Acidification could drastically change marine ecosystems
Ocean Acidification Could Amplify Climate Disruption Dahr Jamail, Truthout, July 23, 2018
- One of the more serious impacts of human-caused climate disruption occurs when seawater absorbs excess carbon dioxide from the atmosphere. When this occurs, the carbon dioxide reacts with the water to form carbonic acid, which then ultimately reduces its pH level. For much of the marine life in the oceans, the consequences of this will be dire.
“Animals that have a calcium carbonate shell such as, corals, coralline algae, pteropods, bivalves and gastropods are negatively affected by ocean acidification,” said Richard Feely, a senior scientist with the National Oceanic and Atmospheric Administration’s (NOAA) Pacific Marine Environmental Laboratory. “In some cases, their shells are weakened or actually dissolve while the animal is still alive. Fish behavior is also impacted by ocean acidification such that some species lose their ability to navigate or avoid predators.”………
- The pH scale measures acidity, and 7.0 is neutral, whereas higher readings are more “basic” and lower readings are more “acidic.” Historically, Earth’s oceans averaged a pH of 8.2, but this is predicted to fall by as much as 0.4 by 2100. Since the pH scale is logarithmic, one pH unit represents a tenfold change. The ocean’s pH level has already dropped from 8.2 to 8.1, which represents a 25 percent drop within just the past century.
As oceans absorb increasing amounts of our industrial emissions of CO2, their pH is expected to drop to a staggering 7.7 pH by 2100, according to professor of marine chemistry Aleck Wang at the Woods Hole Oceanographic Institution. Wang told National Geographic that by 2100, “you are going to start seeing calcium carbonate shells dissolve. It’s not going to be that far away.”
Most scientists studying the impacts of ocean acidification agree that by killing off the types of organisms Feely mentioned (corals, oysters, types of phytoplankton, etc.), major portions of the oceanic food chain could be greatly impacted.
Feely told Truthout that key marine organisms and ecosystem services face contrasting risks from the combined effects of ocean acidification, warming and sea level rise, and that even under the most stringently controlled CO2 emissions scenario, warm water corals and mid-latitude bivalves “are considered to be at high risk by 2100.”
“Under our current rate of CO2 emissions, most marine organisms are expected to have very high risk of impacts by 2100 and many by 2050,” Feely said. “These results are consistent with evidence of biological responses during high-CO2 periods in the geological past. Impacts to the ocean’s ecosystem services follow a parallel trajectory.”
……… According to Feely, high latitude and upwelling regions of the oceans are already “seriously affected by ocean acidification,” and he said that he and his colleagues are “already observing dissolution of pteropod shells in the Arctic and Southern Oceans, and also upwelling regions along the West Coast of North America.”
- ………Feely’s deepest concerns about ocean acidification are that so many ecosystem processes that humans depend on for food and survival are already impacted by both oceanic warming and acidification, and the risks of these impacts to these services only increases with continued CO2 emissions, which currently show little signs of slowing down.
“[The impacts] are predicted to remain moderate for the next several decades for most services under stringent emission reductions,” Feely said. “But the business-as-usual scenario would put all ecosystem services at high or very high risk over the same time frame.”
A 2015 study warned that ocean acidification could cause dramatic changes to phytoplankton, the basis of the entire oceanic food web.
According to a 2016 study published in the journal Nature Geoscience, CO2 is being added to the atmosphere at a minimum of 10 times faster than it had during a major warming event roughly 56 million years ago that caused a major planetary extinction event. https://truthout.org/articles/ocean-acidification-could-amplify-climate-disruption/
July 25, 2018 -
Posted by Christina Macpherson |
2 WORLD, climate change, oceans
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