What would be the impact of an extended period of solar inactivity?

I would expect a leveling of the earth's temperature. I would not expect cooling.

I love Peter J's answer. So the energy output of the sun is not important, we need to look at sun spots that magically transport their energy to the earth through the ether where the fairies collect the energy to make the earth warm.

Let us of course completely ignore the correlation between sunspots and irradiance and focus on the magic sun spots.

http://en.wikipedia.org/wiki/File:Solar-cycle-data...

Edit: It is amazing how thousands of chemists, spectroscopists and other scientists never noticed water in their samples. You would think that at least one of them would have noticed the strong IR absorption peaks at 1500 and 1700 wavenumbers, peaks that are absent for CO2. Oh well, I am sure James E is right because he did an experiment in his garage with a heat lamp.

A 1-2 Watt/Meter^^2 drop in TSI over the next two decades and the negative feedback of reduced atmospheric water vapor in the atmosphere will more than likely lead to a significant drop in globally averaged temperatures. Without the grossly overrated positive feedback of more water vapor in the atmosphere the AGW theory becomes a mute point. And Sunspots are a proxy for the Suns magnetic field strength not TSI.

You are right in that if we do have another "Dalton Minimum" we will not have another little Ice age. That would require another "Maunder Minimum" which at this time very few are seriously saying we are threatened with.

OTOH, there is a strong historical correlation between periods of reduced solar activity and global cooling. Conversely there is also a strong correlation between periods of heightened periods of solar activity and periods global warming.

Now I fully understand that correlation does NOT equal Causation. So I'll admit while I believe this is a strong possibility we do NOT know.

Flip that and if it is ture then in 2 - 3 years it will be self evident. If cooling continues it will be hard to argue against the solar driver.

Now you mentioned solar irradience. Well the this solar minimum is beating the decrease that they based taht opinion on. As of June 2009, Total Solar irradiance was down by 3%. UV solar irradiance was down by 6%.

Soalr wind is at an all time low.

The interplanetary magnetic fuield strength is below what was thought to be the theoretical minimum.

How cold do I think it will get?

I'm not sure but I hope those who have gotten most of these predicitons correct are VERY wrong about how cool it will get.

Nope

You're still looking at solar irradiance... which, apparently, is wrong thing to focus on. (and frankly, we havn't had the ability to measure this accurately enough for long enough to come to any conclusions from these readings.)

Historically, lack of sunspots has meant cold. This isn't deniable. I expect history to repeat itself. A strong correlation that keeps repeating itself is usable even if you don't know how it works.

You can "proxy" all you want, but if it doesn't work, it's useless.

There is a theory about cloud cover and sunspots that seems to have potential. Not that I'm endorsing it -- I still stand by my prediction that if sunspots remain low to non-existant, it will get colder. I'll be eager to admit that I'm wrong if it turns out that I am, but I don't think I will be, or I wouldn't make the prediction.

Considering you are using the NY times and wiki as the basis of most of your argument, I would have to say that a lower solar level will cause a cooling period during those years.

That is just my thoughts that as the heat sent to the Earth decreases the temperature of the Earth will also decrease since green house gases can't trap something that is not their.

This doesn't proof either way AGW or lack there of.

Unfortunately there's not a word to describe my mentat. Equilibriumist goes undefined. GLA(good lord almighty), I made myself laugh.

anyone can tell the suns much brighter now and white in color. its not getting cooler in my opinon. a dude in the bahamas said its really brighter there now. as it is here also.

Dana your key comprehension difficulty is several fold and I will only deal with a couple of them here.

First is that the co2 samples in the examples you use to rate co2 as a greenhouse gas were no dehumidified and so the results were affected and slanted by the samples water vapor content. This argument is over 100 years old where Svante August Arrhenius used humidified co2 to call co2 a greenhouse gas And Knute Angstrom used dehumidified and showed it had such a minor greenhouse effect that it had no realistic effect on climate.

Second sunspots produce high activities beyond just the TIR effect you always quote and the lack of sunspots produce other effects and climate responses that are only partially understood

http://en.wikipedia.org/wiki/Solar_variation

So the main point is you overvalue co2 as a driver of climate and under value the suns effect on the climate. This slants a persons view and cripples their ability to accept 6,000 years of solid evidence that the sun is a 95% driver of what happens in the worlds climate and all other sources of potential variability have less than a 5% probability of affecting climate. Humanities building of large urban areas with buildings, paving and decorative water features has 100 times the potential effect on the worlds climate that co2 from fossil fuels does.

So the swimming pool with its deck in your back yard has more effect on the climate than 100 hummers do. You illustrated yourself that daytime temperatures have not noticeably increased over the last 50 years, it has been nighttime temps that have increased. The only realistic cause of higher nighttime temps is urban heat island and humidity period, nothing else could cause this.

And let's not forget about the PDO cool phase for approximately the next 30 years.