Climate change impacts on the oceans
Global warming, which is the literal warming of the entire planet’s surface temperature, is creating impacts across the globe including the oceans.
The umbrella term for global warming, namely, climate change encompasses all the impacts of this temperature increase which includes rising seas, severe storms, water shortages, droughts, and all sorts of crazy weather. As you can see, climate change promises to impact all of us in one way or another. Some areas and people might be more affected than others given their socio-economic resources, but all will be affected.
We may see a delay in the materialization of the worst-case scenarios of climate change due to the buffering capacity of our oceans. Our oceans play a gigantic role in absorbing heat and man-made carbon emissions. Without their buffering role, our worse climate nightmares would come to pass a lot sooner.
Oceans produce about 50% of the oxygen we breathe and absorb approximately a quarter of our carbon emissions. In addition, oceans also serve as very efficient heat sinks. They absorb more than 90% of the Earth’s heat. To put this in perspective: our atmosphere and continents each absorb only 2% of the heat. As a result, all the world oceans are seeing in increase in sea surface temperatures and water acidity.
Ocean acidification and temperature rise are leading to myriad of problems including sea level rise, loss of coral reef ecosystem, oxygen depletion, fish migration, extreme weather events, etc. And all these cause severe threats to our food security, livelihoods and well-being. Let us take a closer look at each of these impacts.
Sea temperature rise
Between 1901 and 2015, the ocean temperature rose at an average rate of 0.13°F per decade. This might not seem like a lot, but it takes a ton of heat to warm all of the world’s oceans by that much. It is also important to realize that the oceans’ capacity to store additional heat is weakening as the years go by.
Warmer water evaporates much faster, adding to the humidity in the air. This results in heavier rainfalls and allows small ocean storms to escalate into more powerful and larger storms, causing that much more damage.
Higher sea levels
As the oceans warm, the water expands causing the sea levels to rise. This is exacerbated by massive melting of land-based glaciers and ice-caps. We know that human civilizations have always flourished at the coasts and sea level rise threatens to flood many coastal towns and cities worldwide. This spells disaster for people living in low-lying areas, as it would cause shoreline erosion, more powerful storm surges and large-scale economic devastation.
As oceans absorb more carbon pollution created by humans, they become more acidic and this is changing the ocean’s chemistry. Coral reefs, which support diverse marine organisms, are highly vulnerable to changes in the ocean water temperature and chemistry. Ocean acidification is leading to massive coral bleaching in which the corals eject their symbiotic algae and slowly die off. In addition, acidic waters harm many animals at the base of the marine food chains like shelled mollusks (clams and oysters) by dissolving their calcium carbonate shells.
Reduced oxygen levels
World’s oceans have lost about two percent of their oxygen content in just 50 years, according to a new study. Warmer water tends to hold less oxygen. Low oxygen waters can impair reproduction, shorten lifespans, and change behavior of many marine organisms. Furthermore, it speeds up the metabolism of both microbes and larger marine creatures, causing them to consume more oxygen.
Lower oxygen levels in the ocean are already forcing many fish species including tuna, sharks, herring, shad, mackerel, Pacific cod, and swordfish to concentrate into ever-smaller bands of oxygen-rich water near the surface of water. We are also seeing an increase in ocean dead zones worldwide.
We need to recognize the fact that oceans’ ability to store extra heat and carbon also has its limits. Most people misunderstand the concept of “climate inertia” thinking that once we stop emitting greenhouse gases, we will be able to almost immediately reverse global warming. However, this is far from the truth. Even if we stop emitting carbon dioxide the leading greenhouse gas, this very instant, it will take many decades for the climate to stabilize. So, to avoid the worst impacts of climate change, we must halt emissions as soon as possible!
Writer: Amber Ajani