DATE2022-05-12 16:07:37
TITLENorthern Hemisphere subtropical expansion: time-of-emergence of forced signal versus internal variability and regional impacts
AUTHORSRoberta Dagostino (1,2) ,Ascanio Luigi Scambiati (3) ,Johann Jungclaus (1) ,Piero Lionello (3,4)
  1. 1) Max Planck Institute For Meteorology, Hamburg (Germany) ,2) University Of Trento, Trento (Italy) ,3) University Of Salento, Lecce (Italy) ,4) Euro Mediterranean Center On Climate Change, Lecce (Italy)
ABSTRACTThe Northern Hemisphere mid-latitudes will be exposed to hydroclimatic risk in next coming decades because the subtropical expansion. However, it is not clear when the anthropogenic signal will emerge from the internal climate variability. For this purpose, we investigate the time of emergence (ToE) of the hemispheric and regional shift of Northern subtropical margins in the Max Planck Institute Grand Ensemble. For several indicators, the ToE of the poleward shift of Northern subtropical margin will not occur by the end of the 21st century, neither at regional nor at hemispheric scale. The exceptions are the Mediterranean/Middle East and, to a lesser degree, Western Pacific, where the ToE would occur earlier. According to our results, given the fundamental role played by internal variability, trends of Northern Hemisphere subtropical expansion that have been identified over last decades in reanalyses cannot be considered as robust signals of anthropogenic climate change.