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Consumption and Global Growth: How Much Does Population Contribute to Carbon Emissions?
July 6, 2011 By Schuyler Null
When discussing long-term population trends on this blog, we’ve mainly focused on demography’s interaction with social and economic development, the environment, conflict, and general state stability. In the context of climate change, population also plays a major role, but as Brian O’Neill of the National Center for Atmospheric Research put it at last year’s Society of Environmental Journalists conference, population is neither a silver bullet nor a red herring in the climate problem. Though it plays a major role, population is not the largest driver of global greenhouse gases emissions – consumption is.
In Prosperity Without Growth, first published by the UK government’s Sustainable Development Commission and later by EarthScan as a book, economist Tim Jackson writes that it is “delusional” to rely on capitalism to transition to a “sustainable economy.” Because a capitalist economy is so reliant on consumption and constant growth, he concludes that it is not possible for it to limit greenhouse gas emissions to only 450 parts per million by 2050.
It’s worth noting that the UN has updated its population projections since Jackson’s original article. The medium variant projection for average annual population growth between now and 2050 is now about 0.75 percent (up from 0.70). The high variant projection bumps that growth rate up to 1.08 percent and the low down to 0.40 percent.
Either way, though population may play a major role in the development of certain regions, it plays a much smaller role in global CO2 emissions. In a fairly exhaustive post, Andrew Pendleton from Political Climate breaks down the math of Jackson’s most interesting conclusions and questions, including the role of population. He writes that the larger question is what will happen with consumption levels and technological advances:The argument goes like this. Growth (or decline) in emissions depend by definition on the product of three things: population growth (numbers of people), growth in income per person ($/person), and on the carbon intensity of economic activity (kgCO2/$). This last measure depends crucially on technology, and shows how far growth has been “decoupled” from carbon emissions. If population growth and economic growth are both positive, then carbon intensity must shrink at a faster rate than the other two if we are to slash emissions sufficiently.
Pendleton also brings up the prickly question of global inequity and how that impacts Jackson’s long-term assumptions:
Jackson calculates that to reach the 450 ppm stabilization target, carbon emissions would have to fall from today’s levels at an average rate of 4.9 percent a year every year to 2050. So overall, carbon intensity has to fall enough to get emissions down by that amount and offset population and income growth. Between now and 2050, population is expected to grow at an average of 0.7 percent and Jackson first considers an extrapolation of the rate of global economic growth since 1990 – 1.4 percent a year – into the future. Thus, to reach the target, carbon intensity will have to fall at an average rate of 4.9 + 0.7 + 1.4 = 7.0 percent a year every year between now and 2050. This is about 10 times the historic rate since 1990.
Pause at this stage, and take note that if there were no further economic growth, carbon intensity would still have to fall at a rate of 4.9 + 0.7 = 5.6 percent, or about eight times the rate over the last 20 years. To his credit, Jackson acknowledges this – as he puts it, decoupling is vital, with or without growth. Decoupling will require both huge innovation and investment in energy efficiency and low-carbon energy technologies. One question, to which we’ll return later, is whether and how you can get this if there is no economic growth.But Jackson doesn’t stop there. He goes on to point out that taking historical economic growth as a basis for the future means you accept a very unequal world. If we are serious about fairness, and poor countries catching up with rich countries, then the challenge is much, much bigger. In a scenario where all countries enjoy an income comparable with the European Union average by 2050 (taking into account 2.0 percent annual growth in that average between now and 2050 as well), then the numbers for the required rate of decoupling look like this: 4.9 percent a year cut in carbon emissions + 0.7 percent a year to offset population growth + 5.6 percent a year to offset economic growth = 11.2 percent per year, or about 15 times the historical rate.
To further complicate how population figures into all this, Brian O’Neill’s Proceedings of the National Academy of Sciences article, “Global Demographic Trends and Future Carbon Emissions,” shows that urbanization and aging trends will have differential – and potentially offsetting – impacts on carbon emissions. Aging, particularly in industrialized countries, will reduce carbon emissions by up to 20 percent in the long term. On the other hand, urbanization, particularly in developing countries, could increase emissions by 25 percent.
What do you think? Is infinite growth possible? If so, how do you reconcile that with its effects on “spaceship Earth?” Do you rely on technology to improve efficiency? Do you call it a loss and hope the benefits of growth are worth it?
Sources: Political Climate, Proceedings of the National Academy of Sciences, Prosperity Without Growth (Jackson).Topics: aging, climate change, consumption, demography, economics, energy, environment, population, urbanization
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