Climate warming and drought

Sure , the warmer air can hold more moisture so in some areas you get increased precipitation. Precipitation means any water that falls from the sky not just rain. Increased snowfalls can be caused by global warming. Whether drought or floods happens or not depends on the surface geology ( mountains, depressions etc) and the land usage affecting surface or underground water and vegetation cover. The recent wildfires in California removing vegetation caused severe flooding and landslides remember

Percivale said:

While many problems climate change causes are clear, one of the bigger potential ones is increased desertification and drought. Models predict these will increase, yet studies of past climate show that most areas were wetter when it was warmer. This article mentions that:
NASA GISS: Research Features: Pliocene Global Warming: Page 2
Anyone have an explanation for this contradiction?

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During the Pliocene the Earth was not infested with over seven billion large predatory parasites who interfered with all aspects of the biosphere, not just the climate.

Percivale said:

Predatory parasite is either a redundancy or a contradiction, depending how you look at it.

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I think you will find it is an example of alliterative hyperbole used for rhetorical effect.

Percivale said:

If you want to call us that you should call pretty much every living thing that.

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Incorrect. No other living thing has produced the changes to the environment or the damage to biodiversity that has been achieved by humans. Our role as predators is fairly clearly established in biology. Our role as parasites in a metaphorical and perjorative sense should be evident to anyone who views the current world situation objectively.

Percivale said:

And you haven’t pointed out any way that we are causing a change in the rainfall patterns compared to earlier times with an equal temperature.

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The point should be so obvious to anyone who has taken a serious interest in such matters that it should not require examples. However, here is one for you. Human activity has caused the extension of the Sahara desert. Desertification reduces the rainfall over marginal areas. This is well known, but if you are unfamiliar with it I shall seek out citations and provide these to you.

I have to imagine, from your post, that you doubt the role of humans in screwing up the planet. Is that the case?

Percivale said:

While many problems climate change causes are clear, one of the bigger potential ones is increased desertification and drought. Models predict these will increase, yet studies of past climate show that most areas were wetter when it was warmer. This article mentions that:
NASA GISS: Research Features: Pliocene Global Warming: Page 2
Anyone have an explanation for this contradiction?

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Yeah that's an easy explanation. Computer models are often wrong and have a very poor track record in recent years when it comes to predicting changes in the climate.

Percivale said:

I am well aware that humans are causing climate change, and it is an important concern to me. I just want to understand the details better.

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That is immensely encouraging and I apologise for reading into your post motivations and viewpoints that were not there.

Percivale said:

As I continued to think about it I realized that humans have caused desertification. I don’t think that’s the whole reason for the difference in the models though. There may be some differences caused by the Rocky Mountains getting higher since then, and the Panama strait closing, and I’m sure the models are not perfect. Here’s another article on the topic I just read.

http://nora.nerc.ac.uk/id/eprint/14866/1/Salzmann_et_al_2011_Pliocene.pdf

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I would certainly not attribute all of the differences to human intervention, nor is desertification the only one. The destruction of the Amazon rain forest has a profound effect upon weather patterns. There are doubtless many other examples. I believe that until there is a broad acceptance, by the general public, of human responsibility for a substantial number of these changes, politicians will resist taking the necessary steps to slow, halt and ultimately reverse them.

Thank you for the link.

Percivale said:

I don’t feel that insulting the human race will help anything.

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A key part of addressing the problems of alcoholism, as I understand it, is for the alcoholic to stop denying they have a problem, to declare openly "I am an alcoholic". Perhaps some people would consider calling an alcoholic an alcoholic is an insult. I, and Alcoholics Anonymous, do not agree.
So, I am a predatory parasite. I'm not proud of it, but unless I accept that status I assuredly continue to be part of the problem.

Percivale said:

Every creature has changed its environment to the extent it was capable of, we are just more capable, and we are more capable of fixing the damage we have caused.

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We cannot do to much to bring back the hundreds of thousands of species we have led to extinction, but I agree we can halt the process, reverse parts of it and let nature heal the rest over the course of millenia. But the first step is to recognise that, while we have the potential to be the best thing that ever happened to the planet, we are currently, just about the worst.

Percivale said:

Of course the first oxygen producing organisms have made the biggest change to the environment of any creature.

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Absolutely, but I was taking your phrase "living creature" to mean currently living. I probably misread that.