After having done a good bit of reading on some of the climate change sites I mentioned in my previous post on Climategate, I grew bold enough to mention to a friend my growing conviction that the scientific evidence does in fact strongly support human-caused global warming. He raised an objection which was intended to indicate that scientists can’t make up their minds, and basically don’t know what they’re talking about. That objection was: weren’t scientists convinced in the 1970s that the earth was cooling rather than warming, and that we were practically on the verge of an ice age? As I had heard this objection before, and had thought it valid since I seemed to recall those ice age predictions, I decided it would only be fair to see if those climate change sites had any information on this. On the Skeptical Science site, I found a link on the left hand column of the page: Ice age predicted in the 70s. The article was very informative, and contained a number of links to other articles on the subject. I will summarize here the information I found, though I recommend that if you have any doubts about the matter you should check it out for yourself. Go to the source, rather than depend on my summarization. After all, I’m no scientist, and I may have misunderstood what I was reading (although I don’t think so).
In 1971, a brief article coauthored by S.I. Rasool and S.H. Schneider appeared in Science Magazine concerning the effect on climate of aerosol and CO2 levels in the atmosphere. In it, this statement was made: “An increase by only a factor of 4 in globalaerosol background concentration may be sufficient to reducethe surface temperature by as much as 3.5 ° K. If sustainedover a period of several years, such a temperature decreaseover the whole globe is believed to be sufficient to triggeran ice age.” Note that this ice age prediction was based on at least a four-fold increase of aerosol levels. 6 other scientific papers were produced with similar predictions. Many newspapers jumped on this (it made great story), and frequently stated or implied that the consensus of scientists was that we were headed for another ice age. The fact of the matter, though, is that during the same period that those 7 ‘global cooling’ papers were being produced, 42 scientific papers were produced indicating global warming rather than cooling; 20 others were neutral on the matter. (See this article.) So ‘science’ was not unanimous (it rarely is), but it was even then leaning far more toward ‘global warming’ than ‘global cooling’. Today, climate scientists (scientists who focus their studies on climate, and understand the factors involved in its study) are almost entirely unanimous in believing that the climate is warming due to human actions, and that serious consequences will arise if we don’t change our ways.
While deniers of ‘anthropogenic [human caused] global warming’ (AGW) accuse scientists of fraud, it is actually the deniers who are being fraudulent. They tend to introduce as ‘facts’ things that are entirely untrue, and offer brief quotes from articles in their support when the articles quoted actually state exactly the opposite of what the deniers are saying. For instance (from this article):
“A 2003 Washington Post op-ed by James Schlesinger, Climate Change: The Science Isn’t Settled, quoted a 1972 National Science Board report as follows:
“Judging from the record of the past interglacial ages, the present time of high temperatures should be drawing to an end . . . leading into the next glacial age.”
The full quote from the report is as follows:
“Judging from the record of the past interglacial ages, the present time of high temperatures should be drawing to an end, to be followed by a long period of considerably colder temperatures leading to the next glacial age some 20,000 years from now. However, it is possible, or even likely, that human interference has already altered the environment so much that the climatic pattern of the near future will follow a different path.
For instance, widespread deforestation in recent centuries, especially in Europe and North America, together with increased atmospheric opacity due to man-made dust storms and industrial wastes, should have increased the Earth’s reflectivity. At the same time increasing concentration of industrial carbon dioxide in the atmosphere should lead to a temperature increase by absorption of infrared radiation from the Earth’s surface.
When these human factors are added to such other natural factors as volcanic eruptions, changes in solar activity, and resonances within the hydro-atmosphere, their effect can only be estimated in terms of direction, not of amount” [End quote]
The full quote gives quite a different picture than what is implied by the Washington Post excerpt, doesn’t it? It speaks of a possible ice age about 20,000 years in the future, but human interference may have changed things sufficiently that the “near future will follow a different path”! This kind of misdirection by out-of-context quotations seems to be typical of those who vociferously deny the findings of science on AGW. There’s plenty of evidence for such ‘fraud’ among AGW deniers, on those climate change sites I have referred to, for those who are interested in pursuing the subject.
So, were scientists of the 1970s ‘sure’ that we were heading into an ice age? Definitely not! A handful thought that we might be if aerosol levels in the atmosphere continued to rise; but those aerosol levels did not continue to rise. Most scientists, though, thought that the evidence was more in favor of warming than cooling. The developments since then have confirmed the majority view.