Abstract

What is the impact of the ongoing rise in the air’s carbon dioxide (CO₂) concentration on the ecological stability of the world’s deserts and the shrubs and grasslands that surround them? This question weighs heavily on the minds of many, as the nations of the Earth debate the pros and cons of the prodigious CO₂ emissions produced by the burning of fossil fuels. On the downside, there is concern that more CO₂ in the air will exacerbate the atmosphere’s natural greenhouse effect, producing changes in climate that lead to desertification. On the upside, the aerial fertilization effect of additional atmospheric CO₂ may enhance plant prowess, increasing plant water use efficiency and enabling vegetation to reclaim great tracts of desert. The challenge, therefore, is to determine the relative merits of these competing phenomena.