What’s your carbon footprint?

by Steven Milloy

If you’ve tried to find out what that means,
chances are you’ve only gotten half the story.

The notion of a personal “carbon footprint” was created by global warming alarmists to foster a sense of individual accountability with respect to the consumption of energy produced by the burning of coal, oil and natural gas. The idea is that the more energy from these sources you use, the more carbon dioxide (CO2) you cause to be released into the atmosphere, thereby contributing to global warming.

British oil company BP is running television ads featuring hapless man-on-the-street interviewees perplexed by the question “What’s your carbon footprint?” You can calculate your carbon footprint at BP’s web site or at a host of other web sites (results are typically expressed in metric tons of carbon dioxide).

The more entrepreneurial of these web sites then try to capitalize (literally) on any feelings of guilt you may have by offering to relieve your conscience (and wallet) through the purchase of so-called “carbon offsets.”

For prices ranging from $5.50 to $30 per metric ton of CO2 (mt-CO2) emitted annually, you can purchase “off-sets” from sellers who claim they will use your money to neutralize or off-set your personal CO2 emissions – by planting trees or supporting wind/solar energy projects, for example.

We won’t quibble with the precision of the various estimates of CO2 emissions that you might get from the different carbon foot print calculators. They’re extremely crude and likely over- or under-estimate your actual “footprint,” but they’re a useful starting point for considering the question of your personal impact on global temperature.

You’ll still want to hold on to your wallets, though. Those who seek to profit from the carbon footprint concept would have you believe that calculating your CO2 emissions is the first – and last – step in discovering your impact on global temperature. But there’s much more to it than that.

Now you can get the rest of the story at JunkScience.com. We’ve constructed “The Real Carbon Footprint Calculator” – an online tool enabling you to input your estimated CO2 emissions and to find out your potential impact on global temperature. You can also discover how much it would cost to avoid a single degree of warming based on the price of a carbon off-set you might be considering purchasing.

Let’s run though a sample calculation.

The average “carbon footprint” for a U.S. household is 19 metric tons of CO2, according to BP’s web site. Based on that figure, we calculate that the average U.S. household contributes, at most, an infinitesimal 0.0000000000148 degrees Fahrenheit annually to average global temperature – a trivial contribution even when multiplied by the 100 million U.S. households.

Moreover, the carbon off-set hucksters have created such a price scale that if you wanted to purchase enough off-sets at the low-end price of $5.50/mt-CO2 to potentially avoid one degree Fahrenheit of warming based on the average household’s “carbon footprint,” they would reap about $7.04 trillion. An off-set purchase price of $30/mt-CO2 makes the price of potentially avoiding one degree Fahrenheit of warming – and their potential gross revenue – a whopping $38.6 trillion.

In constructing the calculator we decided to err on side of overestimating temperature effects of CO2 emissions by assuming that the relationship between atmospheric CO2 and global temperature is linear – that is, every unit increase in atmospheric CO2 causes a constant unit increase in global temperature.

We know this assumption greatly overestimates the CO2-temperature relationship since, in reality, the relationship is logarithmic in nature – that is, every unit increase in atmospheric CO2 actually has a diminishing effect on global temperature.

Our calculator also errs on the side of overestimating the potential temperature increase related to your carbon footprint by relying exclusively on land-based measurements of historical temperature data.

Land-based temperature data indicate that the average global temperature increased about 0.07 degrees Centigrade per decade during 1880-2005. In contrast, when ocean-based measurements are factored into, average global temperature has increased by only 0.04 degrees Centigrade per decade.

Why did we decide to err on the side of overestimating the impact of CO2 emissions on global temperature? The first reason is that our group of test users had trouble juggling so many leading zeroes in the temperature effect – so we decided to limit the number of leading zeroes to 10, rather than 12 or 13. Next, we wanted to give the carbon footprint promoters every break possible in terms of potential temperature impact of CO2.

We believe that our calculator overestimates the temperature impact of your carbon footprint and underestimates the cost of potentially avoiding one degree Fahrenheit of warming by a factor ranging anywhere from 100 to 1,000.

No doubt global warming alarmists would agree that any one household’s CO2 emissions are trivial, but what if you add up all manmade CO2 emissions?

As a by-product of developing The Real Carbon Footprint Calculator, we calculated that to prevent one degree Centigrade of global warming, mankind would need to avoid emitting about 4 trillion metric tons of CO2 – that would mean no manmade CO2 emissions for 120 years.

Your carbon footprint? Carbon offset-buyer beware. It’s a gimmick designed to part you from your money without providing any measurable environmental benefit.

Steven Milloy publishes JunkScience.com, CSRWatch.com. He is a junk science expert, an advocate of free enterprise and an adjunct scholar at the Competitive Enterprise Institute .

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