• Energy Research

Abstract Maintaining coral reef ecosystems is a social imperative, because so many people depend on coral reefs for food production, shoreline protection, and livelihoods. The survival of reefs this century, however, is threatened by the mounting effects of climate change. Climate mitigation is the foremost and essential action to prevent coral reef ecosystem collapse. Without it, reefs will become extremely diminished within the next 20–30 years. Even with strong climate mitigation, however, existing conservation measures such as marine protected areas and fisheries management are no longer sufficient to sustain the ecosystem and many additional and innovative actions to increase reef resilience must also be taken. In this paper we assess the suite of protections and actions in terms of their potential to be effective according to a set of criteria that include effectiveness, readiness, co-benefits and disbenefits. Even with the best scientific innovation, saving coral reefs will require a well-funded, well-designed, and rapidly executed strategy with political and social commitments at the level of other grand challenges.

AbstractMarine life is controlled by multiple physical and chemical drivers and by diverse ecological processes. Many of these oceanic properties are being altered by climate change and other anthropogenic pressures. Hence, identifying the influences of multifaceted ocean change, from local to global scales, is a complex task. To guide policy‐making and make projections of the future of the marine biosphere, it is essential to understand biological responses at physiological, evolutionary and ecological levels. Here, we contrast and compare different approaches to multiple driver experiments that aim to elucidate biological responses to a complex matrix of ocean global change. We present the benefits and the challenges of each approach with a focus on marine research, and guidelines to navigate through these different categories to help identify strategies that might best address research questions in fundamental physiology, experimental evolutionary biology and community ecology. Our review reveals that the field of multiple driver research is being pulled in complementary directions: the need for reductionist approaches to obtain process‐oriented, mechanistic understanding and a requirement to quantify responses to projected future scenarios of ocean change. We conclude the review with recommendations on how best to align different experimental approaches to contribute fundamental information needed for science‐based policy formulation.

The three recent Special Reports of the IPCC provide an opportunity to understand overarching climate risk, as they cover a wide diversity of risks to natural and human systems. Here we develop a scoring system to translate qualitative IPCC risk assessments into risk scores that, when aggregated, describe global risk from climate change. By the end of this century, global climate risk will increase substantially with greenhouse gas emissions compared to today (composite risk score increase of two- and fourfold under RCP2.6 and RCP8.5, respectively). Comparison of risk levels under +1.5 degrees C and +2 degrees C suggests that every additional 0.5 degrees C of global warming will contribute to higher risk globally (by about a third). Societal adaptation has the potential to decrease global climate risk substantially (by about half) under all RCPs, but cannot fully prevent residual risks from increasing (by one-third under RCP2.6 and doubling under RCP8.5, compared to today).Different frameworks, most notably expert assessments from the IPCC, have been developed to determine risk from climate change over this century. Estimated risk scores quantified from the IPCC assessments show a substantial increase in global composite risk by 2100 for low and high emissions.

Arctic marine ecosystems are experiencing rapid environmental change with respect to warming. This is leading to an increased frequency, duration, and intensity of marine heatwaves. The impact of these stochastic heatwave events have the potential to negatively effect temperature-sensitive, habitat forming, kelp, that exist in the lower Arctic region. We tested the potential impacts of two heatwave events on mixed kelp communities occurring in the lower Arctic by conducting a 1-month ex situ mesocosm experiment in Tromsø, Norway. Each mesocosm was stocked with ~ 2.5 kg fw (fresh weight) of kelp, 200 g fw of snails and mussels, and ~ 750 g of sea urchins. Three experimental conditions were tested: a constant high temperature which was + 1.76°C above a dynamic control, and two heatwave scenarios. Scenario 1 was a long duration at + 2.8°C above the control for 2 weeks, and scenario 2 was a high frequency and magnitude treatment with conditions + 3.8°C above the control. This occurred at two peaks that were one weak apart and returned to + 1.76°C in-between. Three-hour incubations were performed to examine net community productivity (NCP) for the mixed kelp communities. We identified that both heatwave scenarios diminished the total gross production over the experimental period compared to the control and between scenario 1 and scenario 2. Scenario 1 appeared to exhibit the lowest total gross community production over the experimental period.

Further descriptions:* Treatment is the assigned condition: C0, C1, C2, C3 with M0 - M2 as replicates * ID is the tag number assigned to every individual kelp

Arctic marine ecosystems are experiencing rapid environmental changes with respect to warming, ice melt, and terrestrial run-off. The effects of these perturbations can act as multi-stressors where warming sea seawater, in combination with freshening from ice melt, and increased turbidity from terrestrial run-off affect benthic community structure and function. To examine the effects of warming, freshening, and turbidity on habitat forming macroalgae, we conducted a 2-month long ex situ experiment on mixed Arctic kelp communities in Ny-Ålesund, Svalbard from 03/07/2021 - 26/08/2021. Three experimental conditions (with 3x replicates) were tested against a dynamic real-time control where temperature was increased by + 3.3 and + 5.3 °C, salinity was reduced by ~ 4 and ~ 5, and irradiance was statically attenuated by ~ 25 and 40 % in 2 treatments. The third treatment was only warmed by + 5.3 °C from the control. In each 1 m³ mesocosm, oxygen (% O2), temperature, salinity, and photosynthetically active radiation (PAR) were continuously monitored. Mixed kelp communities comprised a biomass of ~ 4 kg fw (fresh weight) and ~ 500 g fw of small fauna. Weekly incubations were performed to calculate net community productivity (NCP) and used to estimate kelp benthic metabolism. We determined non-significant differences across treatments and provide NCP rates for mixed kelp communities in the Arctic.

Arctic marine ecosystems are experiencing rapid environmental changes with respect to warming, ice melt, and terrestrial run-off. The effects of these perturbations can act as multi-stressors where warming sea seawater, in combination with freshening from ice melt, and increased turbidity from terrestrial run-off affect benthic community structure and function. To examine the effects of warming, freshening, and turbidity on habitat forming macroalgae, we conducted a 2-month long ex situ experiment on mixed Arctic kelp communities in Ny-Ålesund, Svalbard from 03/07/2021 - 26/08/2021. Three experimental conditions (with 3x replicates) were tested against a dynamic real-time control where temperature was increased by + 3.3 and + 5.3 °C, salinity was reduced by ~ 4 and ~ 5, and irradiance was statically attenuated by ~ 25 and 40 % in 2 treatments. The third treatment was only warmed by + 5.3 °C from the control. In each 1 m³ mesocosm, oxygen (% O2), temperature, salinity, and photosynthetically active radiation (PAR) were continuously monitored. Mixed kelp communities comprised a biomass of ~ 4 kg fw (fresh weight) and ~ 500 g fw of small fauna. Weekly incubations were performed to calculate net community productivity (NCP) and used to estimate kelp benthic metabolism. We determined non-significant differences across treatments and provide NCP rates for mixed kelp communities in the Arctic.