Tracking Ocean Heat Uptake during the SurfaceWarming Hiatus

Tracking Ocean Heat Uptake during the Surface-Warming Hiatus Objective Globally averaged SST from Ishii data (black) and the CESM ensemble simulations grouped into subsets of warming hiatus (red) and surges (blue). ● Clarify a key confusion about understanding the global warming hiatus by depicting the similarities and distinctions between the pathways of ocean heat uptake during hiatus and under anthropogenic warming. Approach ● Make use of NCAR’s CESM large ensemble simulations and composite subsets for warming surge and hiatus. ● Track the ocean heat uptake in different ocean basins under warming surge and hiatus. The SST trend difference between the ensemble mean of the CESM hiatus and surge groups during 2002 -2012. Stippling indicates region below 95% significance level. Results ● Earlier studies stressing the importance of deep ocean heat penetration for the global warming hiatus can be misleading because the deep heat penetration is not unique to the hiatus, but also shared by the anthropogenic warming, merely reflecting the depth of the meridional overturning circulation. ● It is not the heat uptake in the deep (>700 m) but the heat redistribution in the upper 350 m between the Indian and Pacific basins that is closely tied to the surface warming hiatus. Impact ● This study clarifies a key confusion that plagues understanding the causes of the global warming hiatus, and underscores the importance of the ocean dynamics beyond the simple energetics perspective. Liu W, S-P Xie, J Lu. 2016. “Tracking Ocean Heat Uptake during the Surface Warming Hiatus. ” Nature Communications 7: 10926 DOI: 10. 1038/ncomms 10926.