William A. Gough

The Dynamic Multiscale Nature of Climate Change Vulnerability: An Inuit Harvesting Example

This article advances a vulnerability framework to understand how climatic risks and change are experienced and responded to by Inuit harvesters using a case study from Iqaluit, Nunavut. The article makes important contributions to methodological design in vulnerability studies, emphasizing the importance of longitudinal study design, real-time observations of human–environment interactions, community-based monitoring, and mixed methods. Fieldwork spanned five years, during which sixty-four semistructured interviews were conducted and historical records examined to develop an understanding of the processes and conditions affecting vulnerability. A local land use monitoring team was established, collecting ∼22,000 km of land use Global Positioning System (GPS) data and engaging in biweekly interviews (more than 100) on exposure, sensitivity, and adaptive capacity. This was complemented by analysis of instrumental data on sea ice and climate conditions. Results indicate that sea ice conditions are changing rapidly and affecting trail conditions, safety, and access to harvesting grounds. GPS data and biweekly interviews document real-time adaptations, with traditional knowledge and land-based skills, resource use flexibility, and mobility underpinning significant adaptability, including utilizing new areas, modifying trail routes, and taking advantage of an extended open water season. Sociospatial reorganization following resettlement in the 1950s and 1960s, however, has created dependency on external conditions, has reduced the flexibility of harvesting activities, and has affected knowledge systems. Within the context of these “slow” variables, current responses that are effective in moderating vulnerability could undermine adaptive capacity in the long term, representing overspecialized adaptations, creating the potential for further loss of response diversity and flexibility, and engendering potential downstream effects, creating trajectories of maladaptation. These findings challenge previous research that has argued that current resilience of the Inuit socioecological system is indicative of high adaptive capacity to future change and indicates that climate change might pose more serious risks to the harvesting sector than previously assumed.

Characterization and estimation of urban heat island at Toronto: impact of the choice of rural sites

In this study, the urban heat island of Toronto was characterized and estimated in order to examine the impact of the selection of rural sites on the estimation of urban heat island (UHI) intensity (∆Tu-r). Three rural stations, King Smoke Tree (KST), Albion Hill, and Millgrove, were used for the analysis of UHI intensity for two urban stations, Toronto downtown (Toronto) and Toronto Pearson (Pearson) using data from 1970 to 2000. The UHI intensity was characterized as winter dominating and summer dominating, depending on the choice of the rural station. The analyses of annual and seasonal trends of ∆Tu-r suggested that urban heat island clearly appears in winter at both Toronto and Pearson. However, due to the mitigating effect on temperature from Lake Ontario, the estimated trend of UHI intensity was found to be less at Toronto compared to that at Pearson which has no direct lake effect. In terms of the impacts of the rural stations, for both KST and Millgrove, the trends in UHI intensity were found to be statistically significant and also were in good agreement with the estimates of UHI intensities reported for other large cities in the USA. Depending on the choice of the rural station, the estimated trend for the UHI intensity at Toronto ranges from 0.01°C/decade to 0.02°C/decade, and that at Pearson ranges from 0.03°C/decade to 0.035°C/decade during 1970–2000. From the analysis of the seasonal distribution of ∆Tu-r, the UHI intensity was found to be higher at Toronto in winter than that at Pearson for all three rural stations. This was likely accounted for by the lower amount of anthropogenic heat flux at Pearson. Considering the results from the statistical analysis with respect to the geographic and surface features for each rural station, KST was suggested to be a better choice to estimate UHI intensity at Toronto compared to the other rural stations. The analysis from the current study suggests that the selection of a unique urban–rural pair to estimate UHI intensity for a city like Toronto is a critical task, as it will be for any city, and it is imperative to consider some key features such as the physiography, surface characteristics of the urban and rural stations, the climatology such as the trends in annual and seasonal variation of UHI with respect to the physical characteristics of the stations, and also more importantly the objectives of a particular study in the context of UHI effect.

The influence of tropospheric ozone on the air temperature of the city of Toronto, Ontario, Canada

Weekday/weekend variations in tropospheric ozone concentrations were examined to determine whether ground-level greenhouse gases have a significant impact on local climate. The city of Toronto, Canada, was chosen due to a high volume of commuter traffic and frequent exposure to high ozone episodes. Due to day-of-the-week variations in commuter traffic, ozone concentrations were shown to vary significantly between weekdays and weekends. During high ozone episodes weekend air temperatures were significantly higher than those observed on weekdays. As no meteorological phenomenon is known to occur over a 7 day cycle the observed temperature variations were attributed to anthropogenic activity.

Parameter space exploration of an ocean general circulation model using an isopycnal mixing parameterization

ABSTRACT In this study we have employed statistical methods to efficiently design experiments and analyze output of an ocean general circulation model that uses an isopycnal mixing parameter- ization. Full ranges of seven inputs are explored using 51 numerical experiments. Fifteen of the cases fail to reach satisfactory equilibria. These are attributable to numerical limitations specific to the isopycnal model. Statistical approximating functions are evaluated using the remaining cases to determine the dependency of each of the six scalar outputs on the inputs. With the exception of one output, the approximating functions perform well. Known sensitivities, particularly the importance of diapycnal (vertical) eddy diffusivity and wind stress, are reproduced. The sensitivities of the model to two numerical constraints specific to the isopycnal parameterization, maximum allowable isopycnal slope and horizontal back- ground eddy diffusivity, are explored. Isopycnal modelling issues, convection reduction and the Veronis effect, are examined and found to depend crucially on the isopycnal modelling constraints.

Hydro-Climatic Trends in the Hudson Bay Region, Canada

Long-term streamflow time series were analysed to provide evidence of climate change in the Hudson Bay region. We also investigated whether relationships exist between streamflow and proximal temperature and precipitation time series. The Mann-Kendall test for trend reveals an earlier occurrence of the spring peak flow in three rivers flowing into southern Hudson Bay, with a statistically-significant warming trend for spring temperature. In the northwestern Hudson Bay region, precipitation has significantly increased in all seasons, resulting in increasing trends in the discharge of the Kazan River. In contrast, a decrease in river discharge was detected in central Manitoba, because of warmer temperatures and less abundant rainfall. On the east side of Hudson Bay, statistically-significant streamflow trends were detected for individual months, but temporally and spatially coherent patterns could not be identified. This study of the Hudson Bay streamflow provides evidence of climate change using streamflow and climate data in the Hudson Bay region over the past century. The climate change signal is not spatially uniform and is obscured when the Hudson Bay basin is treated as a single large region.

Interannual Variability of Hudson Bay Ice Thickness

Seasonal sea ice in Hudson Bay plays a key role in determining the regional climatology. In this paper, the relationship between ice thickness with local surface air temperature and snow depth is explored at nine locations in the Hudson Bay region. A weak but statistically significant correlation was found between basin averaged ice thickness and concurrent surface air temperature. At the local scale, however, ice thickness correlated well with winter air temperature at only three measuring sites, explaining the poor relationship at the basin scale. A relationship was also identified between winter ice thickness and previous summers air temperatures at two measuring sites, suggesting that preconditioning of Hudson Bay waters may play a significant role in sea-ice formation in some subregions of Hudson Bay. Simple and multiple linear regression analyses indicate that at the majority of the measuring sites, snow depth is a more important contributor to the inter-annual variability of ice thickness than winter air temperatures. The results of this study have important implications regarding the use of landfast ice thickness data to detect an early climate change signal over Hudson Bay.

Tourism climatology for camping: a case study of two Ontario parks (Canada)

Climate and weather act as central motivators for the travel decisions of tourists. Due to their seasonality, these factors determine the availability and quality of certain outdoor recreational activities. Park visitation in Ontario, Canada, has been identified as a weather sensitive tourism and recreation activity. This study used a survey-based approach to identify and compare stated weather preferences and thresholds, as well as weather-related decision-making for campers at two provincial parks in Ontario, Canada. The two parks were selected for differing physical and environmental characteristics (forested lake versus coastal beach). Statistically significant differences were detected between the two parks in relation to the importance of weather and weather-based decision-making. Specific temperatures that were considered ideal and thresholds that were too cool and too warm were identified for both parks, both during the day and the night. Heavy rain and strong winds were the most influential factors in weather-related decision-making and on-site behavioural adaptations. Beach campers placed greater importance on the absence of rain and the presence of comfortable temperatures compared to forest campers. In addition, beach campers were more likely to leave the park early due to incremental weather changes. The results of this study suggest that beach campers are more sensitive to weather than forest campers.

The Influence of El Niño–Southern Oscillation on Tropical Cyclone Activity in the Eastern North Pacific Basin

AbstractThe interannual variability of tropical cyclone (TC) activity due to El Nino–Southern Oscillation (ENSO) in the main development region of the eastern North Pacific basin has received scant attention. Herein the authors classify years of El Nino, La Nina, and neutral conditions using the multivariate ENSO index (MEI). Storm measurements of the net tropical cyclone activity index and power dissipation index are used to summarize the overall seasonal TC activity and TC intensity between 1971 and 2012. Both measures are found to be statistically dependent on the ENSO phases in the basin’s main development region. However, when the area is longitudinally divided, only the western portion of the development region experienced a significant difference (p < 0.05). Specifically, El Nino years are characterized by more frequent, more intense events compared to La Nina conditions for this subregion. Correlation analyses on the relationships between the MEI and both TC indices demonstrate correlations betwee...

Examining past temperature variability in Moosonee, Thunder Bay, and Toronto, Ontario, Canada through a day-to-day variability framework

Temperature variability in Moosonee, Thunder Bay, and Toronto, Ontario, Canada is examined through a day-to-day variability framework. Statistical measures used in this study include standard deviation (SD), day-to-day temperature variability (DTD), DTD/SD ratio (G), change in day-to-day variability (ΔDTD), and threshold measures of 5°C and 10°C. ΔDTD is the difference between day-to-day change in temperature maximum (DTDtmax) and day-to-day change in temperature minimum (DTDtmin). A distinct seasonal trend is reflected in DTD in Moosonee, Thunder Bay, and Toronto, where ΔDTD is greatest during spring. Monthly ΔDTD averages in Toronto, Thunder Bay, and Moosonee are affected by seasonal variation, the lake effect, and the freeze-up of nearby waterbodies. Yearly averages of ΔDTD have significantly increased over the past recent years in Moosonee and Thunder Bay; a continual increase in climate variability may be detrimental to the subsistence lifestyle of those living in these areas.

Isopycnal mixing and the Veronis effect in an ocean general circulation model

In this study we have run a number of numerical simulations to examine the «Veronis effect» in an ocean general circulation model. This effect is characterized by anomalous interior downwelling, east of the western boundary current of an ocean basin. The impact of varying the horizontal diffusivity and the use of an isopycnal mixing parameterization are examined. Several diagnostics are used. The net volume transport for a sector in the southern part of the domain, east of the western boundary is found to be the clearest indicator of the strength of the Veronis effect. This effect is found to depend crucially on the horizontal diffusivity. The use of an isopycnal mixing parameterization significantly mitigates the interior downwelling problem but is constrained by the required use of a background horizontal diffusivity. Thus, in a geopotential coordinate model an isopycnal mixing parameterization enables the use of a significantly reduced horizontal diffusivity while emphasizing the mixing along isopycnals