Potential Impact of Climate Change on Tanker Design

Abstract

Global warming and extreme weather events reported in the last years have attracted a lot of attention in academia, industry and media. The ongoing debate around the observed climate change has focused on three important questions: will occurrence of extreme weather events increase in the future, which geographical locations will be most affected, and to what degree will climate change have impact on future ship traffic and design of ships and offshore structures? The present study shortly reviews the findings of the Intergovernmental Panel on Climate Change Fourth Assessment Report, AR4, [1] and other relevant publications regarding projections of meteorological and oceanographic conditions in the 21st century and beyond with design needs in focus. Emphasis is on wave climate and its potential implications on safe design and operations of ship structures. A risk based approach for marine structure design accounting for climate change is proposed. The impact of expected wave climate change on ship design is demonstrated for five oil tankers, ranging from Product tanker to VLCC. Consequences of climate change for the hull girder failure probability and hence the steel weight of the deck in the midship region is shown. Recommendations for future research activities allowing adaptation to climate change are given.

Climate change and safe design of ship structures

“…The Hs distribution has been shifted by a constant value corresponding to the specified increase of Hs. The formulation of the conditional distribution of Tz has been kept unchanged (Bitner-Gregersen et al, 2011, 2013b, 2015a. This simplification is considered to be acceptable for extremes but not for fatigue calculations.…”

“…Case a) increasing extreme Hs by a constant value (Bitner-Gregersen et al, 2011), Case b) modifying the joint distribution using closed form expressions for the Weibull scale and location parameter (the shape parameter is kept constant) proposed by Vanem and Bitner-Gregersen (2012), Case c) assuming that the increased extreme significant wave height instead of being a fixed value (as in Case a) is normally distributed with COV=0.25 (Bitner-Gregersen et al, 2015a).…”

Sea state conditions for marine structures' analysis and model tests

“…Thus this database is probably biased towards lower wave heights, see e.g. Bitner-Gregersen et al, (2014d). As mentioned in Section 4.1 the GWS Atlas was published in 1986 and the missing last 30 years data seem to to have impact on extreme values of significant wave height.…”

“…However, the accuracy of the GWS data has been questioned in the literature since the 1990s, especially concerning the wave period as discussed, e.g. by Wing and Johnson (2010), Bitner-Gregersen et al (2014b, 2014d. Note also that the GWS Atlas was published in 1986 thus the last 30 years, when many severe storms occurred, is missing.…”

An Illustration of the Effect of Climate Change on the Ocean Wave Climate - A Stochastic Model

“…It will be investigated how to relate such trends to the calculations of ship structural loads and responses. It is emphasized that potential influence of such trends on structural design, as was discussed in [8] is not considered explicitly herein. Results pertaining to any other projection period, such as 30 or 40 years ahead in time, could also easily have been used.…”