Those who refute the idea of global warming love to claim that the world is getting cooler. All it takes is a brief cold snap or a rainy day for certain parts of society to announce that global warming is some kind of grand conspiracy. When doing so, they often point to the 1970s, a period when parts of the scientific community and the public were briefly gripped by the theory of global cooling. Numerous headlines claimed that the Earth was on the brink of a new ice age, provoking mass curiosity and concern.
This theory, now widely disproven, was rooted in observed climate trends and scientific hypotheses, limited by the technology and knowledge of the time. While the concept of imminent global cooling has since been debunked, the reasons behind its emergence and eventual discrediting provide valuable insights into how our understanding of climate science has evolved.
What Was the Global Cooling Theory?
The idea of Global Cooling emerged in the 1970s and suggested that the Earth was entering a period of massive cooling. The fear was that this would lead to a new ice age. These fears were inspired by observations of a perceived cooling trend from the 1940s to the early 1970s, which seemed to contradict earlier warming trends of the early 20th century.
While the scientific literature of the time was still mostly concerned with global warming, this theory largely gained traction thanks to media reports that featured dramatic headlines warning of imminent widespread climatic disruption and food shortages. Some things never change.
The theory’s core was a mix of historical climate data and fringe scientific hypotheses. Scientists (and reporters) noted that temperatures had dropped a little over a few decades, leading some to claim it was the beginning of a long-term trend. Various reasons for this were put forward, ranging from aerosol pollution to changes in solar activity and natural climate variability. While longer-term climate data soon showed that global cooling was just a theory, modern climate change deniers seize on this outdated theory to this day.
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The “Science” Behind It
Global cooling may have been disproven, but that doesn’t mean the claims behind it weren’t founded in scientific theory. Several factors contributed to the belief that global cooling was happening. The primary drivers were observed cooling trends and concerns over aerosol pollution.
Observed Cooling Trends
As already mentioned, climate data between the 1940s and the early 1970s showed that global temperatures seemed to show a decline. The cooling was modest, but compared to the warming seen in the early 20th century, the difference was stark.
Since our understanding of long-term climate change trends wasn’t what it is today, some scientists were concerned. They were keen to understand these fluctuations, prompting hypotheses that the media seized upon as fact.
Aerosol Pollution
Most 1970s scientific literature on climate change was concerned with how the greenhouse effect was causing long-term warming. However, some scientists were becoming increasingly concerned with aerosols – tiny particles released into the atmosphere from industrial activities – including sulfur compounds.
Aerosols can reflect sunlight into space, increasing Earth’s albedo (reflectivity) and potentially leading to cooling. Studies showed that aerosol levels in the atmosphere were rising, leading some to believe they could lead to cooling. However, this effect was soon shown to be heavily localized and temporary when compared to the greenhouse effect.
Natural Climate Variability
Another area of study was natural changes in Earth’s climate. Things like massive volcanic eruptions can release particles and gases into the atmosphere that temporarily cool the Earth. Since no super-eruptions were recorded between the 1940s and 1970s, this could be ruled out.
However, Milankovitch cycles – long-term changes in Earth’s orbit and axial tilt – are known to drive natural climatic shifts over geological timescales. Some speculated that we were at the start of one of these shifts.
Solar Activity
Changes in solar radiation were also examined. Periods of reduced solar activity, such as the Maunder Minimum in the 17th century, were associated with cooler temperatures. Some scientists hypothesized that a similar reduction in solar output might be occurring, potentially leading to global cooling.
Discrediting Global Cooling
The global cooling theory, much like the cooling it perceived, was short-lived. It was discredited through a combination of continued climate observations, advancements in climate science, and an expansion of our knowledge of greenhouse gases and the problems they cause.
For a start, by the late 1970s and early 1980s, the cooling trend that had sparked all the fuss began to reverse. Global temperatures were on the rise, a trend that has continued to this day. This was the first nail in global cooling’s coffin.
Throughout the 80s and 90s, major advancements were made in climate modeling (thanks to computers) and our understanding of the Earth’s climate system. Computer models allowed scientists to simulate the impacts of numerous factors on global temperatures with greater accuracy. These models consistently showed that the warming effect of increased greenhouse gases far outweighed the temporary cooling effects of aerosols and other factors.
During this time, studies around greenhouse gases gained more and more traction. Multiple studies showed that carbon dioxide (CO2), methane (CH4), and other greenhouse gases were trapping heat in the atmosphere, causing a long-term warming effect. The rise in CO2 levels due to industrialization and deforestation became a focal point of climate research, with strong correlations between these emissions and global temperature increases.
The more data scientists gathered; the more flawed global cooling appeared. Analysis of climate data, ice core samples, tree rings, and long-term historical records all painted a clearer picture of Earth’s climate history. This picture showed that the brief 30-year cooling period was a blip, an anomaly, compared to long-term trends.
By the late 80s and early 90s, the verdict was in. Major scientific organizations, including the Intergovernmental Panel on Climate Change (IPCC), were issuing reports claiming that human activities, particularly the emission of greenhouse gasses, were the primary drivers of recent climate change. Outside of certain media outlets and political parties, global cooling was dead.
However, that doesn’t mean all the research that went into the theory was wrong. It has been well-established that aerosols can cause climate change. This offsets the greenhouse effect in some areas to a minor degree but is essentially a drop in the ocean.
We also know that natural climate variability is a thing. It’s known that certain natural events can cause short-term fluctuations in global temperatures. For example, concerns over how a super eruption could essentially cause a nuclear winter are both well-founded and terrifying.
Conclusion
Global cooling was relatively quickly discredited by the scientific community, but it hasn’t disappeared completely. On the positive side, despite its shortcomings, the theory contributed to our understanding of aerosols, natural viability, and climate cycles, enriched climate science, and highlighted the dominant role of human activity in modern climate change.
On the less positive side, the fearmongering around the theory highlighted how scientific data can be manipulated to make headlines. The media had a field day scaring people with horror stories of a new ice age, while certain groups seized the opportunity to further their own goals. Today, these old news stories are often used to refute genuine fears about global warming.
Top image: The Earth sat in some snow, AI generated image. Source: chayantorn/Adobe Stock
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