This question was closed as "not suitable for" Physics SE. Based on the comments, the voters seemed to think that it belongs to Biology SE instead.
I don't understand this reasoning. Answering this question requires answering two sub-questions:
- What would be the flux of radiation at the Earth's surface if the Earth didn't have a geomagnetic field?
- What would be the impacts of that radiation flux on human health?
The first sub-question is clearly a physics question. The second sub-question is arguably more of a biology question, although I personally feel that the impacts of radiation on biological tissue is a biophysics question that lies well within the intersection of both fields. But even if we granted that the second sub-question was a better fit for Bio SE, then I don't understand why, if the first half is a better fit for Physics SE and the second half a better fit for Bio SE, that makes the whole question not suitable for Physics SE.
One commenter claimed that "the crux of the question" was the second subquestion. I don't understand this claim; one needs to answer both halves in order to answer the question. Arguing over which half is "the crux of" the question seems to me to be about as well-posed as arguing whether the engine or the steering wheel forms "the crux of" a car. You need both in order to function.
(A separate question was also raised, which was which title best summarizes the content of the question. I believe that this is an orthogonal issue to whether or not the question is on topic. My understanding of SE best practices is the purpose of question titles is to quickly convey the point to a viewer, but the title is not considered to be an "official" part of the question for the purpose of answering, and by design it often deliberately omits critical parts of the question.)
It seems to me that in situations like this, where different necessary sub-questions of a question might (arguably) be optimal for different networks, a question should be considered on-topic for any of the networks. Do others agree?