Alarm Bell
Fire Bell
noun
A warn bell is a bell that goes off when you need to be warned about something. This is usually an alarm bell or a fire bell.
けいしょう
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
研究者たちは、どれだけ速く氷山が溶け出しているかについて警鐘を鳴らしている。
Researchers are sounding the alarm on how quickly the icebergs are melting.