Humans Fueling Steady Rise in Ocean Heat Levels, Creating Adversity for Aquatic Species

According to the Primordial soup theory, life originated in the ocean. Now, rising marine temperatures threaten mortal peril to oceanic species, and complications to life on land as well. 

Ocean temperatures reached record peaks in 2022, breaking the previous record set a year earlier, a team of researchers reported last week. Indeed, since 2018, scientists have observed record heat levels in the ocean, with each year eclipsing the last.

Since scientists began to document ocean temperatures in the 1950s, their research has revealed a steady rise in ocean heat levels. In fact, in a 2019 special report, researchers with the United Nations Intergovernmental Panel on Climate Change (IPCC) wrote: "It is virtually certain that the global ocean has warmed unabated since 1970 and has taken up more than 90 percent of the excess heat in the climate system (high confidence)."

Rising marine temperatures are linked to human activity

Further, scientists believe that humans are directly fueling the "unabated" rise in ocean temperatures.

The IPCC followed up on its report in 2021, outlining how the ocean warming processes it had previously detailed are increasing in frequency and severity. In its 2021 report, the panel declared: "Changes to the ocean, including warming, more frequent marine heatwaves, ocean acidification, and reduced oxygen levels have been clearly linked to human influence."

Effects on marine life

It's easy for humans to say, "if you can’t take the heat, get out of the ocean," but that doesn’t do much for the abundance of aquatic life reeling from endless marine heatwaves.

Coral reefs are perhaps the best publicized victims of oceanic heatwaves. A 2021 study published in the One Earth journal found that the world has effectively lost half of its coral reef ecosystems since 1950. As the coral reefs decline, so do all the life forms reliant on the coral reef ecosystem. One Earth researchers found that "at least 63 percent of coral-reef-associated biodiversity has declined with loss of coral extent."

It is important to note that not all species will be negatively affected by a rise in oceanic temperatures alone. But the effects that rising marine temperatures have on ecosystems will ultimately create negative conditions even for those species that can adjust or even thrive with more heat.

For instance, while whale species are able to adjust physically to rising temperatures, the warming waters are detrimental to whale food sources like zooplankton. So, the change in distribution of these preferred food sources poses a significant threat, and means that whales must hunt more frequently, deeper and for longer periods of time. Meanwhile, warmer waters have altered the development of shark brains.

These changes have profound implications for every living thing in the sea. It is no wonder that the IPCC described the effects of rising marine temperatures as observable "from the equator to the poles."

A ripple effect: How rising marine temperatures affect life on land 

Oceanic life will continue to face the brunt of the consequences of rising marine temperatures, but the heating of the oceans also threatens humanity.

Regions that rely on fish (such as Atlantic cod, salmon, brown trout, and Alaskan pollock) for food and commerce will be especially impacted. And that’s just the tip of the (melting) iceberg.

Just as the water in a tea kettle expands as it heats up, so too does the water in the ocean as it grows warmer. As ocean waters expand, sea levels consequently rise — destroying homes, businesses, and coastal, tourism-based economies.

"Coastal areas will see continued sea-level rise throughout the 21st century, contributing to more frequent and severe coastal flooding in low-lying areas and coastal erosion," IPCC researchers warned in the 2021 report. "Extreme sea-level events that previously occurred once in 100 years could happen every year by the end of this century."

Some scientists theorize that warmer waters are sending shark species further north in search of colder waters, and that this in turn is leading to more encounters between sharks and humans. In 2021, the National Oceanic and Atmospheric Administration found that sharks are swimming beyond their typical ranges, following fish populations as they shift northward in search of cooler waters.

Every life form on the planet will be significantly affected in one way or another by this steady rise in heat.

To preserve the various creatures living in the waters that once stirred the ingredients for life itself, humanity must acknowledge its role in climate change and work to mitigate negative effects on the bounty of species in our oceans.

Image credit: Sven Piek/Unsplash