Deep warming
Not to be confused with Deep Heat ...
My friend Jerry Burke (the one who programmed our UV Smartphone Apps) passed on this news item about what the author calls “Deep Warming”. That’s the warming caused by an accumulation of heat from the increased energy-use by humankind (not just from fossil fuels). The potential problem has been recognised for well over a decade.
Jerry asked whether I thought it was important. I don’t think so - at least not for the present. The article’s a bit of a beat-up, and we don’t want to distract ourselves from the more immediate and pressing problem of how to fix climate change caused by increases in greenhouse gases. That’s a problem for the coming decades, whereas this “Deep Warming” is a potential problem for future centuries or millennia.
The problem they raise is that we’re using more and more energy, and all that energy is eventually converted to heat. That eventuality is inevitable. Otherwise a pillar of thermal physics: the Second Law of Thermodynamics would be contravened.
But how much of a problem is it?
Though it wasn’t a problem 10,000 years ago, it’s now becoming significant. Over the last 10,000 years, our per-capita consumption of energy has increased by a factor of 50, and the number of people on the planet has multiplied by another factor of 8,000. So the amount of waste energy that needs to be dissipated now is four hundred thousand times more than it was 10,000 years ago. Despite all that, the imbalance from this source is currently small the authors say, only 2-3 percent of that caused by increasing greenhouse gases.
Significant, but not a game-breaker at present. But that may not be the same in the future. The author argues that there’s no reason to suppose that the per-capita energy use will slow down. At the current increase rate of global energy, he argues that within a couple of hundred years, the imbalance from energy-use could be comparable with the current problem from increasing greenhouse gases. He also argues that increases in efficiency can delay that point of parity, but at best they can delay it by only 100 years or so.
I think that’s all rather alarmist, given that this waste energy problem is currently only 2-3 percent of the present greenhouse gas problem, and the growth in energy use in recent decades is closely matched to the rate of population increase. The current global population is about 8 billion, and is expected to peak at about 10.4 billion later this century: a relatively small increase beyond the current level. Thereafter, a decrease in population is expected (and needed). Recent experience also shows that the rate of energy use per capita eventually stabilises rather than continuing that crazy upward trajectory since pre-industrial times. Given those two factors, it’s hard to imagine a realistic future scenario where the waste heat problem would exceed around ten percent of the current greenhouse gas problem. But it’s definitely just another step in the wrong direction.
Transitioning to renewable energy sources such as wind energy or solar energy helps because no extra generation is needed. Both these sources only capture energy that was originally generated in the Sun. Other ‘dug up’ energy sources, such as nuclear fission or fusion, will add to the problem - and possibly aggravate it if they result in cheaper energy.
Given our inability to rapidly make changes on environmental issues, it’s already time to start thinking about our total energy consumption. Soberingly, it also reminds us that it’s time to think about how we can help control future population levels in Planet Earth. That will also help the more immediate problem of stabilising climate against the ongoing threat of increasing greenhouse gases.
What I’ve written here is just a quick summary of the full article. Read it if you have time. Despite my misgivings, it’s pretty thought provoking.
Note added 24 June 2023. My colleague, Ben Liley, pointed out my arithmetic error above. Yep, I agree that 50 x 8000 = 400,000, not the 40,000 I originally had. He also added:
“More significantly, the linked article claims that the world used 170,000 TWh of energy, but does not say over what period. From other context, it seems to imply that is annual consumption, which corresponds to 19.3 TW average power consumption (all forms, not just electricity). That aligns with the 20 TW that I routinely quote. It then goes on to say that the 0.87 W m-2 of energy imbalance from global warming is only 50 times greater. But I calculate that a global energy imbalance of 0.87 W m-2 over Earth’s surface of 4*π*(6.371e6 m)2 corresponds to 444 TW, which is only 22 times greater than human energy use (not 50 times greater).”
That’s a bit less than the 30 to 50 times greater implied by that 2-3 percent figure I quoted. So, using Ben’s figures, the wasted heat energy is slightly more problematic. Thanks for checking Ben. Interesting to see the calculation.