Did you know that in one day a full-grown oak tree expels 7 tons of water through its leaves?
It's been proven by ecologist and meteorologists that before there were humans, there were no deserts. Turkey was a land of lakes and forests. Lake Chad covered 135,000 square miles and was 40 metres higher than present. The Sahara was a forest. Sea levels were low enough to allow men to walk from Africa to Sicily and into Europe.
Oak and pine forests once covered half of Scotland, but after centuries of exploitation only 1% of the forests remain. Recent flooding in Germany, China and Central America has been officially blamed on de-forestation. 30% of Honduran rainforest has been lost since 1960. 70% of the poor have no other fuel except firewood. Heavy rains wash away fertile topsoil where there are no trees.
The cause of deserts is the axe. For hundreds of thousands of years, men have cut trees for fuel, shelter, pottery, smelting, and ships. The Mediterranean was the birthplace of sea-borne trade. Wheat, timber, oil, silver, and gold were traded throughout the Mediterranean in ships built by the Phoenicians, Romans, and Greeks.
Land was cleared of trees for growing wheat, barley and rye. Glazed pots, timber-fired, allowed beer to be brewed and settlements grew as early men domesticated animals and plants.
Timber fuelled furnaces for the smelting of bronze and iron axes. By the time of the prophets, the deserts had been established. All the great civilisations of history, Phoenicia, Egypt, Abyssinia, Troy, Greece, Rome, Persia, have all left deserts in their wake. As a tree is lost, the moisture that it transpired back into the atmosphere is also lost. Downwind, the air is dryer. The Sahara is downwind of the ancient Phoenician Empire.
As each coastal great cedar was cut for ships or temples, the rains got weaker deep in the desert.
...Each tree is a water reservoir, holding 75% of its weight, requiring up to 140 gallons per day. A million trees can hold 80 million gallons of water.
...All Deserts are Man-Made. Greenhouse gases form a blanket around the Earth, trapping in heat that would otherwise be radiated back to space. This causes the Earth's atmosphere to heat up. If the amount of carbon dioxide in the atmosphere continues to increase at its current rate, it will rise to double its pre-industrial level during the next century. Heat waves and droughts will become more common, and more intense.
The proper work of men is the undoing of deserts. 74,000 years ago, men were burning deserts into the hearts of America, Africa, Arabia, India, China, and Australia. [before there were men, there were no deserts.]
(stolen entirely from here)