The accumulated heat in the oceans grows at a record level for the sixth year

The oceans are warmer than ever and continue their streak of record temperatures for the sixth year in a row, according to a study with data from 2021 published in Advances in Atmospheric Sciences.

The report, written by 23 researchers from 14 institutes, summarizes two international data sets: from the Institute of Atmospheric Physics (IAP) of the Chinese Academy of Sciences (CAS) and the National Centers for Environmental Information of the National Oceanic Administration and Atmospheric (NOAA) of the United States, which analyze observations of the heat contained in the ocean and its impact dating from the 1950s. “The heat content of the ocean is increasing relentlessly globally, and this is a leading indicator of the human-induced climate change, “article author Kevin Trenberth, a distinguished scholar at the US National Center for Atmospheric Research (NCAR), said in a statement. “In this most recent report, we update ocean observations to 2021, while reviewing and reprocessing previous data.”

Over the past year, researchers found that the upper 2,000 meters in all oceans absorbed 14 zettajoules more than in 2020, which is equivalent to 145 times the world’s electricity generation in 2020. By context, all the energy humans use in the whole world in a single year is about half a zettajoule.

“In addition to absorbing heat, the ocean currently absorbs 20 to 30% of human carbon dioxide emissions, leading to ocean acidification; however, warming of the oceans reduces the efficiency of carbon absorption oceanic and leaves more carbon dioxide in the air, “said Lijing Cheng, lead author of the paper and associate professor at the International Center for Climate and Environmental Sciences at IAP-CAS. “Monitoring and understanding the heat and carbon mix going forward is important to track climate change mitigation goals.” The researchers also evaluated the role of various natural variations, such as the warming and cooling phases known as El Niño and La Niña, which greatly affect regional temperature changes. According to Cheng, regional analyzes show that strong and significant ocean warming since the late 1950s occurs everywhere. However, regional marine heat waves are a consequence, with huge impacts on marine life.

“Our previous work showed that it takes scientists less than 4 years of ocean heat measurements to detect a human-induced warming signal from natural variations. This is much shorter than the nearly three decades of measurements needed to detect the global warming using air temperatures near the Earth’s surface. In fact, although in the 10 warmest years, global surface temperatures for 2021 are not the highest on record due to La Niña conditions in the tropical Pacific, among other things. The heat content of the ocean is one of the best indicators of climate change. ” said John Abraham, a professor at the University of St. Thomas. During La Niña, the ocean actually absorbs but submerges the additional heat below the surface.

“With model experiments, our study shows that the warming pattern of the oceans is the result of human-related changes in atmospheric composition.” Cheng said.

“As oceans warm, water expands and sea levels rise. Warmer oceans also put stress on weather systems, creating more powerful storms and hurricanes, as well as increasing rainfall and flood risk. “

“The oceans are absorbing most of the heat from human carbon emissions,” said article author Michael Mann, Distinguished Professor of Atmospheric Sciences at Pennsylvania State University. “Until we reach net zero emissions, that warming will continue and we will continue to break records for ocean heat content, as we did this year. Better awareness and understanding of the oceans are the foundation for action to combat climate change.”