The world’s oceans have been warmer since mid-March than they have been since at least 1982, which has some climate experts worried about faster warming.
Why it matters: Since hotter oceans can cause more frequent and severe extreme weather and climate events, from floods to heat waves, they have major implications for land areas.
•Additionally, the temperature increase might indicate that warming is accelerating in ways that climate models did not predict.
Zoom in: The global average sea surface temperature record is significant and far-reaching, but according to climate scientists, it shouldn’t cause us to lose sight of the wider picture.
• A network of ships, buoys, and satellites recorded a rise in sea surface temperature, which is most likely the result of two trends: an impending El Niño in the tropical Pacific, and another trend that scientists are much more concerned about.
• According to Michael Mann, a climate scientist at the University of Pennsylvania, a lot of ocean heat that had been hiding beneath the ocean surface gets pushed higher when a La Niña event gives way to an El Niño, as is happening right now.
• “A sizable increase” in the tropical Pacific and worldwide ocean surface temperatures is the outcome, according to Mann, who wrote to Axios in an email.
• According to Mann, “La Niña bury some ocean heat beneath the surface and El Niño brings that heat back to the surface.”
Context: Above average ocean temperatures in the equatorial tropical Pacific, along with numerous changes in weather patterns, are what define El Niño events.
• These cyclical patterns in the water and atmosphere are natural occurrences that assist in temporarily accelerating or, in the case of La Niña, slackening the pace of climate change.
• This contributes to the long-term surface temperature record’s staircase-like appearance as opposed to a straight line.
Threat level: Climate experts are more concerned about the constant and record-breaking accumulation of ocean heat throughout the water column than they are about the recent increase in sea surface temperature.
• This is a clearer indication of human-caused global warming than the continuous record sea surface temperatures, according to scientists like Mann and Kevin Trenberth of the National Center for Atmospheric Research (NCAR), who spoke to Axios.
• Due to greenhouse gas emissions from burning fossil fuels and other factors, the seas are responsible for absorbing more than 90% of the extra heat from the Earth’s atmosphere.
• According to a recent study, ocean heat content reached a record high in 2022 and is already affecting crucial ocean currents that transport heat and nutrients throughout the world. Ocean heat content is measured in a column of water that extends from the surface down to 2,000 meters (6,561 feet) deep.
The intrigue: The increase in ocean surface temperature also reflects an increase in world average surface temperatures on land and sea since the last significant El Niño in 2016.
• Thus, it will be simpler to break records because the 2023 El Niño will increase global average temperatures from a higher base.
• This is comparable to a basketball player playing on a court with a floor that gradually gets higher, making it simpler to dunk the ball.
• This may be the reason why ocean temperatures in 2023 have already surpassed those of 2016, and why this pattern may continue for the duration of the expected El Niño.
What they’re saying: Axios was contacted by Kim Cobb, a climate scientist at Brown University, who stated via email that the year 2023 “is off to an alarming start, even before El Niño conditions fully develop later this year.” She pointed out that a new world temperature record is likely to result from even a moderate El Niño.
• However, given the rate of warming, even a new record will probably be surpassed in a few years. Even a powerful natural cycle like the El Niño-Southern Oscillation is starting to get buried in the noise since the planet is warming so quickly right now, according to Cobb.
What we’re watching: How the anticipated El Niño, which is expected to develop between the summer and fall and perhaps become a strong event, changes over time as it affects global average surface temperatures.