How certain are scientists that humans are causing global climate change? Descri

Nearly all environmental scientists agree that Earth's atmosphere and climate are changing. Most environmental scientists have concluded that human activity, particularly the emission of greenhouse gases, is the primary reason for this change. Scientists express conclusions as probabilities, so reports are often written in language that the lay public may interpret as uncertain. Particular climate trends include changes in surface temperature, snow and ice cover, rising sea level and warmer oceans, and alterations to precipitation patterns and intensity. Scientists debate some of the exact mechanisms and extent of the effects of global climate change on humans. The debate continues over how to address climate change in political and economic arenas. There is sometimes discourse among scientists, economists, business leaders, policymakers, and others over these issues because some critics of global climate change have a vested interest in continuing the widespread use of fossil fuels, and they may cast doubt on scientific findings. Furthermore, some greenhouse skeptics are funded by industries such as the coal, petroleum and auto industries that benefit from fossil fuel use. Some of these "skeptics for hire" have considerable sway over policymakers, particularly in the United States.