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Slow global climate change
Support Evergreen Cities legislation in Washington, and take individual action at home.

Global warming is the increase in Earth's surface temperatures, which have been rising at an alarming rate.

According to the Intergovernmental Panel on Climate Change, there is ninety percent agreement among scientists that global warming is caused by human activity — namely, an increase in the amount of carbon dioxide, methane, and other heat-trapping "greenhouse" gases in the atmosphere. The situation has been intensified by the extensive replacement of trees in cities with impervious blacktop and other surfaces.

We can help slow global warming if counties, cities, and towns maintain and increase our urban forests, as called for by the Evergreen Cities Act – legislation that Audubon supported and that became law in 2008. Urban forests help offset climate change by capturing atmospheric carbon dioxide in their tissues, known as “carbon sequestration.” Trees planted around buildings also help reduce the amount of energy required to heat and cool our structures.

The potential benefits of large, healthy urban forests include:

Water Quality Protection. City trees capture rainfall on their leaves and branches and take up water through their roots, acting as natural stormwater capture and retention devices. This natural stormwater management could save Washingtonians more than $2.4 billion that otherwise would have to be handled by tax-supported public works projects.

Improved Air Quality. City trees remove dust and other pollutants from the air. In fact, one mature tree can remove 26 pounds of carbon dioxide from the atmosphere annually – the equivalent of 11,000 miles of car emissions!

Natural Resource Conservation. Because trees modify temperatures around buildings, the amount of fossil fuels required to cool and heat homes and businesses would be reduced.

Healthier Wildlife and Human Habitat. Urban forests provide wildlife habitat, food and shelter for many species of birds, insects, and other wildlife – as well as natural areas for discovery, education, and sanctuary for Washingtonians of all ages.

High Return on Investment. New York City has invested millions in its urban forest, and found that every dollar spent on tree planting and care returns $5.60 in benefits.

Increased Property Values. The value of a property is often increased by its proximity to parks, greenbelts, and other open spaces. Smart Money magazine reported that consumers value a landscaped home up to 11.3 percent higher than its base price.

Improved Human Health. Growing evidence shows that trees help reduce air pollutants that can trigger asthma and other respiratory illnesses. Green spaces also encourage physical activity, a healthy habit for every urban dweller, especially young people.

Trees in our cities rank as one of the most cost-effective ways to improve our water quality, air quality and our quality of life.

Unless the Evergreen Cities approach is adopted and funded at the local level, Washingtonians will not realize any benefits from the law. Audubon Washington’s policy priority is for local governments adopt and fund programs to maintain and increase their urban forests.