The UN's international climate panel (IPCC) indicates that air traffic currently accounts for about 2% of the global emissions of carbon dioxide. Along with the emission of nitric oxides, steam and effects from condensation trails, aviation is estimated to account for 3.5% of the total human impact on climate. Aviation accounts for 4-5% of Sweden's total emissions of carbon dioxide. The transportation sector in turn accounts for over a third of Sweden's total emissions of carbon dioxide.

Like all human activities involving combustion, most forms of aviation release carbon dioxide (CO2) and other greenhouse gases into the Earth's atmosphere, contributing to the acceleration of global warming and (in the case of CO2) ocean acidification. These concerns are highlighted by the present volume of commercial aviation and its rate of growth. Globally, about 8.3 million people fly daily (3 billion occupied seats per year), twice the total in 1999. U.S. airlines alone burned about 16.2 billion gallons of fuel during the twelve months between October 2013 and September 2014

The contribution of civil aircraft-in-flight to global CO2 emissions has been estimated at around 2%.[11] However, in the case of high-altitude airliners which frequently fly near or in the stratosphere, non-CO2 altitude-sensitive effects may increase the total impact on anthropogenic (human-made) climate change significantly.[11] A 2007 report from Environmental Change Institute / Oxford University posits a range closer to 4 percent cumulative effect.[13] Subsonic aircraft-in-flight contribute to climate change[11] in four ways:

The UN's international climate panel (IPCC) indicates that air traffic currently accounts for about 2% of the global emissions of carbon dioxide. Along with the emission of nitric oxides, steam and effects from condensation trails, aviation is estimated to account for 3.5% of the total human impact on climate. Aviation accounts for 4-5% of Sweden's total emissions of carbon dioxide. The transportation sector in turn accounts for over a third of Sweden's total emissions of carbon dioxide.

There are both natural and human sources of carbon dioxide emissions. Natural sources include decomposition, ocean release and respiration. Human sources come from activities like cement production, deforestation as well as the burning of fossil fuels like coal, oil and natural gas.

Due to human activities, the atmospheric concentration of carbon dioxide has been rising extensively since the Industrial Revolution and has now reached dangerous levels not seen in the last 3 million years.1 2 3 Human sources of carbon dioxide emissions are much smaller than natural emissions but they have upset the natural balance that existed for many thousands of years before the influence of humans.

This is because natural sinks remove around the same quantity of carbon dioxide from the atmosphere than are produced by natural sources.4 This had kept carbon dioxide levels balanced and in a safe range. But human sources of emissions have upset the natural balance by adding extra carbon dioxide to the atmosphere without removing any.