Carbon dioxide emissions and reductions from storage and avoided emissions from energy savings were simulated for 91,786 trees planted from 2006 to 2010, of which 30,813 (33.6 percent) were estimated to survive. Early results suggest that these plantings are achieving success in terms of survival, growth, and performance. The Los Angeles tree program was estimated to release 17,048 tons and 66,360 tons of fossil and biogenic carbon dioxide respectively over the 40-year period. The total amount emitted (83,408 tons) was slightly more than the -77,942 tons carbon dioxide that trees were projected to store. The largest sources of carbon dioxide emissions were mulch decomposition (65.1percent), wood combustion (14.5 percent) and irrigation water (9.7 percent). However, the Los Angeles tree program will be a carbon dioxide sink if 40-year projections about the avoided fossil fuel carbon dioxide emissions from energy savings (-101,679 tons) and biopower (-1,939 tons) are realized. The research findings suggest that this tree planting initiative, and possibly others, can be net carbon dioxide sinks, especially if trees are strategically located to reduce energy consumed for air conditioning and heating. Forest Service scientists also found that there is ample opportunity to further reduce emissions. Examples include selecting drought tolerant trees and utilizing wood for wood products or to generate electricity instead of for producing mulch.