Blooming Deserts, a Discussion Piece by G.P.Humphry
One low tech fix sometimes offered for the problem of global warming is tree planting. Many carbon offset schemes are based on the planting of trees. George Monbiot however argues that the hopes raised by such schemes are illusory. Land used for tree planting is land that cannot be used for growing other plants which might also have reduced CO2 emissions. By taking up land that might have been used for crops tree planting may drive local people to fell trees elsewhere to feed themselves. And planting trees in one place may dry up rivers and kill trees elsewhere. The last concern may be overstated. While there is some evidence that too many trees can dry up water supplies generally speaking it is deforestation that dries up such supplies. Nevertheless the environmental value of many tree planting schemes remains questionable.
In principle however it would be possible to plant trees without either diminishing the availability of arable land or affecting water supplies. This would require solar powered desalination plants in the desert, pumping in sea water and treating it to remove the salinity. The water could then be used to irrigate the desert and create new tracts of arable land which could be used both for growing trees and crops. Very hot regions can be exceptionally fertile given sufficient water supplies and when rains do fall on the desert a profusion of plant life springs up. Moreover solar powered desalination is possible even at the current level of technological development. In time the rise in fossil fuel prices and cheaper techniques of desalination and solar power production should make it profitable for private companies to begin the reclamation of deserts. They could buy up tracts of the desert, irrigate and reclaim them and sell the newly fertile to farmers and tree growers.
In time, with rising fossil fuel prices, cheapening solar power and desalination technology and rising food prices produced by population growth, private companies will begin to reclaim the deserts of their own accord. That they are not already doing so suggests that they do not think such a scheme would make a profit under current conditions, or that the waiting time between investment and return would be too long. Intervention by Governments would probably necessary to kick start such a scheme.
In addition to the need to combat global warming there is an additional reason why intervention might be desirable. If things were left to the market, reclamation of the desert might well begin in Australia, America or China. However from a political perspective it would be preferable for the process to begin in the Sahara. The countries around the Sahara are amongst the poorest in the world. Reclamation of the desert would create new opportunities for their citizens and show that there is no necessary contradiction between the fight against global warming and the fight against global poverty.
Under the Kyoto treaty governments which fund carbon offset schemes receive a higher CO2 emissions allowance. Critics have denounced many such schemes as bogus and a cause of land seizures and conflict with local peoples. In principle however there is no reason why genuine schemes with none of these ill effects should not be rewarded. And reforestation of the deserts would displace no one and produce an array of benefits both for local peoples and the wider world
As well as reducing global warming reclaimed deserts could produce food and timber. Palm trees meanwhile, which grow well in arid soil, could be used for production of palm oil, a biofuel which could replace fossil fuels for powering vehicles. Production of this biofuel has been much criticised by environmentalists as forests are currently being cut down to make way for palm plantations. The forest fires started by palm growers have released huge amounts of CO2 and indigenous peoples have been driven from their land so that it can be used for palm growing. Palms for oil are also grown on reclaimed peat swamps which release even more CO2 as the peat dries. Once again however none of these objections would apply to palm trees grown on reclaimed desert.
There is fierce and continuing debate as to how useful deforestation could be in reducing CO2 emissions. Nevertheless most of the arguments for scepticism are irrelevant to forestation of the desert. For example the value of tree planting in colder climes has been questioned on the grounds on the ground that the warming effect of the dark colour of forests may equal the cooling effect of CO2 sequestration. This has no bearing on forestation in tropical climes. Likewise the clearing of vegetation for tree planting is said to increase CO2 emissions, but in the desert there is no vegetation to be cleared. Then there is the risk that forests will become carbon sources as global warming reduces water supplies, dries up soil and kills trees. With forests irrigated by desalinated water however these risks can be minimised by increasing the supply of water.
That the greening of the desert is possible is indisputable. The United Arab Emirates has successfully reclaimed its deserts using, in large part, desalination technology. There is no insurmountable reason why this could not be repeated elsewhere. This is not to say that such an option would be cost free. Desalination appears to have adverse effects on marine life due to the pumping back into the sea of concentrated brine and the chemicals used in the desalination process. Such negative effects must be weighed in the balance when evaluating desalination schemes. However the adverse effects of the process hardly compare with the likely adverse effects on life on earth from global warming. Moreover it should not be beyond the wit of man to design more sustainable methods of waste disposal.
The real problem with any proposal to green the deserts is that even if work started on such a project tomorrow it would be years before it bore fruit. It action is taken to curb emissions in the interim, forestation of the deserts might form part of a longer term solution. It would not however eliminate the need for other more immediate forms of action.
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