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Every Tree Counts In Fighting Climate Change, Says Ecologist

An Itailian stone pine tree sits in the front yard of a residential neighborhood in Cornado.
An Itailian stone pine tree sits in the front yard of a residential neighborhood in Cornado.

Arborists, local governments and volunteers have spent the last year mapping San Diego County’s urban trees to calculate their environmental and financial benefit. So far, the map, organized by the California Center for Sustainable Energy, shows 331,632 trees that have reduced an estimated 24.5 million pounds of carbon dioxide from the atmosphere.

Kelaine Ravdin, an urban ecologist working on the “unofficial” tree counting effort, said the map is currently a small fraction of the county’s urban canopy, but already the data highlights the role trees play in the urban ecosystem. Ravdin said it could be a useful tool for California’s new Cap-and-Trade program.

"The idea there is that cities could plant trees within the city limits and use them for carbon offsets in California’s Cap-and-Trade program," said Ravdin, "where you actually register your project and the trees are verified by a verifier and you submit it to the air resources board."


Ravdin said even though the count isn’t currently getting official credit, the trees are still working to alleviate climate change.

"They actually pull carbon dioxide out of the atmosphere and they use it to make tree stuff like the trunk and leaves and the fruit and the branches," she said. "I like to say that they’re sort of the only technology that can actually help us mitigate the problem as it exists rather than trying to keep it from getting worse in the future."

The map also calculates how many gallons of stormwater trees help filter and how many kilowatt-hours of energy they are conserving. Ravdin hopes the data will also improve municipal oversight for water and air resource management to better specify and manage the trees.