This study provides a holistic view of the coupled ocean-atmosphere-sea ice processes responsible for generating interannual variability in sea ice coverage in the Sea of Okhotsk as well as the ...atmospheric response to this variability. Simulations from the Community Earth System Model Large Ensemble project are analyzed, providing the ability to elucidate the time evolution of these relationships through weekly lead-lag composite analysis, while maintaining a large number of samples to provide robust conclusions. We find that thermodynamic processes involving anomalous ocean-atmosphere heat fluxes affect the timing of initial sea ice growth in the Sea of Okhotsk as early as November. Low-level wind anomalies in the winter affect the extent to which sea ice fully develops, both through advection of the sea ice itself and through changes in the transport of air masses over the Sea of Okhotsk. In this study, the results synthesize and support a diverse set of mechanisms identified in previous observational studies to be responsible for anomalous sea ice conditions, but in a coupled global climate model framework with a large sample size. We also find evidence that anomalous ocean-atmosphere heat fluxes in the winter can trigger an atmospheric response comprised of a local negative sea-level pressure anomaly and Rossby wave that extends over North America. The sign of the turbulent heat fluxes relative to the sea ice anomalies confirm that this is indeed a lagged response of the atmosphere forced by sea ice anomalies. This validates the Rossby wave train response identified in more idealized model simulations with prescribed sea ice and sea surface temperature by demonstrating that this process also occurs in a more realistic coupled model framework.
Under the combined impacts of natural changes and human activities, the past, current, and future marine heatwaves (MHWs) in China's marginal seas and adjacent offshore waters (CMSOW) need a ...comprehensive understanding. This study provides a systematic analysis of the spatiotemporal variations using daily sea surface temperature data and simulates the future trend using 12 climate models. During 1982–2018, the mean annual total days, duration, frequency, and mean intensity of the MHWs in the CMSOW increased by 20–30 days/decade, 5–9 days/decade, 1–2 decade−1, and 0.1–0.3°C/decade, respectively (p <0.01). The maximum sea surface temperature anomalies in the Bohai Sea was over 6–8°C, and the MHW's frequency, duration, and mean intensity were higher than twice the global average, which could have impacted fishery resources and occurrence of harmful algal blooms. The variations of the MHWs in the CMSOW result from the robust ocean surface warming, which is caused by increased solar radiation due to reduced cloud cover, reduced ocean heat loss from weaker wind speed, weakening but warmer Kuroshio, and strong El Niño. In the future, the areas with longer total days and duration will increase; the spatial pattern of frequency has a negative relationship with that of duration while that of mean intensity is mostly unchanged. Year 2040 is a key node for the future changes of MHW under different Representative Concentration Pathways. The trend of total days increases from fast to slow, and frequency shows an opposite trend; the duration and mean intensity rise faster after 2040.
Key Points
The Bohai Sea, Japan Sea, Beibu Bay, and east of Taiwan Island have the highest mean annual total days
Severe MHWs in the Bohai Sea could have impacted fishery resources and occurrence of harmful algal blooms
In the future, 2040 is a key node for the future changes of MHW under different RCPs
Barystatic sea level rise (SLR) caused by the addition of freshwater to the ocean from melting ice can in principle be recorded by a reduction in seawater salinity, but detection of this signal has ...been hindered by sparse data coverage and the small trends compared to natural variability. Here, we develop an autoregressive machine learning method to estimate salinity changes in the global ocean from 2001 to 2019 that reduces uncertainties in ocean freshening trends by a factor of four compared to previous estimates. We find that the ocean mass rose by 13,000 ± 3,000 Gt from 2001 to 2019, implying a barystatic SLR of 2.0 ± 0.5 mm/yr. Combined with SLR of 1.3 ± 0.1 mm/yr due to ocean thermal expansion, these results suggest that global mean sea level rose by 3.4 ± 0.6 mm/yr from 2001 to 2019. These results provide an important validation of remote‐sensing measurements of ocean mass changes, global SLR, and global ice budgets.
Plain Language Summary
Global sea level rise (SLR) is caused by heating of the ocean, and by the input of freshwater from the melting of glaciers and ice caps. Global freshwater input to the oceans from melting ice during the 21st century has primarily been tracked by satellites that measure changes in the mass of the ocean. Here, we show that trends in global SLR can also be accurately tracked by global observations of ocean salinity changes, as freshwater runoff from melting ice enters the ocean and dilutes ocean salinity. These results show that ocean salinity measurements are critical for monitoring global sea level changes, particularly as polar warming intensifies and the melting of ice sheets accelerates.
Key Points
A new full‐depth ocean salinity product yields robust global freshening trend of (35 ± 10) × 10−6 yr−1 from 2001 to 2019
Combined with estimates of sea ice loss, this freshening implies that ocean mass rose by 13,000 ± 3,000 Gt from 2001 to 2019
Sea level rise derived from ocean temperature and salinity measurements is 3.4 ± 0.6 mm/yr, confirming the satellite altimetry trend
Sino-Japanese relations have been repeatedly strained by the territorial dispute over a group of small islands, known as the Senkaku islands in Japan and the Diaoyu islands in China. The rich fishing ...grounds, key shipping lanes, and perhaps especially, potentially rich oil deposits around the islands exacerbate this dispute in a confluence of resource pressures, growing nationalism, and rising military spending in the region. Bridging Troubled Waters reminds us that the tensions over the Senkaku/Diaoyu islands are only a part of a long history of both conflict and cooperation in maritime relations between Japan and China. James Manicom examines the cooperative history between China and Japan at sea and explains the conditions under which two rivals can manage disputes over issues such as territory, often correlated with war. China and Japan appear incapable of putting history behind them, are poised on the brink of a strategic rivalry, and seem at risk of falling into an unintentional war over disputed maritime claims. Bridging Troubled Waters challenges this view by offering a case-by-case analysis of how China and Japan have managed maritime tensions since the dispute erupted in 1970. The author advances an approach that offers a trade-off between the most important stakes in the disputed maritime area with a view to establishing a stable maritime order in the East China Sea. The book will be of interest to policymakers, academics, and regional specialists in Asia, security studies, and international conflict and cooperation.
"How can the lightly armed white-hulled and blue-hulled ships of China's coast guard and maritime militia defeat the heavily armed gray-hulled navies of the U.S. and its allies? Nowhere is this ...urgent question explored more exhaustively than in this incisive book. It should serve as a wake-up call for the American military." -J. William Middendorf, former Secretary of the Navy.
This Special Issue gathers papers reporting research on various aspects of remote sensing of Sea Surface Salinity (SSS) and the use of satellite SSS in oceanography. It includes contributions ...presenting improvements in empirical or theoretical radiative transfer models; mitigation techniques of external interference such as RFI and land contamination; comparisons and validation of remote sensing products with in situ observations; retrieval techniques for improved coastal SSS monitoring, high latitude SSS and the assessment of ocean interactions with the cryosphere; and data fusion techniques combining SSS with sea surface temperature (SST). New instrument technology for the future of SSS remote sensing is also presented.
The merchants of the medieval Hanse monopolised trade in the Baltic and North Sea areas. The authors describe the structure of their trade system in terms of network organisation and attempts to ...explain, on the grounds of institutional economics, the coordination of the merchants’ commercial exchange by reputation, trust and culture. The institutional economics approach also allows for a comprehensive analysis of coordination problems arising between merchants, towns and the ‘Kontore’. Due to the simplicity and flexibility of network trade the Hansards could bridge the huge gap in economic development between the West and the East. In the changing economic conditions around 1500, however, exactly these characteristics proved to be a serious limit to further retain their trade monopoly.
Traditionally, the South China Sea (SCS) issue was not on the negotiation table between the United States and China. However, the tensions between the United States and China over the SCS have ...gradually simmered up to a strategic level. Why and how did the SCS become a flashpoint between the United States and China? Will the United States and China really go to war over the SCS? Why did China adopt an “assertive” policy towards the South China Sea in the 2000s? What will regional actors do in the face of this “new normal” of competition between China and the United States? Will multilateral institutions in the Asia Pacific alleviate the potential conflicts over the SCS disputes? How will US–Chinese competition in the SCS shape the dynamics of Asian security?
This edited book addresses these questions systematically and theoretically, with contributions from leading scholars in the field of US–China relations and Asian security from the United States, Australia, the United Kingdom, and Singapore. It elevates the analysis of the SCS disputes from maritime and legal issues to the strategic level between the United States and China.
A valuable analogue for assessing Earth's sensitivity to warming is the Last Interglacial (LIG; 129–116 ka), when global temperatures (0 to +2 ∘C) and mean sea level (+6 to 11 m) were higher than ...today. The direct contribution of warmer conditions to global sea level (thermosteric) is uncertain. We report here a global network of LIG sea surface temperatures (SST) obtained from various published temperature proxies (e.g. faunal and floral plankton assemblages, Mg ∕ Ca ratios of calcareous organisms, and alkenone U37K′). We summarize the current limitations of SST reconstructions for the LIG and the spatial temperature features of a naturally warmer world. Because of local δ18O seawater changes, uncertainty in the age models of marine cores, and differences in sampling resolution and/or sedimentation rates, the reconstructions are restricted to mean conditions. To avoid bias towards individual LIG SSTs based on only a single (and potentially erroneous) measurement or a single interpolated data point, here we report average values across the entire LIG. Each site reconstruction is given as an anomaly relative to 1981–2010, corrected for ocean drift, and where available seasonal estimates are provided (189 annual, 99 December–February, and 92 June–August records). To investigate the sensitivity of the reconstruction to high temperatures, we also report maximum values during the first 5 millennia of the LIG (129–124 ka). We find mean global annual SST anomalies of 0.2 ± 0.1 ∘C averaged across the LIG and an early maximum peak of 0.9 ± 0.1 ∘C, respectively. The global dataset provides a remarkably coherent pattern of higher SST increases at polar latitudes than in the tropics (demonstrating the polar amplification of surface temperatures during the LIG), with comparable estimates between different proxies. Polewards of 45∘ latitude, we observe annual SST anomalies averaged across the full LIG of > 0.8 ± 0.3 ∘C in both hemispheres with an early maximum peak of > 2.1 ± 0.3 ∘C. Using the reconstructed SSTs suggests a mean LIG global thermosteric sea level rise of 0.08 ± 0.1 m and a peak contribution of 0.39 ± 0.1 m, respectively (assuming warming penetrated to 2000 m depth). The data provide an important natural baseline for a warmer world, constraining the contributions of Greenland and Antarctic ice sheets to global sea level during a geographically widespread expression of high sea level, and can be used to test the next inter-comparison of models for projecting future climate change. The dataset described in this paper, including summary temperature and thermosteric sea level reconstructions, is available at https://doi.org/10.1594/PANGAEA.904381 (Turney et al., 2019).
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