Mesoscale ocean eddies, an important element of the climate system, impact ocean circulation, heat uptake, gas exchange, carbon sequestration and nutrient transport. Much of what is known about ongoing changes in ocean eddy activity is based on satellite altimetry; however, the length of the altimetry record is limited, making it difficult to distinguish anthropogenic change from natural variability. Using a climate model that exploits a variable-resolution unstructured mesh in the ocean component to enhance grid resolution in eddy-rich regions, we investigate the long-term response of ocean eddy activity to anthropogenic climate change. Eddy kinetic energy is projected to shift poleward in most eddy-rich regions, to intensify in the Kuroshio Current, Brazil and Malvinas currents and Antarctic Circumpolar Current and to decrease in the Gulf Stream. Modelled changes are linked to elements of the broader climate including Atlantic meridional overturning circulation decline, intensifying Agulhas leakage and shifting Southern Hemisphere westerlies.

<p>Mesoscale ocean eddies impact atmosphere-ocean gas exchange, carbon sequestration, and nutrient transport. Studies have attempted to identify trends in eddy activity using satellite altimetry; however, it is difficult to distinguish between robust trends and natural variability within the short observational record. Using a novel climate model that exploits the variable-resolution capabilities of unstructured meshes in the ocean component to concentrate computational resources in eddy-rich regions, we assess global mesoscale eddies and their long-term response to climate change at an unprecedented scale. The modeled results challenge the significance of some trends identified by observational studies, as well as the effectiveness of linear trends in assessing eddy kinetic energy (EKE) change. Some anticipated changes to ocean circulation, such as a poleward shift of major ocean currents and eddy saturation in the Southern Ocean, are reinforced by the modeled EKE changes. Several novel insights regarding the evolution of EKE in a warming world are also proposed, such as a decrease of EKE along the Gulf Stream in unison with weakening Atlantic meridional overturning circulation (AMOC); increasing Agulhas leakage; and accelerating, non-linear increases of EKE in the basins of the Kuroshio Current, Brazil and Malvinas Currents, and the Antarctic Circumpolar Current (ACC).</p>

Grape growth and wine production are both closely connected with weather and climate, making anthropogenic climate change a source of great uncertainty for the grape and wine industries. To assess the impacts of climate change on viticulture and oenology in the Fraser Valley, British Columbia, Canada, where no such assessment has been published to this date, a series of key indicators and critical thresholds were selected based on their relevance to the local climatology. Trends among these indicators and thresholds were calculated over a historic period (1970-2019) and projected over the 21st century for one intermediate-emissions and one high-emissions climate change scenario. Historic trends were assessed using Environment and Climate Change Canada weather station data from Abbotsford, British Columbia. Two statistical downscaling methods were evaluated based on their ability to reproduce observed conditions in the Fraser Valley and the most effective method was used to create projections of local, daily climate change scenarios. During the historic period, temperatures increased significantly, while precipitation and moisture variables displayed insignificant trends, reflecting the trends observed across other wine regions in Canada and the Northwestern United States. Throughout the 21st century, warming is expected to continue while precipitation decreases modestly. Extreme heat is projected to become far more frequent, while extreme cold and potential frost days become rare. In the short term, modifications to vineyard and winery operations may be sufficient adaptation strategies. Over the long term, new grape varieties will most likely need to be planted in existing vineyards and suitability for cool-climate varieties may shift northward in direction or upward in elevation.

This study further develops and finally validates the Climate Model Confidence Index (CMCI) as a simple and effective metric for evaluating and ranking the ability of climate models to reproduce historical climate conditions. Modelled daily climate data outputs from two different statistical downscaling techniques (PCIC: Pacific Climate Impacts Consortium; SDSM: Statistical Down-Scaling Model) are compared with observational data recorded by Environment Canada weather stations located in Kelowna, BC (Canada), for the period from 1969 to 2005. Using daily data (N > 13,000), Student’s t-tests determined if there were statistically significant differences between the modelled and observed means while ANOVA F-tests identified differences between variances. Using aggregated annual data (N = 37), CMCI values were also calculated for the individual model runs from each statistical downscaling technique. Climate model outputs were ranked according to the absolute value of the t statistics. The 20 SDSM ensembles outperformed the 27 PCIC models for both minimum and maximum temperatures, while PCIC outperformed SDSM for total precipitation. Linear regression determined the correlation between the absolute value of the t statistics and the corresponding CMCI values (R2 > 0.99, P < 0.001). Rare discrepancies (< 10% of all model rankings) between the t statistic and CMCI rankings occurred at the third decimal place and resulted in a one rank difference between models. These discrepancies are attributed to the precision of the t tests which rely on daily data and consider observed as well as modelled variance, whereas the simplicity and utility of the CMCI are demonstrated by only requiring annual data and observed variance to calculate.