[A-OS09] Climate variability and predictability on subseasonal to multidecadal timescales

[AOS09-05] Synchronized Tropical Pacific Decadal Variability and Cold Ocean-Warm Land Pattern Modulate Global Warming Rate

*Jun-Chao Yang^1,2, Xiaopei Lin^1,2, Shang-Ping Xie³, Yu Zhang^1,2, Yu Kosaka⁴, Ziguang Li^1,2 (1.Frontiers Science Center for Deep Ocean Multispheres and Earth System and Physical Oceanography Laboratory, Ocean University of China, 2.Qingdao National Laboratory for Marine Science and Technology, 3.Scripps Institution of Oceanography, University of California, 4.Research Center for Advanced Science and Technology, University of Tokyo)

Keywords:global mean surface temperature, tropical Pacific decadal variability, cold ocean-warm land pattern, global warming slowdown, global warming acceleration

Internally generated decadal variability modulates global warming rate under anthropogenic radiative forcing. Although the tropical Pacific decadal variability (TPDV) dominates internally generated decadal variability, substantial internal temperature variations in the Northern Hemispheric extratropics are independent of the TPDV, particularly in boreal cold season. These extratropical variations are well tracked by the cold ocean-warm land (COWL) pattern. By analyzing observations and model results, we find that the TPDV and COWL variability vary in phase by chance during the recent three decades as their decadal trends show extremely high correlations. Their synchronized variability strengthens internal modulations on global mean surface temperature, contributing to the early 2000s global warming slowdown and early 2010s acceleration. Because both the TPDV and COWL are strongest in boreal cold season, their synchronized variability also determines the striking seasonality of the recent slowdown and acceleration. Further analyses based on climate model simulations suggest that in a warming future, the co-variability of TPDV and COWL is still important for modulating global warming rate while their respective spatial pattern may change. Although TPDV shows some predictabilities, we highlight that COWL is largely induced by atmospheric internal variability, which limits the predictability of global warming slowdown and acceleration.