think tasks like cooling off dc – and cleaning up the potomac – are over your head? you’re right.

the miliken institute school of public health is the fourth building at the george washington university to include a green roof. a green roof is exactly what it sounds like: a rooftop covered with special absorbent soil and seedum plants. green roofs keep urban areas cool by reflecting sunlight that would otherwise by absorbed into the traditional black tar roof. this prevents urban heat islands, which is what we call a metropolitan area that is warmer than the surrounding communities. they also keep water sources clean by absorbing rainwater that would otherwise become stormwater runoff, potentially causing sewage overflows.

why does this matter? while green roofs alone probably won’t change washington’s climate or put a stop to all pollution, they certainly help. just one acre of green roof can absorb 630,000 gallons of rainwater each year. there are 6,200 acres of rooftop in dc; if every roof was green, we could prevent 3.9 billion gallons of stormwater runoff every year.

erica halvorson is a senior at the george washington university majoring in journalism and mass communication.