Next time you get a drink on a United Airlines, flight you may notice a new cup in your hand.
In an effort to become more eco-friendly, United is replacing its foam cups with recyclable plastic cups.
United is not the only airline thinking about air travel's effect on the environment.
Southwest Airlines has converted diesel-burning ramps, belt-loaders and other equipment to electric power and recently installed plane seats and interiors made with recyclable material.
Delta Air Lines recycles some of its waste and donates money generated to Habitat for Humanity, the nonprofit home building charity.
American Airlines has replaced heavy flight manuals and maps with electronic tablets to reduce the weight of the plane.
Airline travel is responsible for about 2% of the planet's carbon emissions, or about 250 million tons of carbon dioxide each year. That tonnage is expected to grow with the demand for travel rising over the next decade, according to several studies.