Leonard Ornstein, a cell biologist at the Mount Sinai School of Medicine in New York, and Igor Aleinov and David Rind, two climate modellers at NASA, argue that foresting the Australian outback and Saharan Desert would “solve climate change.” While numerous geoengineering schemes have been proposed to mitigate the adverse effects of greenhouse gas (GHG) build-up, many of the more ambitious ideas, including ocean-based aerosol sprayers, space mirrors, C02 air scrubbers, or artificial C02-capturing “trees,” have been examined and labeled cost-prohibitive or dangerous (see earlier post). Others ideas will work, are much cheaper on a small-scale, but require significant investment and regulatory changes to scale up worldwide (see Steven Chu’s call for reflective cool roofs, and more on the idea of creating reflective crops). These researchers, however, argue that massive forestation in equatorial deserts “provides the best, near-term route to complete control of greenhouse gas induced global warming,” and would be cost-effective in comparison with carbon capture and storage (CCS) plans now receiving massive investment (see earlier post).
The scientists outlined their plan in a recent article in the Journal of Climatic Change. According to The Guardian (UK), the plan would involve planting “fields of fast growing trees such as eucalyptus would cover the deserts of the Sahara and Australian outback, watered by seawater treated by a string of coastal desalination plants and channelled through a vast irrigation network. The new blanket of tree cover would bring its own weather system and rainfall, while soaking up carbon dioxide from the world’s atmosphere. The team’s calculations suggest the forested deserts could draw down around 8bn tonnes of carbon a year, about the same as emitted from fossil fuels and deforestation today.”
While the costs of planting a forest in the Sahara would be high (around $1.9 trillion per year), Ornstein argues the plan is cost effective when you consider the cost of CCS and compare the amount of C02 emissions sequestered. In comments to The Guardian (UK), he said: “when that’s compared to figures like estimates of $800bn per year for CCS, our plan looks like a loser. But CCS can address only about 20% of the problem at the $800bn price. Mine addresses the whole thing. And CCS would involve a network of dangerous high-pressure pipelines coursing through the most developed neighbourhoods of our civilisations, compared to relatively benign water aqueducts in what are presently virtually uninhabited deserts.”
According to The Guardian (UK), Saudi Arabia, Libya, Tunisia, Morocco, and other northern African countries, along with central Australia, would all be suitable sites. Forestation must occur in sub-tropical areas where there is little chance of darker forested landscapes soaking up more sunlight and therefore warming the earth’s surface. “Planting trees to combat rising carbon dioxide levels is controversial on a large scale, because most places where it has been suggested, such as Canada and Siberia, are in the northern hemisphere where the resulting change in surface colour, from predominantly light snow and rock to predominantly dark trees, could soak up more sunlight and cancel out the cooling benefit.” The plan would also yield economic and social benefits through new green jobs. Sustainable wood industries could take hold.
Some critics argue the Sahara is already a functioning ecosystem, which locals rely on, and planting forests would destroy it. Ornstein responded: “We must bite the bullet, global warming will not go away by itself … solar, geothermal and wind power can make modest contributions. All of these are part of the fix. But the quicker a forest can be grown, the more time will be available to choose among and to implement such adjustments, and perhaps to develop more attractive substitutes. If sacrifices are required to stem global warming, the almost non-existent ecosystems of the central Sahara and the [Australian] outback seem like reasonable candidates compared to the alternatives.”
In other news, the Prince of Wales announced a new fund to prevent additional deforestation in tropical developing countries like Brazil, Malaysia and Indonesia. The Guardian (UK) writes that a global emergency fund has been set up to “drastically reduce the destruction of tropical rainforests over the next five years.” Some 35 governments of the Informal Working Group (IWG) agreed to the plan.
“The IWG hopes to achieve a 25 percent reduction in annual deforestation rates by 2015. The felling of forests causes almost a fifth of global carbon emissions.”
The U.S. government has pledged $275 million towards rainforest protection. The plan is expected to cost between £13.5bn and £22bn over the next five years. Read the report
Lastly, check out UNEP’s BillionTree campaign, an ambitious global reforestation program, which aims to plant seven billion new trees worldwide in 2009. Companies, organizations or individuals can pledge and register their new trees through the program.