Record-breaking temperatures likely as El Niño persists
The current El Niño event will likely cause record-breaking average surface air temperatures in several parts of the world before waning this summer, according to a new analysis published in Scientific Reports.
“Knowing that these are regions of potential risk sometime this year is a leg up on preparing how you plan to protect lives, property, and living marine resources.”
Researchers say there is a 90% chance that global mean surface temperatures from July 2023 to June 2024 will be the highest ever recorded. Parts of Southeast Asia, Alaska, the Caribbean Sea, and the Amazon will be especially likely to see the effect.
“Knowing that these are regions of potential risk sometime this year is a leg up on preparing how you plan to protect lives, property, and living marine resources,” said Michael McPhaden, a coauthor on the study and climate scientist at NOAA’s Pacific Marine Environmental Laboratory.
El Niño Persists
The El Niño–Southern Oscillation, or ENSO, refers to a climate pattern that determines how heat is stored in the world’s oceans. ENSO includes a warm phase (El Niño), in which weak easterly trade winds leave warm water off the west coast of the Americas, and a cool phase (La Niña), during which these winds are stronger, driving warm surface water westward and causing colder deep water to upwell. These phases change roughly every 2 to 7 years. During El Niño conditions, heat stored in the ocean is released to the atmosphere, which heats the air in the tropics and beyond. Earth has been experiencing El Niño conditions since June 2023, which scientists have already linked to record-breaking temperatures.
Using data on current ENSO conditions, atmospheric greenhouse gas concentrations, concentrations of aerosols, and existing temperature anomalies, researchers modeled the effects of the current El Niño on global average surface air temperatures. The model used data from ENSO’s current inception in June 2023 to its likely transition to a neutral state by July 2024.
The team estimated the strength of El Niño scenarios on the basis of predicted sea surface temperatures within an area of the central Pacific that’s particularly sensitive to ENSO fluctuations, called the Niño 3.4 region. In their projections, moderate El Niño conditions are defined as those with sea surface temperature deviations from 1°C to 1.5°C (1.8°F to 2.7°F) for a minimum of 3 months, and strong El Niño conditions refer to deviations greater than 1.5°C (2.7°F) for a minimum of 3 months.
Two maps of the world show the predicted temperatures under moderate and strong El Niño scenarios. Areas shaded in blue (the Bay of Bengal, the South China Sea, the Caribbean Sea, Alaska, and the Amazon) show regions with expected record-breaking heating. Researchers predicted surface air temperature variation from the 1951–1980 mean for 2024 under (a) moderate and (b) strong El Niño scenarios. Areas shaded in blue show regions with expected record-breaking heating in 2024. Credit: Jiang et al., 2024, https://doi.org/10.1038/s41598-024-52846-2, CC BY 4.0 The current El Niño is considered strong, as sea surface temperature increases have exceeded 1.5°C (2.7°F) since August. The event will likely be among the top five strongest ever recorded, said both McPhaden and Marybeth Arcodia, a climate scientist at Colorado State University who was not involved in the research. Researchers found that if current conditions continue, there is a 90% chance that global average surface air temperatures will continue to break historical records. The Bay of Bengal, Philippines, South China Sea, Caribbean Sea, Amazon, and Alaska are at particular risk.
Future Heat Hazards
Predictions such as those made in the new paper help give communities in affected areas time to prepare for heat-related hazards, Arcodia said. In Southeast Asia, for example, high temperatures could lead to a prolonged marine heat wave, negatively affecting marine ecosystems and leading to economic consequences for coastal communities, according to the authors.
Warming in Alaska, they write, could result in increased rates of glacial retreat, permafrost thaw, and coastal erosion, whereas higher temperatures in the Amazon would increase the likelihood of extreme weather, wildfires, and drought. Current El Niño conditions are exacerbating the rise in temperatures already happening as a result of human-caused climate change, McPhaden said.
“Even though global temperatures are rising because of greenhouse gases, you can get a big spike because there’s this extra boost from El Niño’s release of heat from the ocean to the atmosphere.”
“The next time El Niño comes along, we’re going to see even more extremes.”
Even though the current El Niño event is exceedingly strong and long-lasting, its effects are still temporary, he said: Scientists predict that ENSO conditions will shift toward La Niña by late summer 2024, which would likely lead to cooler global temperatures. But as the climate warms, future El Niños will likely continue to create record-breaking heat, McPhaden said.
“The escalator of climate change only goes up. The next time El Niño comes along, we’re going to see even more extremes.”