That's isn't true globally. For example, see here: https://www.ers.usda.gov/amber-waves/2024/september/global-c...
> Agricultural land area expanded 7.6 percent between 1961 and 2020 and currently occupies 32 percent of the world’s land area. Irrigated area more than doubled.
The process started in the first decade of the 20th century. It was largely finished by the 1980s. As for increases in irrigation, that's a few different things, but the largest part is substance farmers finally getting some infrastructure. I'm sorry to tell you, but the world isn't ending. Guess you will have to find another way to scare the plebs.