The major deserts on earth have come into existence since we've had tools and fire. Starting first with the Sahara. Our civilisation is dependent on exploitation and is ultimately doomed to fail unless we change our culture from exploitation to regeneration and learn to live in harmony with nature.

The slideshow below shows an approximation of the diversity of life from one million years ago to what will most likely happen in one thousand years from today if we don't change our ways. For example, a fertile area with plentiful rainfall planted in monoculture crops is low in life's diversity.

We can reforest all the world's deserts by planting trees, starting first at the forests. As the forest grows it will change the local climate to a more wetter and better able climate to sustain its growth over the grasslands and eventually cover the deserts.

This work is based on public domain data.

And with information from these two websites.