2. Changes in wave climate due to climate change
To assess the changes in wind, wave and water level conditions in Danish waters due to future climate changes, we carried out comprehensive numerical modelling of current, water level and wave conditions. For this, we applied input from a number of different climate models – both global and regional. We did this via an ensemble method. This means that the same climate scenario was modelled with different climate models.
Based on the Intergovernmental Panel on Climate Change (IPCC), climate scenario A1B wind and pressure fields were modelled in the climate models for the period 2070-2099. We then applied these wind and pressure fields as input for our hydrodynamic and wave models. This was used along with an estimated sea level rise to model the current, water level and wave conditions for the 30-year period. We repeated this for a ‘today’ reference period being the period 1961-1990. It should be noted that the ‘today’ scenario also was based on wind and pressure fields from the climate models. Therefore, it was not represented in the actual historical data.
Having modelled the conditions for a reference and a future scenario, it was possible to estimate the relative change in certain variables – for example, the extreme wave heights or the extreme water levels at any location within Danish waters.
3. Estimation of future wave conditions by combining step 1 and 2
Based on the estimated changes in wave conditions through the climate change study, we modified the wave climate established in Step 1 through the hindcast modeling. We adapted it to represent an estimate of the wave conditions, including the effect of future climate changes.
The result could be increased design wave heights, which could mean that damages to structures should be expected in the future, if not mitigated. The effect could also be changed wave directions, which could result in future changes of coastlines.