Human Impacts on Weather and Climate

Abstract Climate change is a worldwide environmental, social, and economic challenge. It includes issues of air pollution, land use, toxic waste, transportation, industry, energy, government policies, development strategies, and individual freedoms and responsibilities. Human use of the atmosphere as an unpriced dumping space has led to the buildup of gases and particles such as carbon dioxide and methane that can alter the energy exchange between the Earth's surface and space. There is a great deal of confusion among policy makers and the public about just how much is known about our climate, and what makes it change. However, although many aspects of the science of climate change are laced with major uncertainties, many others are actually scientifically well established. Human modification of the climate system has far‐reaching implications for human welfare and the health of our planet. Are our actions causing the climate to change in ways or at rates that will threaten natural systems or make human adaptation difficult? This chapter outlines the current state of scientific knowledge regarding human impacts on the climate system.