goal of $10/ton by 2015, among other targets, but the 35-year life cycle for power stations means it may be 2075 before these emissions will be brought under control worldwide. It may also take this long to reduce emissions from process, commercial and residential heating, which accounts for another 20% of GHG forcing.
Food production and landfills account for 25% of GHG forcing, mainly due to methane emissions from livestock and rice production and decaying garbage and nitrous oxide emissions from fertilizer degradation by soil bacteria. No solutions are on the horizon for either of these or for deforestation that accounts for another 10% of forcing.
Additional forcing from halocarbons (5%) comes from leaking refrigeration units in buildings and from industrial use of these chemicals for other purposes. Although chlorofluorocarbon (CFC) emissions are declining due to their phase-out, the replacement gases will result in nearly the same future forcing as today.
Removing carbon dioxide from the air by stimulating plant growth on the scale needed to impact GHG forcing is not practical at present. There is insufficient land on which to plant trees or other vegetation and adding micronutrients like iron to deficient areas of the world’s oceans to increase phytoplankton production is still an unproven technology.
Attacking the problem by reducing solar radiation, the energy source for the greenhouse effect, has generated several impractical solutions, including decreasing incoming sunlight by placing mirrors with diameters in excess of 1000 Km in outer space or billions of reflective balloons in the atmosphere. Injection of reflective sulfate aerosol particles into the stratosphere via rocket shells is feasible, but may damage the ozone layer and increase acid rain.
Because it may take at least 50 years or more to identify and begin deploying technologies that reduce or eliminate GHG emissions, other options that can be implemented more rapidly need to be considered to limit the potential damage from global climate change that is on the horizon.
