But this effect is (or can be) cyclical, as well. I'm sure I have commented previously (although perhaps not in this thread) that the Vikings had a viable, agrarian society flourishing in/on Greenland for almost 500 years, from the 900s to the 1400s. They ultimately abandoned Greenland (now why would they have named it "Green"land, I wonder?) because it became too cold, and there was too much sea ice during the winters. A simplistic view (and I'm a simple sort of guy) might hold that unless and until it becomes too hot to farm on Greenland, we're only seeing a cylcical variation.
First up, consider that while I said that the earth is getting warmer, I didn't mention any harmful effects from just that. I mentioned sea level rise and more severe weather primarily. That it was warmer in Greenland over 600 years ago doesn't matter when all the cities were built(or completely rebuilt) since then.
I've also recently read up a bit more on Greenland. First, it wasn't really an agrarian society from what I read, they were heavily dependent upon livestock and sea life for their food. They were living more like Inuit. Second, the theory for the warming has more to do with the gulf stream than the entire earth being warmer then.
The "it's only cyclical" has problems:
1. We more or less know the cycles, and this ain't one of them.
2. Modeling of our climate doesn't work unless we include forcings for human based emissions.
3. We know the chemistry of the earth now, and we know the concentrations, emissions, and chemical properties of CO2 and various other chemicals, and we see those effects happening in the atmosphere.
And a bar of "too hot to farm in Greenland"? Are you serious? That would indicate that everything south of Greenland would be a wasteland. How about something like "suitable for warmer weather crops than the Barley the Vikings grew"?
How about things like we're predicting that the Arctic Sea will be passable for at least part of the year very shortly?
Even if we accept the mechanics of your explanation ... does that in any way support the true believers' contention that THIS time around it's all caused by mankind, and that we can reverse it if we stop driving cars and eating the meat of farting cows?
You're picking ONE data point, and not a good one. The "true believers" have things on their side like satellite observation data, ice and rock cores, sediment observations, and more on their side.
Also, only the idiots are trying to get you to stop driving and eating meat. More realistically, you're looking at stuff like more non-fossil fuels. Coal power plants are a big one, as coal is pretty much pure carbon. So if we stop burning coal, in favor of nuclear, solar, wind, geothermal and all the others, we cut down our carbon dioxide emissions substantially. Of course, I call the greenies idiots for opposing nuclear power. Next up would be vehicles, but we're getting the batteries to the point that we might be able to create a battery powered passenger plane that is economical.
And it isn't cow farts driving bovine based global warming. It's their belches that actually contains more NG. For that, they're working on changing up the cow's gut fauna, with the bonus that done right, it actually reduces the feed requirements for them.
Should we be advocating for the return of glaciers to northern New York and New England?
No, more that we don't warm things up so much that we lose most of Florida.
If it wasn’t observed, cannot be measured and cannot be tested for falsifiability is it actually science?
What does that have to do with climatology? It can be observed, and is observed. We measure it all the damn time. And yes, we do test it.