Record-Strength El Niño and Climate Change: Scientists Probe the Link
A very strong El Niño is developing in the tropical Pacific and is forecast to be the strongest on record. Researchers say climate change is likely influencing it, but the relationship is still being studied.
Heat has been building in the eastern tropical Pacific for months as an exceptionally strong, or “super,” El Niño takes shape. The climate phenomenon, which recurs every few years, is marked by unusually warm ocean water and affects weather around the world. This year's event has already set several daily records and is forecast to reach unprecedented strength this winter. Scientists are now examining how human-driven climate change, caused by burning fossil fuels, interacts with it.
Forecasts and records
The US National Oceanic and Atmospheric Administration (NOAA) puts the odds of an extremely strong El Niño through December at 100 percent, and above 80 percent that it persists through February. The data show this event has already set multiple all-time daily heat records, including a recent peak of 3.4 degrees Celsius. NOAA issues its forecast as a three-month rolling average, and expects a peak of 2.7 degrees above normal for October to December, though exceeding 3 degrees is not ruled out. If that holds, it would break the record of 2.4 degrees set in the 1982–1983 event.
How climate change affects El Niño
Francisco Estrada, coordinator of the Climate Change Research Program at the National Autonomous University of Mexico, says the phenomenon's magnitude and frequency have grown over the past 60 years, as have its variability and the spread of its effects worldwide. In his view, the question should not be framed as a “natural” versus climate-driven El Niño, but as an interaction between the two processes.
Christopher Callahan, a climate researcher at Indiana University, notes that most models project stronger El Niño amplitude in a warming climate, although many struggle to represent long-term temperature trends in the eastern tropical Pacific. A study published in August using ancient coral data found a rise in El Niño amplitude that coincides with the start of human greenhouse gas emissions, though its authors did not attribute the shift to climate change.
Consequences for society
Callahan says that even if the event itself were not strengthened, it could have unprecedented impacts in a climate already altered by warming. El Niño is known to raise the odds of drought in the Amazon and Indonesia, boost precipitation in the southwestern US and lower the odds of Atlantic hurricanes. Estrada warns that knowledge of these links may become less reliable. Callahan's work indicates that the most severe events can cost the global economy trillions of dollars, and coral reefs are facing mass bleaching. The United Nations and other organizations have urged urgent adaptation measures, and California declared a state of emergency last month.
