POHANG UNIVERSITY OF SCIENCE & TECHNOLOGY (POSTECH)
While the worldwide focus is on achieving carbon neutrality – zero carbon dioxide (CO2) emissions – a new study finds climate change in some regions is inevitable even if CO has increased2 level is reduced. Like CO2 decreases, the Intertropical Convergence Zone (ITCZ) shifts southward, possibly causing persistent El Niño conditions. El Niño refers to an increase in sea surface temperature near the equator by 1 to 3°C above ambient, causing droughts, storms, and floods around the world.
A POSTECH research team led by Professors Jong-Seong Kug and Ji-Hoon Oh (Department of Environmental Science and Engineering) conducted a simulation on a model of the Earth system that can increase and decrease CO concentrations in the atmosphere.2. The researchers observed that the ITCZ, barely moved when CO2 concentration increases, shifts sharply south when CO2 level is reduced. Even if CO2 The concentration is returned to its original level, its center still in the Southern Hemisphere.
The variability of the ITCZ, where 32% of global precipitation occurs, is an extremely important factor in determining precipitation in the tropics and subtropics. The shift could alter the Hadley circulation – the starting point of the global atmospheric circulation – causing anomalies in global climate. Through this study, Professor Kug’s team confirmed that CO2 starts to decrease, the ITCZ moving to the Southern Hemisphere remains warm, unlike the Northern Hemisphere which cools down with CO2 palliation.
Atmospheric CO2 The decline could slowly bring average global temperatures and precipitation back to normal. However, the researchers assert that the climate may appear completely different in some regions. The precipitation change due to the southward shift of the ITCZ is very similar to the pattern during the extreme El Niño. In other words, it is expected that some areas will experience unusual climate conditions where extreme El Niño persists.
Model simulations confirmed that even with an increase in CO2 reduced concentration and returned to baseline values, the Sahel zone including the Sahara and southern Europe around the Mediterranean Sea has reduced its average annual rainfall by 20% from current levels, leading to further desertification. customary. In contrast, North and South America experienced an increase of about 15% in rainfall. In fact, the risk of more frequent flooding has been found in the western regions of North and South America, where rainfall has increased noticeably. In East Asia, including the Korean Peninsula, more rain is likely during the monsoon season due to increased rainfall in summer.
Professor Jong-Seong Kug explains: “It is not possible to properly reflect the complex climate system if only considering global average temperature and precipitation when formulating mitigation policies to prevent climate change, such as carbon neutralization or carbon reduction”. Emphasizing that regional changes such as the southward shift of the KCNC should be fully taken into account, Professor Kug added, “Emissions of greenhouse gases have a lasting effect on the planet, therefore We need to recognize their long-term as well as immediate impacts. affect climate change. ”
Recently published in natural climate change, This study was carried out with the support of the Irreversible Climate Change Research Center funded by the National Research Foundation of Korea.
JOURNEYS
Natural climate change
ARTICLE TITLE
Latency of the mid-tropical to forced CO2 convergence zone
ARTICLE PUBLICATION DATE
December 9, 2021
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