Oceans

Ocean Acidification & Warming

Ocean acidification and ocean warming are two terms that are often discussed when we talk about climate change and the effects of the release of greenhouse gases into the atmosphere. More and more information about the impacts that these processes have on our oceans and marine life has come out in recent decades, leading prominent scientists, politicians, and climate change advocates to express urgency in the need to protect our oceans. In today’s blog, we will take a closer look at what ocean acidification and ocean warming are, the impacts they have, and any actions you can take to help. 

Definitions

Ocean acidification is a significant and harmful consequence of excess carbon dioxide in the atmosphere. At least one-quarter of the carbon dioxide that’s released into the atmosphere is absorbed by and dissolved in the ocean. While at first, scientists thought that this was a good thing since it leaves less carbon dioxide in the atmosphere, which would mean less warming for the planet, scientists have determined that the dissolved carbon dioxide is actually changing the ocean’s chemistry. As carbon dioxide dissolves in seawater, the water becomes more acidic, consequently dropping the ocean’s pH. In the past 200 years, ocean water has become 30% more acidic. Not only is ocean acidity increasing, but the increase is happening at a pace that hasn’t been seen in the last 50 million years. 

Carbon dioxide and other greenhouse gas emissions, not only affect our ocean’s acidity but also contribute to ocean warming. Only about 1% of planet-warming emissions that have been released have stayed in the atmosphere, while the majority of the trapped heat has been absorbed into our oceans. Since the 1970’s the oceans have absorbed more than 90% of all the excess heat energy trapped by carbon dioxide. Our oceans have warmed by roughly one degree Fahrenheit, on average, over the past century, and the pace of warming has accelerated - the top part of the ocean is warming 24% faster than it did a few decades ago.

Ocean acidification and warming have the potential to have significant impacts on aquatic life, sea-level rise, ocean-dependent economies, and even our weather. It’s important to understand the impacts we are already experiencing and the impacts that are yet to come so that we can take the necessary steps to hopefully prevent the worst effects. 

Impacts

Ocean acidification has a range of impacts on marine life, which consequently affects the billions of people around the world who depend on fish and shellfish as their primary source of protein and also the economies around the world that depend on marine life as a source of jobs and other resources and revenue for their communities. The relatively quick speed at which the ocean is becoming more acidic, doesn’t give marine life, which evolved over millions of years in relatively stable conditions, much time to adapt. In fact, we’ve already seen that the shells of some animals are dissolving in the more acidic seawater. 

The impact that ocean acidification has on shelled organisms can have far-ranging effects on other marine organisms. For instance, pteropods (or sea butterflies) are sea snails that are an important part of many marine food webs – everything from tiny krill to whales eat them. Unfortunately, researchers have already observed shell dissolution in pteropods in the Southern Ocean around Antarctica. 

Changes in ocean acidity can also affect non-shell building organisms. Research has shown that the ability of some fish - like clownfish - to detect predators and to find suitable habitats decreases in more acidic seawater. Any changes that affect different fish species' ability to survive will, of course, have effects all throughout the food web. 

Ocean warming can and already does have profound impacts on our marine systems and also on the life we live here on land. Warming oceans affects everything from sea-level rise, coral reefs, and other marine organisms’ ability to survive, to our planet’s weather systems. Ocean warming contributes to more powerful storms, it causes some parts of our planet to see increased precipitation and flooding, while other parts are drier than normal, experiencing increased heat-waves, drought, and wildfires.  

Warm water also takes up more space than cool water does. As our oceans heat up, they expand, eventually contributing to sea-level rise. Thermal expansion has contributed about half of all sea-level rise that we’ve seen so far. Additionally, warmer seawater can impact marine organisms. 

Sunny day flooding in Miami. Photo credit: NOAA

The uppermost part of the ocean is not only warming the fastest but has absorbed most of the heat so far. Additionally, our ocean’s can experience what is called marine heatwaves, where the temperature in the uppermost part of the ocean can spike by several degrees. This part of our ocean is where the majority of our ocean dwellers live, and many of these organisms are sensitive to even slight or short-lived changes in temperature. For example, corals are very sensitive to the temperature in which they live, and a change in temperature of even one degree Celsius can stress corals out, causing them to bleach. Bleaching events have become common in some of our most important coral reef systems, and corals are not always able to recover from these events. 

As we can see, ocean acidification and warming can have profound impacts on our marine ecosystems, on our weather, and on our economies. It’s vastly important for these reasons to ensure that we prevent as much warming and acidification as we can. It’s not a matter of protecting some marine species or not, it’s also about protecting our way of life and preventing future natural disasters that cost billions and cause the loss of human life. With that in mind, here are some actions you can take at home. 

Actions

Because ocean acidification and warming are directly related to how much carbon dioxide is released into the atmosphere, one of the best things you can do at home is to reduce your carbon footprint. You can take the bus, walk, or bike to places instead of driving, check the tire pressure on your cars, switch to green energy, and more. You can find a comprehensive list of ways to reduce your carbon footprint on one of KKB’s previous blog posts about carbon offsets. This blog includes Knoxville specific ways to reduce your carbon and has an in-depth guide to offsetting any carbon you can’t reduce on your own. 

Another way to help is simply to inform your family and friends about ocean acidification and warming. As scientists have only recently realized the extent of the problem, it’s important to spread awareness, so that our communities know to take action. Also remember to use your political capital to support members of our government who want to increase marine protected areas, reduce offshore drilling, and generally want to reduce greenhouse gas emissions. 

With your help, we can not only reduce planet-warming emissions but also protect our marine ecosystems and the ways of life that depend on our ocean economy.