How many years would halving global consumption set back climate change?

March 11, 2024 10:51 AM

Hypothetical: The world’s resource consumption halves overnight due to science fictional reasons. You are writing a pithy headline on the environmental impact of this change along the lines of “Climate change estimates rolled back X years”. What’s a reasonable value for X?

I know that climate change is a complex issue with many overlapping expressions that can’t be summed up in a single number. But sometimes you need a pithy headline.

In case it matters (I don’t think it does, but I wouldn’t need to ask this question if I was sure), here’s the science fictional scenario: For most of modern history, Earth has secretly been supporting the resource needs of another planet of ~8 billion people. One day this support is halted.

For my purposes, we’re ignoring the implausibility of this and all the social/industrial/political disruption caused by such a massive revelation and change.

posted by Lorc to Science & Nature (12 answers total)

For my purposes, we’re ignoring the implausibility of this and all the social/industrial/political disruption caused by such a massive revelation and change.

I've got several friends working directly in climate change and from what I gather from them, this is just... not something you can ignore. Climate change is not one slider, it is hundreds if not thousands of tiny sliders that have a cumulative effect. You remove half the industrial demand of the world, everything changes, and not in predictable ways. (Not to mention, some of the big drivers of climate change, like transportation fuel use, would not be affected by a change in what's shipped offworld, unless the climate numbers are largely (and secretly) driven by the shipping method and not what we currently understand to be the causes.)
posted by restless_nomad at 11:08 AM on March 11 [1 favorite]

Best answer: Halving annual CO2 output would take us back to 1978, emissions-wise. Of course the actual current atmospheric CO2 levels wouldn't change, and so a certain amount of future warming would still be locked in. Hopefully after a few years warming would slow down, neglecting any natural tipping points or feedback loops that we might have tripped over.
posted by BungaDunga at 11:08 AM on March 11 [2 favorites]

Net Zero plans envision us getting to ~0 carbon emissions by 2050, and halving emissions by ~2030. So, assuming the world is working on net zero, it gets us to that a few years earlier.
posted by BungaDunga at 11:14 AM on March 11

The Thanos snap wouldn't just halve resource consumption, it would likely cause collapse of the structures that allow industrial society to function, thus setting the timeline much differently than simply saying, for instance, what would the timeline look like if demand were the mid-70's when we had half the population and used half the energy we use today.
Halving demand would mean prices collapse and energy production might be less feasible, whereas halving production capability would have a different economic effect.
Halving emissions says nothing about demand, it simply redirects demand to other, sustainable resources, which is not the same.
posted by OHenryPacey at 11:17 AM on March 11 [5 favorites]

you can see here from Wikipedia a set of future carbon emissions rates and their consequences. The policy that would very quickly halve emissions (and then drive towards zero) is probably the only one that gets us below 1.5C of warming by 2100. So, a magical reduction of 50% would put us on track to net zero and 1.5C of warming. I am not sure it makes sense to express it in "years setting back climate change" since the absolute amount of carbon we emit directly impacts the absolute amount of net warming we get.
posted by BungaDunga at 12:37 PM on March 11 [2 favorites]

Response by poster: "Do you have that headline for me yet?" your boss bellows from his office. "We need to push the article in the next half hour."

"But Mr Bertruger" you plead, "it's not a straightforward question. Even the term "climate change" refers to so many overlapping factors. The social and industrial impact alone will-"

"And I'm sure the boffins are having a great time arguing about it. That's their job. Your job, which is on the line right now, is to take complex facts and turn them into simple sentences. Get me that headline in 28 minutes or you're fired."
posted by Lorc at 12:44 PM on March 11 [2 favorites]

Hah. Yeah, the thing is, if it doesn't need to be true, it doesn't need to be plausible. So just have 'em claim something at random. You won't be doing anything headline writers don't already do.
posted by restless_nomad at 12:48 PM on March 11

Response by poster: To be more specific and less facetious, I was thinking in terms of tipping points and climate deadlines.
posted by Lorc at 12:51 PM on March 11

So the scenario is actually suddenly we have twice the energy we need to sustain our demand, because our planet's behavior doesn't change, simply we withhold the energy to the other planet?
Currently an optimistic estimate says 30 % of our energy is from sustainable sources. So in the new calculus 60% of our needs are being met. To stop climate change we need to be north of 85% renewable.

My headline might be: Renewables leap toward sustainable climate goals! which would technically be both true and optimistic, without going into the details of the math involved in the leap.
posted by OHenryPacey at 1:07 PM on March 11

If I were writing this headline (I write many), I wouldn't be estimating the time myself, and would use a hedge to put it on the experts who would be commenting on this event, whose estimates would vary widely. I bet some would say 10 years, some 20, some 50. In that case I would probably write "up to 50 years," or a more general scale like "decades" and use hedges like "could" like so:

-Climate changes could put off disaster by 'up to 50 years'
-Climate tipping point may come 50 years later than expected
-Experts say climate rewound to 70s levels after global intervention
-Climate experts claim recent events de-aged climate by decades
-Global policy could defer climate doomsday for decades

The idea is to note the more exciting possibility without preferring or endorsing it, while not discounting more conservative ones, but also ignoring obvious outliers like one guy saying 500 years. Then in the lede you would note that experts' opinions vary and some say blah blah blah. But for the purposes of the headline you would want to highlight the outside of the mainstream.
posted by BlackLeotardFront at 2:30 PM on March 11 [2 favorites]

The simplest headline is that the net-zero target can be moved from 2050 to 2075.
posted by Winnie the Proust at 2:43 PM on March 11

Negative 5? There are suddenly many more resources, everyone is richer, people think the climate crisis is over, and so everyone embarks on a spending spree.

This isn't entirely frivolous: it's more or less what happened after the Black Death, which killed off 40% of the population. Population was lower, but wages rose 200%, inequality fell, land got cheaper, and interest rates were favorable. This all may have set the stage for increased state power, urbanization, and higher GDP in the next century.

Or to put it more simply: You learn that gas is now half as cheap. Do you drive the same amount, saving half your gas money? If so, you spend that money on something else. If not, you drive more, maybe even more than twice as much.
posted by zompist at 8:02 PM on March 11 [1 favorite]