Earlier this year the International Programme on the State of the Ocean (IPSO) convened a workshop of marine scientists to consider the impact of multiple stressors such as warming, acidification and overfishing of the ocean. The scientists concluded that a mass extinction of ocean species will occur if the damage to the ecosystem continues to escalate! Two of the findings which we will discuss were:
1. The ocean is currently absorbing more carbon from the atmosphere than at the time of the last mass extinction millions of years ago.
2. A single mass coral bleaching event in 1998 killed 16 percent of the world’s tropical coral reefs.
In this posting we will discuss how the burning of fossil fuel is changing the “State of the Ocean.” Our burning of fossil fuel has created an overload of carbon dioxide in the atmosphere (my posting entitled “Fossil Fuel and Atmospheric Levels of Carbon Dioxide”). The ocean is becoming more acidic because atmospheric carbon dioxide overload is dropping more carbon dioxide into the ocean (my posting entitled “Atmospheric Carbon Dioxide Levels and Ocean Acidification”).
The atmospheric carbon dioxide overload has also triggered an increase in global temperature (my posting entitled Solar Activity, Greenhouse Gas Levels and Climate Change on our Earth). Rising ocean water temperature is killing the coral reef! Coral reefs are colonial animals and individual coral animals are called polyps. Large number of these polyps grow together into delicately branched colonies. Within the tissue of the polyps are single cell algae called zooxanthellae that require light for photosynthesis. Polyps and zooxanthellae have a symbiotic relationship in which the coral provides the algae with a protected environment and carbon dioxide which the algal cells photosynthesize to generate oxygen and nutrients for the polyps. Coral bleaching or reef death occurs when the zooxanthellae die as the ocean temperature rises. This is deadly not only to the coral but also to young fish and marine life that depend on the coral reef for protection and food. It is estimated that one in every four species in the ocean depends on the coral reef for at least part of their life cycle. Bleaching has wiped out at least half of the coral in the Florida Keys and bleached corals have recently been found as far north as Charleston SC.
The ocean ecosystem is already under tremendous stress. If we continue “business as usual” in our use of fossil fuel the increase in ocean acidification along with the increase in water temperature will put additional strains on the ocean ecosystem. These additional strains could trigger a total collapse of the ecosystem killing off species in a mass extinction that hasn’t been seen in millions of years. As one member of the IPSO workshop appropriately put it “If the Ocean goes down, it’s game over.” The choice is ours! Continue use of fossil fuel or convert to noncarbon based renewable energy sources.
Photo Credit: Fotolia