Climate change impact on extreme wave conditions in the North Sea: an ensemble study

An analysis of today’s mean and extreme wave conditions in the North Sea and their possible future changes due to anthropogenic climate change are presented. The sea state was simulated for the 30-year period 2071–2100 using the wave model WAM and an ensemble of wind field data sets for four climate change realizations as driving data. The wind field data sets are based on simulation outputs from two global circulation models (GCMs: HadAM3H and ECHAM4/OPYC3) for two emission scenarios (A2 and B2, Intergovernmental Panel on Climate Change, Special Report on Emission Scenarios). They were regionalized by the Swedish Meteorological and Hydrological Institute using the regional climate model RCAO. The effects of the climate realizations on the sea state statistics were assessed by analyzing the differences between the patterns in the four CGM/emission scenario combinations and those in two control simulations representing reference wave climate conditions for the 30-year period 1961–1990. The analysis of the four emission scenario/GCM combinations has shown that the future long-term 99 percentile wind speed and significant wave height increase by up to 7% and 18%, respectively, in the North Sea, except for significant wave height off the English coast and to the north in the HadAM3H-driven simulation. The climate change response in the ECHAM4/OPYC3-forced experiments is generally larger than in the HadAM3H-driven simulations. The differences in future significant wave height between the different combinations are in the same order of magnitude as those between the control runs for the two GCMs. Nevertheless, there is agreement among the four combinations that extreme wave heights may increase in large parts in the southern and eastern North Sea by about 0.25 to 0.35 m (5–8% of present values) towards the end of the twenty first century in case of global warming. All combinations also show an increase in future frequency of severe sea state.

[1]  R. Barthelmie,et al.  Winds of change?: Projections of near‐surface winds under climate change scenarios , 2006 .

[2]  H. Storch,et al.  Climate change and North Sea storm surge extremes: an ensemble study of storm surge extremes expected in a changed climate projected by four different regional climate models , 2006 .

[3]  Francis W. Zwiers,et al.  North Atlantic Ocean Wave Climate Change Scenarios for the Twenty-First Century , 2004 .

[4]  U. Willén,et al.  GCM driven simulations of recent and future climate with the Rossby Centre coupled atmosphere - Baltic Sea regional climate model RCAO , 2003 .

[5]  John F. B. Mitchell,et al.  The simulation of SST, sea ice extents and ocean heat transports in a version of the Hadley Centre coupled model without flux adjustments , 2000 .

[6]  Ralf Weisse,et al.  Multi‐decadal atmospheric modeling for europe yields multi‐purpose data , 2001 .

[7]  M. Rummukainen,et al.  A regional climate model for northern Europe: model description and results from the downscaling of two GCM control simulations , 2001 .

[8]  R. Weisse,et al.  Wave climate and long-term changes for the Southern North Sea obtained from a high-resolution hindcast 1958–2002 , 2007 .

[9]  Ralf Weisse,et al.  Estimating near-shore wave statistics from regional hindcasts using downscaling techniques , 2006 .

[10]  Ralf Weisse,et al.  Northeast Atlantic and North Sea Storminess as Simulated by a Regional Climate Model during 1958-2001 and Comparison with Observations , 2005 .

[11]  Lars Petter Røed,et al.  Future wind, wave and storm surge climate in the Northern Seas: a revisit , 2008 .

[12]  H. Tuomenvirta,et al.  Trends of storms in NW Europe derived from an updated pressure data set , 2000 .

[13]  B. Flemming,et al.  Response of the wadden sea to a rising sea level: a Predictive empirical model , 1997 .

[14]  Lennart Bengtsson,et al.  Transient Climate Change Simulations with a Coupled Atmosphere–Ocean GCM Including the Tropospheric Sulfur Cycle , 1999 .

[15]  U. Willén,et al.  The Rossby Centre Regional Atmospheric Climate Model part I: model climatology and performance for the present climate over Europe. , 2004, Ambio.

[16]  L. Røed,et al.  Future wind, wave and storm surge climate in the northern North Atlantic , 2002 .

[17]  Xiaolan L. Wang,et al.  Climate change signal and uncertainty in projections of ocean wave heights , 2006 .

[18]  James A. Carton,et al.  Earth's climate : the ocean-atmosphere interaction , 2004 .

[19]  M. Noguer,et al.  Climate change 2001: The scientific basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change , 2002 .

[20]  Ralf Weisse,et al.  Evaluation of a method to reduce uncertainty in wind hindcasts performed with regional atmosphere models , 2003 .

[21]  J. Houghton,et al.  Climate change 2001 : the scientific basis , 2001 .

[22]  Katja Woth,et al.  North Sea storm surge statistics based on projections in a warmer climate: How important are the driving GCM and the chosen emission scenario? , 2005 .

[23]  V. R. Swail,et al.  Historical And Possible Future Changes OfWave Heights In Northern Hemisphere Oceans , 2006 .

[24]  Wolfgang Rosenthal,et al.  The wave climate of the Northeast Atlantic over the period 1955-1994 : The WASA wave hindcast , 1998 .

[25]  U. Willén,et al.  European climate in the late twenty-first century: regional simulations with two driving global models and two forcing scenarios , 2004 .