The workshop on Arctic Urbanization under Environmental Change was held in Helsinki, 14 -15 January 2020. It involved around 20 participants, discussed ways forward to tackle this complex and highly interdisciplinary challenge. The aim of the workshop was to discuss research issues on Arctic urbanization under environmental and climate change from the social science, humanities and natural science perspectives with a focus on establishing a series of studies around the Arctic in cities that represent different environments and conditions. A goal was also to identify potential study locations including possible twin city pairs for cities with similar environmental and geographical profiles.

Following a series of presentations from participants about existing activities, breakout sessions were also organized to discuss connecting research needs on atmospheric, health and urbanization and designing potential city studies. The main highlights are:
- Participants shared information about on-going initiatives examining relevant issues from a) social perspectives including studies of human-environment relations in urban systems and Arctic specific health challenges which may be further affected by climate change and b) natural science perspectives including collection of observations in several Arctic cities to study air pollution or urban heat islands.
- Several suitable cities were identified, often building on existing knowledge or on-going efforts, in northern Russia and Scandinavia. These studies may contribute to the WMO GURME Twin City approach where data collected in cities with similar characteristics is compared/contrasted and used develop strategies for the monitoring and assessment of risks (and opportunities) associated with weather and air pollution in urban environments.
- Studies should bridge across disciplines and actively involve local and indigenous communities and local stakeholders to better understand natural processes and impacts on human health and the environment in urban areas as the climate warms, e.g. changing landscapes with temperatures above zero or people spending more time outside in winter. It will also be important to examine summertime pollution such as fires as well as wintertime anthropogenic pollution and how these sources may change with climate change. Other sources of pollution (water, contaminants) should be considered.

Background: Urbanization is accelerating globally, also in Northern high latitudes. Cities represent a complex and highly dynamic interface between Earth components (atmosphere, land, water etc.) and societal factors (health, social equity, life quality etc.). At the same time, cities are very sensitive to climate change. This vulnerability is strongly pronounced in the Arctic, a region that is warming at twice the rate as the global average, and has direct and indirect impacts on the local livelihoods, infrastructure, water resources, ecology and air quality. Previous studies of urban sensitivity to climate change have mostly focused on lower and mid-latitude cities and rarely considered analysis of Northern/Arctic cities. Due to the particular climatic conditions and societal organization Northern cities embrace many challenges in the advancement of knowledge about physical, chemical, ecological, socio-economic and environmental change, their relationships and implications for the human-environment system. Some of the important issues that require in-depth studies include the effects of urban meteorology such as heat islands and the interactions of stably stratified boundary layers with urban air pollution episodes in a changing climate. Moreover, due to the cold weather conditions, high-energy consumption is typical of Northern cities. With limited potential for renewable energy generation, adopting sustainable life styles is of particular challenge. In the Arctic, particularly considering the present status, indigenous communities and population level, the urbanization process involves a large spectrum of settlements of various sizes. In order to understand the social-environmental effects of urbanization under rapid climate change a multi-scale approach is necessary in order to be beneficial to the whole Arctic society. A first initiative has been started in Fairbanks, Alaska, together with the international initiative Air Pollution in the Arctic: Climate, Environment and Society (PACES), the University of Alaska Fairbanks (UAF) and further collaborators. The study is called ‘Alaskan Layered Pollution And Chemical Analysis’ project (ALPACA) and aims to understand wintertime (dark, cold) smog formation and its implications for human health (https://alpaca.community.uaf.edu/).

This workshop was organized as part of an IASC Cross-Cutting Initiative on Arctic urbanization and sustainable development (involving AWG, SHWG, TWG). It was co-organized by the international initiative Air Pollution in the Arctic: Climate, Environment and Society (PACES), the Pan Eurasian Experiment (PEEX) and the World Meteorological Organization’s Global Atmospheric Watch Urban Research Meteorology and Environment project (WMO-GURME).