US National Climate Change Assessment on Forest Ecosystems: An Introduction

Abstract

Atmospheric concentrations of carbon dioxide (CO 2 ) and other greenhouse gases have been increasing since the beginning of the industrial revolution in 1850. Over the next century, increasing gas concentrations could cause the temperature on the surface of the Earth to rise as much as 2‐3°C over historic mean annual levels. Variation in annual climate could also increase. The United States experienced one indication of climate change in 1988: The summer of that year was one of the hottest, driest ever recorded across the nation. Barges were stranded on the Mississippi River, and forest fires burned millions of acres in the western United States. In the eastern United States, temperatures were so high that many factory assembly lines had to be shut down. The former Soviet Union states and China also experienced severe drought, while Africa, India, and Bangladesh witnessed torrential rains and flooding. These events triggered televised congressional debates, which concluded that atmospheric greenhouse gas inputs would very likely increase the intensity and severity of weather patterns during the next 100 years. The potential negative effects of global warming—melting of polar ice caps, a rise in the sea level, reduced agricultural and forest productivity, water shortages, and extinction of sensitive species—were also discussed. These findings prompted the passage of the 1990 Global Change Research Act (GCRA) and the establishment of the US Global Change Research Program (USGCRP). The program sponsors ongoing research (over $1.6 billion in 2000)