Global Climate Change
The earth’s climate is changing at a rapid pace. We know global climate change is happening, but less well known is how to address the impacts climate change is having on our seas. The focus of this toolkit is to provide strategies and actions that coral reef managers can take to help coral reefs cope with the effects of climate change, including warming seas. In this toolkit increasing sea temperatures and the bleaching that results are the primary focus and are used as an example of how global climate change will impact our ocean habitats. By building resilience into the design of MPAs and management actions, managers can do something to reduce the expected damage from climate change related impacts.
We are now witnessing, first hand, the following global climate changes:
Increased sea surface temperatures: Increases in ocean temperatures will increase the number of bleaching events.
Rising sea levels: Rising seas linked to climate change may not pose a major threat to coral reefs, as long as the projected rates of sea level rise are low enough for coral growth to keep pace. However, if catastrophic ice-melting scenarios occur, coral reefs may be affected. Rising seas are certain to have major impacts on low-lying coral islands, and on coastal habitats such as mangroves and sea turtle nesting beaches.
Increased storm frequency and intensity: Increased frequency and intensity of tropical storms, as well as more frequent and severe El Niño events, are expected to increase storm run-off. This will result in lower salinity and increased sedimentation, which can smother and kill coral reefs.
Acidification of oceans: Increases in the concentration of carbon dioxide (CO2) in the atmosphere causes an increase in CO2 deposition in the surface ocean, lowering the pH. Resulting acidification of the oceans lowers the amount of carbonate (as calcium carbonate) for corals and other marine organisms, resulting in decreased calcification rates. This reduces a reef’s ability to grow, stay healthy and withstand stress.
Altered oceanic currents: There are various predictions about ocean thermohaline circulation (THC) with regard to changes in temperature and salinity. Although there is uncertainty about how THC may be affected, any changes in path or temperature of ocean currents could affect temperature regimes that ultimately would impact temperature-sensitive coral reefs.