This issue’s interview with Oregon Global Warming Commission Chairman Angus Duncan and articles about the Columbia River Crossing and Willamette River Transit Bridge spurred us here at Metroscape® magazine to take a closer look at the area’s transportation-related greenhouse gas emissions.

In 2010, transportation accounted for a quarter of metropolitan Portland’s emissions of carbon dioxide and other heat-trapping gases — about 31 million metric tons total — according to a Metro inventory. Cars and light trucks accounted for about 14 percent of the total, while transit (e.g., diesel buses and light-rail trains) accounted for 0.01 percent. Other “passenger transport” sources — including aircraft, inter-city trains, and cars and trucks making long-distance trips across the urban growth boundary — accounted for 10 percent of the area’s total greenhouse gas emissions.

The transportation sector accounted for about 37 percent of Oregonians’ greenhouse gas emissions, according to a 2010 state inventory. Light-vehicles accounted for about two-thirds of transportation-sector emissions. Oregon is growing, but will its carbon footprint track with its population? Not necessarily.

Metro forecasts that the population of Portland’s seven-county statistical area — which includes Clackamas, Clark, Columbia, Multnomah, Skamania, Washington, and Yamhill counties — will likely range between 2.9 million and 3.2 million in 2030 and between 3.6 million and 4.4 million in 2060. The State of Oregon, meanwhile, has set a target of reducing emissions 10 percent below 1990 levels by 2020 and at least 75 percent below 1990 levels by 2050.

So how do we grow sustainably? The Oregon Legislature passed legislation in 2009 (H.B. 2001) that requires Metro to develop alternative land-use and transportation scenarios that accommodate planned population and employment growth while reducing emissions from light-duty motor vehicles. In 2014, Metro is slated to adopt a preferred alternative for such strategies, which help advance implementation of the agency’s 2040 Growth Concept.

The transportation sector also figures heavily in the Oregon Global Warming Commission’s “roadmap” for reducing the state’s carbon footprint during the next decade. The commission’s draft recommendations for policymakers include: expanding urban transit, keeping urban footprints compact, managing and pricing parking, supporting electric vehicles, and adopting a low-carbon fuel standard (http://tinyurl.com/7ej9d4e).

Michael Burnham is a graduate student in the PSU Masters of Urban and Regional Planning program.