Last year was the second hottest year on record globally, but for the world's oceans, 2019 was even more punishing: It was, by a sizable margin, the hottest year ever recorded for oceanic environments, with a dramatic increase of underwater temperatures suggesting that the devastation wrought by coral bleaching and tropical storms will only continue if humanity's carbon footprint remains at current levels.

The scale of oceanic warming was put in plainly apocalyptic terms by a study published Monday in the journal Advances in Atmospheric Sciences. According to the findings of 14 international researchers who authored the study, the global oceanic temperature is rising on parallel terms with the heat produced by dropping and detonating five atomic bombs—each on par with the nuclear weapon dropped on Hiroshima, Japan in WWII—into the ocean every second for 25 years.

That might sounds alarmist, but the metaphor was elucidated simply by the study's lead author, Lijing Cheng, an associate professor at the International Center for Climate and Environmental Sciences at the Chinese Academy of Sciences.

Cheng told CNN:

The Hiroshima atom-bomb exploded with an energy of about 63,000,000,000,000 Joules. I did a calculation ... the amount of heat we have put in the world's oceans in the past 25 years equals to 3.6 billion Hiroshima atom-bomb explosions.

The study was conducted when researchers examined ocean temperature data collected from up to 2,000 meters below the surface, dating as far back as the 1950s. Though 2019 was the most stifling year for the world's oceans, researchers say this is part of a longer, frightening trend that's continued unabated for a decade. While the last ten years are the hottest decade ever recorded for oceanic temperatures, the last five years are hottest five consecutive years in the history of the world's oceans.

The rising oceanic temperature provides further irrefutable evidence of climate change hastened by human activity, according to John Abraham, an author of the study and a professor of mechanical engineering at the University of St. Thomas in Minnesota. "If you want to understand global warming, you have to measure ocean warming," he told CNN. "Using the oceans, we see a continued, uninterrupted and accelerating warming rate of planet Earth. This is dire news.”

While much of global warming is reflected in arid conditions, drought, famine and the devastating wildfires currently ravaging Australia, the effects are even more drastic at sea. The ocean absorbs the majority of heat trapped in the atmosphere,, threatening marine ecosystems and exacerbating the severity of hurricanes and tropical storms.

The only recourse, scientists urge, is to curtail carbon emissions at a rapid clip. However, even if the world's biggest polluters are to keep warming below 2 degrees Celsius in accordance with the Paris Climate Accords, it's unlikely that it will stave off a future of disastrous weather events across the globe, scientists say. The United States, for its part, has already started pulling out of the global climate agreement.