How are oceans affected by global warming?

One scary scenario that is often painted while talking about global warming is the rising ocean levels. And well, that is not just exaggerated scare-mongering, but it indeed is true that global warming results in the ocean level rise.

Rising Sea Levels

• Sea level rise by two different mechanisms in the context of climate change. First, as the oceans warm due to an increasing global temperature, seawater expands—taking up more space in the ocean basin and causing a rise in water level. The second mechanism is the melting of ice – such as mountain glaciers and polar ice sheets – which then adds water to the ocean.
• Scientists have determined that global sea level has been steadily rising since 1900 at a rate of at least 0.04 to 0.1 inches per year.
• The survival of coral reefs, mangroves, sea grasses, and other critical habitat-forming species hinges on their ability to move into shallower waters. Critical coastal habitats—for instance, sea turtle nesting beaches—are lost as the sea level rises.

But global warming results in a lot many more negative effects on the ocean than just rising sea levels.

The following are the other effects of global warming on the oceans:

• A Warmer Ocean Affects Biodiversity – The ocean has absorbed 80% of the heat added to the Earth’s system by global warming. Warmer waters cause coral bleaching, which in turn negatively impacts the entire coral ecosystem. Many species will be forced to migrate.
• Melting of the Poles – Global warming causes polar ice to melt. Diminished sea ice results in the loss of vital habitat for seals, walruses, polar bears, penguin, orcas, minke whales, Antarctic krill and other megafauna in the Arctic and Antarctic.
• Changes to the Ocean’s Major Currents – Changes in ocean temperatures and wind patterns—results of overall climate change—will affect and alter oceanic currents. Many animals’ migratory patterns can change as the currents they follow are altered. Many species that depend on ocean currents for reproduction and nutrients will be affected. For example, many reef-building coral and reef fish species rely on dispersal of their larvae by currents.
• Ocean Acidification – Higher amounts of CO2 in the atmosphere results in higher ocean acidification, when CO2 reacts with water. Acidification directly harms the many ocean plants and animals that build shells of calcium carbonate—including many tropical reefbuilding corals, coldwater corals, mollusks and other scallops, crustaceans such as lobsters and crabs, and some microscopic plankton. Many of those same shell-forming organisms provide critical habitat and food sources for other organisms, directly and indirectly impacting the availability of marine food sources for humans.