World celebrates Earth Day Emilie Trudel marches in an Earth Day event in downtown Montreal, Quebec April 22, 2012. Thousands of participa...

World celebrates Earth Day

Emilie Trudel marches in an Earth Day event in downtown Montreal, Quebec April 22, 2012. Thousands of participants joined to commemorate World Earth Day, which is celebrated April 22 annually. REUTERS/Christinne Muschi (CANADA - Tags: ENVIRONMENT SOCIETY)

An Occupy Wall Street movement activist smokes next to a placard while protesting outside a BP fuel station on Earth Day in New York April 22, 2012. REUTERS/Eduardo Munoz (UNITED STATES - Tags: POLITICS CIVIL UNREST ENERGY ENVIRONMENT)

Emilie Trudel marches in an Earth Day event in downtown Montreal, Quebec April 22, 2012. Thousands of participants joined to commemorate World Earth Day, which is celebrated April 22 annually. (REUTERS/Christinne Muschi)

Thousands of cyclists ride across at Budapest's Elizabeth bridge during the Critical Mass bicycle ride across the Hungarian capital, April 22, 2012. The ride was organised to commemorate World Earth Day, which is celebrated April 22 annually. REUTERS/Laszlo Balogh (HUNGARY - Tags: SPORT CYCLING SOCIETY ENVIRONMENT)

Participants wear masks at a parade demanding a stop to all nuclear power plants in Japan as part of an event for Earth Day in Tokyo April 22, 2012. Japan is set to have no nuclear power within weeks for the first time in over 40 years following last year's crisis at the Fukushima Daiichi nuclear plant, which crushed public trust in nuclear power and prevented the restart of reactors shut for regular maintenance checks. REUTERS/Kim Kyung-Hoon (JAPAN - Tags: ENERGY CIVIL UNREST POLITICS BUSINESS)

Participants carry a large traditional carp-shaped wind sock called "Koinobori" at a parade demanding a stop to all nuclear power plants in Japan as part of an event for Earth Day in Tokyo April 22, 2012. Japan is set to have no nuclear power within weeks for the first time in over 40 years following last year's crisis at the Fukushima Daiichi nuclear plant, which crushed public trust in nuclear power and prevented the restart of reactors shut for regular maintenance checks. The carp banners are flown in Japan from April to early May to wish for the good health of children. REUTERS/Kim Kyung-Hoon (JAPAN - Tags: ENERGY CIVIL UNREST POLITICS BUSINESS)

On Sunday April 22, the world celebrates the 42nd annual Earth Day, a global event meant to celebrate the Earth and raise awareness for environmental causes. Even though it's nice to see how far we've come, images from around the planet remind us how much work is still to be done.