Summary

The production of the climate change adaptation plan for Magog result from the 241-2020 resolution adopt unanimously by the municipal council on June 1st 2020. The latter wish to follow up to reports from the Federation of Canadian Municipalities and the Union des Municipalités du Québec on the climate question. Both reports are unanimous, the inaction towards this challenge is expensive and put at risk public health and infrastructure. The conclusions of this plan and the approval of its execution have been endorsed unanimously by the municipal council with the 472-2020 resolution.

The consultation of various stakeholders confirmed the significance of climate change adaptation. An online survey who gathers more than 300 answers from citizens reveals that 97 % of them wish that adaptation strategies are put in place. The protection of natural environment was the most popular option with 82 % of support. The consulted environmental organizations also raise the importance of protecting natural environment and biodiversity. The consulted divisions within the city underlined the anticipate increased cost associated with climate change but was unable to quantify it due to a lack of data.

Magog city is already affected by an increase in temperature. About the third of its population lives in an urban heat island, which amplifies the problem. Regarding precipitation, the annual quantity only increases slightly, but the number of heavy precipitations is increasing. More than 8 % of the real estate assessment is in a flood zone, which makes it a current challenge. Droughts and freeze-thaw cycle are also a problem. Lyme disease and ragweed is also significant in the region.

All the current tendency will be exacerbated in the future. For instance, by 2050, the maximal temperature will increase by 3 °C if the trend continues. The peak flow for the Magog river will increase by 7 % and the minimum flow will decrease by 42 %, which means a wide variety in the precipitation scheme that will require a good management of droughts and heavy precipitations.

Among the evaluated adaptation strategies, there was the protection of wetlands and natural environments, the protection of biodiversity, the greening of urban spaces, the continuation of the protection of riparian buffer stripes, the promotion of green infrastructure, the use of white roofs, the optimization of rainwater management, the continuation of the program to monitor the conformity of the rain gutter and the sampling of water streams, as well as improving the culvert management and the initiatives to save drinkable water.

A hierarchy of those strategies was necessary. Their assessment is usually done with a risk matrix. However, this traditional method was not deem discriminating enough and too broad to take well-informed decisions. The use of a vulnerability assessment was favoured. The formula V = S – AC was used, where V is the vulnerability, S the sensitivity and AC the adaptive capacity. With this approach, it was possible to include the budget, the strategy efficacy and the number of people affected by the strategy in the adaptive capacity variable.

The most effective strategy according to this assessment is the protection of wetlands, riparian buffer stripe, biodiversity and natural environment. All the other strategies have their uses, but they are either costly to deploy on the whole territory (green infrastructure and grey infrastructure) or have a more limited effectiveness in regards of co-benefits (gutter conformity that manages only rainwater, etc.). The adaptation plan has objectives to reach by 2030 to become a more resilient city to climate change and to hazards in general. In order to reach those objectives, the city must, among other things:

• Include every stakeholder in the adaptation strategies, with the citizen at the heart of its preoccupations.
• Understand the sanitary and economic impacts of climate change, and the urge to act.
• Acknowledge that environmental externalities cause economic losses in the long run, especially in a context of climate change. Therefore, all development projects must consider environmental externalities compared to anticipate economic gains to make sure of the profitability of those.
• Prioritize natural environment protection, and especially wetlands, because this measure is the most advantageous to adapt to climate change and decrease its sanitary impacts.
• Publish the technical document on climate change adaptation to contribute to the advancement of knowledge and to help other municipalities. In addition, vulgarize information must be communicated to the public.
• Improve data collection in the field and encouraged scientific research on climate change in order to take well-informed decision that rely on the best evidence-based fact as possible.
• Establish a strategy to integrate green infrastructure in the city development.