Today many politicians and wise people including Prince Charles think that we can cut greenhouse gases to a safe level by 2050 while maintaining economic growth. A simple mathematical calculation suggests otherwise.
Assume the safe level is 50% of today’s emissions. Assume global economic growth of 3% per year from now to 2050. This means we need to reduce the greenhouse gas intensity of the economy by 4.47% per year.
What would it take to achieve that?
Consider the world economy as a collection of assets of different technologies. These assets have varying degrees of greenhouse gas intensity. Some, like coal-fired power stations emit lots of CO2. Others, like ball-point pens, do not emit so much.
Each asset has an average life span and gets replaced after its life span. Power stations have life spans of 30 years or more before they are replaced. Ball-point pens have lives of a few weeks.
When an asset reaches the end of its life span or slips behind the cushions in the sofa, it gets replaced by a similar asset which has newer technology which has lower greenhouse gas intensity.
As the economy grows, more assets are created – using the latest technology – to meet the demands of economic growth.
Assume that whenever an asset is replaced or a new one built, the very latest technology is selected. Let’s assume that the permitting authorities in every region of every country in the world are so smart and up to speed that they are ready to permit technology which came off the drawing board last year. Let’s assume that the economics of the world are such that it is viable to implement last year’s technology today. Let’s assume that the marketing departments of all technology companies are so full of genius marketeers that they can persuade customers to adopt brand-new technologies instantaneously. So let’s assume only 12 months delay between the arrival of a new technology and that technology always being selected for any purchase anywhere in the world.
Let’s assume that technological development gets really good. Assume that every year every single technology becomes on average 5% more GHG efficient. Whether coal-fired power plants or automobiles or aeroplanes or air conditioning units: every single year for the next 43 years, GHG efficiency improves by 5%.
On these assumptions, to cut GHG emissions by 50% by 2050, we have to replace every single GHG producing asset with the latest technology every 4.8 years.
Gore’s Law states that every GHG emitting asset needs to be replaced every 4.8 years with a new one which is 26% more efficient than the previous one.
What happens if there is slippage on the technology improvement … say to 4% annual GHG intensity improvement? Gore’s Law breaks down here. Even if every asset were replaced after one year of operation, we’d only cut emissions by 36% by 2050.
Hopefully, some technologies will cause tectonic shifts in our economy and our lifestyles, leading to much bigger reductions in GHG intensity than those achieved in any individual technology. Inspirational video conferencing could obviate the need for improvements in transport technology. There’s still a chance that the invention of a fashionable pullover could reduce the need for improvements in heating technology.
Until then Gore’s Law tells us that to rely on economic growth and technological improvement is a very risky strategy.