Ocean Acidification: History Repeating Itself
Some 55 million years ago, a huge underwater volcano erupted and released massive amounts of greenhouse gases into the oceans.
It took our oceans 80,000 years to recover.
And today, humans produce around one million tons of greenhouse gas emissions per hour — nearly 10 times the rate of PETM.
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So far, the ocean has absorbed more than 400 billion metric tons of these greenhouse gases. These dangerously high carbon dioxide levels create similar problems to the ones created during PETM, including an increased global temperature, lack of oxygen for ocean life and an increase in the ocean’s acidity.
If such high levels of carbon dioxide emissions caused mass extinction during PETM, you can’t help but wonder what 10 times that rate will do to today’s ocean life.
Carbon dioxide absorbs infrared light, causing the rise in global temperature. The ocean acts as a buffer for greenhouse gases by absorbing a portion of CO2 emissions, which reduces the global temperature that would otherwise be affecting us directly.
But this overabundance of CO2 causes a host of problems. Firstly, CO2 raises ocean temperatures. Recent studies have revealed that during PETM, raised oceanic temperatures resulted in the slowing of global water currents. Oceanic currents exchange colder, deep water and warmer, surface water, regulating temperatures on land. They cause Europe’s relatively warm climate. But just like during PETM, the Atlantic Ocean’s currents are slowing by as much as 30 percent. If trends continue, Europe’s climate could change completely.
Moreover, too much CO2 deprives the oceans of oxygen. This creates “dead zones” that are absent of all marine life for thousands of years, posing a serious threat to biodiversity, as it did during PETM. Without oxygen, fish and other animals are forced to either leave the area or die.
PETM mirrors the current greenhouse gas crisis in yet another way: During PETM, more CO2 absorption by our oceans made the ocean more acidic, which caused mass extinction of calcium-dependent marine life, which absorb calcium from the ocean to grow their skeletons. Today’s calcium-dependent life, like corals and crustaceans, face similar threats as our oceans acidify.
Because of ocean acidification, the Great Barrier Reef’s growth has declined by 13 percent since 1990. Coral reefs are central to marine ecosystems. They are the forests of the oceans, and when they die, so do the fish and other animals that depend on them.
Fifty-five million years ago, PETM killed off up to 50 percent of marine species. Without regulation on greenhouse gases, our oceans face a similarly unhappy fate.
Stop ocean acidification now and tell the EPA to regulate greenhouse gas emissions.
Photo Credit: NOAA, Ocean Explorer