Ocean Acidification

Summary

Paul Andersen explains ocean acidification, the lesser-known counterpart of global warming, caused by increased CO2 levels. Using a simple demonstration, he shows how CO2 reacts with water to lower pH, creating an acidic environment that harms marine life, especially organisms relying on calcium carbonate for shells. The video highlights how this shift in ocean chemistry, alongside the rise in global temperatures, endangers ecosystems like coral reefs and pteropods. The silver lining lies in reducing CO2 emissions, which could alleviate both global warming and ocean acidification, preserving marine biodiversity.

Takeaways

• 😀 Ocean acidification is caused by increased carbon dioxide (CO₂) in the atmosphere, similar to global warming, but it affects oceans through different mechanisms.
• 😀 The demonstration shows how CO₂ dissolves in water to form carbonic acid, which lowers the pH and makes the water more acidic.
• 😀 The pH of distilled water is around 7, but when carbonated with CO₂, the pH drops significantly to 3.6, highlighting the acidity created by CO₂.
• 😀 Carbon dioxide in water forms carbonic acid, which dissociates into bicarbonate and carbonate, with the hydrogen ions driving down the pH of the water.
• 😀 pH is the negative logarithm of the hydrogen ion concentration, so more hydrogen ions result in a lower pH and more acidic conditions.
• 😀 A decrease in ocean pH negatively affects marine life, particularly organisms that depend on calcium carbonate to form shells, such as coral reefs and shellfish.
• 😀 Pre-industrial ocean pH was 8.25, but after industrialization, it dropped to 8.1, which represents a 30% increase in acidity due to the logarithmic scale of pH.
• 😀 By 2100, ocean pH could drop to 7.8, which would significantly impact marine ecosystems, especially organisms that need calcium carbonate.
• 😀 The decrease in ocean pH shifts the balance of carbonic acid, bicarbonate, and carbonate, with carbonate levels dropping and making it harder for shell-forming organisms to survive.
• 😀 The combination of global warming (which causes coral bleaching) and ocean acidification is a double threat to marine ecosystems, especially coral reefs.
• 😀 Reducing CO₂ emissions is key to addressing both global warming and ocean acidification, as it can cool the planet and help stabilize ocean pH.

Q & A

What is ocean acidification and how is it related to global warming?

Ocean acidification is the process where the ocean becomes more acidic due to an increase in carbon dioxide (CO₂) levels in the atmosphere. CO₂ dissolves in ocean water, forming carbonic acid, which lowers the pH of the water. This process is linked to global warming because both are caused by elevated CO₂ levels.

How does carbon dioxide affect the pH of water?

When carbon dioxide dissolves in water, it forms carbonic acid, which dissociates into bicarbonate and hydrogen ions. The increase in hydrogen ions lowers the pH, making the water more acidic.

What was the pH of the water before and after carbon dioxide was added?

Before adding carbon dioxide, the pH of the distilled water was neutral, around 7. After carbonating the water, the pH dropped to approximately 3.6, indicating a significant increase in acidity.

What role does hydrogen ion concentration play in determining pH?

pH is defined as the negative log of the hydrogen ion concentration. Therefore, the more hydrogen ions (H⁺) present in a solution, the lower the pH, which makes the solution more acidic.

How does ocean acidification affect marine life?

Ocean acidification affects marine organisms, particularly those that rely on calcium carbonate, like shellfish and corals. As acidity increases, the availability of carbonate decreases, making it harder for these organisms to form their shells and skeletons.

What is the relationship between carbonate and calcium in marine ecosystems?

Calcium combines with carbonate to form calcium carbonate, which is essential for the shells of marine organisms like shellfish and corals. Lower levels of carbonate in more acidic oceans hinder the ability of these organisms to produce their shells.

How much has ocean pH changed since pre-industrial times?

Since pre-industrial times, the pH of ocean water has decreased from around 8.25 to 8.1. This change, though small in numerical terms, represents a 30% increase in acidity because the pH scale is logarithmic.

What could the ocean's pH be by the year 2100?

By the year 2100, the pH of the ocean could drop to 7.8, which would significantly disrupt marine ecosystems, especially those reliant on calcium carbonate for shell formation.

How do global warming and ocean acidification work together to harm coral reefs?

Global warming causes higher ocean temperatures, leading to coral bleaching, while ocean acidification makes it harder for corals to form their calcium carbonate skeletons. Both factors together create a double threat to coral reefs.

What is the solution to both global warming and ocean acidification?

The solution to both global warming and ocean acidification is to reduce carbon dioxide emissions. Decreasing CO₂ levels will not only help mitigate climate change but also slow down the process of ocean acidification.