Irrigated afforestation of the Sahara and Australian Outback to end global warming

Abstract

Each year, irrigated Saharan-and Australian-desert forests could sequester amounts of atmospheric CO 2 at least equal to that from burning fossil fuels. Without any rain, to capture CO 2 produced from gasoline requires adding about $1 to the per-gallon pump-price to cover irrigation costs, using reverse osmosis (RO), desalinated, sea water. Such mature technology is economically competitive with the currently favored, untested, power-plant Carbon Capture (and deep underground, or under-ocean) Sequestration (CCS). Afforestation sequesters CO 2 , mostly as easily Electronic supplementary material The online version of this article (Climatic Change (2009) 97:409-437stored wood, both from distributed sources (automotive, aviation, etc., that CCS cannot address) and from power plants. Climatological feasibility and sustainability of such irrigated forests, and their potential global impacts are explored using a general circulation model (GCM). Biogeophysical feedback (Charney 1975) is shown to stimulate considerable rainfall over these forests, reducing desalination and irrigation costs; economic value of marketed, renewable, forest biomass, further reduces costs; and separately, energy conservation also reduces the size of the required forests and therefore their total capital and operating costs. The few negative climate impacts outside of the forests are discussed, with caveats. If confirmed with other GCMs, such irrigated, subtropical afforestation probably provides the best, nearterm route to complete control of green-house-gas-induced, global warming.

Carbon farming in hot, dry coastal areas: an option for climate change mitigation

“…Recently, Ornstein et al (2009) investigated this idea in desert regions on a global scale. Using a global climate model, they simulated large-scale reductions of surface temperature in the Sahara and the Australian desert.…”

“…Furthermore, they found that their models predicted a large increase in precipitation in desert regions and related this to the Charney effect (Charney, 1975). With respect to irrigation, Ornstein et al (2009) stated that the extremely valuable aquifers, which are available in some desert regions, should not be further exploited but considered instead the application of recent advances in desalination technology such as reverse osmosis. They discussed the costs and technological requirements to realize such a large-scale, international project covering areas of the order of 10 9 ha.…”

Replacing coal with wood: sustainable, eco-neutral, conservation harvest of natural tree-fall in old-growth forests

“…Alternatively, another SENCH-related solution that we have proposed, "Irrigated Afforestation of the Sahara and Australian Outback to End Global Warming" (Ornstein et al 2009) could be initiated to renewably sequester about 8 additional GtC/yr. We had suggested CCS or nuclear-fission to power the sea-water desalination plants and pumps needed to supply fresh irrigation water to the 'desert forests'.…”

“…When a previously barren area (NPPo = 0, cl1 = 0, cl2 = 0) is afforested or put into sustainable agricultural production, the total CO 2 -footprint/yr will be about (m tC/ha/yr − NPPn tC/ha/yr), even if not harvested, because all net production is above the zero barren baseline. So long as m is small, this can provide a very substantial decrease in atmospheric CO 2 (see Ornstein et al 2009). productivity (NPP) is defined as the difference between the carbon sequestered through photosynthesis and the carbon released as CO 2 due to respiration. Thus, when decay of the fallen trees is prevented, the harvest itself represents an increase in NPP.…”

“…SENCH was accidentally 'discovered' during preliminary analysis of somewhat different strategies of how best to manage very large tree-harvests in a sustainable way. These harvests involve about 8.8 × 10 8 ha of proposed, irrigated tree-plantations on the Sahara and Australian Outback deserts (Ornstein et al 2009). An eco-friendly, uneven-aged, harvest strategy, similar to that developed for northern hardwood old-growth forests (Keeton 2006), may be an attractive alternative approach with similar yields.…”