4.4.4 Installation
Before any plastic is applied to the surface, the ground will probably require some preparation to remove sharp rocks, sticks, hard clods of soil and other material that could puncture the plastic (134). This may require grading of the surface, since the most attractive candidate locations are gravel plains. Plastic mulch laying equipment is commercially available, but is only capable of applying plastic sheeting of 4 feet in width (143). This will require specially designed laying equipment, although there may be commercially available equipment capable of applying wider sheets.
The plastic can be kept in place using natural soil cover around the edges or some other kind of means of affixing it in place will have to be designed. If there is much space between the edge of the plastic and the ground, wind will be able to whip the plastic and can cause it to tear.
It may be desirable to include some holes in the plastic cover to allow for rainfall drainage. However, any holes in the cover are weak points where tears can begin, so this must be carefully considered.
The exact pattern of spacing also has to be determined. This will be important when developing maintenance and monitoring plans. Most likely, the best approach will be to cover as much area as possible to minimize blowing dust and sand from within the covered area. On a much larger scale, it may be necessary to space out the coverage to keep the climate changes from occurring too drastically. For example, instead of applying all the covering in the Sahara, it might be better to divide up the covering so that each year’s allotment is spread over the entire world.
4.4.5 Monitoring
A key requirement of the GAEP is that the surface albedo in the covered areas must be known at all times. This is necessary for several reasons. The effectiveness has to be measured accurately so that reliable estimates of GHG forcing offsets can be calculated and included in climate modeling. Industries and/or governments paying for the coverage in return for “thermal credits” that can be used to offset their emissions under future climate control treaties, i.e., successors to Kyoto will also demand a transparent and auditable mitigation program. Finally, accurate and contemporaneous knowledge of the surface albedo is needed to ensure maintenance is performed in a timely fashion, keeping the albedo above target thresholds.
Measurement data to be collected include many of the parameters monitored in the U.S. DOE Atmospheric Radiation Measurement (ARM) Program (144, 145) and the SURFRAD surface radiation monitoring network (146). These include meteorological, radiometric and surface flux, surface characterization and water vapor data taken both before and after coverage, from inside the coverage areas and from just outside.
