Global temperatures in 2023 have soared to unexpected heights, causing concern among climatologists. With an increase of almost 0.3°C compared to the previous year, the dramatic increase initially puzzled experts. James Hansen, a renowned climatologist, suggested that this could mark the beginning of a new phase of global warming, accelerated by a reduction in air pollution. The director of NASA’s Goddard Institute for Space Studies, Gavin Schmidt, suggested that this unusual increase could reveal gaps in our understanding of climate feedback mechanisms.

El Niño as a key contributor

However, recent studies indicate that changing conditions in the tropical Pacific Ocean, including the transition from La Niña to a strong El Niño, may hold the key to explaining these anomalies. El Niño has long been known for its ability to disrupt global climate patterns. During La Niña events, trade winds push warm water toward Indonesia, allowing cooler deep water to rise to the surface in the eastern Pacific, lowering global temperatures.

In contrast, El Niño pushes warmer water back eastward, effectively turning off the ocean’s “air conditioner.” Studies led by Shiv Priyam Raghuraman of the University of Illinois Urbana-Champaign suggest that the end of a long-lasting La Niña, combined with the onset of a strong El Niño, is responsible for the 2023 temperature rise.

A rare but possible phenomenon

The team analyzed 58,021 years of climate model simulations to understand how often such jumps occur. They found that large temperature increases following El Niño are rare, occurring only 1.6 percent of the time. However, when it is preceded by a long La Niña, the probability of such a jump increases to 10.3 percent.

Their findings are consistent with another study, co-authored by Marianne Tronstad Lund of the Norwegian Center for International Climate and Environmental Research, which noted that global oceans, while warmer in 2023, were not significantly warmer than during past El Niño events.

The ongoing climate debate

While El Niño is seen as the main driver of record heat in 2023, scientists like Schmidt remain cautious. The rate and duration of warming has surpassed typical El Niño patterns, with prolonged warmth as the Earth moves toward another La Niña.

Additionally, the increase in sunlight detected by satellites, potentially due to reduced cloud cover or surface reflectance, raises further questions. For now, El Niño appears to be the most likely culprit, but the broader climate debate continues.