El Niño is a well-known natural phenomenon that involves elevated sea surface temperatures in the tropical Eastern Pacific. Its effect on global weather patterns has raised concerns, particularly regarding extreme El Niño events with heavy rainfall. Conventional wisdom suggests that the rising concentration of greenhouse gases will lead to more frequent extreme El Niño events. However, researchers at Pohang University of Science and Technology (POSTECH) have recently challenged this belief. Their surprising findings indicate that a decrease in atmospheric carbon dioxide could potentially amplify the frequency and intensity of extreme El Niño events. This unexpected discovery underscores the need for a more nuanced approach to climate change mitigation strategies.
Led by Professor Jong-Seong Kug and Gayan Pathirana, the research team at POSTECH conducted simulations using the Community Earth System Model to explore the impact of carbon dioxide levels on extreme El Niño events. Their findings, published in the journal Science Advances, revealed that even with a reduction in carbon dioxide levels, there was no elimination of extreme El Niño events. In stark contrast to common assumptions, lowering carbon dioxide levels did not prevent the occurrence of these events.
The shifting of the intertropical convergence zone, a region sensitive to sea temperature changes, towards the south plays a crucial role in the development of extreme El Niño events. This shift results in increased rainfall in the tropical Eastern Pacific, which contributes to the occurrence of these events. Consequently, even with efforts to reduce carbon emissions, such as the implementation of carbon neutrality policies, extreme El Niño events may still be unavoidable due to the high concentration of carbon dioxide already present in the atmosphere.
Moreover, the simulations conducted by the research team pointed to potential climate regime shifts in regions affected by extreme El Niño events. Areas like tropical South America, Northwestern Australia, and South Asia may experience desertification due to decreased average rainfall. Conversely, extratropical Northern and Southern America, East Asia, and tropical Africa could see an increase in rainfall. To worsen matters, regions already witnessing increased rainfall, such as tropical Africa, North America, and western South America, might face a higher risk of frequent flooding. This new research unveils the ability of extreme El Niño events to not only impact immediate weather conditions but also generate long-term climate effects in various regions.
The Call for Comprehensive Climate Policies
Highlighting the significance of considering more than just global average temperature and precipitation, Professor Kug emphasizes the complexity of the climate system and the necessity of factoring in phenomena like the intensification of extreme El Niño events when formulating climate policies. With the lingering impact of greenhouse gases already present in the atmosphere, evaluating the long-term effects and predicting the societal costs of climate change become essential priorities.
The study conducted by the research team at POSTECH challenges conventional wisdom surrounding the relationship between carbon dioxide levels and extreme El Niño events. The counterintuitive finding that decreased atmospheric carbon dioxide may actually exacerbate the occurrence of these events underscores the need for a more nuanced approach to climate change mitigation strategies. As policymakers and researchers delve deeper into the complexities of the climate system, it becomes increasingly clear that a comprehensive understanding of phenomena like extreme El Niño and their potential long-term consequences is essential for effective climate action.
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