Climate Change and Ocean Acidification
Hawaiian Islands Humpback Whale

Bleached Coral Colony
Increased ocean temperature may cause reef building corals to lose their symbiotic zooxanthellae, a phenomenon known as coral bleaching where coral tissue loses its pigmentation. Credit: Jon Martinez, NOAA, HIHWNMS.

Why is it a concern?

Over the next century, climate change is projected to profoundly impact coastal and marine ecosystems. Climate change related impacts include increased sea level, changes in weather and rain patterns, increased ocean temperatures. Additionally, the same drivers of climate change will increase the acidity of the ocean. Additionally, climate related changes may contribute to other related impacts that may put further stress on marine ecosystems. For example, increased sea level and extreme weather events are already accelerating coastal erosion and sediment runoff, which is turn impacting water quality. Changes in rain patterns and saltwater intrusion induced by sea level rise, may adversely affect species and habitats that are sensitive to salinity shifts, especially in estuarine and freshwater habitats. Increased ocean temperature may cause reef building coral to bleach, become stressed and eventually die. Ocean acidification may slow or halt the calcification of several calciferous species including coral, coralline algae and mollusks and dissolve calcium carbonate structures on the reef.

A comprehensive effort to better understand the impacts of climate change to ecosystems within the sanctuary is needed to manage sanctuary resources. The sanctuary has developed a Resilience to a Changing Climate Action Plan that describes the steps the sanctuary will take to identify potential climate threats to marine resources and dependent communities, as well as the actions the sanctuary will take to plan for and mitigate potential impacts. In collaboration with research partners the sanctuary will work to monitor physical and biological indicators of climate change, make use of climate models, characterize the adaptive capacity of species to climate change, identify vulnerable natural and cultural resources, and understand climate drivers and stressors.

Overview of Research

Project Name PI and contacts Links

NOAA Sentinel Site Cooperative

Doug Harper

Pacific Islands Climate Change Cooperative

Deanna Spooner


Science Needs and Questions

  • What measures are available to managers to address or mitigate CO2 emissions?
  • Which calcifying organisms are most severely affected by ocean acidification?
  • What are the specific existing and potential climate impacts to marine resources, and dependent human communities in the sanctuary?
  • How will climate change affect species and habitat distributions in the sanctuary?
  • Which locations of the sanctuary are most vulnerable and most resilient to climate change impacts?

Education and Outreach Material

Office of National Marine Sanctuaries Climate Change Website

HIHW after tsunami flooding
Sea level rise from global climate change may exacerbate impacts from tsunamis. This photo shows impacts on the Hawaiian Islands Humpback Whale National Marine Sanctuary building in Maui after the tsunami in 2011. Credit: NOAA, HIHWNMS.


IPCC (Intergovernmental Panel on Climate Change). 2007a. Climate change 2007: The physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B.M. Tignor, H.L. Miller (Eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 996pp.

IPCC (Intergovernmental Panel on Climate Change). 2007b. Climate change 2007: Impacts, adaptation and vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Chang. Parry, M.L., O.F. Canziani, J.P. Palu­tikof, P.J. van der Linden, C.E. Hanson (Eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

IWC (International Whaling Commission). 2007. Report of the scientific committee. Annex K. report of the standing working group on environ­mental concerns. J. Cetacean Res. Manage. (Suppl.) 9:227-96.

Mattila, D.K. and J. Robbins. 2008. Incidence of raised and depressed ovoid skin lesions on humpback whales of American Samoa. Report SC/60/DW3 submitted to the 60th annual meeting of the Scientific Committee.

Simmonds, M. 2009. Report of the workshop on cetaceans and climate change. SC/61/Rep4 submitted to the 61st annual meeting of the Scientific Committee of the International Whaling Commission. Madeira, Portugal.