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New methodology protocols affect carbon emissions data for Multnomah County

News Article
Trends from 1990 to 2017 show that Portland must do more to reduce emissions over next decade.

Portland’s carbon emissions inventory shows where to focus carbon mitigation efforts and whether we are on track with emission reduction goals. Since the 2017 Climate Action Plan progress report, staff have worked to update all the annual records in accordance with the new Global Protocol for Community-scale GHG Emission Inventories to align with the Paris Agreement (limiting global warming to 1.5 degrees Celsius). A newly released climate data report shows the new numbers. 

By updating protocols, Portland stays in alignment with other cities around the world, enabling better tracking against long range goals with greater confidence. Updating protocols is a challenge for cities and can create discrepancies with previously reported emissions. For example, to move to the global reporting protocol, Portland had to update accounting methods for emissions from landfilled waste, wastewater treatment, and fugitive emissions. This required finding new data sources all the way back to the 1990 baseline to consistently compare data year over year.

The City of Portland uses multiple emission protocols to compare results and better refine estimates of emissions produced locally. By reviewing data using different protocols, Portland can make up for gaps in individual methodologies. For example, Portland reports electricity sector emissions by greenhouse gas, a level of detail only available for the Northwest Power Pool, although as discussed above, those emissions are lower than the emissions from Portland’s two electric utilities. Therefore, the use of multiple protocols allows Portland to better understand what’s happening locally.

The time required to find and evaluate new data sets for a protocol change delays the frequency of emissions inventory reporting. Changes to protocols that affect data collection and carbon accounting limit comparability with previously reported data using older methodologies. With a baseline year of 1990, protocol changes create substantial new work as more than 20 years of inventories need to be consistently updated.

A success story and a warning

Despite 26 years of climate planning and mitigation, local carbon emission reductions in Multnomah County have hit a plateau, at around 15% below 1990 levels. This is a success story and a warning. The reductions to date are impressive given population growth since 1990, 38% more people and 34% more jobs. Collectively we have reduced per-person emissions in Portland by 38% since 1990, although it is clear reduction efforts need to rapidly accelerate.

Transportation sector emissions are increasing dramatically, currently 8% over 1990 levels, and 14% over their lowest levels in 2012. Portland has experienced year over year increases in transportation related emissions for the past five years, with transportation emissions growing faster than population growth over the same period.

The United Nations International Panel on Climate Change (IPCC) released a special report in October 2018 which projected that limiting warming to the 1.5°C target will require an unprecedented transformation of every sector of the global economy to achieve a 50% reduction in carbon emissions by 2030 and net-zero carbon emissions by 2050. To achieve this, Portland must reduce our local emissions by 35% in the next 11 years, a daunting task.

New carbon emissions inventory reports on trends from 1990 to 2017

Today, carbon emissions from Multnomah County total 7,700,000 Metric Tons CO2e, which is a 15% reduction from 1990 levels.This decline reflects the continued growth of renewable energy resources like wind and solar in the Pacific Northwest, investments in transit and bike infrastructure, dense and walkable neighborhoods, renewable transportation fuels, as well as the transition from fuel oil to natural gas for heating. This means that a person living in Portland today produces 38% fewer carbon emissions than they would have in 1990. 

Read the full report.

Check your own emissions

Households and businesses can assess their own carbon emissions by using free online tools, like the Cool Climate Network’s calculators: