3 luc debontridder climate change and its effects on transport flows
Climate change and itseffects on transport flows and risks Debontridder Luc – Operational scientist – Climatologist Royal Meteorological Institute of Belgium
Topics• Freak or so called rogue waves.• Frequency of winter storms.• Hurricanes - Typhoons.• North Pole ice.
Freak or rogue waves• What ?• Occurances ?• Causes and types ?• Draupner wave• Maxwave project• Link with climate change unknown
What ?Rogue waves have been part of marine folklore for centuries. They aregenerally considered to be unexpectedly high waves which in someinstances come from a direction different from the predominant waves inthe local area. A single rogue wave has certainly been known to spelldisaster for the mariner. They have, over the past twenty or thirty years,come to be recognized as a unique phenomena albeit with severalpossible causes.How strong are they? The force of a breaking freak wave is tremendous.A 12-meter wave in the Linear Model has the force of about 6 MT/m2. Arogue wave, however, has a force of about 100 MT/m2. Modern dayvessels are designed to withstand only 15 MT/m2. It is thereforeunderstandable why some ships do not survive freak waves.
OccurancesShip accidents between 1995 and 1999 from Hapag Loyds accidentdatabase.
Causes and types1) Constructive interference. Several different wave trains of differing speeds and directions meet at the same time. The heights of the crests are additive so that an extreme wave may result when very high waves are included in the wave trains.2) Focusing of wave energy. When storm forced waves are developed in a water current counter to the wave direction an interaction can take place which results in a shortening of the wave frequency. The result is the superimposing of the wave trains and the generation of extreme waves. (ex. Agulhas current). → Extreme wave developed in this regime tend to be longer lived.
3) Normal part of the wave spectrum.The generation of waves on water results not in a single waveheight but in a spectrum of waves distributed from the smallestcapillary waves to large waves. The random nature of waves impliesthat individual waves can be substantially higher than the significantwave height. In fact, observations and theory show that the highestindividual waves in a typical storm with typical duration to beapproximately two times the significant wave height. Some reportedrogue waves are well within this factor of two envelope. Waveshigher than roughly twice the significant wave height fall into thecategory of extreme or rogue waves.
The Draupner WaveOn New Year’s Day 1995, the Draupner oil rig was in the middle of astorm in the North Sea. Its radar sensors were regularly recording waveswith heights of 12 meters, when it was suddenly hit by a freak wave 26meters high The Draupner wave, January, 1, 1995.
The MAXWAVE ProjectThe European Project MAXWAVE deals with both theoretical aspects ofextreme waves as well as new techniques to observe these waves usingdifferent remote sensing techniques. The final goal was to improve theunderstanding of the physical processes responsible for the generation ofextreme waves and to identify geophysical conditions in which such waves aremost likely to occur. Partners of the project GKSS Research Center, Germany Institute of Hydroengineering, Polish Academy of Sciences Norwegian Meteorological Institute (Met No) German Aerospace Center (DLR) UK Meteorological Office Instituto Superior Tecnico (IST), Portugal Meteo France Ocean Waves, Germany Catholic University of Leuven, Belgium Technical University of Berlin, Germany Det Norske Veritas (DNV), Norway
Maximum daily wind speed in De Bilt between 1962 and 2005, and the four climatescenarios for 2050 (coloured points). The thick black line represents the 30-yearmoving average of the observations. The thick coloured and dashed lines connecteach climate scenario with the baseline year 1990. The grey band represents theyear-to-year variation, derived from the observations.Storm surges along the Dutch and Belgian coast are associated with storms comingfrom western to northern directions. The model calculations used for the fourscenarios show only small changes in the number of storms from these directions.
Frequency of hurricanes - typhoons Frequency of North Atlantic Hurricanes depends on multi-decadal changes in surface sea water temperatures and methods of observation !!!!!!
• There is a common misconception that since the global temperature has increased, hurricanesalso must increase in number and intensity.• The primary factor in the ability of a hurricane to strengthen or weaken is the wind shearprofile of the atmosphere - not water temperature.• The recent upturn in tropical cyclone activity was predicted long before Global Warmingbecame a household name.• As we have noted, the number one factor in tropical cyclone intensity is related to theatmospheric wind shear profile. There is even some research that suggests that highertemperatures could actually increase the wind shear profile resulting in a decrease in hurricaneactivity.• The upward cycle in hurricane numbers is expected to continue for several more years. If thistrend were to continue for a considerably longer period, only then could one draw a conclusionthat warmer temperatures have played some part to cause an increase in tropical cycloneformation.• There is no proven scientific evidence that there is a link between climate change and thenumber of hurricanes in the Atlantic basin. In the pacific there is even no change at all. There isa possibility (IPCC 2007) that there will be an increase in intensity, especially in rainfallquantities and not in wind speed.
North pole ice navigation Sea ice extent north pole
● It seems unthinkable, but for the first time in human history, ice is on course to disappearentirely from the North Pole this year.● The disappearance of the Arctic sea ice, making it possible to reach the Pole sailing in a boatthrough open water, would be one of the most dramatic – and worrying – examples of the impactof global warming on the planet. Scientists say the ice at 90 degrees north may well have meltedaway by the summer.● Seasoned polar scientists believe the chances of a totally ice-free North Pole this summer aregreater than 50:50 because the normally thick ice formed over many years at the Pole has beenblown away and replaced by huge swathes of thinner ice formed over a single year.● Each summer the sea ice melts before reforming again during the long Arctic winter but theloss of sea ice last year was so extensive that much of the Arctic Ocean became open water, withthe water-ice boundary coming just 700 miles away from the North Pole.● Technological advances and changing climatic circumstances are bringing us new challengesand opportunities. One of those is increasing maritime transport in Arctic waters, even thepossibility of a new sea route across the North Pole linking the North Atlantic and the NorthPacific in closer commercial relations than ever before.● At the same time new shipping routes will bring new economic opportunities to thecommunities in the North. This applies in particular to Iceland that will be in a key location forservicing the Northern Sea Route in the future.
“Breaking the Ice : Arctic Development and Maritime Transportation”Government of Iceland in Akureyri on March 27-28, 2007