I appreciate your concession that 0.5 deg isn't worrying. I wonder about your 2.5 degree "wheat belt" statement, though.
As somebody who has personally worked on wheat farms in Texas and in Alberta, (these two places, as you may know, have a wide temperature variation between them) I have to say the science behind this statement seems already empirically refuted.
I would submit to you that any extra wheat production you may see in the central US is due to topographical (it's flat), nutritional (good soil), and cultural (daddy was a wheat farmer) influences, more than any propensity of wheat for that exact temperature, as evidenced by the successful wheat farming americans and canadians from Texas to central Alberta)
Different varieties of wheat are adapted to different conditions and some are more productive than others. Ultimately, wheat is still a plant and it still needs water and sun to grow. The climate models suggest that as temperature goes up, midwest droughts will get worse. Natural systems are not orthogonal. A rise in temperature will cause more rainfall in some areas and less rainfall in others.
While we're at it... as you said, wheat is not too finicky. Corn? More finicky. Wonder what will happen to corn. It needs hot, humid summers with just the right amount of rain and sun. When you look at the map from the link, it is pretty apparent there is a big hole in the middle of the "wheat" belt. Hmm I wonder what we grow there? ;)
I wonder where, if at all, that hole is going to move if we have a drier midwest as the admittedly crude climate models predict. And I wonder how a change in climate will impact the current wheat growing regions in terms of rainfall.
Your comment makes great intuitive sense, but I don't think it is quite so clear cut.
Remember, it is a 2.5 degree global temperature shift being discussed, not a 2.5 degree shift in Canada's temperatures. Water vapor is a much stronger greenhouse gas than CO2 is, so the effect of more CO2 is much less pronounced in the lower latitudes. From what I have heard, a 2.5 degree shift in global temperature average caused by increased CO2 would translate into a much larger shift in e.g. Canada's temperatures.
As somebody who has personally worked on wheat farms in Texas and in Alberta, (these two places, as you may know, have a wide temperature variation between them) I have to say the science behind this statement seems already empirically refuted.
I would submit to you that any extra wheat production you may see in the central US is due to topographical (it's flat), nutritional (good soil), and cultural (daddy was a wheat farmer) influences, more than any propensity of wheat for that exact temperature, as evidenced by the successful wheat farming americans and canadians from Texas to central Alberta)