Portland, Oregon, was the first U.S. city (in 1993) to adopt a plan to reduce greenhouse gas emissions. In 2001, Oregon's Multnomah County (within which Portland sits) joined with Portland in adopting a county-wide target of reducing GHG emissions by 10% from 1990 levels by 2010.

Several weeks ago Portland and Multnomah County released their 2005 Global Warming Progress Report. The report announced that 2004 emissions had actually dipped below 1990 levels! The decrease from 1990 emissions admittedly was only by 0.1% — but this still is a far cry from the seemingly inexorable upward march of emissions at the national level.

The report's authors did not realize how much attention their announcement would receive. The New York Times' Nicholas Kristoff dedicated his July 3rd column to Portland's achievement, using it as evidence that President Bush's fear that climate change policy would wreck the U.S. economy is fundamentally misguided. Kristoff concluded: "the City of Portland is proving it flat wrong. . . It confirms the suggestions of some economists that we can take initial steps against global warming without economic disruptions."

Portland’s report does not include much detail regarding how the numbers were calculated. In their defense, the authors simply did not think to provide much methodological detail, not realizing the attention the report would receive (it never had before). In retrospect, they probably wish they had, if only to help show they weren’t cooking the books. Indeed, in reviewing the numbers again after the report’s release, the authors found a mathematical error that meant that aggregate emissions in 2004 were actually above 1990 levels, albeit only marginally so.

It’s quite interesting to look at the numbers underlying the report more carefully in order to really assess what conclusions should be drawn. Do they prove the case for climate change policy, as Nicholas Kristoff claims, or is the truth a bit less black and white?

Here are some key points:

• The numbers, using software developed for the International Council on Local Environmental Intitiatives (ICLEI), are based on some pretty high-level approximations. For electricity, for example, aggregate utility estimates of the number of MWhs sold to residential, commercial, and industrial users were multiplied by the regional average CO2 emissions factor. For the transportation sector, emissions were calculated based simply on fuel sales within Multnomah County, rather than on any estimate of vehicle miles traveled (VMTs) or any other measure.
  
  
• Partially as a result of the highly aggregated data, it’s not easy to figure out the real trends. Are VMTs really decreasing (which would be in marked contrast to nationwide trends), or are relatively more people buying gasoline outside the city and county limits from where they are commuting? Is electricity usage being driven by energy conservation measures, or by Oregon’s economic woes over the last several years? We don’t really know, and the report’s authors do not actually argue that specific emissions reduction measures are responsible for the observed emissions trends. Indeed, a more detailed look at the numbers raises more interesting questions. For example:
  
  1) Aggregate emissions in 2000 were estimated at 7.4% above 1990 levels; for 2001 the number was 4.8%. So the reductions being reported now are quite recent and quite dramatic. Why?
  
  2) While residential electricity use has remained stable, commercial electricity use has risen by 26%, and industrial electricity used has declined by 6%. What explains these patterns?
  
  
• Overall, the results for 2004 seem particularly affected by three factors:
  
  1) A 56% reduction in estimated solid waste-related methane emissions (equivalent to almost 2% of total county emissions), attributable to the fact that Portland changed landfills during the decade and the current landfill has a better methane collection system.
  
  2) Gasoline sales, which can bounce around considerably from year to year, were low in 2004 (with the reduction from 2003 being equivalent to almost 2% of total county emissions).
  
  3) A dramatic fall in industrial energy use since 2000 (more than 20%, and equivalent to almost 5% of total county emissions).

Based on these points, I would suggest a number of conclusions:

• There’s no question that the City of Portland and Multnomah County have accomplished something tangible in terms of greenhouse gas emissions, particularly in the light of the region’s rapid population growth. The 2005 Global Warming Progress Report documents a long list of initiatives that have the goal of reducing GHG emissions and, in many cases, also saving money (from LED streetlights to residential weatherization programs). My own company’s ability to purchase low-cost bus passes for our employees is just one (albeit much appreciated) example.
  
  
• That said, the fact that 2004 emissions came out close to 1990 emissions appears to be significantly due to one-time events (e.g., changing landfills), overarching economic conditions (a slow economy over the last several years), and random factors such as relatively low county gasoline sales in 2004. These three factors add up to 9% of total county emissions, so they’re clearly significant. We don’t know exactly what’s causing the various data trends, so it is not clear that all of these variables will continue to work in Portland’s favor in achieving its 2010 target.
  
  
• As such, it’s risky to suggest that Portland’s efforts to reduce GHG emissions should be lauded as a great success because 2004 emissions are close to 1990 emissions, just as it would be a mistake to label them a failure if next year’s inventory jumps back up. Portland and the County are doing a lot of great things, and they should be recognized for that. But without more research, no one can really know what those efforts are really accomplishing in the context of total GHG emissions. Also, there is a good deal of interaction between Multnomah County and surrounding metropolitan-area counties relevant to GHG emissions; one has to be pretty careful interpreting county-level data in isolation.
  
  
• What is clear is that it’s not appropriate to point to Portland’s and Multnomah County’s 1990 vs. 2004 emissions as proof that the nation as a whole could costlessly reduce its GHG emissions back to 1990 levels. Suggesting such a message has a downside; if people expect all reductions to be free, and then they’re not, will we lose interest?

If climate change is a serious environmental and public policy problem, which I believe it is, we should be seeking to address it at the local, national, and international levels with the tools we have at our disposal. To argue that we should only address climate change if doing so imposes no economic cost, which has been the President’s position, or to fall into the trap of suggesting that we can in fact dramatically reduce emissions costlessly, ultimately throws into question how seriously we’re taking climate change.

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Dr. Mark C. Trexler has more than 25 years of energy and environmental experience, and has focused on global climate change since joining the World Resources Institute in 1988. He is now president of Trexler Climate + Energy Services, which provides strategic, market, and project services to clients around the world.

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