A new study finds that warming has come to influence the formation of El Niño.
During El Niño, warm waters pool in the eastern Pacific and radiate heat into the air, leading to hotter weather across much of the globe. A strong El Niño is now taking shape and, according to NOAA, there is a 99 percent chance that 2023 will be the hottest year ever recorded.
The new study shows that, historically, there was a strong link between changes in solar output and the onset of El Niño, but now El Niño is more heavily influenced by human-caused warming.
For the research, scientists analyzed stalagmites collected from two caves on Alaska’s Prince of Wales Island. The stalagmites, formed by the slow, but varied drip of groundwater, serve as a record of the climate over the past 3,500 years, and indicate when El Niños took place.
The research, published in Geophysical Research Letters, shows that until around 50 years ago changes in solar output played a major role in the formation of El Niños. “From the 1970s onwards, however, we see clear signals that can only be attributed to the consequences of man-made climate change,” lead author Paul Wilcox, of the University of Innsbruck, said in a statement.
Recent research shows that warming has led to more frequent and extreme El Niños. The new study, said Wilcox, reveals that “climate change may have led to a climatic tipping point being crossed in the 1970s with the initiation of a more permanent El Niño pattern.”