climate change to under 50% by 2050 would exceed the entire carbon budget in conventional scenarios. In 2013, the National Center for Atmospheric Science at the University of Reading forecast that increasing levels will result in a significant increase in in-flight turbulence experienced by transatlantic airline flights by the middle of the 21st century. Aviation emissions grow despite efficiency innovations to aircraft, powerplants and flight operations. Air travel continue to grow. In 2015, the Center for Biological Diversity estimated that aircraft could generate of carbon dioxide emissions through 2050, consuming almost 5% of the remaining global carbon budget. Without regulation, global aviation emissions may triple by mid-century and could emit more than of carbon annually under a high-growth, business-as-usual scenario. Many countries have pledged emissions reductions for the Paris Agreement, but the sum of these efforts and pledges remains insufficient and not addressing airplane pollution would be a failure despite technological and operational advancements. The International Energy Agency projects aviation share of global emissions may grow from 2.5% in 2019 to 3.5% by 2030. By 2020, global international aviation emissions were around 70% higher than in 2005 and the ICAO forecasts they could grow by over further 300% by 2050 in the absence of additional measures. By 2050, aviation's negative effects on climate could be decreased by a 2% increase in fuel efficiency and a decrease in emissions, due to advanced aircraft technologies, operational procedures and renewable alternative fuels decreasing radiative forcing due to sulfate aerosol and black carbon. Noise Air traffic causes aircraft noise, which disrupts sleep, adversely affects children's school performance and could increase cardiovascular risk for airport neighbours. Sleep disruption can be reduced by banning or restricting flying at night, but disturbance progressively decreases and legislation differs across countries. The ICAO Chapter 14 noise standard applies for aeroplanes submitted for certification after 31 December 2017, and after 31 December 2020 for aircraft below , 7 EPNdB (cumulative) quieter than Chapter4. The FAA Stage 5 noise standards are equivalent. Higher bypass ratio engines produce less noise. The PW1000G is presented as 75% quieter than previous engines. Serrated edges or 'chevrons' on the back of the nacelle reduce noise. A Continuous Descent Approach (CDA) is quieter as less noise is produced while the engines are near idle power. CDA can reduce noise on the ground by ~1–5 dB per flight. Water pollution Airports can generate significant water pollution due