Ash leaves come in pairs. Chicago’s urban forest is in trouble. By Marjorie Isaacson Due to infection by the emerald ash borer, the majority of Chicago's ash trees will die. East Village residents are fundraising to treat ash trees. Chicago has about 20% tree coverage, far below the national average. The city’s tree inventory includes 43,000 green and white ash trees, a major segment of that population. Due to infection by the emerald ash borer, the majority of these trees will die. Trees provide many benefits: cleaning air and water, cooling temperatures in the summer and contributing to human physical and psychological health. Trees also remove carbon dioxide from the air. Preserving and adding to the urban forest is one of the primary strategies in Chicago’s climate change mitigation plans. To make this happen, Chicago has embarked on a massive tree-planting campaign. But while these new trees are a good investment in the future, it will be many years until they reach the si