Pollution math
Friday, June 8, 2007
By Joe Nation
OK, it’s time to get serious about reducing our greenhouse gas emissions. After a steady stream of bad news from scientists, Californians are paying attention.
But what to do? Buy hybrids? Install solar panels? Ride a bike rather than drive to work? Recycle more? Sure. Each of those will help. But few Californians understand how much (or how little) each of those individual efforts will accomplish.
Before we reduce, we need to understand just how much we spew towards the heavens. Each year, Californians emit nearly 500 million metric tons of greenhouse gases, a per capita average of 13 metric tons. (A metric ton, 2205 pounds, is 1.1 times the vernacular “ton.”) The U.S. average is 20 metric tons, while the global average is about 4 metric tons.
The math is simple. Every person in this state on average emits 29,000 pounds of CO2, methane, and other greenhouse gases each year. That’s 80 pounds each day, or about 3.3 pounds each hour. How in the world did we get to this place? And, more importantly, what can we do about it?
First, we can start by understanding our own individual carbon footprints. Virtually everything we do comes at some cost in greenhouse gas emissions: driving to work, cooling the house, flying away for vacation, and so on.
Individuals can estimate their own carbon footprints with the many carbon calculators on the Internet. But users beware. Many carbon calculators have different formats, require different inputs, and not surprisingly, can yield very different conclusions.
Let’s start with emissions from driving at http://driveneutral.org, a local non-profit. Drive Neutral estimates that a 25 mpg car using gasoline at 12,000 miles per year emits 9,312 pounds of CO2, or about 4.2 metric tons. (Drive Neutral allows users to choose gasoline, bio diesel, diesel, or natural gas for their calculations.) Other sites, http://terrapass.com, http://safeclimate.net, and http://carbonneutral.com showed similar results, although input variables are often different. (E.g., http://carbonneutral.com allows users to choose engine size, but not mpg.) Bottom line. According to the U.S. EPA, each gallon of gas consumed emits 19.6 pounds of CO2. Until plug-in hybrids, hydrogen fuel cell, or some other new technology arrives, the best solution here is to drive less and drive a car with higher fuel economy.
Trading in that 15 mpg SUV for a 30 mpg hybrid SUV (yes, it exists) cuts your annual emissions in half (from more than 7 tons to 3.5). And it will also save you $1340 each year in gas. Even better, why not go Full Monty and try a hybrid sedan at more than 50 mpg? That will cut your emissions from 7 to just over 2 metric tons and save nearly $2,000 in gas each year.
Many calculators estimate emissions from air travel, which makes up about 5% of the total in California. I estimated emissions from a 5,200 mile round trip from SFO to JFK at http://begreennow.com, http://carbonfund.org, and http://climatecare.org. Total emissions in each case were about 1 metric ton, although another site estimated emissions as high as 2.3 metric tons. Bottom line. Be wary of calculator results for air travel. Assume (conservatively) that your share of a plan trip to New York is at least one ton and perhaps more. The best solution? Fly only when you must. And then offset those emissions.
Some carbon calculators estimate footprints at home, mostly from your electricity and natural gas use. But these also can provide a wide variety of answers because of the uncertainty about where many of us purchase those fuels. PG&E customers receive about one-half of their power from sources with no CO2 emissions (e.g., large hydro and nuclear), while customers at the Los Angeles Department of Water and Power receive one-half of their power from coal, which emits about 70% more emissions than natural gas.
Even so, “at home” calculators are of some use. The most detailed is the U.S. EPA calculator at http://www.epa.gov/climatechange/emissions/ind_calculator.html. It walks users through gas, electric, and fuel oil costs. Bottom line? Switch—if you can—to renewables like wind, solar (only 1% of our current total), biomass, and geothermal. Those generally cost slightly more than conventional power, but their long-term emissions reductions are a bargain.
The EPA site also highlights the benefits of other activities. Replacing 20 incandescent light bulbs with energy star bulbs will reduce emissions about one ton. Installing double pane windows reduces emissions more than 1.5 metric tons. Recycling aluminum, glass, plastic, and steel reduces emissions more than 400 pounds.
In the affluent Bay Area, don’t be surprised if your initial footprint resembles a size 18 (tons) or worse. But at least you’ll know your starting place, how to reduce, and truly how steep that climate change mountain is.
Joe Nation, a former member of the state Assembly, teaches microeconomics and climate change at the University of San Francisco.