That's because land use change -- deforestation, urbanization, conversion of lands to agriculture, and agriculture itself -- contribute over 30% of global greenhouse gases (about 20% are commonly attributed to deforestation and 12-14% to agriculture).
Science Daily gets into how nations attending the upcoming Copenhagen climate change treaty negotiations will need to come up with solutions to this crisis in global land use:
Across the U.S. as a whole, approximately 50 percent of the warming that has occurred since 1950 is due to land use changes (usually in the form of clearing forest for crops or cities) rather than to the emission of greenhouse gases," said Stone (Georgia Tech City and Regional Planning Professor Brian Stone). "Most large U.S. cities, including Atlanta, are warming at more than twice the rate of the planet as a whole -- a rate that is mostly attributable to land use change. As a result, emissions reduction programs -- like the cap and trade program under consideration by the U.S. Congress -- may not sufficiently slow climate change in large cities where most people live and where land use change is the dominant driver of warming."
According to Stone's research, slowing the rate of forest loss around the world, and regenerating forests where lost, could significantly slow the pace of global warming.
"Treaty negotiators should formally recognize land use change as a key driver of warming," said Stone. "The role of land use in global warming is the most important climate-related story that has not been widely covered in the media."
What are the solutions?
Stone recommends slowing what he terms the "green loss effect" through the planting of millions of trees in urbanized areas and through the protection and regeneration of global forests outside of urbanized regions. Forested areas provide the combined benefits of directly cooling the atmosphere and of absorbing greenhouse gases, leading to additional cooling. Green architecture in cities, including green roofs and more highly reflective construction materials, would further contribute to a slowing of warming rates. Stone envisions local and state governments taking the lead in addressing the land use drivers of climate change, while the federal government takes the lead in implementing carbon reduction initiatives, like cap and trade programs.
Somebody should also tell Stone about the potential for carbon intensive farming methods to help us reduce agricultural emissions of the heat trapping gas, carbon dioxide (as well as of the powerful greenhouse gas, nitrous oxide, which is emitted from farms that overuse nitrogen fertilizers).