Intensification of the Atlantic Multidecadal Variability Since 1870: Implications and Possible Causes.

The Atlantic multidecadal variability (AMV) acts as a key source of multidecadal variability and plays an important role in climate change in many regions of the Northern Hemisphere, resulting in great social and economic impacts. This paper shows that, since the late 19th century, the AMV has experienced a significant increasing trend. The AMV intensified at a rate of 0.0040°C per decade from 1870 to 2014, which is statistically significant at the 95% confidence level. The AMV teleconnects the amplified signal from the North Atlantic across the Eurasian continent to North America through a circumglobal teleconnection pattern, which further intensifies the regional climate variability and climate extremes in North Africa, Europe, East Asia, and North America. Results from the single‐forcing and all‐but‐one‐forcing experiments of the Community Earth System Model, version 1, indicate that anthropogenic aerosol emissions have played a more important role in the AMV intensification compared to other external forcings, especially during the period from the 1900s to 1990s. Key Points: The AMV has experienced a significant increasing trendThe intensified AMV has amplified the regional climate variability and climate extremes in the Northern HemisphereAnthropogenic aerosol emissions have played an important role in the AMV intensification [ABSTRACT FROM AUTHOR]