I’ve previously mentioned my hobby of talking to/arguing with strangers on the internet, and a while back I decided to copy and paste one of the conversations onto my blog, since it seemed wortwhile. Since then I’ve periodically added to the series when something interesting and fun comes up. So, without further ado, here is the latest installment of Conversations with Strangers, taken from the comments thread of this Huffington Post article.
Stranger:
So if a change in ice mass at a pole can cause the earth to sway from its position, then isn’t it possible over time that population changes could do the same thing? It that is possible, then couldn’t China and other over populated areas produced the same “balance” issue? Now, if this is possible, that could mean that Chna is a leader in carbon emissions and “Population Sway”.
That’s a rather different issue. To begin with, the total mass of humans on the planet is really, really small compared to the amount of ice we’re talking about. It’s hard to picture the scale, but the entire human population of the planet can fit in an area slightly larger than the size of Rhode island. That’s one layer of non-compressed human, an average of a bit less than two meters thick. (source https://what-if.xkcd.com/8/ 😀 )
For comparison, there was a chunk of the Larson B ice shelf that broke off in 2002 that was the same surface area as our crowd of all humanity, bit it was 220 meters thick.
That’s way more than 200x the mass of all of humanity put together, all in one place, and that’s just one piece of ice from one ice shelf.
When we talk about ice melt due to global warming we’re talking about simply massive amounts of weight. The ice loss in Iceland has been enough that the island is actually gaining elevation because of the lost mass on top of it.
It’s hard to keep the scale in mind, but even our largest cities don’t really compare, since their three-dimensional space is mostly air.
Some of the biggest skyscrapers might have a similar impact to the kind of ice masses we’re talking about, except that that’s only for their one little column, and they’re mostly hollow, whereas glaciers are often much taller than any skyscraper, solid, and with a few thousand more solid super-skyscrapers stacked right against them.
Humanity doesn’t compare, mass-wise.
It’s possible our extraction and re-distribution of fossil fuels is contributing. We’ve emitted a little under 600 billion tons of CO2 from fossil fuel use. That works out to about the same weight as 8 years of melting of Alaska’s glaciers at the current melt rate. That’s a lot less than what’s going on with the masses discussed in this article, but it’s not nothing. It’s possible that that redistribution of mass from coal and oil deposits into the atmosphere has affected things a little but, but it’s unlikely that it’s been enough to be detectable, especially since it’s been happening over the course of a century. Remember – only 8 years for Alaska’s ice melt to move the amount of weight of ALL of our fossil fuel use. (https://www.washingtonpost.com/news/energy-environment/wp/2015/06/17/alaskas-glaciers-are-now-losing-75-billion-tons-of-ice-every-year/)
The only reason our fossil fuel use has any impact at all is that the atmosphere is so much thinner than the planet, and when it comes to blocking heat energy, it doesn’t take a high concentration of any particular greenhouse gas to make a significant difference, just like you don’t need much ink in a glass of water to block visible light https://www.youtube.com/watch?v=81FHVrXgzuA
Addendum: After this comment exchange, someone else asked a similar question about fossil fuel extraction, and it occurred to me that it’s worth mentioning that a portion of extracted petroleum is not burned, and is turned into things like plastic, rubber, and lube. A very rough guesstimate based on an Exxon post about how great oil is would place that at maybe 25% to 30% of extracted oil. That’s a minority of oil extraction, and that mass is spread all over the planet by human activity, so again, probably not something that’s going to have a big impact on Earth’s axis.
It’s also worth pointing out that the 600 billion tons of CO2 doesn’t equate to that much carbon extracted. The EIA puts the coal:CO2 ratio at a little under 1:3, depending on the kind of coal in question. Specifically one ton of coal generates 2.86 tons of CO2, with the additional weight coming from atmospheric oxygen. Of course, we could add in rock moved around in the extraction process, and if we wanted to, the total weight of all materials extracted for everything from everywhere, but the reality is that the direct mass moved around by our industrial activity is pretty small compared to the mass being moved around as a result of CO2-driven warming
And for those who are questioning it, XKCD is TOTALLY a valid source of scientific information!
Another factor that can reduce the impact or the mass of a population and its cities is where the material comes from. Changes in Earth’s spin only happen when the mass is moved. If people are consuming local resources for water, food, and building supplies, the effect on Earth’s balance is even more negligible.
Yup.
There are a lot of factors to consider, but a lot of it comes down to the fact that the scale of ice sheets and glaciers isn’t really clear to most people, and neither is the scale of the change we’re causing.
@Abe Drayton,
Yes, even if people, water, food, and construction materials were moved in such a way to maximize a change in Earth’s balance, it would still be dwarfed by the mass in ice sheets.
It should also be pointed out that the actual amount of the pole shift remains tiny – less than 1 degree per million years. The Huffington Post article confuses that by quoting 75 degrees, which is a change in the direction of the pole shift, not its amount.
@Dave Evan #5 – Yeah, I’ve spent a good chunk of time talking about that in the comments. That bit of confusion was why I made the follow-up blog post.
When I first looked at the primary article, I was pretty sure it used the same language, which didn’t help the confusion. It’s possible I’m mis-remembering and they got it right the first time, but I think they’ve since adjusted the language in the primary article to make it clearer.
Either way, it’s not like The Huffington Post is known for good science reporting, good editing, or clear writing.
So would even a tiny pole shift have a measurable effect on the forces in play for tectonics?
I honestly don’t know, but I suspect not.
The researchers did not seem to think so, at least given their statement that the shift was no cause for alarm, and since the axis moves around a bit anyway, and this hasn’t caused a significant change in speed, it shouldn’t have any measurable impact.
I think the bigger concern would be the effect of weight release on the tectonic plates under the melting ice.