The future forecast for people moving to urban areas is continuing to intensify. As cities grow to incomprehensible sizes sustainable development is vital to counter any negative effects of urbanization. A concrete jungle doesn't just refer to a Bob Marley hit... it is the true nature of an urban landscape. Impervious surfaces can range anywhere from 50 percent to 95 percent like that of Manhattan. These surfaces, such as asphalt and rooftops, absorb and re-release the sun's energy making it consistently hotter. Modifying the landscape like this creates what is called an urban heat island- an area that is significantly hotter than its surroundings. This urban, rural disparity can become a serious problem with any amount of global warming.
How can we mitigate the urban heat island effect? Eco-roofs are being deployed in cities across the world. A roof covered in green vegetation is not only aesthetically pleasing, it also provides a crazy amount of benefits to metropolitan areas. Green-roofs assist in countering the heat island effect via evaporative cooling during transpiration. In Riyadh, Saudi Arabia eco-roof research found that temperatures dropped a shocking 16 degrees Fahrenheit during the hottest month!
What other functions do eco-roofs have? They absorb particulate matter, sequester CO2, produce oxygen, create food production space, create habitat for birds, insects, & plants, improve stormwater water management, and improve building insulation both in terms of heating and cooling. Quite an impressive list! If by adding plants to our roofs we could increase biodiversity, reduce air pollution, combat climate change effects, increase food security, and save money all at the same time... what do we have to lose?
Portland, Oregon is on the forefront of the eco-roof movement where there are hundreds of thousands of square feet of vegetation that are replacing the city's impervious surfaces. Portland State University has an ongoing grant with the National Science Foundation looking into gaining a better understanding of eco-roof services. This summer I have joined the Climate Change and Aerosol Research team where my work in the Green Building Lab is looking at how volatile organic compound profiles look on these eco-roofs. Note: an example of volatile organic compounds are most scents and are both naturally occurring and man made. However, my interest is in those created from soil. I'm obtaining substrate samples from roofs in SW Portland and running them through a Proton Transfer Reaction Time-of-Flight Mass Spectrometer. This very technical sounding instrument, which indeed is pretty technical, basically uses highly-sensitive chemistry to detect gas traces. At the end of my project I should be able to identify VOCs, quantify their concentrations, and understand some of the abiotic and biotic drivers. Ultimately, I hope that my results will contribute to the small pool of knowledge on eco-roofs and improve their many important ecological functions!