- 1. Climate change and itseffects on transport flows and risks
Debontridder Luc Operationalscientist Climatologist Royal
Meteorological Institute ofBelgium
2. Topics Freak or so called rogue waves. Frequency of winter
storms. Hurricanes - Typhoons. North Pole ice. 3. Freak or rogue
waves What ? Occurances ? Causes and types ? Draupner wave Maxwave
project Link with climate change unknown 4. 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. 5. OccurancesShip accidents
between 1995 and 1999 from Hapag Loyds accidentdatabase. 6. 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. 7. 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. 8. The
Draupner WaveOn New Years 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 highThe Draupner wave, January, 1, 1995.
9. 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 OfficeInstituto Superior Tecnico (IST),
PortugalMeteo France Ocean Waves, GermanyCatholic University of
Leuven, Belgium Technical University of Berlin, GermanyDet Norske
Veritas (DNV), Norway 10. Frequency of winter storms. 11. 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. 12. Frequency of hurricanes - typhoonsFrequency
of North Atlantic Hurricanes depends on multi-decadal changes in
surfacesea water temperatures and methods of observation !!!!!! 13.
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. 14. North pole ice
navigation Sea ice extent north pole 15. 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. 16. Breaking the
Ice : Arctic Development and Maritime TransportationGovernment of
Iceland in Akureyri on March 27-28, 2007