Aliens, if they exist, will face global warming too, but maybe not quite like us

Any civilization will do more complex things over time, use ever more energy, and eventually heat up their planet. But with greenhouse gases, we've turned a long-term issue into a near-term crisis.

Global warming on Earth is reaching dangerous levels. The United Nations Climate Change conference for 2022, COP27, which began this week in Egypt, will involve many fine speeches, discussions of potentially game-changing agreements on sharing of burdens, and then — little real action. Almost certainly. Over the past 50 years, greenhouse gas emissions have continued rising, even faster than concern over global warming itself.

It’s all making many people more than a little nervous, quite literally. Some psychologists now consider eco-anxiety — driven by an awareness of our lack of action, and the unpredictability of the timing and location of worsening climate impacts, an issue of growing worldwide importance. As one biologist recently commented,

Climate anxiety is something that’s already mainstream, I don’t need to define it. If you got this far, you probably already know what it is…. That feeling you get when you know that no matter how hard you work to help humanity doing research in health, the biggest threat to human health right now is something that seems insurmountable.

What is that feeling of purposelessness that comes from knowing that, that organism that you study and dedicate days on end to understand, will be extinct within your lifetime?

Honestly, it’s all pretty depressing.

And what I’m going to write next isn’t intended to make anyone feel better. This is our problem, and we’ll only get one chance to face up to it. Even so, it might be somewhat helpful to realise that our Earth-based global warming problem is probably not unique. Our predicament may have already played out many times in the universe — not for humans in Earth, but for aliens on other planets (if, of course, they exist).

Only, we may have made the problem worse, and brought ourselves to the moment of an existential reckoning more quickly than was necessary.

Astrobiologists study the origins, evolution, distribution and future of life in the universe, and they largely agree that any civilization in our universe will almost certainly have experienced planetary warming much like we have. One difference: it may not have been driven by greenhouse gases, although that could have happened also. More fundamentally, their trouble would come from their use of energy — and the seemingly unavoidable tendency of civilizations to use ever more of it over time.

Here’s the problem. Like humanity, any developing civilization will do more complicated things on a larger scale over time, and that naturally means gathering and using ever more energy. In his 2015 book Foragers, Farmers, Fossil Fuels: How Human Values Evolve, Ian Morris tells the story of increasing energy use by humans here on Earth, as we went from hunter gatherers to farmers to users of fossil fuels. This transition was driven in large part by our ability, through these changes in lifestyle and technology, to extract ever more energy from our environment on a per capita basis.

Morris estimates that early human hunter-gatherers, finding energy through foraging, used around 5,000 kcal per person per day. Later, after we turned to farming and the use of domesticated animals, we were able to harness as much as 30,000 kcal per day. In the late seventeenth century, the exploitation of coal and steam power marked another leap — by 1970, with fossil fuels, humans were consuming some 230,000 kcal per person per day.

Use more energy, do more things, make life easier. It’s a simple recipe that works, if one doesn’t think too much about secondary consequences.

Using ever more energy also leads to a fundamental problem — waste heat. Anytime we use energy — to heat a room, dig a hole, drive a car down a road — that energy ends up partially stored in the changes we’ve made in the physical world, and also in more heat in the environment. Driving the car wears down tires, deposits a thin layer of rubber on the road, transmits sound to long distances, stirs up wind currents, and pumps hot exhaust into the air — among other things. Energy, physics tells us, is conserved, the total amount never changing; it only changes form.

Hence, the energy we use from fossil fuels or from solar cells or from any energy source whatsoever always ends up, eventually, as waste heat in the environment. It might get stored temporarily in other ways, but it ultimately ends up as heat. Merely using energy means heating the planet. There’s no avoiding this.

The good news is: Currently, this is not much of a problem. The heating generated by our waste energy is only about 1/30th as large as the energy imbalance from greenhouse gases. But our civilization isn’t — barring some catastrophe — going to stop developing. Look at how profoundly we’ve changed in just the last century. Given another 500 years, or 1,000 years, where will our technology be?

This matters because, over the past few centuries, our energy use has doubled roughly every 35 years and, if that continues, in 150 years or so we’ll be using enough energy that our waste heat alone will cause warming similar to today’s greenhouse gas warming. The warming problem that we will (I hope) have just solved will, as it happens, just feed us into a more difficult warming problem. It’s just physics, sadly.

There’s a slim possibility we could soon find evidence of such problems having occurred on other planets — if there really is life elsewhere in the universe. Four years ago, a NASA workshop reported on the various signs of alien technology we might be able to detect on distant exoplanets — planets orbiting others stars.

In principle, scientists might find evidence of other civilizations by detecting excess heating on other planets, caused by those civilizations’ use of energy.

Scientists refer to these as “technosignatures,” meaning signs of technology which could not come about by any ordinary physical process, but would be a sign of intelligence. These could include things like specific narrow band radio signals, huge “megastructures” designed to capture energy from a nearby star, or simply planetary heating — because any civilization will be gathering and using lots of energy and heating their planet as a result.

More recently, another scientific report reviewed the various projects now being planned to search for such evidence in the near future. Some lessons about our future predicament could be available on distant planets, if we can manage to find them.

In any event, planetary heating is in our future — the very near future and further out as well. Many people find this conclusion surprisingly hard to swallow, I guess because it implies some fundamental restrictions on our future here on Earth. We can’t go on using ever more energy, and, at the same time, expect the planet’s climate to remain stable. Can’t happen.

This is important to remember, I think, as we try to face up to the extremely urgent challenge of global warming linked to fossil fuel use and greenhouse gases. This is just the beginning of our problems, a testing ground, if you will, to see if we can manage some kind intelligent and coordinated response. Handle this challenge, and we will then get the chance to tackle an even harder one — how do we begin to limit our use of energy.

We might then be somewhat better prepared, more capable and resilient as a species.