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Effects of Population Change on CO2 Emissions

World population

Image by Arenamontanus via Flickr

After being silent for nearly a month, I am back to blogging and now committed to write, at least, a new post every week.  This week’s post is on the link between demographic trends and CO2 emissions. Please feel free to leave your comment below.

Population growth has been affecting energy use and greenhouse gas emissions growth for the last several decades. The relation between demographics and carbon emissions seems to be obvious. As the human population grows so does the demand for energy; as more energy from fossil fuel is used, more greenhouse gases are produced. Energy demand and emissions can also be affected by a range of demographic dynamics, such as urbanisation, aging and household size, according to a study featured this week in the Proceedings of the National Academy of Science (PNAS).

The implications of demographic change for global emissions have been assessed by Brian O’Neil – from the Climate and Global Dynamics Division and Integrated Science Program, National Center for Atmospheric Research – and colleagues. These researchers developed a set of economic growth, energy use, and emissions scenarios using data from 34 countries, representing 61% of the global population, and an energy–economic growth model. The model used – the Population-Environment-Technology (PET) model – accounts for the effect of (i) population growth rates on economic growth rates, (ii) age structure changes on labour supply, (iii) urbanisation on labour productivity, and (iv) anticipated demographic change (and its economic effects) on savings and consumption behaviour.

O’Neil and colleagues show that both changes in population composition and size can have a significant effect on emissions in certain regions. For example, they estimate that aging can reduce emissions by up to 20% in the long term, particularly in developed country regions. Urbanization, on the other hand, can increase projected emissions by more than 25% in developing country regions. A slow population growth could help to achieve 16-29% of emissions reductions suggested to be needed to avoid dangerous climate change by 2050. By the end of the century the effect of slower population growth could be even greater, accounting for reductions of 37-41% in emissions from fossil fuel use. Given such significant influence of demographics on emissions, the study suggests that family planning policies would have an important role in mitigating climate change.

Global Demographic Trends and Future Carbon Emissions. O’Neil, B. et al. (2010), PNAS, Vol 107, no. 41, www.pnas.org/cgi/doi/10.1073/pnas.1004581107

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