: cyclones occurred in both the South
Page 44 and 45: 8. Predicted effects of climate cha
Page 46 and 47: environmental factors (that are kno
Page 48 and 49: 9. Observations and projections for
Page 50 and 51: 9.3 Report by Cook G.D. Cook (2007)
Page 52 and 53: (the ‘TIM’ cyclones). The latte
Page 54 and 55: are slightly conservative but adequ
Page 56 and 57: • Improving the understanding of
Page 58 and 59: Cyclonic wind speeds - Darwin 1960-
Page 60: ACKNOWLEDGEMENTS The support of Dr

PDF | 2 MB - Australian Building Codes Board

Create successful ePaper yourself

Delete template?

Save as template?