The quote you're referring to came from the study's lead author, a Brit. Presumably he was referring to soccer (which everyone else calls "football"). Furthermore, a soccer field and an American football field are reasonably close in area, so it gets the point across in any case.
However, I will now refer to explosives exclusively in units of Bald Eagles when referring to their mass, and "star spangles" when referring to their energy output.
By analogy with another type of football, i.e. rugby football which was nicknamed rugger in the old days. Soccer was always a nickname, and association football the formal name.
The term "football" was used in medieval England to refer to sports played on foot as opposed to on horseback. There was a class element too as football games (of which there were many types) were played by the common man while equestrian sports were the realm of the elites. There were even laws passed regulating how much "football" could be played so it wouldn't distract from other peasant responsibilities.
This isn't a uniquely American thing to be fair, in the UK it's not unusual to discuss area in terms of football pitches or for very large areas, Wales.
To be fair, who actually has a mental model of what 20,779 square kilometres or 8,023 square miles (the area of Wales expressed as a number) actually looks like? Doesn't matter if you're using imperial or metric, it's not very intuitive beyond the human scale.
If you're trying to communicate 'this much rainforest disappeared' or 'look how large this landmass-sized Antarctic iceberg is' to a wide audience a well-known area is a reasonable way to do it. In Britain basically everyone knows roughly what the size of Wales is relative to the other countries of the UK, even if they don't know its exact size.
20,779 square kilometres you say? Thats trivial, its roughly strip of 20km that is 1000km long. Or 200x100km. If you can't imagine that, thats mostly problem of your practical imagination, I have the image of such area in my head immediately and can map it into various parts of regions around me rather easily.
I don't play football, nor soccer nor rugby nor baseball or similar sports, just like you most probably don't climb on rock. I am not pushing my metric of '2 spans of typical rope length for alpine tightrope 2-people setup ' or similar obscure metric, do I.
What is good about metric is that once you have a good feel for different lengths of mm, cm,meters and kilometres you don’t need to worry about things like “10 Super Bowl stadiums”. You can easily extrapolate what 27km2 means, it doesn’t have to “look like” anything.
That really isn't true. You in particular may be good at such extrapolation, but people as a rule are not. They need a concrete example to relate back to.
The UK is arguably worse than the US in this regard. The US has mainly stayed with a system that sticks to one measurement across use cases. If I burn fuel at a rate of x miles per y gallons, I purchase it at the pump in gallons. If Tommy Atkins burns fuel at a rate of x miles per y gallon, he purchases it at the pump in liters; there's an extra step for conversion.
Ah, but minutes (or an hour) don't have any context to a person. "A bomb dropped every two thirds of the duration of a football game, excluding breaks". No, that sounds too mathy. Perhaps "three bombs per two games".
What a low value comment. In this case, a European football (soccer) field/pitch is reasonably close in size to an American football field. If the article had used square feet or acres, your comment might be more relevant. Google tells me that FIFA football pitch size is 105 meters long by 68 meters wide (7140 sq m). American football field size is 110 meters long by 53 meters wide (5830 sq m).
