Climate change is strengthening El Niño, corals reveal
El Niño has intensified by almost 36 per cent fossil corals have revealed, providing the strongest evidence that global warming is strengthening the climate pattern.
Scientists analysed a 1,000-year archive preserved in fossil corals from the Galápagos archipelago to conclude that El Niño has intensified over the past four decades, when compared to 1850.
“We don’t see a time in the past where El Niños have been as strong as today, and we show that the strength of El Niño changes in parallel with warming global temperatures,” said lead author Julia Cole, professor and chair of the University of Michigan Department of Earth and Environmental Sciences in a press statement. “Our findings tell us that the big El Niño events of the last 40 years are not normal in the context of the last thousand years,” she added.
The study does not directly attribute the strengthening of El Niño to climate change. Rather, it suggests that the intensification coincided with rapid post-industrial warming, exceeding the natural variability of El Niño and putting forward the planet’s human-induced warming as the most probable possibility.
Along with other coral results studied in other parts of the Pacific, the findings indicate “There’s something about this important source of climate extremes that has already changed in recent decades,” said Kim Cobb, a climate scientist at Brown University who was not part of the study, in a statement published in Science.
El Niño, a natural phenomenon that, that occurs every 2-7 years, causes the tropical Pacific Ocean to become warmer than usual. Under usual circumstances, trade winds blow along the equator from east to west, pushing warm water from South America toward Australia. When these trade winds weaken, warm water expands eastward towards South America, triggering an El Niño event.
This shift influences atmospheric circulation, causing heavy rainfall to move from Indonesia to the central Pacific, inducing droughts in the western Pacific. The shift weakens the trade winds further, enabling El Niño conditions to remain for 1-2 years. Despite the fluctuations in temperature and precipitation being limited to the tropical Pacific, its impact is felt across the world.
In the US, the deserts in the Southwest receive more rain as storm tracks shift southwards, while rainfall reduces in the Northwest.
Similar changes are seen around the world leading to less rainfall or droughts in countries such as India and flooding in other parts that lead to crop failure. Wildfires also affect millions of people.
Forecasters have warned of a Super El Niño this year that may become the strongest in almost a century.