Can Economic Growth Last?

[Chris Coles]

This has just showed up on Slashdot and makes for a very interesting read.

| Limits On Growth of Energy Use and Economies
| from the but-infinite-growth-sounds-fun dept.
| posted by Soulskill on Tuesday August 02, @20:00 (Power)
| with 462 comments
| https://hardware.slashdot.org/story/11/08/02/2315207/Limits-On-Growth-of-Energy-Use-and-Economies?utm_source=newsletter&utm_medium=email

[0]snoop.daub writes "Dr. Tom Murphy, professor of astrophysics at UCSD, has a new blog called 'Do The Math,' and the first few posts are doozies. In the first, he shows [1]the impossibility of continued exponential growth in energy use. Even if a new, 'free' energy source is developed, thermodynamic limits on efficiency mean that the heat associated with converting this energy into useful work will increase the temperature of the earth to unbearable levels within 300 years. In the second, [2]he extends the argument to economic growth. The timescales there are faster, only 50-100 years. Fascinating stuff. Time to stop breeding, folks, or to get our butts into space."
Discuss this story at:
https://hardware.slashdot.org/story/11/08/02/2315207/Limits-On-Growth-of-Energy-Use-and-Economies?utm_source=newsletter&utm_medium=email#commentlisting
Links:
0. mailto:snoop.daub@gmail.com
1. http://physics.ucsd.edu/do-the-math/2011/07/galactic-scale-energy/
2. http://physics.ucsd.edu/do-the-math/2011/07/can-economic-growth-last/

[touchring]

Re: Can Economic Growth Last?

There's unlimited energy - from coal.

[unlucky]

Re: Can Economic Growth Last?

It's an interesting read, but is it plausible? First Dr Murphy argues that if we rely on renewable power (from sunlight) we will need the full output of the Sun within in 1450 years (to continue growing at the historical rate of 2.9% since 1650). However, humanity abandoned renewable energy sources some time ago in favor of fossil fuels precisely because of their scaling problems. The 2.9% historical growth rate was only sustained because of this abandonment.

Next Dr Murphy argues that if we use non-renewable power sources, then the temperature of the Earth will start to rise about 100 years from now and become unbearable in 300 years. But that is not a concern if the energy is used in space.

Dr Murphy concludes that "continued growth in energy use becomes physically impossible within conceivable timeframes". But he has not demonstrated that. Even if he had demonstrated it, he ought to add a caveat that the known laws of physics are much younger than the 2.9% growth trend, and they are likely to change before the limits they impose are actually reached.

[c1ue]

Re: Can Economic Growth Last?

The problem with Dr. Murphy's approach is that:

1) Linear extrapolation of present trends is always wrong

2) It is certainly true that modern man uses far more energy than 1800s man, or Stone Age man, or Hunter Gatherer man. However while overall energy use in the United States, for example, is high, in reality the per capita use has in fact fallen significantly:

Note that the total energy use increased from 85-ish quads to maybe 100-ish quads from 1977 to 2000 (17%). However, the US population went from 220 million in 1977 to 280 million in 2000 (27%). This decrease in per capita energy use is reflected in the slashdot article in fact.

3) The assumption made is also that human population will continue to increase 300 years. That is an extremely poor assumption - the basis for Dr. Murphy's calculations was a straight energy use graph but without population correlation.

Looking at population: World population in 1650 was around 500 million; year 2000 population is around 6 billion. That's a 2.7% growth rate - or significantly higher than the 2.3% increase in energy use.

Given that world population is increasing around 1.14% (according to wiki) - I'd say almost every single premise Dr. Murphy bases his alarming conclusion on is false.