Moving our agriculture north doesn't work either, because of the poor quality of soil in what is currently the tundra/taiga.
If you have a handful of magic beans that will grow a magic beanstalk, that will be resistant to the temperature and weather and soil changes caused by global warming, sure, by all means, share it with us, and I'll stop worrying. We don't have that handful, though, and I'm not keen on hope-based planning.