"The key point is that most of the evidence indicates that current C02 levels are sufficient to put the earth on a warming trend as has occurred naturally in the past".

We have been in the longest interglacial period for long time. IMO this must make us vulnerable to runaway warming and biospheric dystrophy.

What caused the drought ?

What caused the Hadley Cell circulation to change ?

Global dimming can work in reverse as industrial output slows.
I think its interesting actually that the heat island effect of cities is well known yet how a city effects the regional then lager climate patters is barely studied. Obviously how the soil is tilled and when it is tilled changes the moisture content of the soils. And obviously changes in coal burning change the amount of particulate matter in the air but the combination of the two or even both individually are not well studied at the climate level.

Another example I'm interested in moving to Oregon a lot of the cities now have flooding problems I found it interesting that houses that had been built 50-100 years ago now where being flooded obviously the flood peaks had probably increased. A suspicious cause is of course removal of the forest cover. Although this obvious link is actually debated. However moving outward increased erosion is so obvious that its accepted by all this dumps more sediments into the streams and thence into the ocean which in turn acts to increase algae blooms helped along of course with our fertilizers. These blooms eventually cause the dead zone ocean conditions as the material rots. This may withdraw C02 and it might add methane who knows I've not found any studies. But my point is that local changes can eventually cause larger regional changes. How these are linked into our larger regional climate systems seems to be a real blank spot.

In general the interest focuses eventually on water vapor the forgotten greenhouse gas.

http://www.waterencyclopedia.com/Ge-Hy/Global-Warming-and-the-Hydrologic...

http://lwf.ncdc.noaa.gov/oa/climate/gases.html#wv

Water Vapor is the most abundant greenhouse gas in the atmosphere, which is why it is addressed here first. However, changes in its conentration is also considered to be a result of climate feedbacks related to the warming of the atmosphere rather than a direct result of industrialization. The feedback loop in which water is involved is critically important to projecting future climate change, but as yet is still fairly poorly measured and understood.

As the temperature of the atmosphere rises, more water is evaporated from ground storage (rivers, oceans, reservoirs, soil). Because the air is warmer, the relative humidity can be higher (in essence, the air is able to 'hold' more water when its warmer), leading to more water vapor in the atmosphere. As a greenhouse gas, the higher concentration of water vapor is then able to absorb more thermal IR energy radiated from the Earth, thus further warming the atmosphere. The warmer atmosphere can then hold more water vapor and so on and so on. This is referred to as a 'positive feedback loop'. However, huge scientific uncertainty exists in defining the extent and importance of this feedback loop. As water vapor increases in the atmosphere, more of it will eventually also condense into clouds, which are more able to reflect incoming solar radiation (thus allowing less energy to reach the Earth's surface and heat it up). The future monitoring of atmospheric processes involving water vapor will be critical to fully understand the feedbacks in the climate system leading to global climate change. As yet, though the basics of the hydrological cycle are fairly well understood, we have very little comprehension of the complexity of the feedback loops. Also, while we have good atmospheric measurements of other key greenhouse gases such as carbon dioxide and methane, we have poor measurements of global water vapor, so it is not certain by how much atmospheric concentrations have risen in recent decades or centuries, though satellite measurements, combined with balloon data and some in-situ ground measurements indicate generally positive trends in global water vapor.

Sorry for such a large quote but I got the impression from your response that you felt that you understood the cause from a wiki entry on the dust bowl.

I'd suggest its more complex and that we don't really understand what we have done. The combination of particulate and sulfur dioxide pollution from industrialization and various farming practices regardless of how well they control erosion since its soil moisture thats the issue do influence the local water vapor cycles and thence the global climate. My opinion is we will soon learn that C02 is really only a cycle initiator and that changes in water vapor dominate the climate cycle.