Along with innovative technology and advanced science, the 21st century has seen a growing culture of environmental responsibility around the world.
Government action is one way to encourage or require people to "go green."
With the environment among the most widely discussed topics around the world, these five countries are finding ways to make the conversation a positive one:
The Champs-Élysées is one of 13 areas in Paris that is part of a new initiative called "Paris Respire," translated as "Paris Breathes." This environmental push eliminates all motor traffic in parts of the city on one Sunday per month.
Dubbed by the French as "the world's most beautiful avenue," the the Champs-Élysées launched its first car-free Sunday on May 8.
According to the city's air pollution tracker, nitrogen dioxide emissions on the road decreased by one-third on the first day of the initiative.
The first day was largely successful as locals and tourists gathered to witness, photograph and celebrate the congestion-free area.
Following a dangerous air quality alert in March, Mexico City put a program into effect that orders all vehicles off of the roads one day per week.
According to AccuWeather Senior Meteorologist Jason Nicholls, the mountains that surround Mexico City play a role in the smog issues.
"The mountains act as a natural barrier to prevent smog from clearing the valley. Think of the city like being in a bowl," Nicholls said.
In an effort to persuade people to follow the new ban, free subway and bus rides were offered within the city.
Though the ban will only last until late June, officials hope to create long-term changes to transportation within the city.
This past May, the entire country of Portugal ran on renewable energy for more than four consecutive days.
Solar, wind and hydro power covered the country's full electricity usage during that time period.
Francisco Ferreira, president of NGO Zero Portugal, a sustainability organization, told the Independent that Portugal's investments in renewable resources now allows their electricity system to reach 100 percent of the renewable energy it produces.
Though this isn't the first time the country has run on renewable sources alone, the most recent feat broke a clean energy record.
A project recently began that will install intelligent traffic lights at all intersections in the city of Copenhagen. These special traffic lights will allow for bikes and buses to have priority over vehicles on the road.
The initiative aims to reward people traveling in an eco-friendly way by making their commute faster and easier.
City officials estimate that bus passengers will see a five to 20 percent reduction in travel times. Cyclists will see a 10 percent reduction.
The technology has the potential to allow buses that report being behind schedule to catch up with the help of the lights.
The timing of the lights will also allow cyclists who maintain a certain speed to cruise through the city without stopping.
Kiruna, a city established in northern Sweden in 1900, is relocating two miles east with a sustainable future in mind.
The country's northernmost city is moving mainly to escape the expansion of mines closing in on the city, but the government is looking to make the new town significantly more sustainable.
The Swedish city is currently an uncharacteristic part of the environmentally-friendly country. The new Kiruna will be notably denser, with most locations being just a walk away, and will contain more green areas.
The city has also created a factory for residents to recycle supplies and large materials for builders to use in the new city.