The El Niño Southern Oscillation, characterized by irregular shifts between unusually warm (El Niño) and cold (La Niña) conditions, has existed for at least 250 million years and is often of increasing magnitude, according to a new report. It is said that it has grown bigger. Studying modeling.
The El Niño Southern Oscillation, which occurs in the central and eastern equatorial Pacific Ocean, is a characteristic mode of interannual climate change and has significant impacts on the Earth's climate and ecosystems. Image credit: Li others., doi: 10.1073/pnas.2404758121.
Climate scientists are studying the El Niño phenomenon. That's because El Niño, a huge patch of unusually warm water on either side of the equator in the eastern Pacific Ocean, alters the jet stream and can dry out the northwest United States and soak the southwest with extreme rain.
The corresponding cold mass, La Niña, could push the jet stream northward, drying out the southwestern United States while also causing drought in East Africa and making South Asia's monsoon season more intense.
“Each experiment confirms an active El Niño Southern Oscillation (ENSO), most of which are stronger than the current one, some of which are somewhat stronger, and some of which are slightly stronger,” said Dr. Shinen Hu of Duke University.
Hu and his colleagues used the same climate modeling tools used by the Intergovernmental Panel on Climate Change (IPCC) to project climate change into the future, except they looked back in time.
This simulation is so computationally intensive that researchers were unable to model it continuously every year for 250 million years. Instead, they made 10 million year “slices” – 26 of them.
“The model experiments were affected by various boundary conditions, including differences in land-sea distribution (on different continents), differences in solar radiation, and differences in carbon dioxide,” Dr. Hu said.
Each simulation was run over thousands of model years for robust results and took several months to complete.
“At times in the past, the amount of solar radiation reaching Earth was about 2% lower than it is today, but global warming carbon dioxide was much more abundant, and the atmosphere and oceans were much more dense than they are today. It was very warm,” Dr. Hu said.
During the Mesozoic Era, 250 million years ago, South America was located in the middle of the supercontinent Pangea, and an oscillation occurred in the Panthalas Ocean to its west.
Current research shows that historically the two most important variables in ENSO magnitude appear to be the ocean's thermal structure and the “atmospheric noise” of ocean surface winds.
“Previous studies have mainly focused on ocean temperatures, but this study has paid less attention to surface winds, which appear to be very important,” Dr. Hu said.
“So part of the point of our research is that in addition to the thermal structure of the ocean, we also need to pay attention to atmospheric noise and understand how those winds change. .”
“Atmospheric noise, or wind, can act to give this pendulum a random kick.”
“We find that both factors are important in understanding why El Niño was much stronger than it is now.”
“If we want to make more reliable predictions of the future, we first need to understand the past climate.”
of study Published in this week's Proceedings of the National Academy of Sciences.
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Shan Li others. 2024. El Niño Southern Oscillation has been active continuously since the Mesozoic era. PNAS 121 (45): e2404758121;doi: 10.1073/pnas.2404758121
Source: www.sci.news
