Table 2.1: Projections of climate-change effects
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| Driver | Variable | Direction and Magnitude of Change | Confidence |
|---|---|---|---|
| Sea level change | Mean sea level | Rise of 0.14-0.18 m by 2050 (most-likely mid-range) Rise of 0.3-0.5 m by 2100 (most-likely mid-range) | *** |
| Extreme & spring tide level | Similar rise as mean sea level for open coasts; may vary in shallow estuaries depending on siltation rates. | ** | |
| Waves, swell | Wave climate | Potential increase of swell conditions on south and west coasts (through increased windiness from westerlies). | ** |
| Extreme waves | Some indication of increased wind intensity of storms that could affect most coasts. Frequency of storms likely to be similar (certainty very low). | ** | |
| Storm tide | Storm surge height | Some indication that storm-surge magnitude may increase (through increased storm intensity). | ** |
| Extreme storm-tide level | Increases from mean sea-level rise (see above) and some indication storm-surge magnitude may increase. | ** | |
| Currents | Tidal currents | Effects likely to be minimal and very localised e.g., estuary tidal inlets. | * |
| Sediment supply | Sediment supply from rivers | Likely to be changes in sediment delivery to the coast, but magnitude or direction of change uncertain (droughts in eastern areas may hold back sediment in rivers, but higher intensity rainfall may increase sediment run-off). | * |
| Cliff erosion | Possible increase in erosion or land-slipping of unconsolidated cliffs from extremes in soil hydrological processes (drought vs. intense rainfall). | * | |
| Longshore transport | Changes likely to vary depending on location, and related predominantly to wave climate (magnitude and direction). | * | |
| Tsunami | - | Climate change will not impact on the occurrence or frequency of tsunami events. Run-up and inundation extent likely to be increased slightly due to higher mean sea levels. | ** |
Table 2.1 shows the likely effects (direction and/or magnitude of climate change on the various drivers of coastal hazards. It shows the degree of present confidence in these predictions as follows:
*** indicates that climate change is generally accepted as impacting on the driver and that the direction of change is known, even if the magnitude is uncertain;
** indicates that a realistic and consistent allowance should be made, but there is low confidence in the actual magnitude of change;
* implies that there is little present-day evidence or future projections that change will occur, but that possible scenarios should be considered in any analysis.
