It is not only the rising levels that are affecting the coasts. It has been found in research that a warming planet will also alter the ocean waves along with more than 50% of the world’s coastlines.
South Australia stands a chance to see longer, more southerly waves if the climate warms by more than two degrees beyond the pre-industrial levels. These southerly waves could alter the stability of the coastline.
Scientists look at the way waves have shaped our coasts – forming beaches, spits, lagoons, and sea caves
Changing climate will drive changes in wind patterns around the globe and this, in turn, will alter rain patterns, for example by changing El Nino and La Nina patterns. Similarly, these changes in winds will alter global ocean wave conditions.
As per the recent research, it has been analysed that 33 years of wind and wave records from satellite measurements found average wind speeds have risen by 1.5 metres per second, and wave heights are up by 30 cm – an 8% and 5% increase, respectively, over this relatively short historical record.
These changes were most pronounced in the Southern Ocean, which is important as waves generated in the Southern Ocean travel into all ocean basins as long swells, as far north as the latitude of San Francisco.
As part of the Coordinated Ocean Wave Climate Project, ten research organisations combined to look at a range of different global wave models in a variety of future climate scenarios, to determine how waves might change in the future.
If the 2℃ Paris agreement target is kept, changes in wave patterns are likely to stay inside natural climate variability.
Less than 5% of the global coastline is at risk of seeing increasing wave heights. These include the southern coasts of Australia and segments of the Pacific coast of South and Central America.
On the other hand, decreases in wave heights, forecast for about 15% of the world’s coasts, can also alter coastal systems.
Some areas will see the height of waves remain the same, but their length or frequency change. This can result in more force exerted on the coast, perhaps seeing waves run further up a beach and increasing wave-driven flooding.
Similarly, waves travelling from a slightly altered direction can change how much sand they shunt along the coast – important considerations for how the coast might respond.
While each of these wave characteristics is important on its own, our research identified that about 40% of the world’s coastlines are likely to see changes in wave height, period and direction happening simultaneously.
Flooding from rising sea levels could cost US$14 trillion worldwide annually by 2100 if we miss the target of 2℃ warming.
Image Credits – Scimex
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