Even on the background of the amplified arctic warming, this heat pollution has created permanent urban heat islands (UHIs) where urban temperatures are by one-two degrees higher than those in the surrounding areas. Distinct to mid- and low-latitudes, such pronounced UHIs in the arctic are found even in small settlements like Longyearbyen, Svalbard with 2500 inhabitants.

Although the arctic UHIs are known for decades, it has been overlooked that many of them exist long enough for vegetation, land cover patterns and local ecosystems as whole to adapt to the warmer micro-climates. This adaptation opens windows of opportunity to empirically resolve at least some critical debates about the magnitude and structure of suggested feedbacks between vegetation, hydrology, permafrost and essential climate variables (Blok et al., 2010). Combination of high-resolution in-situ, satellite, reanalysis climate data with biological productivity indices and high-resolution three-dimensional process modelling, as proposed in HIARC, will help to estimate the environmental impact of the heat pollution and urbanization. It will also help to calibrate/restructure the land cover and dynamic vegetation modules used to simulate the pan-arctic climate change on the adaptation time scales up to 2050 and beyond (Zhang et al., 2013). This targeted combination of high-resolution data sources is rather unexplored as such resources became available only recently and the previous research has been biased towards pan-arctic but low-resolution assessments.

The anthropogenic heat pollution as an important environmental factor has not yet received necessary attention in the research studies. High-profile Law & Stohl (2007) review discussed chemical but not heat pollution. This is not surprising if we account for the fact that the theoretical understanding of the amplified polar climate response mechanisms began to emerge only in recent years. These mechanisms link static stability of the lower atmosphere (Esau et al., 2012; Zilitinkevich et al., 2013) and broader integral effects in physical environment (reduced freezing in permafrost in wintertime, dryer surface soil layer in summertime, etc.) into a feedback chain sustaining micro-climate changes. This chain proliferates initially very localized urban effects over larger areas.

The anthropogenic heat pollution in the arctic is caused by its urbanization and industrialization mostly driven by migrants (Bogoyavlenskiy & Siggner, 2004; Glomsrød & Aslaksen, 2006). At present, more than 85% of the total arctic population of 4 million people are living in cities. From 50% to 92% of them (depending on country) are migrants from southern territories. The migrants are attracted by jobs. In the severe arctic climates, migrants recreate resemblance of their southern environment, building wind sheltering urban architecture, planting trees and implementing convenient construction technologies. These practices improve city comfort (and hence lower labour price tag) but in longer perspective exacerbate heat pollution and warming of micro-climates. These longer and more geographically distributed effects have been so far studied very little if at all. Rather, the attention was focussed on minimization of immediate local effects (e.g. permafrost thaw under the buildings) on infrastructure (Streletskiy et al., 2012). HIARC will bring these effects into focus looking at three levels of human-environment interactions in selected urbanized areas. At the individual level, we will study adaptation of bio-medical responses among migrants and the heat pollution from infrastructural objects. At the community level, we will study the urban dynamics, socio-cultural development and conflicts caused by changes in micro-climates. At the regional level, we will study feedbacks between environmental and climate changes over the recent decades and in the longer historical perspective.