And water for Mexico City.
On the other hand, Ceratonia oreothauma, a newly discovered carob species of Somali and Yemen's night frost-prone highlands might well stand frost in Mexico's cold areas. As such they might help rejuvenating the plague-infested forests of Mexico City's endangered aquifers (2300 m.), two months from their total depletion in record-heat year 1998. Just imagine.....30 million with no water...and that heat will come again for sure.. 

Oreothauma-seeds weren't easy to get. Tree planting is not a top priority for Mid East rulers, and seed sent by the British Kew gardens at Inifap's request got stuck in Mexico's customs, as usual. Still, four oreothauma's, from seed from Ibb of Magreb'aus, Yemen (1500 m.) are now growing near the Tamazulapam swimming pool. One started yielding 3 years ago, but guests take the pods with them, so there are still only four of them.

THE GARLIC KING. 
This all goes very slow. To really to speed up things test pilot plots should be set up at different heights on wasteland slopes. Carobs, olives, white sapotes, 100 trees to the hectare, interspersed with faster growing trees for wood only - acacias, colorines (Erythrinas). Maintained by (paid) villagers from nearby, and Inifap - provided with a telephone and internet.
It would not cost much. But it would require the initiative, consistency, follow-up, and planning Sagar has never had.. Commitment to the land Mexicans claim to love.  In short, change. And change is the new agriculture minister, Mexico's "Garlic King" Usabiaga, said to want in an interview last year:  "clean out Sagar, those 35,000 bureaucrats who don't even PRETEND to work" (El Financiero, Sept. 25).
Whether he will, whether he can, a ver a ver lo que hace, let's wait and see, and so far we haven't seen much. But a Sagar

shake-up can hardly harm the countryside and might well be a must to break its paralysis and prevent the flood of migrants to the U.S. from turning into a tidal wave. Mr. Usabiaga, he himself from one of Mexico's three main emigration states, Guanajuato, is certainly aware of that. 

Meanwhile Mr. Nelson Mandela had thousands of olives planted at his Qunu ranch in the East Cape, and Kimberley County did so in the West Cape - summer rainfall areas both. And internet sites show thriving Australian carob farms..
Yes, it can be done. If only...

1. Quality pods from budded trees consist for 40 to 50% of sugars.
2. One ton of pods yields 15 kilos tragasol. The US imported 2,500 metric tons in 1981, at U$ 3.50 per kilo. 
3. Mean temperatures increase an average 1º F for every 300-foot downward, or 0.5º C. per 100 metres. Frosts may damage Ceratonia siliqua in Mediterranean areas over 500 metres, equivalent to 2,200 metres in the Mixteca.