chalk it up to the state of the world

tooth and nail with great vigour and determination:

這條新聞則是震驚全世界的德國的killing rampage。
同一天，連續兩件(美國和德國，真是太恐佈了),
據說，兇手曾經在前一天上網，預告這件事，下面是有關的報導。

Earlier, Heribert Rech, interior minister of the state of Baden-Wurttemberg, quoted the postings attributed to Kretschmer as saying, "Everyone laughs at me. No one recognizes my potential. I mean this seriously."
"I have got a weapon here and tomorrow I am going to go to my former school and give them hell. Maybe I would escape, keep your ear to the ground. You'll hear from me tomorrow morning. Just notice the name of the place, Winnenden. Don't say anything to the police," Rech quoted.

另外上星期，美國CNN有一關報導，有一名男子，他的老婆帶著他的小孩到巴西，然後訴請離婚，後來這位女子死後，這名老爸想要要回監護權。他也用了這句話。

King: How did you hear she died?
Goldman: I have friends who, kind of, have an ear to the ground in Brazil, and there were some articles that came out in some local Brazilian newspapers and they did some on the Internet and said she'd passed away.

keep an ear to the ground---to devote attention to watching or listening for clues as to what is going to happen.

這條新聞是這震驚全美阿拉巴馬州的killing rampage, 下面這句話，是居民的反應。
Area residents were shocked that such mayhem should occur in their area,
but they chalk it up to the state of the world.
將它歸究於目前世界動盪不安的局面。

chalk it up to experience informal
to accept a failure or disappointment calmly and regard it as an experience that you can learn something from
to say that something is caused by something else

下面這句話則是在講由非洲移民來的人，由於無法溶入美國生活，已經有些人被激進份子吸收。
所以，這是一項警訊。
The idea that Ahmed was radicalized in the United States raised red flags throughout the U.S. intelligence community.

If you refer to something as a red flag, you mean that it acts as a danger signal.
這個片語讓我想到wake up call都是警訊的意思。