s/r home  | issues  | authors  | 44 contents

Synthesis/Regeneration 44   (Fall 2007)

Why 80%?

by Stan Cox

When late last year the S/R editorial board decided to tackle the question of how to reduce the United States’ energy consumption by 80%, it was the first time I had heard that figure. In the months since, however, I’ve been hearing “80%” from all kinds of sources. On April 14, for example, a national “Step it Up” event, encompassing more than 1400 actions across the country, called for an 80% reduction in US carbon emissions. But the relative contributions of energy reduction and renewable energy generation toward achieving that goal were left unspecified.

In many cases, it’s not clear how people have arrived at the 80% figure (either for emissions or energy reduction), but various rough calculations based on global estimates from different sources all tend to point in that direction. Let’s look first at the need for reductions in carbon emissions and then at how much less energy we’ll have to use to achieve those reductions.

… if Americans are to be good global citizens by 2050, we will have to slash current per capita emissions by 85 to 93%.

The 2005 Millennium Ecosystem Assessment, produced by more than 1360 experts worldwide working over a four-year period, concluded that 15 of the 24 key “services” that ecosystems provide to humanity are in decline because of human activity. Scientists responsible for the climate-change section of the report estimated that just to keep planet-wide temperatures from rising more than two degrees Celsius (that being a threshold beyond which research suggests that runaway heating will occur) will require that humanity’s carbon emissions must begin to decline by around 2015 and be held to between 3 and 7 billion metric tons per year by 2050. [1] That would be about 800 to 1800 pounds per year per person worldwide.

The United States currently pumps out about 12,000 pounds of carbon per person. Therefore, if Americans are to be good global citizens by 2050, we will have to slash current per capita emissions by 85 to 93%. But the US population is expected to grow from 300 to 400 million by 2050, so those cuts will have to be 88 to 95%. In his 2006 book Heat: How to Stop the Planet from Burning, George Monbiot concludes that emissions will need to be cut even more deeply and rapidly, to 725 pounds per person by 2030. That would mean reductions of 90% across the wealthy world, reaching 87% in the UK and 94% in Australia and the US within a quarter-century. [2] Monbiot’s may be a worst-case scenario, but in highly unstable situations like the one we face, reality usually ends up at the worst case or beyond.

Analyses based on other data lead to similar conclusions. The work done on ecological footprints by the Oakland-based group Redefining Progress [3] finds that an index of worldwide per capita “biocapacity” (the ability to support the human “footprint”) was at a value of 15.7 in 2005. The global footprint was 21.8 (from that came their widely cited conclusion that humanity is overshooting the planet’s support system by 39%). Rich nations, of course, are the worst offenders. Their footprint calculations show that per capita consumption and waste production in Western Europe, if practiced worldwide, would reach almost four times the level that the planet could support. In the United States, the per capita footprint is seven times the globally supportable level. The US is somewhat better endowed than the world as a whole when it comes to biocapacity, having a value of 20.8 per person. However, the footprint of the average American is the planet’s biggest, at 109. To bring our resource use, waste production (including carbon emissions), and general ecological impact into line with our national biocapacity would require an overall reduction of 81%; to be good world citizens and live on our share of world biocapacity would mean a cut of 86%. Because of the crucial importance of energy, reducing our ecological footprint by 86% will mean cutting carbon emissions by at least 86%, probably more.

All of those reductions are big — shockingly so. If valid, they mean that emissions will have to be cut by more than the Step it Up organizers’ goal of 80%. If we accept that the carbon emissions and ecological footprints of Americans will have to shrink by 85 to 95%, how much less energy will we need to use? As Don Fitz argues in this issue of S/R, the cornucopian concept being promoted by big environmental groups — that we can cut emissions by 80% and still supply our current, voracious level of energy consumption solely through renewable energy — is a very bad joke. But let’s be perhaps overly optimistic and assume that half of our energy consumption by 2050 will come from totally renewable sources. [4] Then if we are going to live on 5% of our current emissions, we’ll be able to use 10% as much energy as we do now. If it’s 15% of current emissions, we can use 30% as much energy as now.

So energy consumption will have to be reduced by 70 to 90%; split the difference and call it 80. And that relies on another pie-in-the-sky assumption: that all future economic growth be accomplished without adding to carbon emissions. Taking everything into account, the prediction that we’ll have to use 80% less energy appears, if anything, to be optimistic.


1. Millenium Ecosystem Assessment, Ecosystems andHuman Well-Being: Policy Responses, Washington, DC: Island Press, 2005, p. 381

2. http://www.monbiot.com/archives/2006/09/21/an-87-cut-by-2030/

3. Redefining progress, 2005 ecological footprint of nations http://www.rprogress.org/publications/2006/Footprint%20of%20Nations%202005.pdf

4. True renewability means forgetting grain ethanol and nuclear power, for example, while accounting for the vast expenditure of nonrenewable resources that will be required to build a truly renewable infrastructure. Efforts to derive 100% of energy from truly renewable sources will run up against inevitable, irresistible economic pressure to exploit available fossil fuels.

[7 jan 08]

Synthesis/Regeneration home page | s/r 44 Contents