Yeah, combating spreading desertification is good as it protects the existing ecosystems that surround the desert. But some people have a misguided belief that deserts are useless areas and greening entire deserts would be a net positive. Deserts are an incredibly complex environment, even if we know less about them than areas where we humans live in larger numbers.

We know the Sahara desert is responsible for soil replenishment of Carribbean islands and South America. The knock on effects of removing a desert could be disastrous.