Twin Cities scientist: 'Heat of 5 to 6 Hiroshima atom bombs per second' into Earth's oceans

Study finds warmest oceans on record in 2019

Ocean heat content
Ocean heat content
Advances in Atmospheric Sciences

University of St. Thomas scientist John Abraham is part of a team of scientists that finds the Earth’s oceans were the warmest on record in 2019.

John Abraham
John Abraham
University of St. Thomas

The study was published this week in the journal Advances in Atmospheric Sciences. The team includes top climate scientists in this area of study including some names you may recognize like Penn State’s Michael Mann and Kevin Trenberth from the National Center for Atmospheric Research.

The scientists used two separate metrics to assess ocean heat content (OHC) in the Earth’s oceans. The data shows that the Earth’s oceans were the warmest on record in 2019 going back to at least 1950. And the past five- and 10-year periods are also the warmest on record.

In other words, the trend of ocean warming is strong and unambiguous.

Abraham sent me a summary of the paper that includes a pretty sobering measure of how much energy is going into the Earth’s oceans. The amount of heat accumulating in Earth’s oceans is equivalent to five to six Hiroshima atom bombs of energy per second, 24 hours a day, every day of the year.

So, what did the data tell us? First, 2019 was the hottest year ever in the world’s oceans. And while each year, people eagerly await the Earth’s air temperature, it turns out the oceans are far more important.

What the oceans are telling us is bad news. Shown below are the 2019 results compared with prior years. Ocean heat is provided back to the late 1950s. While scientists measure heat in a unit called a Joule; the amount of heat in the oceans is so large, we report it in zeta Joules. What is a zeta Joule? It is 1,000,000,000,000,000,000,000 Joules.

That is a number that is hard to fathom. To put this in perspective, the amount of heat we are putting into the oceans is equivalent to 5-6 Hiroshima atom bombs of energy per second, 24 hours a day, every day of the year!

NOAA buoy
A National Oceanic and Atmospheric Administration monitoring buoy in Chesapeake Bay.

Oceans are an excellent thermal sink for the Earth’s climate system. Climate scientists know that oceans are absorbing more than 90 percent of Earth’s warming effect due to greenhouse gas-induced climate change.

That’s helped limit the atmospheric warming to around 1 degree Celsius so far. But the ability of Earth’s oceans to temper the atmospheric heat rise will eventually decrease.

And we know the interaction between warmer oceans and the atmosphere drives stronger and wetter storms like Hurricane Harvey.

We’ve seen an unprecedented rapid intensification of hurricanes in the past decade over Earth’s hotter, supercharged oceans. And warmer and more acidic oceans are bleaching and killing vast swaths of coral reefs worldwide. These reefs are critical habitats and food sources for Earth’s marine life and food chain.

Coral bleaching
A bleached coral reef.

This study of Earth’s warming oceans provides a more complete assessment of how the human-generated increase in greenhouse gases is impacting the planet’s overall climate system.