Recent climate change, environmental design, and ecological conservation policies require new and existing urban developments to mitigate and offset carbon dioxide emissions and for cities to become carbon neutral. Some North American models and tools are available and can be used to quantify the carbon offset function of urban trees. But, little information on urban tree carbon storage and sequestration exists from the European Southern Alps. Also, the use of these North American models in Europe has never been assessed. This study developed a protocol to quantify aboveground carbon (C) storage and sequestration using a subsample of urban trees in Bolzano, Italy, and assessed two existing and available C estimation models. Carbon storage and sequestration were estimated using city-specific dendrometrics and allometric biomass equations primarily from Europe and two other United States models; the UFORE (Urban Forest Effects Model) and the CUFR Tree Carbon Calculator (CTCC). The UFORE model carbon storage estimates were the lowest while the CUFR Tree Carbon Calculator (CTCC) C sequestration estimates were the highest. Results from this study can be used to plan, design, and manage urban forests in northern Italy to maximize C offset potential, provide ecosystem services, and for developing carbon neutral policies. Findings can also be used to predict greenhouse gas emissions from tree maintenance operations as well as estimating green waste yield from landscape maintenance activities and its use as biofuel and compost. Managers need to be aware that available models and methods can produce statistically different C storage and sequestration estimates.Keywords: i-Tree Eco; growth rates; allometric equations; ecosystem services; CTCC model Introduction Climate change is one of the most important and pressing environmental, economic, and security issues our world faces today (Barnett 2003;IPCC 2007;Karagiannis & Soldatos 2010). Urban areas are steadily growing throughout the world (Grimm et al. 2008) and by 2030 it is expected that 60% of the world's population will be living in cities (Rydin et al. 2012). Thus, as urban environments become more important as living space for humans, they are an increasing source of carbon emissions.Several studies in North America, China, and Australia (Brack 2002;Zhao et al. 2010;Dobbs et al. 2011;Martin et al. 2012;Roy et al. 2012), and more recently in the United Kingdom and Germany (Davies et al. 2011;Strohbach & Haase 2012;Strohbach et al. 2012), have shown that trees in urban environments remove carbon dioxide from the atmosphere through growth and photosynthesis, and store excess carbon as biomass in roots, stems, and branches. Indirectly, urban trees also reduce building energy used for cooling through their shade and climate amelioration effects, thereby reducing CO 2 emissions from decreased energy production (Akbari et al. 2001).The estimation of tree carbon sequestration depends on species types and their mortality and growth characteristics as well as their overall con...