Tourists have big shoes. Climate scientists and other experts suggest that the size of the footprint — carbon and otherwise — left by global travelers is about four times larger than previously thought. Sustainable tourism is a hot topic, and in light of Japan's goals to grow the number of inbound tourists to 40 million by 2020 and all the way up to 60 million a decade later, it's one that deserves attention. Fortunately, there are ways to ease the environmental impact of the tourism boom, and they're not limited to planting trees to offset carbon emissions (though that's a good place to start).

To green their travels, visitors can take a number of actions that, when performed by enough people, can make a big difference. Sophie Walker, sustainability coordinator at InsideJapan Tours, encourages people to say "no" to the disposable chopsticks doled out at convenience stores and restaurants, and to instead drop by a 100-yen store to pick up a reusable pair they can take home. She also recommends refusing plastic bags when shopping, refilling water bottles and recycling in designated bins wherever possible.

"We promote sustainable travel in Japan as we'd like to give (visitors) the opportunity to have a positive social, environmental and economic impact," Walker says.