“Because most global warming emissions remain in the atmosphere for decades or centuries, the choices we make today greatly influence the climate our children and grandchildren inherit. The quality of life they experience will depend on if and how rapidly California and the rest of the world reduce these emissions.”
In California and throughout western North America,
Signs of a changing climate are evident. During the last 50 years, winter and spring temperatures have been warmer, spring snow levels in lower and mid elevation mountains have dropped, snow pack has been melting one to four weeks earlier, and flowers are blooming one to two weeks earlier.
During the past 100 years, average temperatures have risen more than one degree Fahrenheit worldwide. Research indicates that much of this warming is due to human activities, primarily burning fossil fuels and clearing forests, that release carbon dioxide (CO2) and other gases into the atmosphere, trapping in heat that would otherwise escape into space. Once in the atmosphere, these heat-trapping emissions remain there for many years—CO2, for example, lasts about 100 years. As a result, atmospheric concentration of CO2 has increased more than 30 percent above pre-industrial levels. If left unchecked, by the end of the century CO2 concentrations could reach levels three times higher than pre-industrial times, leading to dangerous global warming that threatens our public health, economy, and environment.
