"Global change alters the capacity of the Earth to sustain life. It encompasses global climate change and processes that interact with climate to affect Earth systems. The impacts of global change are being felt now, both around the world and here in the United States. America and the world are getting warmer, global sea level is rising, and some types of extreme weather events are becoming more frequent and more severe. The most recent decade was the hottest ever recorded, and temperatures are projected to rise another 2°F to 4°F in most areas of the United States over the next few decades. In some regions of the country, prolonged heat and drought are contributing to larger wildfires and longer fire seasons. For coastal communities, sea level rise, combined with coastal storms, has increased the risk of erosion, flooding, and damage to property and infrastructure. The rising temperature and increasing acidity of ocean water is combining with other stresses, such as overfishing and pollution, to impact marine ecosystems and resources. Climate impacts on agriculture and water supplies have been increasing and are projected to become more severe. Extreme heat, sea level rise, and heavy rains are threatening infrastructure like roads, airports, port facilities, energy systems, and military bases. Climate change affects human health through more extreme weather events, decreased air quality, and changing ranges of diseases transmitted by food, water, and insects."
U.S. Global Change Research Program: http://www.globalchange.gov/