Scientists are concerned the Earth may be entering a period of global cooling, potentially leading to a new ice age.
The scientific consensus through the 1970s actually favored warming from CO2 emissions, though some papers did address aerosol-driven cooling. The 'global cooling' narrative was a media oversimplification. By the 1980s the warming signal was dominant in scientific literature.
What changed?
In 1974, Newsweek ran a story describing a new climatological concern: evidence that the Earth might be heading into a period of global cooling, potentially severe enough to threaten agriculture. A 1974 CIA report assessed the geopolitical risks of climate change, meaning cooling, primarily, as a serious national security concern. Time magazine published similar coverage. The impression created was of a scientific community worried about a coming ice age.
The reality was more complicated. The scientific literature of the 1970s contained papers addressing both cooling and warming mechanisms. On the cooling side: industrial aerosols and sulfate particles, produced by burning fossil fuels, reflect sunlight and could potentially offset or exceed the warming effect of carbon dioxide emissions. On the warming side: CO2 was accumulating in the atmosphere, and the basic greenhouse physics had been understood since Svante Arrhenius calculated it in 1896. A retrospective review of the peer-reviewed literature from the 1970s found that papers predicting warming significantly outnumbered those predicting cooling, but the cooling papers attracted disproportionate media attention.
What reached classrooms was often the media version: scientists were debating whether warming or cooling was the greater risk, and cooling had received significant recent attention. Some curricula through the late 1970s presented global cooling as a live scientific concern alongside or instead of warming. A student graduating in 1979 was more likely to have encountered the cooling narrative than the warming one, not because that was what the literature said, but because that was what newspapers had reported and what had filtered into science textbooks and classroom discussions.
By the early 1980s, the picture had clarified. The aerosol cooling effect was real but limited in scope; the CO2 warming trend was persistent and measurable. In 1979, a National Academy of Sciences report chaired by meteorologist Jule Charney concluded that doubling atmospheric CO2 would likely raise global average temperatures by 1.5 to 4.5°C. That range, the ‘Charney sensitivity’, remains essentially unchanged in the scientific consensus four decades later. The cooling narrative faded from scientific prominence, though it persisted in popular memory and was later selectively invoked to cast doubt on climate science generally.
