Another Record: Ocean Warming Continues through 2021 despite La Niña Conditions

The increased concentration of greenhouse gases in the atmosphere from human activities traps heat within the climate system and increases ocean heat content (OHC). Here, we provide the first analysis of recent OHC changes through 2021 from two international groups. The world ocean, in 2021, was the hottest ever recorded by humans, and the 2021 annual OHC value is even higher than last year’s record value by 14 ± 11 ZJ (1 zetta J = 1021 J) using the IAP/CAS dataset and by 16 ± 10 ZJ using NCEI/NOAA dataset. The long-term ocean warming is larger in the Atlantic and Southern Oceans than in other regions and is mainly attributed, via climate model simulations, to an increase in anthropogenic greenhouse gas concentrations. The year-to-year variation of OHC is primarily tied to the El Niño-Southern Oscillation (ENSO). In the seven maritime domains of the Indian, Tropical Atlantic, North Atlantic, Northwest Pacific, North Pacific, Southern oceans, and the Mediterranean Sea, robust warming is observed but with distinct inter-annual to decadal variability. Four out of seven domains showed record-high heat content in 2021. The anomalous global and regional ocean warming established in this study should be incorporated into climate risk assessments, adaptation, and mitigation.

Spatial Distributions of 226Ra and 228Ra in the Indian and Southern Oceans in 2020 and Their Implications for Unique Currents

We examined the spatial variations in 226Ra and 228Ra concentrations from the surface to a depth of 830 m in the Indian and Southern Oceans during December 2019–January 2020. Notably, 226Ra concentrations at the surface increased sharply from 30°S to 60°S along an ~55°E transect (1.4 to 2.9 mBq/L), exhibiting small vertical variations, while 228Ra became depleted, particularly in the Southern Ocean. These distributions indicated the ocean-scale northward lateral movements of 226Ra-rich and 228Ra-depleted currents originating from the Antarctic Circumpolar Current (ACC). Using 226Ra concentrations, the fractions of the ACC at depths of 0–800 m were estimated to decrease from 0.95 to 0.14 from 60°S to 30°S through 0.56 at 43°S. The fractions in the subantarctic area the western Indian Ocean were higher than those previously reported from the eastern, indicating the preferential transport of the ACC. The fractions obtained were approximately equivalent to those in the western Indian section in the 1970s. This could be attributed to the minimal effects of the southward shift of the polar front due to global warming over the last 40 y, implying no notable changes in soluble material transport systems from the Southern Ocean to southern Indian Ocean.

Hydrothermal Vents May Add Ancient Carbon to Ocean Waters

Data from a long-distance research cruise provide new insights into carbon cycling in the eastern Pacific and Southern Oceans.

Taxonomic review of the subfamily Lohmannellinae (Acari: Trombidiformes: Halacaridae) with morphological comparisons among genera

Taxonomic review of the halacarid subfamily Lohmannellinae is carried out with regard to morphology, biology, habitat, geographical distribution, and bibliography. The subfamily is one of 16 subfamilies in the family Halacaridae and consists of five genera, Lohmannella, Porolohmannella, Scaptognathides, Scaptognathus, and Xenohalacarus, which include 38, 1, 11, 31, and 1 known species, respectively. The genera Scaptognathides, Scaptognathus, and Xenohalacarus are marine, Porolohmannella is a freshwater inhabitant, and Lohmannella lives in marine and freshwater. The species in this subfamily are mostly arenicolous and probably carnivorous or omnivorous in feeding habits. As for the geographic distribution, Lohmannella shows almost cosmopolitan distribution; Scaptognathus is also widely distributed except for polar regions. The genus Scaptognathides is distributed more in southern oceans than in the northern circle, and Xenohalacarus is restricted to the Coral Sea. The freshwater genus Porolohmannella has wide inland distribution except for the African, South American, Australian, and Antarctic continents. Based on morphological comparisons among five genera, Scaptognathus is regarded as the most unique taxon and Lohmannella and Porolohmannella as rather conservative taxa in the subfamily.

Refining the sea surface identification approach for determining freeboards in the ICESat-2 sea ice products

In Release 001 and 002 of the ICESat-2 sea ice products, candidate height segments used to estimate the reference sea surface height for freeboard calculations included two surface types: specular and smooth dark leads. We found that the uncorrected photon rates, used as proxies of surface reflectance, are attenuated due to clouds resulting in the potential misclassification of sea ice as dark leads, biasing the reference sea surface height relative to those derived from the more reliable specular returns. This results in higher reference sea surface heights and lower estimated ice freeboards. The resolution of available cloud flags from the ICESat-2 atmosphere data product is too coarse to provide useful filtering at the lead segment scale. In Release 003, we have modified the surface-reference-finding algorithm so that only specular leads are used. The consequence of this change can be seen in the composites of mean freeboard of the Arctic and Southern oceans. Broadly, coverages have decreased by ∼10–20 % because there are fewer leads (by excluding the dark leads), and the composite means have increased by 0–4 cm because of the use of more consistent specular leads.

On the Accuracy of Voluntary Observing Ship’s Records

A one-to-one comparison of the significant wave height reported by Voluntary Observing Ships (VOS) with the ERA-interim database is performed. A preliminary filtering procedure allows excluding reports affected by the most evident observations’ errors and removing the systematic biases in order to clean up the database. A statistical analysis confirms the previous finding regarding the goodness of the database when analyzing average values, but also highlights a large spreading of the observations. The work identifies critical areas and conditions in which the mismatch between numerical data and observations is more significant. The pattern of the differences reveals a regional consistency with VOS overestimating the significant wave height in marginal and enclosed seas as well as in the western sides of the oceans, while showing good matches in the eastern sides and offshore areas, except in the southern oceans where VOS leads to underestimations. The causes of such differences are finally discussed.