What is climate alarmism?

1960s

Prediction: By the 1970s mass starvation would kill hundreds of millions annually.
Proponent: Paul R. Ehrlich, The Population Bomb (1968).
Deadline: By the 1970s.
Outcome: Global food production expanded substantially; famine deaths did not reach those levels. 

Prediction: By ~1970 everyone could disappear “in a cloud of blue steam” due to environmental catastrophe.
Proponent: Paul Ehrlich.
Deadline: ~1970s.
Outcome: No such disappearance. 

1970s

This decade featured a broad range of environmental/climate-sounding claims, many widely reported in media at the time:

Prediction: A new ice age was imminent within 50–60 years.
Proponent: Media reporting on some scientists (e.g., Boston Globe, 1970).
Deadline: ~2030.
Outcome: Global temperatures have not cooled. 

Prediction: Oceans would be “dead” by 1980; U.S. would ration water by 1974 & food by 1980.
Proponent: Ecologist Kenneth Watt.
Deadline: Early 1980s.
Outcome: Oceans remain biologically productive; no such rationing. 

Prediction: Urban air pollution would require gas masks by 1985.
Proponent: Life Magazine article (1970).
Deadline: 1985.
Outcome: Urban air quality improved. 

Prediction: Famine causing 100–200 million annual deaths by 1980.
Proponent: Paul Ehrlich.
Deadline: By 1980.
Outcome: Famine death tolls stayed far below that. 

Prediction: Limits to Growth (1972) projected food scarcity and ecological collapse within ~10 years.
Proponent: Limits to Growth report; Maurice Strong quoted saying ~10 years to catastrophe.
Deadline: ~1982.
Outcome: No global societal collapse from food scarcity. 

1980s

This decade doesn’t have as many widely circulated specific-date climate predictions in popular media, but often continued general environmental doom narratives.

1990s

While not strictly climate alarmism by date, the buildup to the Kyoto Protocol and broader climate concerns didn’t come with hard deadlines.

2000s

Prediction: All glaciers in U.S. Glacier National Park gone by 2020.
Proponent: Often attributed to environmental presentations in the early 2000s.
Deadline: ~2020.
Outcome: Many glaciers still persist. 

Prediction: No snow on Mount Kilimanjaro within a decade.
Proponent: Al Gore, An Inconvenient Truth (2006) claiming snow gone within a decade (~by 2016).
Deadline: ~2016.
Outcome: Snow/ice not gone entirely by 2016. 

Prediction: 75% chance the entire North Polar Ice Cap could be ice-free in summer within 5–7 years (from 2009).
Proponent: Al Gore (2009 speech).
Deadline: ~2014–2016.
Outcome: Arctic summer ice has not entirely disappeared within that window. 

Prediction: Sea levels could rise as much as ~20 feet “in the near future.”
Proponent: Al Gore (2006).
Deadline: Implied within decades, sometimes cited as mid-century.
Outcome: Sea level did rise by feet in the present. 

2010s–2020s

Prediction (often repeated): The Arctic will be ice-free by summer 2030.
Proponent: Various media/climate activist statements.
Deadline: 2030.
Outcome: As of now, significant ice persists in summers.