Earth Day 2012

April 22 will mark Earth Day worldwide, an event now in its 42nd year and observed in 175 countries. The original grass-roots environmental action helped spur the Clean Water Act and Clean Air Act in the United States. Gathered here are images of our planet's environment, efforts to utilize renewable alternative sources of energy, and the effects of different forms of pollution. -- Lane Turner and Leanne Burden Seidel (35 photos total)

A ladybug in flight spreads its wings as it flutters from grass blade to grass blade at Rooks Park in Walla Walla, Wash. on April 2, 2012. (Jeff Horner/Walla Walla Union-Bulletin/Associated Press)

A Japanese snow monkey relaxes in a hot spring in the Jigokudani valley in northern Nagano Prefecture, Japan on Feb 10, 2012. The macaques descend from the forests to the warm waters of the hot springs in the mornings, and return to the security of the forests in the evenings. (Nick Ut/Associated Press) 

Elephants forage on March 20, 2012 in the Tsavo-east National Park in the wake of a dramatic increase in elephant killings for their prized tusks. Kenya's estimated 30,000 elephants are under growing risk as incidences of poaching continue to mount despite efforts by the government and international wildlife agencies. (Tony Karumba/AFP/Getty Images)

An Ibex stands on a cliff-edge above the Ramon Crater in southern Israel's Negev Desert on March 5, 2012. (Amir Cohen/Reuters)

A view of the southern lights between Antarctica and Australia captured by Dutch astronaut Andre Kuipers on board the International Space Station on March 3, 2012. (ESA/NASA via AFP/Getty Images)

The moon appears over Mount Vrenelisgaertli (2904 metres/9527 feet) near the eastern Swiss town of Glarus on March 14, 2012.

A guide climbs inside the Niah Great Cave at Niah National Park in the Malaysian state of Sarawak on Borneo Island on March 29, 2012. Niah Caves contain the oldest remains of Homo sapiens found in Borneo, and feature the world’s largest limestone cave entrance as well as ancient rock paintings. Studies published recently have shown evidence of the first human activity at the Niah caves from ca. 46,000 to ca. 34,000 years ago. (David Loh/Reuters)

Daffodils bloom in St James's Park as the sun rises in London March 20, 2012. (Toby Melville/Reuters)

Mount Etna spews volcanic ash during an eruption on the southern Italian island of Sicily on April 1, 2012. (Antonio Parrinello/Reuters)

A woman walks at the new Gemasolar solar power plant the day of its inauguration in Fuentes de Andalucia, Spain on October 4, 2011. (Marcelo del Pozo/Reuters)

The experimental aircraft "Solar Impulse" with pilot Andre Borschberg onboard flies at sunrise above Payerne's Swiss airbase during the first attempt to fly around the clock fueled by nothing but the energy of the sun. (Fabrice Coffrini/AFP/Getty Images)

An Argentine vehicle takes part in the Atacama Solar Challenge, a solar car race in the Atacama desert in northern Chile, in Calama, Chile on October 2, 2011. (Martin Bernetti/AFP/Getty Images)

The PlanetSolar, the first solar-powered boat to travel around the world, arrives in Singapore on October 12, 2011. The boat is topped by 500 square meters of black solar panels. (Roslan Rahman/AFP/Getty Images)

Octavia Ccahuata combs her daughter's hair in the kitchen of their house, which is part of the "Hot Clean House" ecology project in the Andean town of Langui in Cuzco, Peru on March 9, 2012. The project uses solar power to warm houses and energy-saving technologies for cooking in the highlands of Cuzco. (Mariana Bazo/Reuters)

Dr. Karen Gleason holds paper substrate with vapor printed electrodes, which will hold solar cells. Gleason is the leader of a research team at MIT that invented a way to print solar power cells on paper so durable that it can be folded up. (Dina Rudick/Globe Staff)

A worker walks through solar panels at the Ohgishima solar power plant operated by Tokyo Electric Power Co. (Tepco) in Kawasaki City, Japan on December 22, 2011. (Tomohiro Ohsumi/Bloomberg)

A solar panel stands on the roof of a house in Halliberu, India on January 11, 2012. Across India and Africa, startups and mobile phone companies are developing so-called microgrids, in which stand-alone generators power clusters of homes and businesses in places where electric utilities have never operated. (Kuni Takahashi/Bloomberg)

Kashif shows solar geysers on the roof of his seminary in Murree, Pakistan on March 6, 2012. Pakistanis are increasingly realizing that year-round sun is a cheap answer to an enormous energy crisis. Pakistan needs to produce 16,000 megawatts of electricity for daily demand, but falls short by providing only 13,000 megawatts. (Farooq Naeem/AFP/Getty Images)

Employees and visitors stand beside the mounting block holding a 48-meter blade being tested at the newly opened Wind Blade Testing Center in Charlestown, Mass. on June 3, 2011. (Josh Reynolds for The Boston Globe)

Workers assemble a wind turbine which will be set in place high on the Major League Beasball aseball stadium in Cleveland on March 23, 2012. The innovative design developed by Majid Rashidi, chairman of Cleveland State University's department of engineering technology, is a wind-deflecting structure with small-scale turbines that can generate power at low wind speeds. (Amy Sancetta/Associated Press)

The first of the four world's largest underwater turbines floats on October 19, 2011 in Brehec bay in Plouezec, France. The four immersed tide-powered turbines will produce power for around 3000 homes in 2012. (Fred Tanneau/AFP/Getty Images)

Senior Engineer Clifford Goudey talks about the wave energy converter prototype seen in the foreground at Resolute Marine Energy workshop/lab in Newburyport, Mass. on February 10, 2012. (Lisa Poole for The Boston Globe)

A geothermal energy plant taps deep underground heat from the southern San Andreas Fault rift zone near the Salton Sea on July 5, 2011 near Calipatria, California. (David McNew/Getty Images)

Acacia tree saplings are inter-planted with Cassava with the aim of trapping the carbon dioxide from the atmosphere, a practice that has led to the creation of the first carbon-well in Africa to have been registered by the United Nations Framework Convention on Climate Change in Ibi, Democratic Republic of Congo on October 11, 2011. (Gwenn Duborthomieu/AFP/Getty Images)

A boy is hit by waves as he collects recyclable materials from garbage washed onto the shore along Manila Bay in Manila on August 27, 2011. (Cheryl Ravelo/Reuters)

A woman collects a sample of the water flowing from a sewer into the Jian River in Luoyang, China on December 13, 2011. Red dye was dumped into the city's water network by two illegal dye workshops. (STR/AFP/Getty Images)

Palm trees reflect at the Rancho La Brea Tar Pits on November 23, 2011 in Los Angeles. The popular tourist spot and scientific treasure overflows during heavy rains. Polluted runoff then flows through storm drains to Ballona Creek and the ocean. (Ricardo DeAratanha/Los Angeles Times/Associated Press)

Oil floats on the surface near an illegal oil refinery in Ogoniland, outside Port Harcourt, in Nigeria's Delta region on March 24, 2011. (Sunday Alamba/Associated Press)

Workers drain a leaking sewage tank at a copper mine in Shanghang, China on July 13, 2010. One of China's biggest gold producers was ordered to pay $4.62 million by a local court for a toxic spill. The court also issued prison terms ranging between three years to 42 months to five staff who were found to be involved in the incident, which affected water supplies for 60,000 people. (Stringer/Reuters)

Illegal loggers remove timber along a river in a forest south of Sampit, Indonesia on November 13, 2010. Indonesia's rain forests store billions of tons of carbon, so preserving those forests is regarded as crucial in the fight against climate change. (Yusuf Ahmad/Reuters)

A surfer walks past cargo containers washed ashore from the stricken container ship Rena at Waihi Beach, New Zealand on January 10, 2012. Half of the ship Rena, stranded on a New Zealand reef for more than three months, sank after breaking up in rough seas and littering beaches with cargo and debris. (Brendon O'Hagan/Bloomberg)

A child searches for coins thrown in the polluted Yamuna river by Hindu devotees for ritual offerings in New Delhi on January 22, 2012. River Yamuna is one of the most polluted rivers of the country despite numerous efforts made to keep it clean. Delhi alone dumps around 3,296 million liters per day of sewage in the river. (Sajjad Hussain/AFP/Getty Images)

Workers collect pesticide at a burial site near the village of Savichi, Belarus on November 14, 2011. About 950 tons of pesticides were extracted from the ground and loaded into plastic barrels to be recycled in Germany. (Vasily Fedosenko/Reuters)

Heavy pollution surrounds the China Central Television headquarters building (right) in Beijing on January 18, 2012. The US embassy, which has its own pollution measuring system and which rates anything over 150 as unhealthy, was showing an index of 403, or 'hazardous'. (Ed Jones/AFP/Getty Images)

A gas mask covers the face of independence hero Leonardo Bravo's statue in Mexico City on February 28, 2012. Activists are protesting pollution by placing gas masks on statues of Mexican heroes. (Eduardo Verdugo/Associated Press)