Earth Day has now reached its 50th year, and according to the Earth Day Network (EDN) over one billion people in 192 countries are thought to have taken part in last year’s event.

Celebrated every year on April 22, the global day of environmental action is thought to be the largest secular observance in the world.

Each Earth Day, individuals and organisations from across the globe participate in action intended to world towards a healthier environment for future generations.

When did Earth Day get started?

The celebration marks the anniversary of the birth of the environmental movement in 1970.

Modern environmentalism is largely credited as starting with the publication of Rachel Carson’s bestselling book Silent Spring – documented the effects of the indiscriminate use of pesticides – in 1962.

10 photographs to show to anyone who doesn't believe in climate change Show all 10 1 /10 10 photographs to show to anyone who doesn't believe in climate change 10 photographs to show to anyone who doesn't believe in climate change A group of emperor penguins face a crack in the sea ice, near McMurdo Station, Antarctica Kira Morris 10 photographs to show to anyone who doesn't believe in climate change Floods destroyed eight bridges and ruined crops such as wheat, maize and peas in the Karimabad valley in northern Pakistan, a mountainous region with many glaciers. In many parts of the world, glaciers have been in retreat, creating dangerously large lakes that can cause devastating flooding when the banks break. Climate change can also increase rainfall in some areas, while bringing drought to others. Hira Ali 10 photographs to show to anyone who doesn't believe in climate change Smoke – filled with the carbon that is driving climate change – drifts across a field in Colombia. Sandra Rondon 10 photographs to show to anyone who doesn't believe in climate change Amid a flood in Islampur, Jamalpur, Bangladesh, a woman on a raft searches for somewhere dry to take shelter. Bangladesh is one of the most vulnerable places in the world to sea level rise, which is expected to make tens of millions of people homeless by 2050. Probal Rashid 10 photographs to show to anyone who doesn't believe in climate change Sindh province in Pakistan has experienced a grim mix of two consequences of climate change. “Because of climate change either we have floods or not enough water to irrigate our crop and feed our animals,” says the photographer. “Picture clearly indicates that the extreme drought makes wide cracks in clay. Crops are very difficult to grow.” Rizwan Dharejo 10 photographs to show to anyone who doesn't believe in climate change Hanna Petursdottir examines a cave inside the Svinafellsjokull glacier in Iceland, which she said had been growing rapidly. Since 2000, the size of glaciers on Iceland has reduced by 12 per cent. Tom Schifanella 10 photographs to show to anyone who doesn't believe in climate change A river once flowed along the depression in the dry earth of this part of Bangladesh, but it has disappeared amid rising temperatures. Abrar Hossain 10 photographs to show to anyone who doesn't believe in climate change A shepherd moves his herd as he looks for green pasture near the village of Sirohi in Rajasthan, northern India. The region has been badly affected by heatwaves and drought, making local people nervous about further predicted increases in temperature. Riddhima Singh Bhati 10 photographs to show to anyone who doesn't believe in climate change A factory in China is shrouded by a haze of air pollution. The World Health Organisation has warned such pollution, much of which is from the fossil fuels that cause climate change, is a “public health emergency”. Leung Ka Wa 10 photographs to show to anyone who doesn't believe in climate change Water levels in reservoirs, like this one in Gers, France, have been getting perilously low in areas across the world affected by drought, forcing authorities to introduce water restrictions. Mahtuf Ikhsan

After selling 500,000 copies in 24 countries, the book sparked a growing public awareness of environmental matters that crystallised in the first Earth Day.

The initial concept came to US senator Gaylord Nelson after witnessing the impact of a massive oil spill in Santa Barbara, California.

Nelson wanted to channel the energy of the anti-war movement into action for the environment, and this culminated in 20 million Americans taking to the streets to demonstrate for a environment

What has Earth Day achieved over the years?

The first Earth Day united Americans from across the political spectrum, and within a year the action had led to the formation of the United States Environmental Protection Agency, as well as the Clean Air, Clean Water and Endangered Species Acts.

Earth Day 1990 was credited with giving a significant boost to recycling efforts worldwide, paved the way for the 1992 UN Earth Summit.

At another milestone, Earth Day 2000 chose to address the growing issue of global warming and the switch to clean energy sources.

For the 40th anniversary of Earth Day in 2010, the network behind the celebration launched a campaign to plant one billion trees, a target that was achieved in 2012.

In 2016, leaders from 175 countries used Earth Day as the backdrop for signing the historic Paris climate agreement, which aims to stop the planet from warming 2C above pre-industrial levels.

What does Earth Day look like today?

In 2019 Earth Day turned its attention to big environmental issue of plastic pollution.

Its goals include supporting efforts around the world to eliminate single-use plastics, and drive support for tighter regulations concerning plastic disposal.

“EDN will educate millions of people about the health and other risks associated with the use and disposal of plastics, including pollution of our oceans, water, and wildlife, and about the growing body of evidence that decomposing plastics are creating serious global problems,” said the organisation’s president Kathleen Rogers, in a statement.

“Our goals include ending single-use plastics, promoting alternatives to fossil fuel-based materials, promoting 100 per cent recycling of plastics, corporate and government accountability and changing human behaviour concerning plastics.”

What is International Mother Earth Day?

International Mother Earth Day is similar to Earth Day, as it is also celebrated on 22 April every year.

The day, adopted in 2009, invites "all Member States, the organisations of the United Nations system, international, regional and subregional organisations, civil society, non-governmental organisations, and relevant stakeholders to observe and raise awareness of International Mother Earth Day, as appropriate," according to the United Nations.

The biggest focus of the day is climate change, which will be discussed during the commemoration of the 10th anniversary of International Mother Earth Day.

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