quite a disrespectuful and ofensive person, aren't you?
the amount of humus an ecosystem can produce is NOT unlimited. it's simply wrong that it could produce endless amounts of humus.
if it would be that way ... nature would have done so, right? but the amount of humus is dependent on a number of things like climate, water, etc. a peat like you mentioned can only exist under certain circumstences.
let's start with the basics:
http://en.wikipedia.org/wiki/Soil_horizon
as you rightly mentioned ... it took nature hundrets and thousands of years to create those bogs in ireland. it didn't happen over night. and it happened under certain (wet) conditions which only exist in some places in the world. for example in northern europe, in one of the most densly populated areas of europe. good luck setting it under water again.
in untouched natural areas the humus layer can be at max. 3 soil horizons thick (source: Bodenkundliche Kartieranleitung, 5. Auflage, Hannover 2005).
another question ... where does the humus come from? is it created naturally? ... because if so ... it'll take centuries to regenerate natural bogs. which would be a good thing anyway if it could be done. and still it wouldn't be enough.
ok. so there goes again another one of your theories... let's eliminate the next one.
the reforestation of the rainforest. yeah ... good luck with that. everybody wants that besides a few people who actually don't care and cut it down. tell them they should stop.
and then we make the desserts green. good luck creating your irish peat in the sahara dessert with your unlimited thick humus layers.
you know what? it'll cost an "unlimited" amount of money, time and energy if you will do it the way it was done in this little piece of land. but still it'd be great to make the desserts green.
i'm all for it. it would take centuries, unthinkable amounts of money and workforce to make the sahara green, i don't know where you'll take all the water from ... which is already lacking in some of those areas ... but still ... i like the idea.
the max planck institute actually looked up the possibilities for europe. well, no chance that with reforestation and similar solutions you could solve the problem.
growing trees for sure is a way to reduce the co2 amount in the atmosphere. but they do it already. and it's not enough. in austria the land covered by forests increased over the last decades. and it did so in other regions of europe and the world. including the us i think.
there are MANY things people have to do. not one thing. and it wont help if you live in fantasy land.
what is needed are pragmatic and doable solutions for the short and the long run. in all possible ways. not just one way.
as an architect i'd say that there are huge amounts of possibilities to reduce the amount of engergy an average household needs. to name one example.