El Nino set to double: Studies show rising threat

Extreme weather events might become twice as frequent in the near future compared to now. This conclusion is drawn from studies of the shells of single-celled foraminifera that lived about 21,000 years ago during the last glacial period. The research indicates that current climate models are accurate, reinforcing concerns that El Nino events will become increasingly intense.

El Nino, also known as the El Nino-Southern Oscillation (ENSO), is a recurring climate pattern linked to water temperatures in the Pacific Ocean, especially in its central and eastern tropical parts. This phenomenon is strongly associated with elevated sea surface temperatures in the equatorial zone.

Warm ocean waters have low nutrient levels, directly leading to a decline in fish catches. Additionally, the weakening of trade winds stops the upwelling ocean current, which usually brings cold, nutrient-rich water from the ocean depths, replacing it with warmer surface waters. The term "El Nino" comes from the Spanish word for "child" and is connected to the Christmas period when this phenomenon intensifies. The opposite condition, La Nina, involves cooling ocean waters.

The research highlights El Nino's significant impact on global climate, as it contributes to an increase in average temperatures and results in more frequent extreme weather events worldwide. Current climate models suggest that global warming, driven by greenhouse gas emissions, leads to greater variability in the El Nino cycle and more frequent occurrences of this phenomenon.

However, a major challenge for climate researchers is that accurate observations of El Nino have only been conducted for a few decades, and the climate models are not perfect. This complicates efforts to determine the direct impact of global warming on El Nino. Professor Kaustubh Thirumalai from the University of Arizona and his collaborators sought to address this issue by developing a record of changes in El Nino from 21,000 years ago, a time when Earth's climate was significantly cooler. Their findings were published in a scientific paper.

Researchers obtained climate data by analyzing the chemical composition of foraminifera shells—microscopic organisms living near the sea surface. The temperature of seawater affects the chemical makeup of these organisms' shells, which, after death, settle on the ocean floor, forming layers of marine sediments. These sediments provide past climate data consistent with contemporary climate models' findings.

Confirmation of these models suggests an increased likelihood that El Nino events will occur much more frequently in the future, potentially leading to more frequent extreme weather conditions on Earth.

During the last glacial period, when the climate was cooler, El Nino occurred less frequently. Scientists propose that this phenomenon results from interactions between winds in the Pacific Ocean and the layer of warm water on its surface.

As global warming progresses, this layer becomes thinner, making it easier for winds and ocean currents to move warm water eastward and trigger intense El Nino events. Scientists expect that El Nino could occur once every ten years rather than once every two decades, as it did in the past.