Why are our winters getting colder if the world is warming up? In fact, since the 2000s, extreme weather events have occurred often in East Asia and North America, defying average estimates of climate change. Although a weakened jet stream and Arctic warming have been attributed by many experts to the decline in Arctic sea ice, climate model experiments have not sufficiently supported these theories. An unprecedented cold snap in February 2021 triggered a huge power outage in Texas; in order to prevent massive socioeconomic damage, climate models are necessary to precisely predict the likelihood of catastrophic weather events. Leaders in climate technology have recently made it a priority to be able to anticipate the climate for the next ten or more years.
The Center for Irreversible Climate Change at Yonsei University (President Seung-hwan Seo) and senior researcher Mi-Kyung Sung of the Sustainable Environment Research Center jointly discovered the role of mid-latitude oceans as a source of anomalous waves, which are particularly frequent in East Asia and North America, opening the door for a mid- to long-term response to winter climate change, according to a statement released by the Korea Institute of Science and Technology (KIST).
Because ocean currents carry thermal energy in addition to suspended and dissolved particles, they have a significant influence on the weather and climate of nearby nations. The KIST-Yonsei joint research team specifically refers to areas that experience rapid temperature changes in a narrow latitudinal band as “ocean fronts,” such as the Gulf Stream in the Atlantic Ocean and the downstream region of the Kuroshio Current in the Pacific Ocean. They believe that the increase in extreme cold waves is primarily due to the atmospheric wave response to the excessive accumulation of heat in these ocean fronts. From the early 2000s until recently, the abnormal cold trend in North America coincided with the intensification of heat accumulation near the Kuroshio Current, and in East Asia with the buildup of heat near the Gulf Stream in the North Atlantic. The frequency of winter cold waves and unusually high temperatures is regulated by the oceanic frontal area, which functions as a thermostat.
In oceanic frontal zones, the process of heat accumulation might take years or even decades. In the continental areas that defy the global warming trend, a warming hiatus may happen during this time. On the other hand, continental regions seem to undergo a dramatic acceleration of warming during decades of ocean frontal cold. This implies that the recent trend of decadal cooling is basically supported by transient natural variability in the global climate system and that as the buildup of heat in the oceanfront is released, we can anticipate an increase in the frequency of unusually warm winter weather.
Contrary to conventional sea ice theory, these effects are also shown in climate model experiments that alter the amount of heat accumulation at ocean fronts. This indicates that the conclusions drawn from both climate model experiments and observations are consistent. This demonstrates how crucial it is to effectively simulate oceanfront variability in climate models in order to enhance our capacity to forecast medium- and long-term changes in climate over the ensuing ten years.
These regional temperature variances could alter significantly as future global warming accelerates and modifies the ocean’s structure. Experiments using climate models with higher levels of greenhouse gases have indicated that North America is likely to see fewer and shorter warming hiatuses, while East Asia is likely to see more intersections between acceleration and warming hiatuses. The Kuroshio Current and Gulf Stream’s varying oceanic reactions to global warming are what cause these disparate continental responses.
“Applying the effects of ocean fronts revealed in this research to global warming climate models can improve climate change forecasts for the near future,” stated Dr. Mi-Kyung Sung of KIST. “It will provide important references for long-term forecasts of winter energy demand and the construction of climate change response infrastructure to prevent climate disasters such as the 2021 Texas power outage.”