2019 and 2020 books are in the
Odds and Ends
A very snowy hill
26 2, 10:19pm
I get what you are saying, but
1) I believe things are not that simple. There are several more things to take into consideration, first electrecity isn't clean in most countries (and especially, contrarily to common belief it's not that clean in denmark, it's more clean than in certain countries due to wind power, but less clean than in France for example, because of that same wind power). Second, batteries are not environmentally neutral either. They imply some particularly bad mining activities.
On the other hand, agriculture could be cleaner than it is. You can't suppose that everything is green when you produce electricity (when it's not the case in most countries) just because it could be the case (which is debatable anyway) and compare it with our current agricultural system which could certainly be upgraded to become way more clean than it is (getting into details would require a lot of time, but let's just agree with the fact that not everything is perfect the way our agriculture model is).
I see the point you are trying to make that we should always treat this problem with rationality and avoid acting on belief that "natural" activities are always better but I'm not sure you chose your example very well.
2) Physical activity is not only health related, some people do it because they enjoy it (crazy eh ?), so now there is a whole new philosophical debate wether you should stop enjoying your life so the planet can live but well, once you go down that road you are one step away to justify mass killing in order to save the planet...
3) More importantly, I think this is not the point of the comics, she said she knew she was acting silly and the justification Denmark gave might be seen as denmark rationalizing his silliness (especially while he's saying this to Sweden and Norway who are probably two of the top countries in terms of environmental conscience and actual environmental practice).