Consider a trip from New York to Los Angeles. Flying 2,500 miles in economy class will burn about 0.29 metric tons of carbon per passenger, according to the International Civil Aviation Organization’s carbon emissions calculator. And it will cost about $3.26 to offset the approximately six hour, one-way flight using the travel offset calculator by Cool Effect, a nonprofit organization. If you round up to a full ton of carbon, you’d still only spend $3.30 to $13.18 on the Cool Effect website, depending on the project.