Oxfam is an NGO based in the US (specifically Boston, Massachusetts). They work towards solving climate change, water shortages, natural resources, and more.
World Wildlife Fund
The World Wildlife Fund is based in Switzerland. They are a global organization working to mediate the effects of climate change, water shortages, loss of wildlife and forests, and more.
Green America is an NGO that is based in America. They are working towards create a sustainable society. Through food, economics, and energy.
CEE Bankwatch Network
CEE Bankwatch Network is an NGO based in Eastern Europe. The goal of the organization is to work with the finances of sustainability. They also often work with local communities.
Bombay Natural History Society
The Bombay Natural History Society is a pan-Indian NGO. The goal of the organization is preservation of biodiversity. Accomplishing this through education and research.
The Environmental Protection Agency (EPA) of the US
The EPA is a US government agency. It has been a part of the government for over 50 years. Works with the climate among other responsibilities.
The US Fish and Wildlife Service
The US Fish and Wildlife service is another US government agency. However, the US Fish and Wildlife Service is more specialized and works with the conservation of wildlife.