Saturday, September 28, 2013

John Cook's Climate Change Mythbusters 11

This is part of a series reposting material from John Cook's Skeptical Science website. Although he is a physicist rather than a specialist in climate science, he is a convinced "global warmist" and tries to rebut frequently-raised objections to the theory. However, it is always possible to question the data (e.g. this valuable note about measuring temperature) and the line of argument. Please help advance the debate - with facts and logic.

What were climate scientists predicting in the 1970s?

What The Science Says:
The vast majority of climate papers in the 1970s predicted warming.
Climate Myth: Ice age predicted in the 70s
"[M]any publications now claiming the world is on the brink of a global warming disaster said the same about an impending ice age – just 30 years ago. Several major ones, including The New York Times, Time magazine and Newsweek, have reported on three or even four different climate shifts since 1895." (Fire and Ice)
In the thirty years leading up to the 1970s, available temperature recordings suggested that there was a cooling trend. As a result some scientists suggested that the current inter-glacial period could rapidly draw to a close, which might result in the Earth plunging into a new ice age over the next few centuries. This idea could have been reinforced by the knowledge that the smog that climatologists call ‘aerosols’ – emitted by human activities into the atmosphere – also caused cooling. In fact, as temperature recording has improved in coverage, it’s become apparent that the cooling trend was most pronounced in northern land areas and that global temperature trends were in fact relatively steady during the period prior to 1970.

At the same time as some scientists were suggesting we might be facing another ice age, a greater number published contradicting studies. Their papers showed that the growing amount of greenhouse gasses that humans were putting into the atmosphere would cause much greater warming – warming that would a much greater influence on global temperature than any possible natural or human-caused cooling effects.

By 1980 the predictions about ice ages had ceased, due to the overwhelming evidence contained in an increasing number of reports that warned of global warming. Unfortunately, the small number of predictions of an ice age appeared to be much more interesting than those of global warming, so it was those sensational 'Ice Age' stories in the press that so many people tend to remember.

The fact is that around 1970 there were 6 times as many scientists predicting a warming rather than a cooling planet. Today, with 30+years more data to analyse, we've reached a clear scientific consensus: 97% of working climate scientists agree with the view that human beings are causing global warming.

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