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The diatom Pseudo-nitzschia H. Peragallo is perhaps the most intensively researched genus of marine pennate diatoms, with respect to species diversity, life history strategies, toxigenicity, and biogeographical distribution. The global magnitude and consequences of harmful algal blooms (HABs) of Pseudo-nitzschia are particularly significant because of the high socioeconomic impacts and environmental and human health risks associated with the production of the neurotoxin domoic acid (DA) among populations of many (although not all) species. This has led to enhanced monitoring and mitigation strategies for toxigenic Pseudo-nitzschia blooms and their toxins in recent years. Nevertheless, human adaptive actions based on future scenarios of bloom dynamics and proposed shifts in biogeographical distribution under climate-change regimes have not been implemented on a regional scale. In the CoCliME (Co-development of climate services for adaptation to changing marine ecosystems) program these issues were addressed with respect to past, current and anticipated future status of key HAB genera such as Pseudo-nitzschia and expected benefits of enhanced monitoring. Data on the distribution and frequency of Pseudo-nitzschia blooms in relation to DA occurrence and associated amnesic shellfish toxin (AST) events were evaluated in a contemporary and historical context over the past several decades from key northern CoCliME Case Study areas. The regional studies comprised the greater North Sea and adjacent Kattegat-Skagerrak and Norwegian Sea, eastern North Atlantic marginal seas and Arctic gateways, and the Baltic Sea. The first evidence of possible biogeographical expansion of Pseudo-nitzschia taxa into frontier eastern Arctic gateways was provided from DNA barcoding signatures. Key climate change indicators, such as salinity, temperature, and water-column stratification were identified as drivers of upwelling and advection related to the distribution of regional Pseudo-nitzschi

Det naturvetenskapliga kunskapsläget kring klimatförändringen blir allt starkare vilket till exempel har rapporterats i rapporten Klimat i förändring 2021 – Den naturvetenskapliga grunden från FN:s klimatpanel, IPCC, 2021. Den globala medeltemperaturen har höjts med mer än 1,1 grader sen andra halvan av 1800-talet. Detta beror i huvudsak på människans utsläpp av koldioxid till atmosfären. Fortsatta utsläpp kommer att leda till ännu större temperaturökning framöver. Exakt hur stora de framtida förändringarna av klimatet kan bli är inte känt eftersom det beror på hur stora de framtida koldioxidutsläppen blir, och eftersom det finns osäkerheter kring exakt hur mycket en ökning av koldioxidhalten påverkar klimatet. Trots detta är det klart att det förutom högre temperaturer för alla jordens regioner också kommer leda till förändringar i nederbördsförhållanden och olika typer av väderextremer. Utbredning av snö och is beräknas minska och den globala havsnivån fortsätta stiga. Dessa typer av förändringar förväntas få en lång rad konsekvenser både för samhälle och naturmiljö.Den här rapporten tar upp vilken klimatinformation som finns tillgänglig för det svenska samhällets klimatanpassningsarbete, hur informationen kan användas, vilka begränsningar den har och vad som kan förbättras. Fortsatt utveckling av metodik och modeller är en viktig komponent för att kunna ta fram och förbättra klimatinformation för klimatanpassningsarbetet liksom vikten av att säkerställa långa tidsserier för att spegla klimatets variabilitet och förändring. Stora ensembler av högupplösta klimatscenarier behövs för att kunna analysera, förstå och beskriva framtida klimatförändring under olika utsläppsscenarier. Detta gäller särskilt för att kunna göra sannolikhetsberäkningar av extrema väderhändelser, vilket är en central del i den riskanalys som behövs för att kunna anpassa samhället till både dagens klimat och det klimat vi kan få i framtiden. Rapporten pekar på betydelsen av långsiktighet i arbe, The scientific basis related to climate change grows stronger, for example as reported by the latest report by the first working group of the IPCC in 2021. Primarily as a result of human emissions of carbon dioxide to the atmosphere, the global mean temperature has increased by more than 1.1 degrees since the second half of the 19th century. Continued emissions will lead to even larger increases in the future. Exactly how strong is unknown as the size of future emissions is not known and as there is an uncertainty related to the climate sensitivity. Despite this, it is clear that, in addition to higher temperatures in all areas, also precipitation will change as will different types of extreme conditions. The extent of snow and ice will decline and global sea level continue to rise. Such changes are expected to lead to various consequences both for society and the environment.The report presents what types of climate information that are available for work on climate change adaptation, how the information can be used, what limitations it has and what can be improved. Continued development of methods and models is one key component to be able to produce and improve climate information supporting climate change adaptation. Another relates to ensuring the existence of long time series reflecting variability and change. Large ensembles of high-resolution climate scenarios are needed to analyse, understand and describe future climate change under different scenarios. This is especially important for calculating probabilities of extreme weather events, which is a key component of the risk analysis. The report points to the importance of a longterm approach in the work with producing climate change information, and that it is important to involve the whole chain from observations and models to users of the information.

The marine dinoflagellate Alexandrium Halim represents perhaps the most significant and intensively studied genus with respect to species diversity, life history strategies, toxigenicity, biogeographical distribution, and global magnitude and consequences harmful algal blooms (HABs). The socioeconomic impacts, environmental and human health risks, and mitigation strategies for toxigenic Alexandrium blooms have also been explored in recent years. Human adaptive actions based on future scenarios of bloom dynamics and shifts in biogeographical distribution under climate-change parameters remain under development and not yet implemented on a regional scale. In the CoCliME (Co-development of climate services for adaptation to changing marine ecosystems) project these issues were addressed with respect to past, current and anticipated future status of key HAB genera and expected benefits of enhanced monitoring. Data on the distribution and frequency of Alexandrium blooms related to paralytic shellfish toxin (PST) events from key CoCliME Case Study areas, comprising the North Sea and adjacent Kattegat-Skagerrak, Norwegian Sea, and Baltic Sea, and eastern North Atlantic marginal seas, were evaluated in a contemporary and historical context over the past several decades. The first evidence of possible biogeographical expansion of Alexandrium taxa into eastern Arctic gateways was provided from DNA barcoding signatures. Various key climate change indicators, such as salinity, temperature, and water-column stratification, relevant to Alexandrium bloom initiation and development were identified. The possible influence of changing variables on bloom dynamics, magnitude, frequency and spatial and temporal distribution were interpreted in the context of regional ocean climate models. These climate change impact indicators may play key roles in selecting for the occurrence and diversity of Alexandrium species within the broader microeukaryote communities. For example, shifts to high

Stratified oceanic turbulence is strongly intermittent in time and space, and therefore generally underresolved by currently available in situ observational approaches. A promising tool to at least partly overcome this constraint are broadband acoustic observations of turbulent microstructure that have the potential to provide mixing parameters at orders of magnitude higher resolution compared to conventional approaches. Here, we discuss the applicability, limitations, and measurement uncertainties of this approach for some prototypical turbulent flows (stratified shear layers, turbulent flow across a sill), based on a comparison of broadband acoustic observations and data from a free-falling turbulence microstructure profiler. We find that broadband acoustics are able to provide a quantitative description of turbulence energy dissipation in stratified shear layers (correlation coefficient r = 0.84) if the stratification parameters required by the method are carefully preprocessed. Essential components of our suggested preprocessing algorithm are 1) a vertical low-pass filtering of temperature and salinity profiles at a scale slightly larger than the Ozmidov length scale of turbulence and 2) an automated elimination of weakly stratified layers according to a gradient threshold criterion. We also show that in weakly stratified conditions, the acoustic approach may yield acceptable results if representative averaged vertical temperature and salinity gradients rather than local gradients are used. Our findings provide a step toward routine turbulence measurements in the upper ocean from moving vessels by combining broadband acoustics with in situ CTD profiles.

Future climate biogeochemical projections indicate large changes in the ocean with environmental conditions not experienced at present referred to as novel, or may even disappear. These climate-induced changes will most likely affect species distribution via changes in growth, behavior, evolution, dispersal, and species interactions. However, the future risk of novel and disappearing environmental conditions in the ocean is poorly understood, in particular for compound effects of climate and nutrient management changes. We map the compound risk of the occurrence of future novel and disappearing environmental conditions, analyze the outcome of climate and nutrient management scenarios for the world’s largest estuary, the Baltic Sea, and the potential consequences for three charismatic species. Overall, the future projections show, as expected, an increase in environmental novelty over time. The future nutrient reduction management that improves the eutrophication status of the Baltic Sea contributes to large novel and disappearing conditions. We show the consequences of novel and disappearing environmental conditions for fundamental niches of three charismatic species under different scenarios. This first step toward comprehensively analyzing environmental novelty and disappearing conditions for a marine system illustrates the urgent need to include novelty and disappearing projection outputs in Earth System Models. Our results further illustrate that adaptive management is needed to account for the emergence of novelty related to the interplay of multiple drivers. Overall, our analysis provides strong support for the expectation of novel ecological communities in marine systems, which may affect ecosystem services, and needs to be accounted for in sustainable future management plans of our oceans.

Harmful algal blooms (HAB) are recurrent phenomena in northern Europe along the coasts of the Baltic Sea, Kattegat-Skagerrak, eastern North Sea, Norwegian Sea and the Barents Sea. These HABs have caused occasional massive losses for the aquaculture industry and have chronically affected socioeconomic interests in several ways. This status review gives an overview of historical HAB events and summarises reports to the Harmful Algae Event Database from 1986 to the end of year 2019 and observations made in long term monitoring programmes of potentially harmful phytoplankton and of phycotoxins in bivalve shellfish. Major HAB taxa causing fish mortalities in the region include blooms of the prymnesiophyte Chrysochromulina leadbeateri in northern Norway in 1991 and 2019, resulting in huge economic losses for fish farmers. A bloom of the prymesiophyte Prymnesium polylepis (syn. Chrysochromulina polylepis) in the Kattegat-Skagerrak in 1988 was ecosystem disruptive. Blooms of the prymnesiophyte Phaeocystis spp. have caused accumulations of foam on beaches in the southwestern North Sea and Wadden Sea coasts and shellfish mortality has been linked to their occurrence. Mortality of shellfish linked to HAB events has been observed in estuarine waters associated with influx of water from the southern North Sea. The first bloom of the dictyochophyte genus Pseudochattonella was observed in 1998, and since then such blooms have been observed in high cell densities in spring causing fish mortalities some years. Dinoflagellates, primarily Dinophysis spp., intermittently yield concentrations of Diarrhetic Shellfish Toxins (DST) in blue mussels, Mytilus edulis, above regulatory limits along the coasts of Norway, Denmark and the Swedish west coast. On average, DST levels in shellfish have decreased along the Swedish and Norwegian Skagerrak coasts since approximately 2006, coinciding with a decrease in the cell abundance of D. acuta. Among dinoflagellates, Alexandrium species are the majo

SMHI har analyserat hur havsisens utbredning och beskaffenhet i Bottenviken, Bottenhavet, Ålands hav och Norra Östersjön kan komma att förändras i ett perspektiv på 20 respektive 50 år, vilket motsvarar runt år 2040 och 2070. Analyserna utgår från sju indikatorer som beskriver olika aspekter av havsisens förändring. Indikatorerna är framtagna i samråd med Sjöfartsverket och valda både utifrån tillgång till data och med syfte att vara relevanta ur isbrytningsperspektiv.Som underlag för analyserna ligger historiska observationer från SMHI, det Finska Meteorologiska Institutet (FMI) och Sjöfartsverket, samt klimatscenarier framtagna i tidigare projekt.Klimatscenarier som representerar två olika utsläppsscenarier (RCP4,5 och RCP8,5) har analyserats från totalt tio olika klimatmodellsimuleringar. Klimatscenarier baserade på det lägre utsläppsscenariet (RCP2,6) saknas i underlaget eftersom befintliga klimatmodellsimuleringar för detta scenario bedömdes ha för låg kvalité. Tidsramen för denna utredning medgav inte heller framtagande av nya klimatscenarier.Resultatet av analyserna visar att framtidens isvintrar blir lindrigare med avseende på havsisens maximala utbredning jämfört med kontrollperioden (1975–2004). Issäsongens längd blir också kortare, med störst förändring i de södra delområdena. Inget scenario indikerar dock helt isfria vintrar, och åtminstone Bottenviken väntas i medel bli helt istäckt även i framtiden. I södra Bottenviken kommer is tjockare än 10 cm dock att försvinna för RCP8,5. På 20 års sikt är förändringen av den maximala isutbredningen mindre tydlig på grund av en fortsatt stor naturligt förekommande väderdriven mellanårsvariation. På 50 års sikt däremot är signalen tydligare och visar minskad isutbredning och en något mindre mellanårsvariabilitet.Istäcket förväntas bli tunnare i medel i samtliga delområden och utbredningen av tjock deformerad is förväntas minska. Modellerna saknar dock förmågan att simulera så kallade stampisvallar. Dessa vallar bil, SMHI has analysed how sea ice conditions in the Bothnian Bay, Bothnian Sea, Åland Sea and northern Baltic Proper may change in a 20 and 50 year perspective relative to 2020. The study is focused on seven indicators describing different aspects of sea ice change. The indicators were identified jointly with the Swedish Maritime Administration (SMA), and chosen based on available data and relevance to ice breaking.The study is based on historical observations from SMHI, the Finnish Meteorological Institute (FMI) and SMA, and climate scenario data from previous projects.Climate scenarios representing two different representative concentration pathways (RCP4.5 and RCP8.5) have been analysed based on a total of ten different climate model simulations. Scenarios based on the lower representative concentration pathway (RCP2.6) are absent because existing datasets for this pathway do not have sufficient quality for sea ice parameters. The time frame for this assignment did not allow for new climate scenario simulations to be produced.The results show that future winters will gradually, on average, have a smaller maximum ice extent compared to the control period (1975-2004). Ice seasons will also get shorter, with the largest differences in the southern areas. None of the scenarios yield ice free winters, and at least Bothnian Bay is expected to become fully ice covered on average, also during future winters. However, in the RCP8.5 scenario, ice with an average thickness of 10 cm or more disappears from the southern Bothnian Bay.In a 20-year perspective, changes in maximum ice extent are less distinct due to large inter-annual variations. In a 50-year perspective the change becomes more distinct and shows decreasing ice extents and smaller inter-annual variations.Level ice is expected to get thinner on average in all analysed areas, and the presence of heavily deformed ice is expected to decrease. However, models lack the ability to simulate brash ice barriers, which are form

The ocean is an important pathway to a low-carbon and climate resilient society, e.g. in areas of blue carbon, green shipping, offshore renewable energy, aquaculture, fi shery and coastal adaptation. Currently, 26 EU member states have made their National Adaptation Strategy (NAS) and/or National Strategy Plan (NAP) which needs a strong climate information service. European Global Ocean Observing System (EuroGOOS) has a strategy to expand existing operational marine service to climate change in 2020-2030. As focal points of national marine, climate and/or weather services, ROOS (Regional Sea Operational Oceanographic System) members have extensive experiences in working with citizens, stakeholders and decision-makers at national, regional and municipality levels. This paper will review current marine climate service capacity in ROOS members, identify gaps in modelling, products and service, and propose a seamless earth system approach for developing EuroGOOS and ROOS marine climate service capacities.

The hydrodynamics within small boreal lakes have rarely been studied, yet knowing whether turbulence at the air-water interface and in the water column scales with metrics developed elsewhere is essential for computing metabolism and fluxes of climate-forcing trace gases. We instrumented a humic, 4.7 ha, boreal lake with two meteorological stations, three thermistor arrays, an infrared (IR) camera to quantify surface divergence, obtained turbulence as dissipation rate of turbulent kinetic energy (epsilon) using an acoustic Doppler velocimeter and a temperature-gradient microstructure profiler, and conducted chamber measurements for short periods to obtain fluxes and gas transfer velocities (k). Near-surface epsilon varied from 10(-8) to 10(-6) m(2) s(-3) for the 0-4 m s(-1) winds and followed predictions from Monin-Obukhov similarity theory. The coefficient of eddy diffusivity in the mixed layer was up to 10(-3) m(2) s(-1) on the windiest afternoons, an order of magnitude less other afternoons, and near molecular at deeper depths. The upper thermocline upwelled when Lake numbers (L-N) dropped below four facilitating vertical and horizontal exchange. k computed from a surface renewal model using epsilon agreed with values from chambers and surface divergence and increased linearly with wind speed. Diurnal thermoclines formed on sunny days when winds were < 3 m s(-1), a condition that can lead to elevated near-surface epsilon and k. Results extend scaling approaches developed in the laboratory and for larger water bodies, illustrate turbulence and k are greater than expected in small wind-sheltered lakes, and provide new equations to quantify fluxes., Funding Agencies|Swedish Research CouncilSwedish Research Council [210-2012-1461, 2009-1692, 2011-3575, 2012-00048, 2016-04829]; European Research Council (ERC)European Research Council (ERC) [725546]; FormasSwedish Research Council Formas [2018-2022]; U.S. National Science Foundation through DEB grant [1753856, DEB 0919603, ANS 01204267, ANS 1737411]