Record ocean temperatures show that the seas are warming faster than expected, with significant impacts globally. Oceans absorb over 90% of the heat trapped by greenhouse gases, and since March 2023, daily global ocean surface temperatures have set new records. February 2024 saw a full year of 1.5℃ surface air temperature warming.
This unexpected warming is causing widespread damage. For example, in 2023, the water temperatures off the coast in Florida were warmer than a hot tub, resulting in massive coral bleaching. Other effects include deep sea de-oxygenation and increased rainfall.
Michael McPhaden of National Oceanic and Atmospheric Administration (NOAA) attributes the record heat to rising greenhouse gases and a major 2023 El Niño event. Other factors include the 2022 Tonga volcano eruption and a 2020 mandate reducing sulphur dioxide emissions from shipping, which has lessened heat-reflecting clouds.
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El Niño's Role:
- The 2023 El Niño event significantly contributed to ocean warming. El Niño is characterized by warmer-than-average surface waters in the tropical Pacific, which enhance evaporation and transfer vast amounts of heat to the atmosphere, amplifying global temperature increases.
- The 2023 El Niño event significantly contributed to ocean warming. El Niño is characterized by warmer-than-average surface waters in the tropical Pacific, which enhance evaporation and transfer vast amounts of heat to the atmosphere, amplifying global temperature increases.
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Deep-Sea De-Oxygenation:
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Deep-sea de-oxygenation refers to the reduction of oxygen levels in the deeper parts of the ocean. As surface waters warm, their capacity to hold dissolved oxygen decreases, and this warmer, less oxygen-rich water can spread to deeper layers. This de-oxygenation can disrupt marine ecosystems, affecting species that rely on certain oxygen levels for survival, and can alter nutrient cycles, impacting the overall health and productivity of the oceans.
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Volcanic Eruptions and Atmospheric Changes:
- The 2022 eruption of Tonga’s Hunga Tonga-Hunga Ha'apai volcano released unprecedented amounts of water vapor into the atmosphere. This additional water vapor has a greenhouse effect, trapping more heat and contributing to the overall warming of the planet.
- The 2022 eruption of Tonga’s Hunga Tonga-Hunga Ha'apai volcano released unprecedented amounts of water vapor into the atmosphere. This additional water vapor has a greenhouse effect, trapping more heat and contributing to the overall warming of the planet.
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Regulatory Changes in Shipping:
- In 2020, the International Maritime Organization mandated a switch to low-sulphur fuel sources for commercial tankers. This reduced sulphur dioxide emissions, which previously formed atmospheric sulphates that reflected sunlight and created cooling effects. The reduction of these cooling effects may have led to a slight increase in global warming.
- In 2020, the International Maritime Organization mandated a switch to low-sulphur fuel sources for commercial tankers. This reduced sulphur dioxide emissions, which previously formed atmospheric sulphates that reflected sunlight and created cooling effects. The reduction of these cooling effects may have led to a slight increase in global warming.
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Regional Warming Anomalies:
- Certain areas, such as the northern Atlantic, are experiencing extraordinary warmth beyond what can be explained by known factors. Researchers are investigating additional influences, including long-term ocean heating and cooling cycles, to understand these regional anomalies better. This ongoing research is crucial for improving climate predictions and understanding the full scope of oceanic and atmospheric interactions.