What is ocean acidification?

The death of the coral reef

Everyone’s heard of climate change, and recently one of our biggest concerns has been plastic in the ocean. But the huge volumes of fossil fuels we’re burning has another negative impact on our oceans: ocean acidification.

When we burn fossil fuels, we release carbon dioxide (among other gases) into the atmosphere. At least one quarter of this dissolves in our oceans. Scientists used to think this was a good thing, as it meant that less carbon dioxide was ending up in the atmosphere and contributing to the greenhouse effect. However, when carbon dioxide dissolves in water, it forms carbonic acid, which lowers the pH of the water. In the past 200 years, ocean water has become 30% more acidic – faster than any known change in ocean chemistry in the last 50 million years. As the oceans continue to absorb carbon dioxide, their capacity as a storehouse will diminish and even more carbon dioxide will end up in the atmosphere.

The increased acidity of oceans also has a huge impact on marine life. Many of the chemical reactions that sea creatures rely on to survive are sensitive to very small changes in pH. The increased acidity of the oceans has impacted the chemical communication, reproduction and growth of the animals that live in it, for example making it harder for some creatures to build shells, which they rely on for protection.

This has also impacted coral reefs. Acidification of the oceans limits coral growth by eroding existing coral skeletons and slowing the growth of new ones. Coral reefs are also damaged by rising sea temperatures, which cause them to expel the algae that live inside their tissues, bleaching them white. The loss of coral reefs affects the whole ocean ecosystem as coral reefs are a crucial habitat for many marine animals.

Ruby V