Coral reefs important in mitigating climate change impacts – PICRC study

As a small island nation, Palau is vulnerable to climate change impacts, such as sea level rise, ocean acidification, as well as more frequent and more intense typhoons. Globally, many countries are building sea walls to help in reducing wave height and water levels as a result of intensifying storms. Fortunately, in Palau, the reefs surrounding the island are still in good condition, thus providing the needed protection against strong storms. However, as seen in 2012 and 2013, with Typhoons Bopha and Haiyan, typhoons are getting stronger and our current reef system will not be enough to protect the lowest lying coasts.

In a recently published paper in the scientific journal, Natural Hazards and Earth System Science, scientists from Palau International Coral Reef Center (PICRC) and University of the Ryukyus, investigated the effects of climate change on Melekeok State. Authors of the paper “Projecting of wave height and water level on reef-lined coasts due to intensified tropical cyclones and sea level rise in Palau to 2100” include Dr. Chuki Hongo and Dr. Haruko Kurihara from the University of the Ryukyus, and Dr. Yimnang Golbuu from PICRC.

This study focused on the reef off of Melekeok and its potential in reducing wave action to the low-elevation coast of Melekeok. The study had two objectives: (1) provide quantitative projections of wave height and water level in the present reef compared to future reef projections (degraded and healthy); and (2) to estimate the potential of the reef to grow, as well as the needed production rate in order to effectively reduce the current risks to the low-lying coastline.

The study looked at the reef in Melekeok and predicted the risk of coastal damages in the case of more frequent and intense typhoons that are likely to occur by the end of the 21^st century (Year 2100). The study concluded that if the reef continues to grow and remain healthy, it will act as a natural barrier and will aid in the reduction of wave impacts to the shore by reducing wave height and strength. On the other hand, if the reef is degraded, with continued sea level rise and intensifying typhoons, wave motion and water levels will negatively impact the coastline, flooding the roads and eroding the coastline.

The take home messages from this study are as follows: (1) it is necessary to continue monitoring coral cover, coral larval recruitment, as well as the occurrences of stressors, such as typhoons and bleaching events; (2) maintain and improve the health of the reef by enhancing the protected areas with appropriate management strategies; (3) consider alternatives such as restoration efforts i.e. coral transplanting projects; (4) establish evacuation protocols in case of typhoon-related emergencies; and (5) set up technology to accurately predict typhoon intensities and subsequent impacts such as flooding.