Choosing personal carbon reduction goals

Under Article 3 of the Kyoto Protocol, the United States was to bring its annual carbon dioxide equivalent emissions down to a level equal to 93% of its 1990 emissions during the “commitment period” 2008 to 2012.   According to the World Resources Institute (their CAIT tool), including all greenhouse gases, and the net impact of land use changes (deforestation, reforestation, afforestation), United States was emitting 5,703.0 MtCO2e in 1990 (the little e means inclusive of equivalent methane and other greenhouse gas amounts).  93% of that level would be 5,303 MtCO2e.  The population of the United States in 2007 is just over 300 million, so the per person allowance is 17.7 tCO2e. 

 In 1990, only 81% of the emissions were actual carbon dioxide — the rest were methane and other greenhouse gases.  So for an actual carbon dioxide allowance, figure approximately 81% of the 17.7 total — 14.4 tons of CO2 alone.  And, as detailed in the another post , roughly 60% of the carbon emissions are from commerce and industry, so, for a personal Kyoto compliance amount, use 40% — figure a little over 5 metric tons — 11,000 pounds — of Co2 per year per person.  Compare the Vermont Earth Institute above for a similar computation. 

 The family of four below is 13% over its 44,000-pound Kyoto-2008 budget but could meet its budget by skipping its high impact vacation travel.

 To comply with the much more aggressive 80% reductions that now appear to be minimally necessary over the next few decades, the target would work out to roughly 1 metric  ton — 2200 pounds — of CO2 per year per person.  On this budget, which would translate to 8800 pounds for the family of 4, the family could not remotely function within its existing lifestyle.  If it were to downsize to an apartment in a building with 5 or more units and foresake all fossil-powered travel, it might be close to budget.  Of course, this assumes only the energy efficiency in place today, as reflected in current average household consumption levels.

 A question that the data generally available seems to leave largely unanswered is how much ability consumers have to affect through buying decisions the 60% of carbon emssions which derive from commerce and industry.

Illustrative Carbon Budget for Family of Four 


 Some comparative notes about this family’s budget — apart from the optional air travel, there is nothing unusual about this example:

Car #1 (economy car) 10000  miles at  35  miles per gallon x 19.5  gives       5,571 lbs. of carbon  
Car #2 (mini-van) 7000  miles at  18  miles per gallon x 19.5  gives       7,583 lbs. of carbon  
Gas heating–single family home (2100 sq. ft.): 1200  therms x 11.7  gives     14,040 lbs. of carbon  
Electric bill for home     8000  kwh x 1.3  gives     10,400 lbs. of carbon  
One cross country air trip for family 24000  passenger miles 0.5  gives     12,000 lbs. of carbon  
                 49,595 total direct carbon footprint
                 12,399  lbs per family member




  • This family of four drives less and consumes less gasoline than the average New England household with vehicles, which drives 22.6 thousand vehicle miles and consumes 1,086 gallons of gasoline, as compared to 17,000 miles and 674 gallons of gasoline in the illustration.  The illustration family thus saves 8000 lbs against the average.  See 2001 statistics
  • The family’s natural gas consumption appears typical based on its size and location — it spends 1200 therms or 120,000,000 btu’s on natural gas for heating, hot water and gas drying — roughly 20% above the average household using gas in its climate zone.  (Boston, Massachusetts is in climate zone 2  — fewer than 2,000 cooling degree days and 5,500 to 7,000 heating degree days.  In climate zone 2, the average household U.S. with gas uses 20.5 million btu for water heating and 72.9 million but for space heating; a gas dryer and/or stove may account for another 8.7 million BTU on average, butappliance numbers are more variable.)   However, the larger household size size and the fact of residing in a single family home probably suffice to account for the difference from average.  Single family homes consume approximately 10% more gas for heating than the average across all households (three time as much as dwellers in apartment buildings).  Note thathousehold heating requirements do not vary dramatically by the number of persons in the household, so having more people in the household brings down per person cost; water heating requirements are roughly twice as high for households of four as for single households.  Adding 10% to average for space heating (+7.3 million btu) and increasing the average for water heating (by 1/3 — the ratio of 4 person households to the average — + 7 million btu) would bring the expected number very close to the observed 120 million btu — 116.7 = 72.9+20.5+8.7+7.3+7)
  • Total household energy consumption (including gas and only the delivered amount of electricity, not the energy losses associated with generation and transmission) is the 120,000,000 btus of gas plus 8,000×3412 btu of electricity (1 kwh equals 3412 btu) or 147.3 million btu. This is 30% high relative to U.S. average for households in climate zone 2 of 114.0 million btu.  However, four person households run 19.3% above the average household, leaving only an 8% difference from average which appears very consistent with residence in full-sized single family home as opposed to an apartment.

Published by Will Brownsberger

Will Brownsberger is State Senator from the Second Suffolk and Middlesex District.