A rational approach to climate change consists of accounting for GHG emissions where they are and cutting them where they are. Meat production and fossil energy are 2 large causes of GHG emissions, and so we must significantly reduce both. There's no debate to be had about this, it's just facts and numbers.

The point is not to make people for eating meat, just like it's not to make people guilty for lighting and heating their homes with coal-powered electricity. It's just to live sustainably. Let's not deny the facts because we don't like to hear them.

Is eating less beef a decrease in life comfort? Yes, it certainly is. It's still much, much better than living in a +2°C hotter world, in which getting any food at all will become challenging.