Recognizing the existence of world scale problems takes time. For instance, the above Google "Ngram" search show that world hunger was not recognized as a serious problem until relatively recent times. However, starting in the 1960s, considerable efforts were dedicated to increasing agricultural yields (the "Green Revolution"), with a certain degree of success. But was the problem really solved? Or was it only postponed - or even worsened - as a result of agriculture becoming totally dependent on fossil fuels? Something similar may happen in the future for the problem of climate change; it may be recognized, at last, but that doesn't mean it will be solved.
Apart from a small number of diehard deniers, most people are perfectly aware that we have a serious problem with climate change. The public is just confused by a bombardment of contradictory statements pushed in the media, but probably that all what is needed to change the terms of the debate is just a push in the right direction. The pope's encyclic on climate - expected for this week - could do just that, reaching a "tipping point" in the general perception of the problem.
After the tipping point, a consensus may be reached that the idea that climate change doesn't exist or is not caused by human activity is not just wrong, but positively dangerous for society. Something comparable to such ideas as - say - that there is really no evidence that smoking causes cancers, that wearing a seat belt while riding a car is useless, and that crack is no more dangerous than coffee as a recreational drug.
Of course, we can't be sure that the pope's encyclic will have this effect; but, suppose it does, then what can we expect to happen? Optimistically, we could think that most of the work is done and that, from then on, something serious and effective will be done to stop global warming. Unfortunately, things will not be so easy.
How hard acting against climate change is likely to remain may be understood by considering another big and serious problem affecting humankind: world hunger. It had not been always recognized and it was only with the 1960s that it became a standard feature of our intellectual horizon. At that point, nobody would have dreamed to say that world hunger was a hoax designed by a conspiracy of scientists who wanted to keep their fat research grants to study a problem that doesn't exist. The debate was effectively over, but that, alone, didn't solve the problem.
Mainly, the attempt to eliminate world hunger was based on brute force; that is, on increasing agricultural yields. It was what we call today the "Green Revolution." As you know, the results of these efforts are often described in glowing terms, a triumph of human ingenuity over the limits of nature. It is also true, however, that the world hunger problem was never completely solved; it could not be if every increase in agricultural yield was matched by a corresponding increase in human population. And it may well be that the Green Revolution was not just a "non-solution," but something that made the problem worse by turning agriculture into an industrial activity wholly dependent on fossil fuels and artificial fertilizers.
Something similar could happen if we pass the turning point of the perception of climate change. The Google Ngram data, below, indicate that the interest in the problem is rapidly growing and we may be close to reaching the tipping point in perception that world hunger reached in the 1960s.
If we compare the result of the Ngram data for "world hunger" and for "Climate Change", we see that the perception of climate change trails that of world hunger by some 30 years. So, it may be high time for arriving to a general consensus on the climate problem.
The result, however, may not be as good it could be hoped. The sudden appearance of the dramatic reality of climate change in the mediasphere could lead to forget that the best (and probably the only) way to get rid of fossil fuels fast enough to avoid a climate disaster is to make them obsolete by means of renewables. So, we could see a mad scramble toward quick and dirty solutions; actually, non-solutions or solutions that worsen the problem.
One of these non-solutions is "geo-engineering" as it is normally described, that is spreading a reflective layer in the upper atmosphere. That would do something to reduce global warming, but nothing to avoid the acidification of the oceans and its regional climatic effects (e.g. droughts) are all to be discovered. Or think of carbon capture and storage: a desperate and expensive attempt to keep using fossil fuels ("eat the cake and still have it") by literally sweeping the problem under the carpet - where nobody can guarantee for how long it will stay. And what about biofuels? An excellent way to starve a great number of people in order that a small elite could keep using their expensive metal toys called "cars".
We all know that climate change is a wicked problem. Probably, in the near future we are going to discover how exactly wicked it is. Maybe the Pope himself would tell us not to expect miracles. We need to keep working hard at it, and we still have a fighting chance to avoid catastrophe.