It’s Shark Week, a good opportunity to look at one of the major threats facing sharks and all sea life: ocean acidification. Here are the top three things you need to know about this dangerous consequence of burning fossil fuels:
- Ocean acidification is a direct result of CO2 emissions from the burning of fossil fuels into our atmosphere. As more and more CO2 absorbs into the ocean this decreases seawater pH, making the oceans more acidic. This has the greatest repercussions for calcifying organisms like shellfish and corals, but it is also setting off a chain reaction that will affect the entire ocean ecosystem and our planet. Ocean acidification endangers marine habitats, coastal regions, fisheries, livelihoods, environmental stability, food security and the carbon cycle of the entire earth. Significant changes are predicted to occur in as little as 45 years, with more severe effects to happen by 2100.
- Ocean acidification affects shark’s sense of smell. A recent study found that high levels of CO2 impaired shark’s sense of smell and caused them to actually avoid odor cues of prey. High concentrations of CO2 also changed the attack behavior of sharks. This could have significant implications for how sharks feed, further endangering already at-risk species. While sharks and other ocean species have been able to adapt to increased concentrations of CO2 in the past, the current changes are happening so rapidly that scientists are unsure whether timely adaptation is even possible.
- Ocean acidification changes the blood composition of sharks. Another recent study showed that increased concentrations of CO2 cause changes in shark’s blood chemistry. Blood also has a pH, and as waters become more acidic sharks have to take on, or accumulate, bicarbonate in order to regulate the pH of their blood.In the study, sharks subjected to the higher CO2 levels also showed changes in nocturnal swimming behavior. Again, it’s unclear whether sharks will be able to adapt to these changes.
Ocean acidification is already happening — seawater pH has decreased by 0.1 units, which equates to a 30 percent drop. Tiny shellfish called pteropods, or sea butterflies, are already showing shell dissolution in colder polar waters — ocean acidification will happen first in colder waters because CO2 absorbs more readily into colder versus warmer waters. This could have further implications for cold-water sharks such as the Blue Shark, Spiny Dogfish, Salmon Shark and several others.
Despite the incredibly severe implications of ocean acidification, most research has only occurred since 2004 and funding for this research continues to be well below what is needed. This threat is a direct result of CO2 emissions from burning fossil fuels and mitigating it means significantly reducing emissions, and ultimately ceasing reliance on fossil fuels. The urgency of the situation also means that there is no time to waste on false solutions to emissions like offsets, cap-and-trade and other pollution trading schemes that fail altogether or only produce slow, minimal reductions. Ocean acidification is an irrefutable phenomenon and must be taken seriously for the health of our oceans and our planet.
For more information on ocean acidification see our report: Ocean Acidification: How CO2 Emissions and False Solutions Threaten Our Oceans.