EarthTalk is a weekly environmental column made available to our readers from the editors of E/The Environmental Magazine
Dear EarthTalk: I’m sure there are many good environmental reasons to build a rooftop garden. Can you enlighten? And also I’d like to know how to go about creating one and whether or not some municipalities might offer incentives to do so. – Linda, via e-mail
Indeed there are many good reasons to build a rooftop garden, or a so-called “green roof”—whereby layers of soil and plants on top of homes and buildings provide a host of environmental “services” for the living space below as well as for the surrounding ecosystem. Unlike traditional roofs, green roofs thrive on (and filter) precipitation, decreasing the amount of pollution-laden stormwater run-off draining into our waterways. And thanks to the process of photosynthesis, the plantings create oxygen, cleanse the air and absorb carbon dioxide before it gets into the atmosphere and adds to our global warming woes.
Green roofs also provide insulation: All those layers of organic material help keep a structure warm in the winter and cool in the summer, and help cut energy use and costs. Migrating birds and other wildlife have been known to take a shine to green roofs, especially in urban areas where natural habitat options are limited. Likewise, homeowners and building residents tend to view their green roofs as oases of peace and tranquility within otherwise noisy and concrete-laden urban environments.
According to Green Roofs for Healthy Cities, a nonprofit industry association, green roofs are gaining popularity. North Americans added some 3.1 million square feet of them to their buildings in 2008 alone—up 35 percent from 2007. Part of the uptick can be attributed to increasing awareness of the benefits of green roofs among urban planners, building owners and managers, and homeowners, all who have pressured policymakers to ease the burden of zoning and permitting for such beneficial projects.
Chicago now sports some 535,000 square feet of green roofs—the most in North America. Other leading lights in the green roofs movement include Washington, DC, New York City, Philadelphia, Baltimore, Montreal, and Vancouver, British Columbia. Dozens of smaller cities have also embraced green roofs. Grand Rapids. Michigan sports some 75,000 square feet of them, and Princeton, New Jersey and Newtown Square, Pennsylvania each play host to 50,000 square feet citywide. Inquiring at city hall is the best way to see if your city or town offers incentives for creating a green roof or greening an existing one.
Relief for the costs of installing a green roof might be on the way from the federal government. As part of the Clean Energy Stimulus and Investment Assurance Act she authored earlier this year, U.S. Senator Maria Cantwell (D-WA) is calling for residential and commercial property owners who install green roofs or retrofit existing roofs to recoup 30 percent of their costs in the form of a federal tax credit.
Do-it-yourselfers will find a treasure trove of information on how to create and install a green roof at the website Greenroofs.com. The site’s keyword-searchable directory offers links to manufacturers of kits to make installing your own green roof that much simpler, as well as to professional installers across North America and groups working on urban greening issues.
Dear EarthTalk: I haven’t heard much of late about big oil spills like the infamous Exxon Valdez. Has the industry cleaned up its act, or do the media just not report them? – Olivia G., via e-mail
In the wake of 1989’s massive Exxon Valdez oil spill in Alaska’s Prince William Sound, when 11 million gallons of oil befouled some 1,300 miles of formerly pristine and wildlife-rich coastline, much has been done to prevent future spills of such magnitude.
For starters, Congress quickly passed the 1990 Oil Pollution Act which overhauled shipping regulations, imposed new liability on the industry, required detailed response plans and added extra safeguards for shipping in Prince William Sound itself. Under the terms of the law, companies cannot ship oil in any U.S. waters unless they prove they have response and clean-up plans in place and have the manpower and equipment on hand to respond quickly and effectively in the case of another disaster.
Also, the law mandates that, by 2015, all tankers in U.S. waters must be equipped with double hulls. The Exxon Valdez had only one hull when it ran aground on Bligh Reef and poured its oil into Prince William Sound, the southern end of the oil pipeline that originates 800 miles to the north at Prudhoe Bay. By comparison, a 900-foot double-hulled tanker carrying nearly 40 million gallons of crude oil did not leak when it crashed into submerged debris near Galveston, Texas in March 2009.
According to the U.S. Coast Guard, average annual oil spill totals have dropped dramatically since new regulations took effect in 1990. Between 1973 and 1990, an average of 11.8 million gallons of oil spilled each year in American waters. Since then, the average has dropped to just 1.5 million gallons, with the biggest spill (not including those resulting from Hurricane Katrina in 2005) less than 600,000 gallons
Despite these improvements, critics say the industry still has more work to do. While protections have been beefed up in Prince William Sound, other major American ports still lack extra precautions such as escort tugboats and double engines and rudders on big ships to help steer them to safety when in trouble.
Another area that the 1990 law doesn’t cover is container ships that don’t transport oil as their cargo but which carry a large amount, anyway, for their own fuel for the considerable distances they travel. Such ships could also cause a major spill (anything more than 100,000 gallons, by Coast Guard standards). Yet another concern is the great number of smaller oil spills that occur every day at industrial locations (including but not limited to oil refining and storage facilities) and even in our own driveways. These will continue to add up to a heavy toll on our environment, even if another oil tanker never spills at sea again.
And while the total number and volume of oil spills is down dramatically from bygone days, the trend of late warrants concern. The National Oceanic and Atmospheric Administration’s (NOAA’s) Office of Response and Restoration reports that oil spills in U.S. waters have risen again over the past decade, with 134 incidents in 2008 alone. Green leaders worry that if Bush administration plans to expand offshore oil drilling are not overturned by President Obama, oil spills in U.S. waters could remain a sad fact of life.
Image credits: Ruth Rogers, courtesy Flickr; Getty Images
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