What factors can control global climate?
The public may think, from reading press accounts, that carbon dioxide emissions are the only thing that influences climate. The real issue is vastly more complex. Aside from the fact that other greenhouse gases are important, there are numerous factors that influence long-term climate trends, and many of them are natural processes that are quite oblivious to the presence of humans. Sea surface temperatures, sunspots, volcanic eruptions, and forest fires are just a few of the items that must be factored in.
Also, many human activities besides fossil fuel burning may play a role in changing the planet’s climate. Albedo refers to the amount of the sun’s light that is reflected back into space. The albedo of bare ground may be only 10—20 percent and, by contrast, 85 percent or more from fresh snow and 90 percent or more from dense clouds. The average albedo of the Earth as a whole (35 - 45 percent) is a critical term in under standing global climate. Large-scale changes in land use due to farming, grazing, urbanization, and deforestation affect not only albedo but soil moisture and cloud cover, which in turn affect global temperature.
As a measure of just how complicated the global change issue is, it appears that the simple practice of fertilizing fields may increase the potential for global warming. Along with tillage of grasslands, the result is that the land absorbs less methane and produces more nitrous oxide. Together these effects could account for 20 percent of the possible global warming that might occur. On the other hand, other agricultural practices might be able to mitigate global change processes.
The U.S. government has called for more research into global climate change before massive and expensive controls are placed on carbon dioxide sources. Recent federal budgets have earmarked over one billion dollars in research for global climate-related issues.