text: The Kyoto Protocol, even if implemented by all industrialized countries, including the United States, would only barely slow the increase in GHG concentrations.Actually reducing GHG concentrations below todays levels (~385 ppm) may well exceed human capability in this century. Even outright de-industrialization of the United States might not be enough to lower GHG levels, since most emissions growth in the 21st century is projected to occur in developing countries .