Canaries in the coal mine
The phrase "canaries in the coal mine" originally referred to the use of canaries by miners to detect harmful gases like methane and carbon monoxide, as these birds would succumb to toxic conditions before human miners were affected. This concept has evolved to symbolize any early warning sign of impending danger, particularly in the context of environmental threats posed by climate change. Various ecosystems, species, and climatic events serve as indicators of this global crisis; for instance, vulnerable animal populations like polar bears and certain amphibians are particularly impacted by rising temperatures and extreme weather events. The alarming increase in global temperatures has been linked to severe outcomes, including more intense heat waves, droughts, and stronger tropical storms, which disproportionately affect the most vulnerable communities. Species such as frogs and butterflies, along with the degradation of their habitats, highlight the broader ecological repercussions of climate change. As these indicators face increased threats, they signal a warning for both the natural world and human societies, suggesting that the impacts of climate change will extend beyond the currently affected groups if action is not taken. Understanding these "canaries" is crucial for recognizing the urgent need for environmental preservation and climate action.
Subject Terms
Canaries in the coal mine
Definition
Originally, canaries were used in coal mines, because small quantities of methane gas and carbon monoxide are deadly to them. Thus, a canary in a coal mine would die long before these substances became lethal to the miners carrying it. The term has come to be used to describe any such sensitive indicator of an emergent threat or problem. Several species and events act as “canaries” in the “coal mine” represented by global warming. These include the ecosystems and species most vulnerable to increases in extreme weather patterns (those most threatened by extreme heat, drought, flooding, hurricanes, and so on); ice sheets and other frozen formations in danger of melting; endangered animal species such as polar bears, amphibians, and butterflies; and plants vulnerable to increased or invasive exotic insect populations.
Significance for Climate Change
Nineteen of the twenty hottest years since 1850 occurred after 1980, and the Earth was warmer in 2023 than at any time in the past two thousand years. Periods of extreme heat place strain on people, animals, and plants and can be responsible for hundreds of human deaths in a given area. A record European in 2003 is blamed for the loss of over fifty thousand human lives. In such heat waves, the most common causes of death are pollution or preexisting medical conditions that are aggravated by the heat. Because those with such conditions are more sensitive to heat waves than are healthy people, they may be considered to function as canaries in the coal mine.
Warm air holds more water than does cold air. Thus, with warmer temperatures, more moisture is removed from the ground, and droughts occur. The droughts, such as those in Africa, kill millions of people through starvation and increased vulnerability to disease. Warmer temperatures also mean that rain or snow falls harder in a shorter period of time, increasing the risks of flooding. Monsoons—patterns of heavy rainfall that particularly affect Asia—strengthen and weaken in relation to the Earth’s temperature. Major flooding is responsible for the loss of human lives and property, as well as the destruction of crops. The most vulnerable to this destruction are the poorest members of society, those with the fewest resources.
Tropical storms (also known as hurricanes, cyclones, or typhoons) are becoming stronger and more frequent. Oceans store a vast amount of heat in their depths, and warm ocean waters give rise to tropical storms and provide the fuel they need to grow. Because of the many factors involved with the storms, there is no clear evidence that they may occur more frequently as a result of global warming. The strength of the storms in the Atlantic Ocean, however, does appear to be affected somewhat by global warming. Extremely powerful Category 5 hurricanes have become more common and include Hurricane Matthew (2016), Hurricanes Maria and Irma (2017), Hurricane Michael (2018), Hurricanes Dorian and Lorenzo (2019), Hurricane Ian (2022), Hurricane Lee (2023), and Hurricanes Beryl and Milton (2024).
The rate of change and level of warming are far above average for the Arctic region. The warm temperatures cause melting of the ice sheets near the shore, so life for subsistence whalers and seal hunters becomes more difficult. In addition, less ice near the shore means that violent storms are not kept offshore and crash into the coastal towns, eroding the coastline.
Polar bears are greatly affected by the decreasing and warmer Arctic temperatures. The bears hunt for seals on in the springtime. When the ice is gone, the bears fast on land. With ice-free spells lengthening, cub birth weights are dropping, females are becoming thinner, and desperate bears are appearing in human settlements seeking food. A study published in Carbon Brief in 2022 indicated that female polar bears were giving birth to smaller litters because of melting sea ice. If polar bears cannot adapt to a land-based life, they may become extinct in the wild.
As glaciers in the Arctic and Antarctic melt, sea levels rise and the oceans become warmer and more acidic. As the sea level increases, millions of people living close to the ocean and in drought- or flood-prone areas will be greatly affected, as lower-lying areas are more prone to flooding and storm surges. Venice is already sinking in the rising waters and is threatened by storm surges. Minor flooding requires residents and visitors regularly to wade through ankle-deep water in the streets.
Amphibians and reptiles, because of their need for a particular range of air temperature and their slow mobility, cannot adapt to climate changes quickly. Frogs are among the most worldwide, and climate change is responsible for several cases of depletion or extinction. Climate change helps fungi attack amphibians more effectively, while drought allows light to penetrate shallow water sources and weaken the developing embryos of some toad species. In 1987, after an unusually warm, dry spring, twenty of fifty frog species vanished completely in Costa Rica.
Butterflies, which have been carefully studied for centuries, indicate climate change as well. Drought and flooding can cause a population to crash. Slowly rising temperatures, as well as other pressures that restrict their range, threaten the populations. As temperatures rise and climate zones move, some species have expanded their habitat northward.
Insects are extremely adaptable to change, but their presence may not be beneficial. Insects may eat crops, and warming northern forests are being devastated as beetles that thrive in warmer climates migrate into them. As temperatures warm, parasitic diseases are more likely to spread and become more severe. Mosquitoes carrying malaria are expanding their territory by about 3 miles per year, according to a 2024 article in Science Alert. Dengue fever, caused by four potentially fatal mosquito-borne viruses, is also on the increase. Cases of the West Nile virus are showing up farther north each year.
The frogs, butterflies, and trees suffering from climate change are canaries in the coal mine. They act as signals of the dangers to stronger and more resilient species that may develop if global warming continues. By the same token, those segments of human society most vulnerable to climate change now will not remain the only segments vulnerable in the future. These canaries demonstrate dangers that will only increase if the Earth’s temperature continues to rise.
Bibliography
DiMento, Joseph F. C., and Pamela Doughman, eds. Climate Change: What It Means for Us, Our Children, and Our Grandchildren. Cambridge, Mass.: MIT Press, 2007.
Henson, Robert. The Rough Guide to Climate Change: The Symptoms, the Science, the Solutions. New York: Penguin Putnam, 2006.
Lomborg, Bjørn. Cool It: The Skeptical Environmentalist’s Guide to Global Warming. New York: Alfred A. Knopf, 2007.
"Ocean Warming Has Intensified Recent Hurricanes." Climate Central, 20 Nov. 2024, www.climatecentral.org/climate-matters/hurricane-strength-attribution. Accessed 19 Dec. 2024.
Tandon, Ayesha and Roz Pidcock. "Polar Bears and Climate Change: What Does Science Say?" Carbon Brief, 7 Dec. 2022, interactive.carbonbrief.org/polar-bears-climate-change-what-does-science-say/index.html. Accessed 19 Dec. 2024.
Watson, Clare. "Malaria-Carrying Mosquitos Are Expanding Their Territory Almost 3 Miles a Year." Science Alert, 20 Feb. 2024, www.sciencealert.com/malaria-carrying-mosquitos-are-expanding-their-territory-almost-3-miles-a-year. Accessed 19 Dec. 2024.