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Rage, rage against dimming of the light

By David Solomon - posted Tuesday, 15 May 2007

Global warming advocates frequently claim that the way for society to reduce carbon dioxide emissions is for individuals to make sacrifices to their lifestyle in the name of reducing their carbon footprint.

Thus people are encouraged to feel guilty about everyday components of their life, such as holiday air travel, driving cars to work, using electrical appliances and so on.

Judging by prominent global warming advocate Al Gore's power bill, (20 times that of the average American), one may be forgiven for thinking such activists are perhaps more interested in reducing your consumption rather than their own.


But the result of this sacrifice, we are assured, is that such actions combined will save the planet. The website for Al Gore's documentary, An Inconvenient Truth, informs readers that "small changes to your daily routine can add up to big changes in helping to stop global warming".

But can they? It is a question worth asking before cancelling your next holiday. And the evidence we have isn't encouraging. On March 31 at 7.30pm, Sydney residents participated in Earth Hour, for which they were urged to turn off all electrical devices for one hour as a protest against global warming. A poll by AMR Interactive, published in The Sydney Morning Herald, claimed that more than 57 per cent of Sydney participated in this event, meaning 2.2 million NSW residents sat in complete darkness or candlelight for an hour.

So exactly what drop in electricity consumption did such a sacrifice buy us? Simply taking the difference between predicted consumption and actual consumption (as press reports purported to do) doesn't prove that this drop is due to Earth Hour because it may simply be due to some other variable that isn't being measured. One way around this problem is to compare the drop during Earth Hour with the drop at other times of the day and see how big it is.

Having analysed eight years of NSW electricity consumption, once you control for other potential factors, the drop in statewide electricity consumption during Earth Hour is estimated at only 6.33 per cent when measured as the difference between actual and predicted consumption during Earth Hour.

But this effect is a significant overstatement of the true impact. When you examine whether the declines during Earth Hour were large compared with the rest of that day, it turns out that more than 67 per cent of the apparent decline during Earth Hour was due to factors operating throughout the entire day. When these are accounted for, the estimated reduction in electricity use during Earth Hour is a tiny 2.1 per cent, statistically indistinguishable from zero.

Percentage drops in consumption that were as large as those during Earth Hour began as early as 5am that day and it stretches credibility to claim that this was all due to Earth Hour. In fact, Earth Hour-sized declines in electricity consumption (from their predicted levels) have occurred every four days in the past eight years, due entirely to natural variation in electricity consumption. This makes it extremely problematic to do as Earth Hour supporters did and simply declare any drop during that period as a victory for the event.


The environmental effect of the reported drop in electricity consumption in the Sydney central business district was reported rather optimistically by Sunanda Creagh in The Sydney Morning Herald as being the "equivalent of taking 48,613 cars off the road for one hour". Melbourne Herald Sun columnist Andrew Bolt, displaying a perhaps firmer grasp on the true economic significance of the event, noted that this meant taking a paltry six cars off the road for a year. As it turns out, it appears likely that these estimates significantly overstate the true effect of Earth Hour. Statistically speaking, Earth Hour appears to have been a complete flop.

These numbers speak to the question of exactly how society is to go about achieving certain environmental policies. The Labor Party's present environmental policy calls for reductions in greenhouse gas emissions of 60 per cent by 2050. Half of Sydney sitting in darkness brought us a reduction in NSW electricity of about 2.1 per cent.

It is time to start asking exactly how the environmental movement plans to produce its enormous cuts in greenhouse gas emissions, in serious detail. Symbolic, feel-good policies such as badgering ordinary people to buy energy efficient lightbulbs do not appear to be the answer to anything.

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First published in The Australian on May 9, 2007.

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About the Author

David Solomon is a finance PhD student at the University of Chicago graduate school of business. He has recently completed a research paper examining the effects of Earth Hour on NSW electricity consumption.

Creative Commons LicenseThis work is licensed under a Creative Commons License.

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