Field data from 10 USA cities and national urban tree cover data, it is estimated that urban trees in the coterminous USA currently store 700 million tonnes of carbon ($14,300 million value) with a gross carbon sequestration rate of 22.8 million tC/yr ($460 million/year).
Crane, D.E., and Nowak, D.J. (2002). Carbon Storage and sequestration by urban trees in the USA. Environmental Pollution, 116, 381-389.View Resource