"An Out-of-Bounds Anomaly"
Unprecedented ocean heat, the approach of La Niña, and 2024's hurricane season
Visualization made by Mary Kolbas and Tammy Zhang
May 16, 2024
What's causing record ocean temperatures?
There's a number of different factors that scientists have speculated are driving these warmer waters—including El Niño (a recurring climate pattern often associated with warmer conditions in many regions), new international laws reducing shipping pollution inadvertently causing less sunlight to be blocked from the Earth, and the 2022 Tonga volcano eruption adding tens of millions of tons of water vapor into the atmosphere.
However, experts agree that the primary factor remains climate change, with the oceans being estimated to have absorbed about 90% of human-driven warming in the last 150 years. Dr. Zeke Hausfather, a climate scientist at Berkeley Earth, expressed: "The level of warmth we are seeing today is only possible because of the warming over the past 150 years due to human activity."
Another factor contributing to hurricanes this year: La Niña.
La Niña refers to the periodic cooling of ocean surface temperatures in the central and east-central equatorial Pacific. This cooling weakens vertical wind shear and trade winds in the Atlantic, where tropical storms and hurricanes that hit the eastern United States develop. Weaker winds are less able to disrupt the structure and formation of developing storms, contributing to a greater number of storms in La Niña years compared to El Niño years.
Furthermore, Dr. Phil Klotzbach, a researcher at Colorado State University, stated that La Niña years tend to see an increase in hurricanes forming in the western side of the development zone, increasing the chances that a storm makes landfall and therefore increasing the risks to coastal areas.
La Niña and El Niño Intensity vs. Atlantic Basin Storm Frequency
Since June of last year, the Earth has been experiencing an El Niño event in which warmer Pacific ocean temperatures have created conditions that have helped surpress hurricanes. However, the National Oceanic and Atmospheric Administration (NOAA) has announced this past April that El Niño has weakened, with La Niña conditions having an almost 70% chance of occurring during 2024's Atlantic hurricane season (running from June 1 to November 30).
Looking ahead to 2024's approaching hurricane season, it's important to keep in mind that forecasts made this early in the year aren't always the most accurate. However, it's reasonable to expect that this season is more than likely to be one of the most active on record.
Dr. Gregory Johnson, an oceanographer at the National Oceanic and Atmospheric Administration, noted: "The ocean has been doing us a big service by delaying global warming considerably—but it comes at a cost."
- NOAA's Atlantic Storm Totals Dataset
- NOAA's Extended Reconstructed Sea Surface Temperature (ERSST) Dataset
- NOAA's Oceanic Niño Index (ONI) Dataset
- 'Alarming' Ocean Temperatures Suggest This Hurricane Season Will Be a Daunting One - The New York Times
- What This Year's 'Astonishing' Ocean Heat Means for the Planet - The New York Times