The rate and impacts of sea level rise vary considerably around the world, but the contribution of human-caused climate change to increases in local and regional flood risks has not yet been systematically explored. Because such information is critical to local decision making, legal proceedings, and loss and damage determinations, we quantify human-caused climate change's contributions to sea level rise at worldwide locations using budget-based and semiempirical model methods. Results show that human-caused sea level rise is quantifiable at 97% of 519 tide gauge sites and is responsible for 58% (44 to 65%) of the observed daily extreme water level exceedances over 2000-2018. On average, human-caused sea level rise has caused a near-tripling in the number of days with attributable exceedances since the 1970s.

Baleen whales migrate from productive high-latitude feeding grounds to usually oligotrophic tropical and subtropical reproductive winter grounds, translocating limiting nutrients across ecosystem boundaries in their bodies. Here, we estimate the latitudinal movement of nutrients through carcasses, placentas, and urea for four species of baleen whales that exhibit clear annual migration, relying on spatial data from publicly available databases, present and past populations, and measurements of protein catabolism and other sources of nitrogen from baleen whales and other marine mammals. Migrating gray, humpback, and North Atlantic and southern right whales convey an estimated 3784 tons N yr-1 and 46,512 tons of biomass yr-1 to winter grounds, a flux also known as the "great whale conveyor belt"; these numbers might have been three times higher before commercial whaling. We discuss how species recovery might help restore nutrient movement by whales in global oceans and increase the resilience and adaptative capacity of recipient ecosystems.

Understanding how rising global air and sea surface temperatures (SSTs) influence tropical cycloneintensities is crucial for assessing current and future storm risks. Using observations, climatemodels, and potential intensity theory, this study introduces a novel rapid attribution frameworkthat quantifies the impact of historically-warming North Atlantic SSTs on observed hurricanemaximum wind speeds. The attribution framework employs a storyline attribution approachexploring a comprehensive set of counterfactuals scenarios-estimates characterizing historicalSST shifts due to human-caused climate change-and considering atmospheric variability. Thesecounterfactual scenarios affect the quantification and significance of attributable changes inhurricane potential and observed actual intensities since pre-industrial. A summary of attributableinfluences on hurricanes during five recent North Atlantic hurricane seasons (2019-2023) and acase study of Hurricane Ian (2022) reveal that human-driven SST shifts have already driven robustchanges in 84% of recent observed hurricane intensities. Hurricanes during the 2019-2023 seasonswere 8.3ms-1faster, on average, than they would have been in a world without climate change.The attribution framework's design and application, highlight the potential for this framework tosupport climate communication

Marine heatwaves, increasingly frequent, impact marine ecosystems and services. Still, understanding how temperature affects observed responses remains limited due to complex interactions among temperature, abiotic and biotic factors, and community dynamics. Here we try to fill this gap by exposing simulated plankton communities to seasonal heatwaves of 4°C with a trait- and size-structured model that accounts for protists and the life cycle of copepods. Despite the short lifespans and fast growth rates of plankton, results show that heatwaves affect communities differently and for an extended period up to six years after their appearance. Temperature affects species physiology and ecosystem dynamics, directly and indirectly, shaping structure and biomass. Species traits, interactions, and functional diversity under changing temperatures emerge as pivotal. Our study advances mechanistic insights into marine heatwave impacts, highlighting the complex connections between temperature, species traits, and ecological interactions.

Plankton community structure changes seasonally in response to the annual cycles of stratification, temperature, and primary productivity. These communities also change from year-to-year, in some cases exhibiting persistent regime shifts. How changes in physical conditions structure the plankton community and why conditions persist is a fundamental question in oceanography. Continuous plankton recorders have been used to sample the plankton community across the Gulf of Maine since 1961. Historically, this community has had a classic subarctic structure dominated by Calanus finmarchicus. However, during the 1990s, C. finmarchicus became less prominent, and a more diverse community of smaller copepods emerged. This shift was related to an influx of cold, low-salinity water. We show that a similar community shift occurred around 2012. We use high-resolution hydrographic data to link the shift to an influx of saltier water and warmer conditions. By comparing the 1990s with the recent decade, we develop a synthesis for how physical changes lead to community shifts. Our synthesis suggests that the link between the 1990s and 2010s is enhanced water column stratification. We further propose that ecological interactions link declines in C. finmarchicus with the emergence of the more diverse community, drawing parallels with classic food web ecology.

Ocean temperatures are rising and hit record levels around the world in 2023. While trends are clear and likely strongly connected to human-caused climate change, the oceans also exhibit variability on the daily level, leading to local extremes such as marine heatwaves. We present an operational system to estimate the impact of human-caused climate change on daily sea surface temperatures anywhere in the ocean. This system uses a multi-method approach combining observed trends and paired control/forced climate model runs from CMIP6. Our approach is novel in its flexibility and ease of application for global, daily use for any day since the beginning of the satellite era (1982-2023). The system allows for rapid evaluation for further study of attributable ocean temperatures and real-time communications of attributable ongoing events. We apply the system to well-documented heatwaves in the Tasman Sea, Gulf of Maine, and Mediterranean Sea over the past decade, as well as global conditions in July 2023, to confirm that the system produces estimates consistent with other attribution methods, and to simulate how our system handles interesting events as they are occurring. Each of these events strongly reflected impacts of climate change: their temperatures were consistently made at least four times as likely to occur in our human-influenced climate than in a world without climate change. Meanwhile, in July 2023, almost all ( >70 %) of the ocean's temperatures were made at least twice as likely to occur on any given day. Rapid attribution of daily ocean temperatures provides a pathway for quantifying the influence of climate change on ecological impacts like coral bleaching and on ocean-generated/influenced storms like tropical cyclones.

Capsule summary. Extreme temperatures in the UK (July 2022) and India/Pakistan (Spring 2022) are confidently attributed to climate change using an automated system. Similarly attributable extremes occurred frequently worldwide in 2022.

Oceanographic changes are occurring more rapidly in recent decades, with new implications for ocean ecosystems and adjacent human communities. It is important to bring attention to these changes while they are unfolding rather than after they have occurred. Here we report on a rapid shift toward colder, fresher water in the deep Gulf of Maine that, as of mid-June 2024, has persisted for at least six months. The shift likely represents an influx of Labrador Slope Water and resembles conditions that predated a major warming shift that occurred in 2011–2012. Deep-water oceanographic conditions in the Gulf of Maine have a strong influence on ecosystem dynamics, including the prey of critically endangered North Atlantic right whales, the seasonal and disease dynamics of American lobster, and the distribution and abundance of kelp forest communities, among others. Oceanographic surprises have an important role in this system, and monitoring how this shift unfolds, oceanographically and ecologically, will give new insights into how oceanographic signals can inform our understanding of ecosystem responses.

Anthropogenic warming is altering species abundance, distribution, physiology, and more. How changes observed at the species level alter emergent community properties is an active and urgent area of research. Trait-based ecology and regime shift theory provide complementary ways to understand climate change impacts on communities, but these two bodies of work are only rarely integrated. Lack of integration handicaps our ability to understand community responses to warming, at a time when such understanding is critical. Therefore, we advocate for merging trait-based ecology with regime shift theory. We propose a general set of principles to guide this merger and apply these principles to research on marine communities in the rapidly warming North Atlantic. In our example, combining trait distribution and regime shift analyses at the community level yields greater insight than either alone. Looking forward, we identify a clear need for expanding quantitative approaches to collecting and merging trait-based and resilience metrics in order to advance our understanding of climate-driven community change.

As climate change intensifies, there is a pressing concern regarding how ecological communities respond to disturbances occurring at different intensities and time scales. We explored how the type of disturbance influences the dynamics of a marine community. A pulse disturbance is an abrupt, high-magnitude shift in conditions that can cause immediate and significant impacts to an ecological community. Alternatively, press disturbances are long-term, multi-generational pressures acting on communities over time. The Northeast US Continental Shelf Large Marine Ecosystem (NES LME) is one of the fastest-warming regions in the world and has experienced historic overfishing. Assemblage shifts in the NES LME have previously been characterized; however, these were prior to an unprecedented pulse disturbance marine heatwave (MHW) event in 2012 followed by punctuated MHWs over the last decade. We quantified community change across the NES LME using a community trajectory analysis, a multivariate tool that utilizes geometric analyses and comparisons of community trajectories, to quantify shifts in dynamic beta diversity. We hypothesized that the pulse MHWs would strongly influence ecosystem structure; however, no significant impact was detected. Our analysis indicates that the NES LME continues to tropicalize. However, it was not the pulse MHW events that seemed to drive change but rather ecosystem overfishing and rising temperatures. We quantified beta diversity over time in marine communities undergoing abrupt environmental changes and press disturbances. When expanded globally, this analysis can compare how variable disturbance pressures may result in different manifestations of beta diversity change within marine assemblages.

Ocean waters of the Northeast US continental shelf have warmed rapidly in recent years, with sea surface temperatures rising 2.5 times faster than those of the global oceans. With this strong warming trend, the frequency and duration of marine heatwaves have increased. These temperature changes stood out as a distinct warm temperature regime during the 2010s. During this decade, fish population characteristics also differed from the past. Species distribution shifts were detected for many species, demonstrating one way species could adapt to warming conditions. However, for most species, distribution shifts were insufficient to avoid warmer surface or bottom temperatures. As species occupied warmer habitats, growth patterns aligned with expectations for warming temperatures. Consistent with the temperature-size rule, some species exhibited faster growth at early life stages but plateaued at smaller body sizes; other species, however, experienced reduced growth across all ages, indicating thermal stress. Finally, population productivity indexed by the recruit-to-spawner ratio declined significantly during the 2010s for some populations. Changes in these three processes—distribution, growth, and productivity—indicate the emergence of climate change signals across multiple Northeast US fish populations. These effects create new challenges for fishery managers and industry participants operating in the context of non-stationarity and uncertainty.

Rights-based fisheries management - a management system that apportions harvesting rights of fisheries re-sources to individuals or groups of individuals based on pre-determined allocation criteria - has become more common in the past three decades due to its potential to achieve resource sustainability while improving eco-nomic efficiency. Policies that determine access and allocation of fishing opportunities are often complex as they are designed to achieve multiple management objectives. Climate change alters distribution and productivity of fishery resources, reducing the ability of many of the existing history-dependent allocation policies to achieve the original management objectives. This paper aims to develop an empirically grounded typology of allocation policies, synthesizing practical and academic understanding of fisheries allocation. We examined allocation policies of 54 randomly selected fisheries managed by rights-based management instruments. We use this ty-pology to examine possible climate change impacts and responses on harvester-level allocations. Examining the 54 cases, we find that 89 % of these fisheries allocate fishing opportunities at least partly based on historical catch or access, and only 5 % use socio-economic criteria such as ethnicity or an equal share principle. We find 87 % of the systems are managed by catch quotas, and their ability to meet biological, social, and economic objectives depends on stock assessment quality. Yet, climate-informed stock assessments are critically lacking assessment and quota updates can take multiple years, creating a mismatch in sustainable and realized fishing opportunities. The developed typology and discussions provide useful terminology and lessons for managers and practitioners to prepare for climate challenge impacts.

The great whales (baleen and sperm whales), through their massive size and wide distribution, influence ecosystem and carbon dynamics. Whales directly store carbon in their biomass and contribute to carbon export through sinking carcasses. Whale excreta may stimulate phytoplankton growth and capture atmospheric CO2; such indirect pathways represent the greatest potential for whale-carbon sequestration but are poorly understood. We quantify the carbon values of whales while recognizing the numerous ecosystem, cultural, and moral motivations to protect them. We also propose a framework to quantify the economic value of whale carbon as populations change over time. Finally, we suggest research to address key unknowns (e.g., bioavailability of whale-derived nutrients to phytoplankton, species- and region-specific variability in whale carbon contributions).

Ecosystem forecasting has potential societal value, for industry, recreation, and human health applications to name a few. The complexities of ecological systems, the expenses associated with monitoring them, and the suddenness at which forecasts become needed often make forecasts impractical. We tested a novel rapid spin-up daily forecasting system for jellyfish — Cyanea capillata (lion’s mane jellyfish), Aurelia aurita (moon jellyfish), and Staurostoma mertensii (whitecross jellyfish) — in the Gulf of Maine. The system blended satellite data with citizen reports collected via email and social media. The forecasting system took 1–3 weeks of tuning before performance plateaued, after which forecast performance was consistently high. Good model performance did not always correspond with good forecast performance, and predictor variables whose contribution improved model performance in some cases had the opposite effect on forecast performance. An adaptive learning mode provided a very modest improvement in performance. In a test of forecast range, forecast performance decreased significantly at a forecast range of around 1 week. Overall, the approach appeared to be a promising avenue toward rapid spin-up of forecasts for undermonitored systems.

Greenhouse gas emissions are warming the ocean with profound consequences at all levels of organization, from organismal rates to ecosystem processes. The proximate driver is an interplay between anthropogenic warming (the trend) and natural fluctuations in local temperature. These two properties cause anomalously warm events such as marine heatwaves to occur with increasing frequency and magnitude. Because warming and variance are not uniform, there is a large degree of geographic variation in temporal temperature variability. We review the underappreciated interaction between trend and variance in the ocean and how it modulates ecological responses to ocean warming. For example, organisms in more thermally variable environments are often more acclimatized and/or adapted to temperature extremes and are thus less sensitive to anthropogenic heatwaves. Considering both trend and variability highlights the importance of processes like legacy effects and extinction debt that influence the rate of community transformation.

Human-driven climate change has caused a wide range of extreme weather events to become more frequent in recent decades. Although increased and intense periods of extreme weather are expected consequences of anthropogenic climate warming, it remains challenging to rapidly and continuously assess the degree to which human activity alters the probability of specific events. This study introduces a new framework to enable the production and communication of global real-time estimates of how human-driven climate change has changed the likelihood of daily weather events. The framework's multi-method approach implements one model-based and two observation-based methods to provide ensemble attribution estimates with accompanying confidence levels. The framework is designed to be computationally lightweight to allow attributable probability changes to be rapidly calculated using forecasts or the latest observations. The framework is particularly suited for highlighting ordinary weather events that have been altered by human-caused climate change. An example application using daily maximum temperature in Phoenix, AZ, USA, highlights the framework's effectiveness in estimating the attributable human influence on observed daily temperatures (and deriving associated confidence levels). Global analyses show that the framework is capable of producing worldwide complementary observational- and model-based assessments of how human-caused climate change changes the likelihood of daily maximum temperatures. For instance, over 56 % of the Earth's total land area, all three framework methods agree that maximum temperatures greater than the preindustrial 99th percentile have become at least twice as likely in today's human-influenced climate. Additionally, over 52 % of land in the tropics, human-caused climate change is responsible for at least five-fold increases in the likelihood of preindustrial 99th percentile maximum temperatures. By systematically applying this framework to near-term forecasts or daily observations, local attribution analyses can be provided in real time worldwide. These new analyses create opportunities to enhance communication and provide input and/or context for policy, adaptation, human health, and other ecosystem/human system impact studies.

Fish contribute to the export of carbon out of the euphotic zone. They ingest organic carbon fixed by phytoplankton, store it in their tissues for their lifetime, and contribute to long-term sequestration by producing sinking fecal pellets, respiring at depth, or via their own sinking carcasses. While the flux of carbon through fish is small relative to the export flux by plankton, humans have a direct influence on fish communities and thus on the magnitude of carbon storage and flux. We use a size spectrum model to examine the combined effect of fishing and trophic dynamics on the total carbon stored as biomass of a simulated community of fish. By sampling 10,500 possible fishing strategies that randomize fishing mortality and size-selectivity, we consider optimal strategies that balance several UN Sustainable Development Goals addressing (1) food security, (2) climate action, and (3) marine conservation. The model shows that fishery management strategies that preferentially conserve large species increase overall carbon stored in the fish community. This study presents a perspective for considering carbon storage and sequestration in fisheries management alongside alternative objectives such as food production and biodiversity conservation. Our study focused on the state (total carbon in the living community). Incorporating rate processes like fecal pellet flux, vertical migration, and natural mortality would build toward a more holistic carbon approach to fisheries management.

The Gulf of Maine has recently experienced its warmest 5-year period (2015–2020) in the instrumental record. This warming was associated with a decline in the signature subarctic zooplankton species, Calanus finmarchicus. The temperature changes have also led to impacts on commercial species such as Atlantic cod (Gadus morhua) and American lobster (Homarus americanus) and protected species including Atlantic puffins (Fratercula arctica) and northern right whales (Eubalaena glacialis). The recent period also saw a decline in Atlantic herring (Clupea harengus) recruitment and an increase in novel harmful algal species, although these have not been attributed to the recent warming. Here, we use an ensemble of numerical ocean models to characterize expected ocean conditions in the middle of this century. Under the high CO2 emissions scenario (RCP8.5), the average temperature in the Gulf of Maine is expected to increase 1.1°C to 2.4°C relative to the 1976–2005 average. Surface salinity is expected to decrease, leading to enhanced water column stratification. These physical changes are likely to lead to additional declines in subarctic species including C. finmarchicus, American lobster, and Atlantic cod and an increase in temperate species. The ecosystem changes have already impacted human communities through altered delivery of ecosystem services derived from the marine environment. Continued warming is expected to lead to a loss of heritage, changes in culture, and the necessity for adaptation.

Ocean acidification (OA) is increasing predictably in the global ocean as rising levels of atmospheric carbon dioxide lead to higher oceanic concentrations of inorganic carbon. The Gulf of Maine (GOM) is a seasonally varying region of confluence for many processes that further affect the carbonate system including freshwater influences and high productivity, particularly near the coast where local processes impart a strong influence. Two main regions within the GOM currently experience carbonate conditions that are suboptimal for many organisms—the nearshore and subsurface deep shelf. OA trends over the past 15 years have been masked in the GOM by recent warming and changes to the regional circulation that locally supply more Gulf Stream waters. The region is home to many commercially important shellfish that are vulnerable to OA conditions, as well as to the human populations whose dependence on shellfish species in the fishery has continued to increase over the past decade. Through a review of the sensitivity of the regional marine ecosystem inhabitants, we identified a critical threshold of 1.5 for the aragonite saturation state (Ωa). A combination of regional high-resolution simulations that include coastal processes were used to project OA conditions for the GOM into 2050. By 2050, the Ωa declines everywhere in the GOM with most pronounced impacts near the coast, in subsurface waters, and associated with freshening. Under the RCP 8.5 projected climate scenario, the entire GOM will experience conditions below the critical Ωa threshold of 1.5 for most of the year by 2050. Despite these declines, the projected warming in the GOM imparts a partial compensatory effect to Ωa by elevating saturation states considerably above what would result from acidification alone and preserving some important fisheries locations, including much of Georges Bank, above the critical threshold.