Urban forests include developed sites adjacent to streets and buildings, parks, residential areas, and schools, as well as natural areas designated as preserves and large urban wooded areas.
Urban forestry can be an important mechanism for increasing stored carbon as trees in urban areas can have significant biomass and carbon sequestration (Nowak et al. 2013). Carbon sequestration rates in individual trees within urban areas can exceed those in natural forests due to greater foliar biomass and reduced competition from lower tree densities, as well as irrigation and fertilization (Jo and McPherson 1995)—and a changing climate may be further accelerating these growth rates in urban areas (O’Brien et al. 2012; Pretzsch et al. 2017). Trees can have an additional important influence on carbon mitigation in urban zones by reducing the energy requirements for building heating in winter due to wind protection and summer cooling from tree shading (Nowak et al. 2010).
Examples of adaptation tactics are:
- “Greening” areas that currently have low canopy cover by adding street trees and other vegetation
- Strategic planting of trees to provide building shading or cooling benefits
- Creation of parks and green spaces on abandoned or underutilized spaces, such as brownfields
- Integration of trees as part of low-impact development or storm water runoff projects
Trees can remove CO2 and greenhouse gases from the atmosphere. Planting more trees in cities can help mitigate the effects of climate change but the emissions of CO2 and greenhouse gases also need to be reduced.
Scientists agree that we can best put the brakes on climate change by doing two things:
- Immediately cutting back carbon emissions.
- Developing a workable system for pulling excess carbon from the atmosphere using currently available technology. The most realistic approach appears to be the planting of more trees.
The Benefits of Urban Forests to Remove CO2 and Help Mitigate Climate Change
The term "urban forest" refers to all trees within a densely populated area, including trees in parks, on streetways, and on private property.
Carbon capture and energy savings:
Urban forests-like any forest-help mitigate climate change by capturing and storing atmospheric carbon dioxide during photosynthesis, and by influencing energy needs for heating and cooling buildings; trees typically reduce cooling costs, but can increase or decrease winter heating use depending on their location around a building and whether they are evergreen or deciduous. In the contiguous United States alone, urban trees store over 708 million tons of carbon (approximately 12.6% of annual carbon dioxide emissions in the United States) and capture an additional 28.2 million tons of carbon (approximately 0.05% of annual emissions) per year (8, 9). The value of urban carbon sequestration is substantial: approximately $2 billion per year, with a total current carbon storage value of over $50 billion (8). Shading and reduction of wind speed by trees can help to reduce carbon emissions by reducing summer air conditioning and winter heating demand and, in turn, the level of emissions from supplying power plants (10). Information from Urban Forests and Climate Change - US Forest Service - USDA.