Ice Age clues foreshadow more extreme weather patterns

September 25 () –

The last ice age peaked about 20,000 years ago and was marked by extensive glaciation and dramatic climate changes. that transformed oceans, landscapes and ecosystems.

A new study led by the University of Arizona suggests that Earth’s last ice age may provide crucial information about future El Niño weather events. El Niño is one of the most influential weather patterns affecting global climate.

The study, published in ‘Nature’combines data from ancient shells of marine organisms with advanced climate models to shed light on how El Niño patterns might change in a warming world. El Niño is a climate phenomenon characterized by irregular but periodic warming of sea surface temperatures in the central and eastern Pacific Ocean. This causes disruptions in global weather patterns and triggers extreme events such as droughts, floods and heat waves.

“El Niño is a formidable force of nature: it induces droughts, floods and forest fires, altering marine and terrestrial ecosystems across the planet, with widespread social impacts across numerous sectors, from agriculture to the aviation industry,” says Kaustubh Thirumalai, co-lead author of the study and an assistant professor in the Department of Geosciences at the University of Arizona.

El Niño events occur approximately every two to seven years, and anticipating how these events might change in the future is a major challenge for climate scientists. “There are several state-of-the-art climate models that suggest different responses of El Niño to current and future human-caused warming,” Thirumalai says. “Some say El Niño variations will increase, others say they will decrease—it’s a complex, multifaceted phenomenon. So, Addressing what might happen with El Niño is a key priority for climate science“.

To address this uncertainty, the research team, which included collaborators from the University of Alberta in Canada, the University of Colorado at Boulder, the University of Texas, Middlebury College and Woods Hole Oceanographic Institution (all in the United States), looked back in time. They focused on the Last Glacial Maximum, a period about 20,000 years ago when ice sheets covered much of North America and Europe.

The researchers used the Community Earth System Model, developed to simulate the Earth’s climate system and predict future climate scenarios, to simulate climate conditions from the Last Glacial Maximum to the presentThis model is a collaborative project led primarily by the National Center for Atmospheric Research, with contributions from numerous institutions. The modeling portion of the study was conducted by co-lead author Pedro DiNezo at the University of Colorado at Boulder.

To validate this model, Thirumalai and his team compared the model results to data from the remains of tiny marine organisms called foraminifera, which are found in ocean samples taken from the seafloor and containing layers of sediment deposited over thousands to millions of years. “These beautiful microscopic creatures, floating in the upper layer of the ocean, They build shells that set the temperature of the ocean when they were alive“, Thirumalai says.

As foraminifera grow, they secrete shells from materials in the surrounding seawater. The chemical composition of these shells changes depending on the temperature of the water, which allows us to preserve a snapshot of the ocean conditions at the time the shell was formed..

When foraminifera die after a few weeks of life, their shells sink to the bottom of the ocean and become part of the sediment. By analyzing shells from different sediment layers, Scientists can reconstruct ocean temperatures from thousands of years ago and compare them to model simulations of past climatesThe team analyzed individual foraminifera shells, allowing them to capture seasonal temperature variations that would otherwise be impossible to detect.

The study concluded that El Niño variability was significantly lower during the Last Glacial Maximum compared to today, and that extreme El Niño events in the future could become more frequent as the planet warms. This could lead to more intense and frequent climate disruptions around the world. Importantly, these findings suggest a common mechanism for extreme El Niño variations under both Ice Age and future conditions, allowing researchers to validate the climate model prediction.

“This gives us more confidence in the model’s projections for the future,” Thirumalai said. “If it can accurately simulate past climate changes, it is more likely to give us reliable predictions about future changes in the El Niño system.”