Long-term observations confirm that our climate is now changing at a rapid rate. Over the 20th century, the average annual US temperature has risen by almost 1 F ( .6 C). There is new and stronger evidence that most of the warming over the last 50 years is attributable to human activities. The science indicates that the warming in the 21st century will be significantly larger than in the 20th century. Human activities have altered the chemical composition of the atmosphere through the buildup of greenhouse gases - primarily carbon dioxide, methane, and nitrous oxide. In order to avoid global warming and its impacts, we, as a society, must come up with the solutions for improving our common situation and thereby preserving this magnificent planet, our only home, for the benefit of future generations.
Humans are exerting a major and growing influence on some of the key factors that govern climate by changing the composition of the atmosphere and by modifying the land surface.
The human impact on these factors is clear. The concentration of carbon dioxide (CO2) has risen about 30% since the late 1800s. The concentration of CO2 is now higher than it has been in at least the last 400,000 years. This increase has resulted from the burning of coal, oil, and natural gas, and the destruction of forests around the world to provide space for agriculture and other human activities. Rising concentrations of CO2 and other greenhouse gases are intensifying Earth's natural greenhouse effect. Global projections of population growth and assumptions about energy use indicate that the CO2
Concentration will continue to rise, likely reaching between two and three times its late-19th-century level by the year 2100.
America already has the solutions to start solving global warming. All we need is someone to take the lead.