Scientists predicted global cooling in the 1970s

What we know

The idea that scientists in the 1970s were unified around fears of an imminent ice age is a frequently repeated claim used to suggest that climate science is unreliable or prone to reversing itself. The claim traces largely to a handful of popular press stories, most notably a 1975 Newsweek article titled "The Cooling World," which speculated about global cooling based on a short-term dip in Northern Hemisphere temperatures during the 1950s to 1970s, partly driven by rising sulfate aerosol pollution that reflected sunlight.

A detailed 2008 survey of the peer-reviewed climate literature from 1965 to 1979, published in the Bulletin of the American Meteorological Society by Thomas Peterson, William Connolley, and John Fleck, found that of the papers taking a position on future climate trends, seven predicted warming, forty-four projected continued or accelerated warming from greenhouse gases, and only seven predicted cooling. The scientific consensus, even in that decade, leaned toward warming once the competing effects of aerosols and greenhouse gases were both considered, and by the late 1970s most climate scientists recognized that continued CO2 buildup would eventually overwhelm the temporary cooling effect of aerosols.

The brief mid-century cooling trend itself is well explained. Industrial pollution before the Clean Air Act and similar legislation in other countries released large quantities of sulfate aerosols, which reflect sunlight and have a cooling effect on regional and global scales. As pollution control laws reduced sulfate emissions from the 1970s onward, particularly in North America and Europe, this cooling influence diminished, and the underlying warming trend driven by rising greenhouse gas concentrations became dominant again. NASA's Goddard Institute for Space Studies and NOAA's temperature records both show a clear resumption of warming from the late 1970s through today, with the years since 2015 ranking among the warmest in the instrumental record dating back to the 1880s.

The persistence of the "1970s cooling consensus" myth owes much to the ease of citing a single magazine cover rather than reviewing the underlying scientific literature. Media coverage of speculative or minority scientific positions has historically outpaced coverage of the more cautious, hedged conclusions in technical journals, creating a public impression that does not match the archived record of published research. Climate scientists at the time were already debating the balance between aerosol cooling and greenhouse warming, and the eventual resolution of that debate, that warming would dominate, was borne out by subsequent decades of temperature data.

The Peterson, Connolley, and Fleck survey also found that news coverage of the cooling hypothesis during the 1970s was disproportionate to its actual weight within the scientific literature of the time, a mismatch the authors attributed partly to the more dramatic and accessible framing of an impending ice age compared to the more technical, hedged language typical of papers projecting continued greenhouse warming.

This history matters because it is often deployed to argue that current warming projections might similarly be overturned. But the physical basis for greenhouse warming, established through the work of Svante Arrhenius in the 1890s and refined by decades of radiative transfer physics, is fundamentally different from a short-term aerosol-driven cooling blip, and it has been validated repeatedly through direct observation of the atmosphere, oceans, and ice sheets since.

Common claims

• Scientists in the 1970s predicted an ice ageMostly false - a few papers raised concerns; warming dominated peer-reviewed literature
• Since scientists were wrong about cooling, we shouldn't trust warming predictionsFalse premise - there was no consensus for cooling; warming has been consistently projected
• Media in the 1970s reported on a cooling scareTrue - but media coverage misrepresented the scientific literature

Evidence hierarchy

All sources

• The Myth of the 1970s Global Cooling Scientific ConsensusBulletin of the American Meteorological Society · 2008
• The 1970s Global Cooling Zombie MythSkeptical Science · 2019
• World of Change: Global TemperaturesNASA Earth Observatory · 2024
• Climate at a Glance: Global Time SeriesNOAA National Centers for Environmental Information · 2024

Related terms