If the MWP doesn't count b/c it wasn't "globally synchronous" - how's that different from today?

I'm afraid I agree with you but you won't convince some people no matter what evidence you provide. There are many anecdotal ways to show the MWP was warmer than today, and there are tree ring studies that show it was warmer as well, but those are treated as dismissively as you were treated by some previous responses. If the data doesn't fit the theory it is tossed aside as Jim Hansen did with balloon data that didn't fit AGW or the surface station data keeps getting adjusted without explanation.

You can't argue that it's gotten warmer since 1850 but a few years ago you would have to admit that this date coincided with the end of the Little Ice Age. But they've now relegated that to a local event as well to try to end that debate. Has it warmed? Yes. What caused the warming? Solar activity, natural cycles and greenhouse gases. I can admit that GHG has an effect and yet not worry that they'll cause the Earth to flood or burn. They never have in the past and they won't do that now, the Earth can regulate it's own temp and it has no care at all for what we humans consider 'optimum' temperature.

Satellite data continues to show cooling over the past 6 years and yet AGW theory survives under it's new title of climate change. A return to the glacial part of our ice will no doubt only prove their theory, at least to them. Meanwhile, consider two things: CO2 inhibits the same three parts of the infrared spectrum that water vapor does (see the link) and that there is only so much infrared for it to interact with. Where do the claims of apparently unlimited warming from CO2 come from when there is a finite amount of infrared to be blocked? If our total atmosphere causes warming amounting to 33C how can they argue that doubling the amount of a trace gas (.04% of the atmosphere is CO2) will cause dramatic warming of 10C or more?

Looks like you are caughtt up in a lot of buzz words. People use these big words to mask the fact theydon'tt' fully understand something. Averages are what you have to understand here. Temperaturess vary over time and over distance. I live in Nebraska it will be warmer here in July then it is now (January) This is notgloball warming, but if I average all of those daily temperatures together over a 20 year period and it warmer AND the same can be said for MOST other places on earth than that is global warming. And according to the thermometers and the math, the earth is warming. So no it does not have to begloballyy synchronous but global averages do have to be going up over a period of time. Also the longer that time frame the stronger the argument is for global warming. The numbers show the earth began to warm up shortly after thebeginningg of of the Industrial Revolution, bolstering the argument that recentGloball warming is caused by the burning of fossil fuels. The earth has warmed up and cooled down many times before but seldom as quickly as it is right now and when the earth's temperature haschangedd this rapidly in the past is hascausedd massextinctionn.

It's all about the global average. The key word is "global".

During the MWP, there were various regional warming periods (and likewise regional cool periods). There's no question about that. But if a global average is computed for any period of time during that, it's was well below our current global average.

When people talk about the current global warming being 0.8 C and probably another 2 - 4C by the end of this century, they are talking about the global average. There will be some regions that will probably experience a +8C warming (far more than any comparable regional warming during the MWP) and others less.

Some regions in the north have already experienced +4C warming.

Regional warming can be caused by nothing more than changes to the wind pattern. Global warming, in contrast, requires additional energy in the entire climate system. That's what occurring now.

The warming appeared to occur in different decades[1].

This is consistent with composite reconstructions based on tree rings, boreholes etc[2].

Source 1 was the preface to a book 'The Medieval Warm Period' which collected a series of papers on the MWP. Iirc, some of those that found warming found it occurring at different times. If the areas weren't warmer all together then the mean temperature wouldn't be higher than today, which is consistent with reconstructions.

A. The Medieval Warm Period probably was a global event. The temperature change during this period has been well studied in the Northern Hemisphere, but not in the Southern Hemisphere. This is basically what scientists are saying. They are saying that the MWP effected at least the Northern Hemisphere, but this is little evidence that it's globally synchronous.

"Little evidence" doesn't mean that it didn't happen, it just means that there is little evidence.

B. No one dismisses the fact that the MWP occurred. The MWP was warm, just not as warm as even the temperatures from the early 20th Century: http://en.wikipedia.org/wiki/File:2000_Year_Temper...

Edit: You said, "There's no way to explain that short of temperatures at least as high as today's temperatures."

Is that a peer-reviewed scientific argument, or just your opinion?

Was the MWP warmer than today? Paleoclimatology can help us understand some of the expected effects of a rising global temperatures (Lakes drying up completely, Droughts far worse, higher tree lines -- your examples, not mine). The projected future temperature change is based on physics, and not on past temperature reconstructions.

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"The "deniers" on Y/A repeatedly post examples of colder than normal weather in certain regions, in some cases for prolonged periods, as evidence against global warming."

The problem with these posts is when they are presented with facts they ignore them one person last week posted -24 in NY when it is quite easy to lookup the actual weather online not only was it much warmer than -24 it turned out -4 was the official coldest recorded temp for NY.

This is the problem with many of these posts it is not colder than normal but there is more snowfall than usual. The suggestion by many of those posting is that this is the start of a new ice age, this will come as welcome news to those who live in Melbourne Australia who today had their 5 day with temps over 40c which has now broken a 100 year record.

I don't really follow the logic of the rest of your question as I've not seen any one dismissing the MWP, it happen there is historic data to show it happened, but that data also shows the warming was not as much as the current warming.

http://en.wikipedia.org/wiki/File:2000_Year_Temper...

The MWP was a global event, see the climate records for say China or New Zealand and its there. See the following link for MWP studies all over the globe supporting it:

http://co2science.org/data/mwp/mwpp.php