canary in the coal mine

English

Noun

canary in the coal mine (plural canaries in the coal mine or canaries in coal mines)

1. Alternative form of canary in a coal mine
   • 2006, Al Gore, An Inconvenient Truth: The Planetary Emergency of Global Warming and What We Can Do About It, Rodale (2006), →ISBN, page 176:

     The second canary in the coal mine — along with the Arctic— is Antarctica, the largest mass of ice on the planet by far.

   • 2007, Kentwood D. Wells, The Ecology and Behavior of Amphibians, The University of Chicago Press (2007), →ISBN, pages 784-785:

     Many authors state, almost as a truism, that amphibians are more vulnerable to environmental insults than are other vertebrates and therefore might serve as a kind of “canary in the coal mine,” an indicator of environmental degradation (e.g., Carroll 1999).

   • 2009, Erica Manfred, He's History, You're Not: Surviving Divorce After 40, GPP Life (2009), →ISBN, page 167:

     Sex is the canary in the coal mine. It's the first thing to go when a marriage is in trouble.