An asymmetric variation of hot and cold SST extremes in the China Seas during the recent warming hiatus period

Yan Li,Yiwei Liu,Yan Wang,Qingquan Li,Qingyuan Wang

doi:10.1038/s41598-020-79854-2

Abstract

Extreme sea surface temperatures (SSTs) attract much attention in recent years. However, the detailed spatial and temporal pattern of the extreme SSTs in China Seas has not been well understood. Using the daily SST data set of OISST v2 from January 1, 1982 to December 31, 2013, and based on four extreme SST indices, the frequency and intensity of SST extremes in the China Seas were examined. The analysis showed that the annual mean SST exhibited cooling trend, on pace with a trend of − 0.34 °C/decade during 1998–2013, confirming the previous studies that China Seas also experienced the recent global warming hiatus. But during this recent global warming hiatus, there was a notable asymmetric pattern of greater cooling trends in cold SSTs as compared to the hot SSTs in this region. During 1998–2013, the cold days (CDs) frequency increased significantly by 13 days per decade and cold SST extremes which were below the 10th percentile of each year (SST10p) notably decreased by 0.4 °C per decade. Hot days (HD) and hot SST extremes which were above the 90th percentile of each year (SST90p) slowed down, but without any distinct tendency. Meanwhile, the rates of SST10p and CDs were highly heterogeneous in space. Cold extremes in the near-shore areas are much more sensitive to the global warming hiatus than these in the eastern of the Kuroshio Current. Importantly, hot extremes do not reveal any distinct cooling tendency during 1998–2013, there were more frequent hot days and more intense hot SSTs in this region comparing with 1982–1997. These hot extremes could push some marine organisms, fisheries and ecosystems beyond the limits of their resilience, with cascading impacts on economies and societies.

Highlights

The globally averaged combined land and ocean surface temperature has experienced a significant acceleration in warming from the early-1980s to the later-1990s1–3, but has nearly stalled or paused during approximately 1998–2013, a phenomenon always call ‘global warming hiatus’[4]
Shen et al.[19] found that the recent warming hiatus in China was reflected by cooling of cold extremes, but hot extremes do not reveal any pause in its warming pace
Using the cumulative sum test and bootstrap analysis, we detected a significant temporal breakpoint at 1998 in this time series. This breakpoint divides the whole period into two periods, with a significant warming trend of 1982–1997 (0.23 °C/decade) and notable cooling trend of 1998–2013 (− 0.34 °C/decade) (Fig. 2a)

Summary

Introduction

The globally averaged combined land and ocean surface temperature has experienced a significant acceleration in warming from the early-1980s to the later-1990s1–3, but has nearly stalled or paused during approximately 1998–2013, a phenomenon always call ‘global warming hiatus’[4]. Few studies have paid attention to the changes of water temperature extremes in the China Seas during the recent global warming hiatus. The coastal China Seas has a variety of special coastal ecosystems including coral reef, mangroves, tidal marshes, seagrass meadows, and form many marine biological communities and commercial fisheries areas. It is of great significance for the sustainable development of society and economy in coastal China. This vital region is greatly influenced by global climate change through the East Asian monsoon, run-off from major rivers, the Kuroshio Current and anthropogenic a ctivities[26,27,28]. The study area in our work is focused on the coastal China Seas and its adjacent seas with the approximate range of (15°–45°N, 105°–130°E) (Fig. 1)

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