On December 16, 2019, the latest study, titled The Pacific Decadal Oscillation under greenhouse warming was published online by Nature Climate Change, the sub-publication of the top international academic journal Nature. The work was jointly completed by the scientific research team of the Institute for Advanced Ocean Study( IAOS), with Dr. Li Shujun as the first author, and academician Wu Lixin, director of IAOS as well as professor Cai Wenju as the joint corresponding authors.
The Pacific Decadal Oscillation (PDO) is the most prominent form of decadal variability over the North Pacific, characterized by its horseshoe-shaped sea surface temperature anomaly pattern(Fig. 1). In its warm phase, the PDO displays anomalous cooling in the central and western regions of the North Pacific, encircled by warming along the western coastline of North America. The PDO has changed its phase several times since 1900. These ‘regime shifts’ have exerted far-reaching impacts on marine ecosystems, agriculture and global climate conditions. For example, PDO can influence precipitation in different regions of China and induce extreme weather events such as floods by modulating east Asian atmospheric circulation. However, under the background of global warming, it is still unclear how the predictability of PDO will change and the relevant mechanism, which is one of the hot issues in the inter-annual to decadal climate prediction, and plays an important guiding role in the formulation of relevant climate response policies by national policy-making departments.
In this study, multiple observation data and CMIP5 ocean–atmosphere coupling multi-mode data were used to combine with the ocean–atmosphere coupling over the North Pacific, and it was found that global warming would lead to decreased predictability of PDO and inter-model consistency (as shown in figure 2). The mechanism is that with global warming, the strengthening of the upper ocean layer induces the propagation of oceanic baroclinic Rossby waves, which leads to the decrease of the the periodicity of PDO and the weakening of the signal strength of sea surface temperature, making PDO more difficult to detect.
The research team, led by academician Wu Lixin, has been committed to the research of ocean dynamic process and climate change prediction. Focusing on a predictable ocean, the results reveal for the first time the predictable response of decadal variability over the North Pacific, highlighting IAOS's global leadership in the field of ocean–atmosphere interaction and interdecadal prediction.
Reference: S. -J, Li, L. -X, Wu*, Y. Yang, T. Geng, W. -J. Cai*, B. -L. Gan, Z. -H, Chen, Z. Jing, G. -J. Wang and X. -H. Ma, 2019: The Pacific Decadal Oscillation less predictable under greenhouse warming. Nature Climate Change, doi:10.1038/s41558-019-0663-x
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