Sunday, October 7, 2007

Potential GHG reduction for regionally-directed food purchasing

A team of University of Washington students and professor(s) recently released a comprehensive report on the local food system entitled the "Seattle Food System Enhancement Project". Within this work is their Greenhouse Gas Report that compares the ghg emissions of a local plate of food to a comparable global plate. The team used a life cycle assessment approach using the ISO 14040 definition. Their methods are an attempt to create "A benchmark for examining the greenhouse gas impact of cultivating and transporting specific items of food into the city of Seattle."

The foods compared, and their ghg emissions:
  • Regional plate
    • WA apple, asparagus, potato; Alaska wild salmon
    • GHG emissions = 2,102 grams CO2e
  • Global plate
    • New Zealand apple, Peruvian asparagus, Idaho potato, Norway farmed salmon
    • GHG emissions = 3,083 grams CO2e
Net savings for local plate: 981 grams CO2e

I decided to start playing with this number and try to calculate potential ghg reductions if this was applied to a segment of the whole state population for part of the year.

There are about 6.4 million people in WA state. The major assumptions for my calculations are that 20% of the population would eat a comparable plate of lower carbon food for half the year (182 days). These assumptions are further tied to carbon savings that are comparable with this plate of food. Why such variables? Well, the research is just not there to elaborate on this pressing issue. We absolutely have to do more of these calculations to understand where ghg reductions can occur, but in the meantime I am going to work with such estimates. I also understand that people are not going to eat this same meal for half the year, but I will assume that 20% of the people could eat a plate of food, or total food for the day, that has a comparable ghg savings.

From these parameters comes the notion that if 20% of WA state residents ate a similar plate of lower carbon food for half the year we could reduce our food carbon footprint by 228,534 Metric Tons CO2e per year (.23 MMT CO2e/yr).

Here is a screenshot of my spreadsheet (click for larger image):

These types of savings are no small potatoes. I am a member of the Agriculture Technical Working Group for WA State's Climate Advisory Team. A medium reduction goal is 0.1 to 1.0 MMTCO2e per year by 2020.

Items for further research:
  1. What are the ghg reductions for other regional products?
  2. What are the economic impacts of such a change in purchasing?
    1. Local multiplier work shows a strong positive gain.
    2. Impacts on this trade-dependent state less clear.
Source: " Seattle Food System Enhancement Project", Program on the Environment Certificate in Environmental Management Keystone Project, 2006-2007, p.79,


Norma said...

There's a much better reason to eat locally grown--how safe is the food we're importing, now that we see what's happening with the lead paint and the poisoned pet food? We Americans pay hefty taxes to support the FDA, USDA, and HHS, so let's take advantage of it. I don't believe we can do a thing to reverse the climate based on past cycles, but we can sure protect our own families.

Bokashicycle said...

These are certainly interesting observations and calculations. However there is a frequently overlooked calculation that has to do with the GHG emissions related to disposing of the organic waste after the meal.

We have a blog ( and make a real effort to educate people who want to know more about this subject. Little is said about how polluting composting is and that is where a lot of the organic waste with current planning is headed. There is a better and non-polluting way to handle that organic waste.

Bokashi Fermenting involves using anaerobic fermentation with bokashi culture mix. This method of treating waste is 5 X faster then composting and produces no GHG. Composting sends tons of carbon dioxide in the air. Fermenting produces no GHG (see pilot GHG study at

Current policies of handling organic waste involve transporting the heavy organic waste to compost sites (consuming petro fuel in the process) and then turning and handling it on site (more petro fuel plus particulate contributions to GHG emissions) releasing heat and carbon dioxide all contributing to the GHG problem. With Bokashi fermentation no transfer off site is required (for residential use).

You can treat organic waste (all waste....meat, bones, egg shells, diary products, etc.) with fermentation at the site where the feed stock was generated for all residential sites and the home owners and municipalities save a lot because trash hauling requirements are reduced. The soil on site is improved with restoration of soil microbes and virtually 100% of the carbon and nitrogen goes back into the soil, not up in the air as pollutants.

It is easy to adopt the same process for prisons, schools, cafeterias, restaurants, markets, etc. and put that fermented product back to the farms in the soil supporting then a sustainable farming policy without contributing to GHG.

By these policies we would be able to grow those food reserves locally and use them effectively. In the end it makes sense to restore the waste cleanly back to the local land where great savings are evident.

I agree entirely with the issues as outlined but hope people will soon see that the other side.....handling the organic waste is currently a polluting problem not being properly addressed.