What are the differences between "ignore" and "neglect"?

Question

I came across the following statement:

People have either ignored or neglected these effects because...

I think there must be some subtle differences between the two bold words. Anyone could point out it? You are appreciated.

Answer 1

When one

ignores something

one is actively not paying any attention, on purpose

She ignored his advances until he left her alone.
The referee ignored the crowd's screaming for a penalty.

When one

neglects something

one may have forgotten about, or not been aware of a critical situation for something one was supposed to take care of or oversee

Their electricity bill was very high since they neglected to turn off the lights.
The plant was never watered and died of neglect.

Your example sentence would be more correct as

People have either ignored or neglected...

Answer 2

1. ignore
   to refrain from noticing or recognizing
2. neglect
   to pay no attention or too little attention to; disregard or slight

However, neglect also has a meaning that implies a sense of responsibility:

[3.] to be remiss in the care or treatment of

So, the word ignore suggests that the people are aware of the effects, but do not give it much thought or do anything about it. It is possible that they are not obligated to take any action. On the other hand, using the word neglect, the author suggests that the people have a responsibility to do something about these effects, like remedy them, record them, report them, etc.

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Note, there is a matter of "People has". As I understand it, the word people is plural. So I think it should be People have, unless there is a good reason it should be otherwise that has been omitted.