Over the past 100 years, human activities such as the burning of coal and gas have increased the carbon dioxide in the atmosphere, causing the oceans to warm and become more acidic. For all the animals that live in the ocean, this means the environment they live in is changing. For cold-water corals, these changes mean that they may start to grow slower, need more food to survive, and may not even be able to grow in some areas. There may also be changes in how much food is available, as their food may also grow slower in warmer, more acidic waters. We need to learn more about how these corals will react to the changes, by studying how they survive now, and by doing laboratory experiments to see how they respond to different conditions.