The ability of coastal wetlands to attenuate wave and stabilize shorelines has been increasly recognized. However, the effectiveness of vegetation-based coastal protection under the wave climate change is not clear at a global scale. Here, we evaluate the historical change of global coastal vegetation capacity to attenuate storm waves, by using global data and a vailidated modelling method. We show that although global mean significant wave height (Hs) and peak wave period (Tp) have only changed less than 5% over the last three decades (1979 - 2010), the co-varation of them leads to widespread and complex outcomes of the wave attenuation in coastal wetlands. Four types of outcomes have been identified: positive synergy, negative synergy, antagonistic Hs, and antagonistic Tp. Globally, 30% of the mangrove coastline and 47% of the saltmarsh coastline are impacted by wave climate change (changed rate > 5%), with ~8% and ~6% of each coastline at serious risk (wave attenuation reduced by 10%), such as Europe, Southeast Asia, and the West Coast of the U.S. Our results provide the first assessment of global changes in coastal wetlands’ wave attenuation capacity, which can be of value in ideatifying future hot spots for implementating nature-based coastal protection and hybrid protection measures.
 

Coastal Vegetation,,climate change,Wave