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The paper explores spatial and temporal variability of rainfall and temperature in Bilate catchment based on monthly data of 11 meteorological stations. Precipitation Concentration Index (PCI) and Pearson product moment correlation were used to estimate monthly concentrations and associations between annual and seasonal rainfall. Similar methods were used to analyze the association of ENSO with rainfall variability using Eastern Equatorial Pacific (Niño 3.4) data, Sea Surface Temperature (SST), and Southern Oscillation Index (SOI). Rainfall and temperature series were tested for trends using the Mann–Kendall test. Rainfall in the catchment is highly seasonal and concentrated in Kiremt (June–September), followed by Belg (February–May). Belg rainfall was highly variable. Annual rainfall was relatively stable in the upper catchment and variable in the lower catchment. PCI values are expected to increase as annual and seasonal rainfall decrease. The middle catchment had significant negative trends in annual and Belg rainfall. November–March SST is strongly associated with Belg rainfall variations throughout the catchment, and ~49% of the variability can be explained by Equatorial Pacific SST. Annual and seasonal temperature significantly increased in middle and lower parts of the catchment in the past 30 years. Warming was ~0.05°C/yr to 0.17°C/yr. [ABSTRACT FROM AUTHOR]

Caribbean small island developing states (SIDS) are highly vulnerable to the impacts of climate change. Food security is a key issue in the region, and is related to vulnerability in the natural and human system. This short research paper, which reports on a systematic search of the academic literature and is part of a larger research project on climate change adaptation in Caribbean coastal communities, investigates two central questions: (1) what challenges to food security are Caribbean SIDS facing due to climate change? and (2) what strategies, if any, are being used to adapt to these challenges? We review peer-reviewed articles published after the release of Working Group II's contribution to the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change in 2014, which included a chapter on vulnerability and impacts in small islands (Chapter 29). We find that post AR5 articles confirm that climate change will have a significant effect on agriculture and fisheries in the Caribbean, mainly through changing patterns of weather, air and sea surface temperatures, and water availability. These studies highlight the importance of considering the social dimensions of food security in the region when identifying and implementing adaptation strategies, particularly in the context of achieving the Sustainable Development Goals. These social dimensions include the Caribbean's historical and social context as well as its demographics, which feature varying population densities and poverty rates. They serve to increase vulnerability but are imperative considerations for understanding and minimizing the threat climate change poses to food security in the region. [ABSTRACT FROM AUTHOR]

The Earth's climate is largely determined by its energy budget. Since the 1960s, satellite remote sensing has been used in estimating these energy budget components at both the top of the atmosphere (TOA) and the surface. Besides the broadband sensors that have been traditionally used for monitoring Earth's Energy Budget (EEB), data from a variety of narrowband sensors aboard both polar-orbiting and geostationary satellites have also been extensively employed to estimate the EEB components. This paper provides a comprehensive review of the satellite missions, state-of-the art estimation algorithms and the satellite products, and also synthesizes current understanding of the EEB and spatio-temporal variations. The TOA components include total solar irradiance, reflected shortwave radiation/planetary albedo, outgoing longwave radiation, and energy imbalance. The surface components include incident solar radiation, shortwave albedo, shortwave net radiation, longwave downward and upwelling radiation, land and sea surface temperature, surface emissivity, all-wave net radiation, and sensible and latent heat fluxes. Some challenges, and outlook such as virtual constellation of different satellite sensors, temporal homogeneity tests of long time-series products, algorithms ensemble, and products intercomparison are also discussed. [ABSTRACT FROM AUTHOR]

Populations within the same species range edge may experience contrasting local conditions and exhibit diverse levels of environmental tolerance. This heterogeneity within a range boundary has seldom been considered in studies forecasting the impact of anthropogenic habitat alteration and climate change on species distributions. Moreover, any ecological prediction under changing environmental conditions requires a good understanding of the combined responses of organisms to multiple stressors, in particular the effects on key life cycle stages of species. The intertidal seaweed Fucus serratus is a dominant species on northern Atlantic shores and whose southern limit is in the NW Iberian Peninsula. We examined how early developmental stages of southern-edge populations of this foundation alga responded to the combined effects of environmental stressors, including salinity and aerial and seawater temperature. Four populations from two different areas of the NW Iberian coast were considered: two populations from open shores on the northern coast and two populations from the western rias on the Atlantic coast. The study findings revealed inter-population variability in the response to heat stress, with greater survival of germlings from the northern populations than those from western rias. Environmental conditions are still more benign within western rias, under the influence of strong summer upwelling events. The results also suggest the key role of aerial thermal stress in determining the southern limit of distribution of the target species. The future of these heterogeneous edge populations from NW Iberian Peninsula depends on trends in climate change and the ability of populations to cope with these. Environmental changes may already be occurring at rates that exceed the plastic and adaptive potential of edge populations in N Spain, while the future of western rias as climate refugia for this and other foundation alga is also uncertain. [ABSTRACT FROM AUTHOR]

We assembled water-temperature data (1.0–15 m depth horizon) from several field studies (spanning 2003–2020) within Pelorus Sound to generate composite time-series of temperature at four locations. We also examined satellite-sensed sea-surface temperature records for the region (2002–2019). Time-series were deseasoned and Sen-slopes were calculated as measures of long-term trend. All of the in-situ slopes and most of the satellite slopes fell inside the range 0.2–0.4°C decade−1. Within the in-situ data, warming appears to have been less rapid during the spring (September-November) quarter than in others. In the satellite data, warming was slower during both the winter and spring quarters. The satellite data indicate that warming has been less rapid inside the Sound than the nearby oceanic waters. Air temperatures inside the Sound have warmed at a rate similar to the nearby water (and a lesser rate than the oceanic ones) and riverine heat inputs have not changed appreciably. We infer that warming has been driven mainly by import of warming oceanic waters. We discuss the implications of future warming for the two marine crops grown in Pelorus Sound (Chinook salmon and Greenshell™ mussel) drawing upon literature concerning their responses to temperature. [ABSTRACT FROM AUTHOR]

We test the paradigm that in a future warmer ocean, shallower winter mixing will lead to less net primary production (NPP), by investigating whether warming between 2002 and 2018 led to changes in NPP in the Tasman Sea/New Zealand region. The 2002–18 trend in sea surface temperature (SST) was positive over most of the region, and was driven by increasingly warmer summers and marine heat waves (MHWs) rather than year-round warming. In contrast, the trends in sea surface chlorophyll (SSC) and NPP were generally positive over the Subtropical Front (STF) and in a subtropical band north-east of New Zealand, but negative elsewhere. Regressions between SSC and SST, and between spring SSC and the coldest SST during the preceding winter, show similar spatial patterns to the SSC trend. We suggest these findings reflect different ecosystem functioning in the subtropical and subantarctic biomes that are separated by the STF. We conclude that any future warming is likely to lead to less production in the Tasman Sea, but more production over the STF. Three recent MHWs had different impacts on production, but generally led to less surface biomass north of the STF and more biomass south of the front. [ABSTRACT FROM AUTHOR]

We analysed the data of swordtip squid Uroteuthis edulis caught in the eastern Tsushima Strait, from April to September between 2012 and 2018, to consider the relationships among mantle length and body and gonad weights, associated with the estimated seasonal migratory routes and itineraries improved by the quantitative results of the tracer experiments. Our analyses have enabled us to reveal the characteristics of kensaki-type squid and the reasons for their appearance. We identified the kensaki-type U. edulis as male individuals, caught mainly in April–June, with long slender bodies, probably adapted to empirical duration of the cold sea water temperature in the Sea of Amakusa. Researchers and fishermen have referred to the seasonal migrating group including such males as a spring-migrating group. However, the females belonging to the spring-migrating group had no kensaki-type characteristics. Moreover, contrary to that achieved by the males, the female squid had acquired greater maturation in the spring than in any other seasons. These data demonstrated that the females continued to grow to maturation even in the cold sea waters, implying a different female strategy for reproduction from that of male squid. We are concerned that the commercially valuable kensaki-type squid may decrease in the future because the water temperature in the northern East China Sea is gradually rising, probably due to global climate change. [ABSTRACT FROM AUTHOR]

The Yalgorup Plain of southwestern Australia is underlain by two limestone formations and a linear quartz-sand formation containing limestone lenses. These limestones record carbonate deposition in seagrass banks during the Pleistocene; they are capped either by a prograding beach-ridge system of small cuspate forelands or a quartz-rich shore-parallel coastal barrier. The cuspate forelands formed behind protective offshore limestone reefs within a given Pleistocene wind-and-wave field, while the quartz-rich coastal dune barrier formed under enhanced swell conditions. These formations record three different Pleistocene interglacial depositional events, separated by unconformities, each linked to a distinct climate and mean sea level. Foraminiferal assemblages within the two limestones and within the limestone lenses of the quartz-sand formation faithfully record changes in minimum seawater temperature, reflecting these changes in climate. They indicate a cycle of warm–cool–warm water accumulation of carbonates. Such a record of both climate and sea level history for southwestern Australia is unique, contributing greatly to the Pleistocene coastal sedimentary history of limestones within southwestern Australia. These formations occur within the globally unique setting of Western Australia and are conserved within a National Park and represent an outstanding record of Quaternary coastal geomorphic development in terms of both carbonate and siliciclastic sedimentation linked to both climate and sea level changes. Given their array of lithofacies, environmental setting, sea level and climate changes, as well as their biostratigraphy reflecting these changes, these formations form a sedimentary 'package' that is of global geoheritage significance, with many of its inherent geological features also of global to national geoheritage significance. [ABSTRACT FROM AUTHOR]

The recovery of bleached corals is crucial in ensuring the persistence of the coral reef ecosystem function. This study investigated whether relocating bleachedPlatygyra sinensiscolonies was a viable measure to accelerate their recovery. During a mild bleaching event in 2014, eight bleached colonies ofP. sinensiswere relocated from an affected reef at Sultan Shoal, Singapore, to a reef at Kusu that was less impacted. Another eight colonies at Sultan Shoal were tagged as controls. After five months, 88% of relocated bleached colonies at Kusu showed full recovery whereas only 25% of the control bleached colonies at Sultan Shoal had recovered. The differential coral recovery among the two sites was most likely due to lower seawater temperatures and faster water flow at Kusu, which helped to mitigate the effects of thermal stress on the bleached corals. This relocation study demonstrated that relocating bleachedP. sinensisto sites with more favourable environmental conditions is a viable approach to reduce bleaching impacts for this species. [ABSTRACT FROM AUTHOR]

Global climate change is affecting the planet’s biodiversity, altering marine ecosystems and modifying species distributions. Using historical and recently collected data, changes in depth distribution of two hydrozoan taxa (Ectopleura croceaandMilleporaspp.) with different life histories, ecology and geographic distributions were compared to trends in sea surface temperature (SST).Ectopleura crocea, a temperate species, used to be very common in Italian seas on shallow water artificial substrata, where it settled mainly between spring and autumn. In the Maldives, three species of the tropical hydrocoralMillepora(M. platyphylla,M. latifoliaandM. tenera) were reported as common from the early 20th century until recently.Milleporaunderwent mass mortality during a bleaching event linked to a thermal positive anomaly caused by El Niño and lasting from April to July, 1998. Similarly,E. croceadisappeared from Italian surface waters where it was once abundant. Both the temperate and the tropical hydrozoans survived at moderate depth and recolonized shallow water habitats in recent years. These two hydrozoan examples support the depth refugia hypothesis, according to which marine organisms may shift to deeper habitats to avoid shallow water heatwaves and increased temperature variability. Return to shallow water has been possible only after acclimation such as shifting season of occurrence from summer to winter–spring (E. croceain Italian seas) or possibly through species replacement (Milleporain the Maldives). Continued field research is needed to understand and evaluate the effect of climate change on marine species distribution. [ABSTRACT FROM PUBLISHER]

Remotely derived environmental variables, including sea surface height anomaly (SSHA), sea surface temperature (SST), chlorophyll-a (chl-a), eddy kinetic energy (EKE), mixed layer data set of argo float (MLD), Niño 3.4 index, and bigeye tuna catch data for the period 1997-2008, were used to analyse ocean climate variability and how they relate to the hotspots of bigeye tuna catch in the eastern Indian Ocean off Java. The empirical orthogonal function (EOF) was performed to obtain a more detailed structure of the spatio-temporal ocean variability in the region. The results showed that the first EOF modes of chl-a, SSHA, and SST accounted for 42.8%, 36.5%, and 27.4% of total variance, respectively, and these corresponded to the interannual signal. The maps of spatial patterns of the first EOF modes of SSHA, SST, and chl-a gave very typical values for cold-water SSHA, low SST, and high chl-a concentration along the southern coast of the Indonesian archipelago; and warm-water SSHA, high SST, and low chl-a concentration in the offshore region to make frontal areas along the latitudinal line around 10-12° S. The EOF analysis further revealed a strong relationship between the El Niño event and favourable oceanographic conditions, resulting in a significant increase in bigeye tuna catch. The average hook rate of 0.71 (0.43) was recorded during El Niño (La Niña). Major hotspots were located away from the confluence region and frontal areas around 11-16° S and 110-118° E and were thus demonstrated as the most favourable oceanographic conditions for bigeye tuna fishing in the eastern Indian Ocean off Java. [ABSTRACT FROM AUTHOR]