Climate Change: What Was Known, When?

Climate models have a strong record in helping scientists foresee a warmer world and its impacts.

But in fact the way we know about climate change for sure is that scientists are measuring temperatures all over the world. They are no longer basing the science of climate change only on models. They are using cold, hard, observable facts.

People have known about climate change for over 100 years. This is not new science. Since the 1980s a lot of data from a lot of different sources have added to the certainty that climate change is increasing and getting worse by the year.

Scientists have publicly speculated about climate change since 1938 or even before. There is a fascinating story here about the beginnings of the science of climate change and how people thought about it then. Here is a tiny excerpt of that story.

From Grandfathers’ Tales to Nuclear Fears (1930s-1950s)
The first hint of actual global warming came from public memory. In the 1930s, grandfathers were heard to say that when it came to weather, the younger generation had it easy. Gone were the early frosts and daunting blizzards of their own youth. The popular press began to publish articles, pointing out that in fact rivers were not freezing over as formerly and so forth. Science reporters found experts who confirmed that crops and codfish were now harvested in northern zones where they had not been seen for centuries. When meteorologists scrutinized the records, they confirmed that a warming trend was underway. As Time magazine put it in 1939, “gaffers who claim that winters were harder when they were boys are quite right… weather men have no doubt that the world at least for the time being is growing warmer.”(9)

[much later in the story] . . . .

Suspicions of a Human-Caused Greenhouse (1956-1969)
Now that it seemed plausible that human technology could alter the planet as a whole, journalists found it easier to suggest that the greenhouse effect of CO2 from fossil fuels was a possible cause of global warming. Evidence that the world had been growing a bit warmer had become strong enough to convince most meteorologists. In a 1955 news conference, the head of the U.S. Weather Bureau said that a significant rise in average global temperature (3.6°F, that is, 2°C) had been seen in the previous fifty years.(24) During the 1950s, newspaper readers could repeatedly run across small items with anecdotes of warming, such as crops and codfish flourishing hundreds of miles north of their former ranges. Easier to visualize were stories of mountain glaciers retreating. (That turned out to be confusing, however, since mountain glaciers advance and retreat erratically, depending less on global temperature than on purely local variations in snowfall.) On a larger scale, in 1959 the New York Times reported that the ice in the Arctic Ocean was only half as thick as it had been in the previous century. Still, the report concluded, “the warming trend is not considered either alarming or steep.”