since i´m also a believer of the aquatic monkey theory i guess stating that the gaia theory shouldn´t be so far off :\ besides technically the gaia theory does work imho all sub sistems of the planet are always working to make life possible on earth (not confortable tough) but it also states that changes in one of the sub systems implies a new cycle on the earth "mood" so as i said before the sahara becomes a jungle/savanah imho we will watch a new ice age on the northern hemisphere wich if we believe is a repetition of the previous one´s then the sahara will be the driest it as ever been until it returns to a kind of balance

as for people discrediting the theory or hypothesis a few of the last works made on what killed off the australian mega fauna say it was mainly due to human indirect action it seems that humans slash and burning techniques (either for hunting or for agriculture now you pick) activly changed the continent climate by making fires more frequent wich tilted the balance of the entire continent into less nutrient rich but more fire resistant vegetable life (i wonder if this could be one of the reasons why the sahara is crippled)

so the daisyworld thingie where biodiversity means a more healthy world shouldn´t have such a broad understanding since one specie can effectivly wipe out several other species and thus be counter productive to the "daisyworld"

and ibrahim what i understood about solar cycles is that there is 3 main vectors/causes on the way that the earth and the sun interact and thus depending on how all of 3 are alligned we can have warmer colder or more temperate climates and yes i know they have diferent time spaces on how to work but they can actually be combined and thus we should be able to mathematically predict the new time where the earth will turn into a snowball or a freaking desert but that doesn´t take into account other aspects of the interaction since we can´t predict solar flares and solar higher or lower activity wich can balance out the outcome or increase the effect

also according to the gaia theory living beings and a few geological effects could counter the solar effects by changing the stratosphere quimistry and thus the reason why i wonder if human actions and development didn´t acticvly contributed for the original saharan rapid desertification

i would like to point out i´m a generalist in terms of knowledge and not an expert in any area (well maybe touristic marketing) so all i say should be considered with a bit of salt and further references should be researched instead of taking my word for it