Global average surface temperatures have risen at an average rate of 0.13°F per decade since 1901. Since the late 1970s, however, the United States has warmed at nearly twice the global rate. Worldwide, 2000–2009 was the warmest decade on record, and existing heat records are being surpassed year after year. Complicating the issue is the fact that the causes of this warming are hotly disputed and not well understood. Although manmade greenhouse gas emissions are widely acknowledged as a contributing factor to climate change, controversy has emerged over the extent of their involvement. A report by Dr. John R. Christy for the U.S. Senate accused existing climate models of overestimating the impact of greenhouse gases, citing balloon and satellite temperature data that showed warming of only 0.3-0.4°C total, rather than the 1°C suggested by the models. In general, 102 IPCC models typically predict 2.5x the temperature rise.
In practice, warming atmospheric temperatures make it more difficult for aircraft to maintain lift, and the effects are already being felt. In June 2017, a heat wave in Phoenix, Arizona grounded over forty flights, and similar cases are likely to occur as temperatures rise. Fokker faced similar issues when America West operated F70 out of Phoenix, forcing them to make an AFM addendum making operations until 53 °C possible. Furthermore, as air density and lift generation decline, a recent study suggests that between 10% and 30% of fully-loaded aircraft will have to reduce their weight loads to take off. Airports at lower elevations with denser air, such as JFK or Charles de Gaulle, will be less impacted. Some, including Dr. Richard Lindzen, argue that climate dangers to aviation are minimal, since aircraft are designed to withstand ambient tempartures up to 15°C above average and few operate in areas that would require load reduction. However, due to the fact that multiple flights have been impacted by rising temperatures already, the risks of climate change must still be considered.
- Heat waves
- Increased precipitation duration and intensity
- More frequent and intensified winds and storms
- Rising sea levels and ocean acidity levels affecting operations of sea level airports, on average 1-1.5 mm/year.
- Changed bird migration routes