A Tree’s Life is a project to monitor red maple growth in your yard. We even give you the supplies. It’s really just one supply called a dendrometer, and it does most of the work. So if you have a red maple (Acer rubrum) in your yard, and a few minutes of free time per year we would like your help in monitoring the growth of your tree. The objectives of the project are to understand how climate and urbanization affect tree growth and health, and thus ecological services like carbon sequestration and air and water filtration. Despite the importance of mature trees, there is a lack of experiments to measure the effects of warming on tree growth and services. Urban areas are warmer and often have higher CO2 concentrations than their rural counterparts. This means urban trees may grow faster or slower than rural trees, but it also means we can use urban warming as a surrogate for global warming. Cities may be sentinels that predict how plants and animals respond to climate change. Our goal is to measure adult tree growth in urban, suburban, and rural areas with the help of volunteer citizen scientists. We will provide the citizen scientists with a dendrometer, a tool that measures tree trunk growth without injuring the tree (it will need to remain on the tree for at least a year, hopefully longer). We will ask citizen scientists to report tree growth and a few other details about their tree periodically. In return, participants will learn about how their tree compares to others across the country. Although this seems very simple, it provides valuable data to determine how different altitudes, latitudes, and urban conditions affect tree growth and carbon sequestration. Ultimately, we plan to have citizens measuring thousands of trees across the country.