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Thomas Murphy, a professor of physics at the University of California, San Diego, believes that although no one can predict with absolute certainty that the planet will reach an unavoidable crisis by the end of this century, our trajectory cannot continue for much longer. His assessment was recently published in a Nature Physics commentary paper.
Murphy, an astrophysicist by training, became interested in planetary boundaries after teaching a course on energy and the environment. Students investigated the physics of energy, how to calculate energy demand and resources, and the ensuing environmental effects. Murphy realized that resource and energy consumption issues were more severe than previously believed.
The Earth's resources are limited; this is evident when considering fossil fuels, mined minerals, and land. However, it is difficult to envision a time when humanity will have to adjust its lifestyle to account for these limitations.
The author of the book Energy and Human Ambitions on a Finite Planet, asserted that "In the past, the Earth was able to accommodate our increasing resource demands," "But keep in mind that there have never been 8 billion people on Earth, and we are all pursuing higher consumption demands. Future resource projections cannot be based on historical data. This is uncharted territory."
Murphy calculated future energy consumption using our historical growth rate of a factor of ten every century to demonstrate this point. If the global energy consumption of humans is currently 18 TW (terrawatts), it will increase to 100 TW by 2100, 1,000 TW by 2200, and so on. We would outperform the Sun's entire output in all directions in 1,300 years and the total solar power incident on Earth in 400 years.
Using the same growth rate to extrapolate future levels of waste heat (the end product of all our energy use, which is ultimately radiated into space) also provides a bleak outlook: the amount of waste heat produced would accelerate, leading to a rise in global temperatures. The Earth's surface would reach the boiling point of water in just over 400 years.
Murphy makes it clear that this extrapolation of energy use and waste heat is not accurate and is not a forecast. It was created to demonstrate that our uninterrupted historical growth cannot continue indefinitely. In actuality, the progression indicates that the period of unrestricted energy consumption on Earth will be relatively brief in comparison to the duration of civilization.
Even the most pessimistic economists will admit that the Earth's physical resources have a finite amount. However, many argue that this won't have an impact on economic growth because once money is "decoupled" from physical resources, it will be able to grow unrestricted by the depletion of fossil fuels or minerals.
Murphy states, "Some might say money doesn't have to obey the laws of physics or that we can sustain economic growth through innovation," "But those things are not immune to limits. Even if you think about life in the virtual realm -- that requires physical resources too, to build and run those computers. We're seeing that for bitcoin mining and the massive amounts of energy it consumes."
Murphy acknowledges that many economic activities do not necessitate the intensive use of physical resources; for instance, work in the legal and financial sectors primarily uses computers, lighting, and heating, but does not involve the fabrication of concrete and steel. While it may be simple to assume that the proportion of decoupled activities will keep rising while resource demands keep falling forever, the need for physical resources eventually reaches a point where it can no longer be reduced. Humans, as Murphy points out, will always require food.
He observes that the perceived advantages of economic growth are two-sided. People may be lifted out of poverty and given better access to water, food, and health care as the economy grows. As their populations increase and their standard of living improves, their resource demands exceed the planet's capacity and threaten to eliminate these advantages.
The real solution, according to Murphy, is long-term planning and a fundamental shift in how we view ourselves as a species. "Our interaction with the planet must change. We must have the humility to recognize that the Earth is not our property. But how do you persuade someone of something that has never happened, is yet to come, and calls for giving something up? I'm hoping we can start sowing some seeds soon that will eventually produce wiser choices."
Reference: Thomas W. Murphy. Limits to economic growth. Nature Physics, 2022; DOI: 10.1038/s41567-022-01652-6
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