Economic growth, population growth and climate change

A report by Dr David Knight, Winchester Action on Climate Change and the Foundation for Economic Sustainability.

Download the paper (PDF document)

Recent work cited in our report shows that the remaining global fossil fuel resources (mainly coal) would produce an enormous 9-13 trillion tonnes of greenhouse gas emissions. If all of it were burnt without capturing the carbon it would be enough to raise the average global temperature some 18 degree C, may be more. This 9-13 trillion tonnes is large compared with the 0.5 trillion tonnes already produced since the start of the Industrial Revolution. Nearly half of this 0.5 trillion tonnes remains in the atmosphere causing serious problems resulting from a warming of only 0.6 degree C. A recent report by independent consultants shows that there are planned mega fossil fuel projects which would add nearly 2 trillion tonnes of carbon by 2020 . Discharging all of this to the atmosphere would set the world on a path to warming 5 -6 degree C, already the stuff of nightmares. Discharging the additional 7-10 trillion tonnes would be an act of insanity.

To return the atmosphere to a safe level of carbon dioxide requires annual emissions to fall almost immediately, and to cease almost completely by 2050.

Our paper sets out to discover what are the socioeconomic causes of climate change and how knowledge of this would help us to face up to this extremely challenging and vital target.

This paper presents overwhelming evidence that economic growth rather than population growth has been the main factor responsible for climate change while population growth has made a smaller but still large contribution. Changes in the efficiency with which energy is used and in the fuel mix accounts for the rest but has to date had a relatively smaller effect on emissions.

The strong evidence for the above comes from:

1. Household surveys of income and emissions in UK
2. A country-by-country comparison of economic activity with energy use and emissions in 2006
3. A country-by-country comparison of environmental impact with income, emissions, population growth, population density, and population size
4. Two different studies of year-to-year changes in emissions, expenditure, population size, energy efficiency and the quantity of carbon to produce a unit of useful energy (called “carbon intensity of the fuel mix”)

The report concludes that there are 4 approaches to reducing carbon emissions:

1. Economic contraction
2. Population contraction
3. Energy efficiency
4. Lower carbon fuel mixes (renewables, nuclear?, fossil fuel burning with CC&S)

and two other ways to help to reduce global warming:

1. Actively removing CO2 from the atmosphere for example by extensive tree planting in places where there are no trees.

2. Reflect more solar radiation back into space e.g. by increased cloud cover. Maintaining existing forests and planting new ones would also assist in this.

It also concludes that:

1. Increases in energy efficiency and lower carbon energy sources are vital but alone, these are unlikely to achieve the required level of decarbonisation.
2. Planned population descent is highly desirable in the longer term but is unlikely to be of much assistance in reaching the 2050 target.
3. Planned carbon and economic descent and a fairer distribution of income from the richest individuals and countries to the poorest would provide the quickest and most effective means of reducing emissions. This could be achieved by Cap & Share or Cap & Dividend carbon trading schemes although the political barriers to this are formidable.
4. It is also necessary to consider plans to actively remove carbon dioxide from the atmosphere and to reflect more solar radiation into space. A huge increase in the number of trees on the planet would help to achieve emissions reductions and would have other advantages.

Our findings present abundant evidence that economic growth is the main determinant of increased fossil fuel emissions. The report highlights the enormous scale of the challenge facing the world , and suggests that policies should be targeted at social groups and countries whose economic activities make them responsible for the largest emissions.