On Earth there are numerous second and third order effects to consider. For example, Sahara is considered a very important source of phosphorus for the Amazon r

On Earth there are numerous second and third order effects to consider. For example, Sahara is considered a very important source of phosphorus for the Amazon rainforest [0] and making Sahara green could have a huge negative impact on it. Meanwhile on Mars impact of terraforming mistakes on population is much smaller because it would be already shielded heavily from external environment. [0]: https://en.wikipedia.org/wiki/Saharan_dust https://en.wikipedia.org/wiki/Saharan_dust