Journal Article food security climate change climate change impact 1.5°C warming 142M471B3J Carbon Dioxide Grain Proteins N762921K75 Nitrogen Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. agricultural technology advance atmospheric carbon dioxide concentration climate change adaptation crop models crop yield ensemble mean ensemble median extreme low yields grain protein model ensemble multimodel ensemble prediction wheat wheat production yield trends