To the vexation of school children and elation for their parents, residents living along the I-95 corridor of the northeastern United States know that El Niño in the Pacific will result in a dryer, warmer, and less snowy winter throughout the Appalachian, as certain as the adage 'April showers bring May flowers.' Such meteorological patterns where interannual variability in ocean temperatures affects climate have been long established in the field.

Global warming caused by anthropogenic forcings and natural feedback processes have likewise affected climates and ecosystems throughout the world. For example, scientists have shown a connection between the rapid warming of the Arctic region to the increase in terrestrial gross primary productivity (vegetation growth) in high latitudes. Paradoxically, however, areas along the mid latitude have experienced anomalous climates, ranging from harsh and cold winters throughout the northern North America and severe droughts in its southern states.

Research conducted by Jin-Soo Kim and Professor Jong-Seong Kug from the Division of Environmental Science and Engineering at Pohang University of Science and Technology (POSTECH), in collaboration with Professor Su-Jong Jeong from the School of Environmental Science and Engineering at South University of Science and Technology of China, has shown that the warmer Arctic has triggered cooler winters and springs in North America, which has in turn weakened vegetation growth and lowered carbon uptake capacity in its ecosystems. This achievement has been published in the journal Nature Geoscience.

The team analyzed an index of sea surface temperatures from the Bering Sea and found that in years with higher than average Arctic temperatures, changes in atmospheric circulation resulted in the aforementioned anomalous climates throughout North America. In those years of intense cold and low precipitation, the team found that the unfavorable conditions adversely affected vegetation growth -- including crop yields -- which in turn decreased carbon uptake capacity by about 14%. In other words, although Arctic warming has increased carbon uptake in the Northern Hemisphere, this research has shown that the resulting interannual variability in Arctic temperatures can affect regions further away in North America and may counteract the initially observed increases in carbon uptake.

Professor Kug notes that further research is needed to obtain a general conclusion on the matter, but this research delivers important implications for climate adaptation because the analysis shows that if current warming trends continue, it is feasible to conclude that the ecosystems in regions affected by the anomalous climate will suffer greater damages due to the cold and dry spells.