I am a sunspot watcher from way back. You blew the credibility for me when you mentioned greenhouse gasses. Don't buy any part of the globul warming bunk. I am not a climatologist, but my family has farmed in this county for 110+ years. Weather patterns are variable, but man will never predict them accurately (exception- very short term).
Could we have a global food crisis? Yes, especially if a bunch of greenie weinee tree huggers get control. The fools at the UN and the greenies could starve a bunch of us, but I choose to not participate. Country boys can survive, and I will feed my family. We could be 100% self sufficient again, but at this point it is not worth it.
The phenomenon is well understood. The dispute over CO2 doesn't involve whether or not it can actually hold in heat but on the issue of "forcing", which is a bit more obscure and not well understood by anyone. In fact, "forcing", even if it exists, is probably overwhelmed by other forces of far greater power ~ e.g. variation in Sun's intensity (it blinks and winks eh), cosmic rays creating clouds, etc.
Now, regarding "farming in America", I've had ancestors engaged in that practice for thousands of years ~ although my European ancestors only got started in the game about 500 years ago, and then that was just a small minority of them. The most numerous category extended their "farming" beyond birch trees to corn and stuff within the last 360 years.
The family story passed down for centuries is that if you don't like the weather wait a while. it'll change.
As far as farming in ice age conditions is concerned, my Sa'ami forebears depended on Lingonberries. You don't want to eat the tiny birch shoots ~ they have too much cyanide for safe consumption. My entire digestive system pretty much recoils at the idea that wheat is good for you but I am prepared for a return to normal ~ where the Ice Sheets come sliding down the plain.....
The major heat retaining component of the Green Planet Gases is water vapor. You also need rain to support green plant life. In gaseous (vapor) and liquid (moisture) form it has a high density for heat. You can see that by comparing how quickly the atmosphere cools off at night when you are overcast verses when you have clear night skies. An overcast sky contains a high density of moisture (liquid water), which can hold a higher density of heat.
An El Nino event is really a large scale Green Planet Phenomenon due to the large increase of atmospheric water vapor generated by equatorial heat evaporation (heated El Nino waters). The truth is El Nino is the dominant Green House Gas emitting event on the planet. Much greater then human influence. That is the truth the watermelons hope to hide from you.