In 2020, the Sierra Club responded to the COVID-19 pandemic by emphasizing the connection between environmental health and public health. The organization advocated for policies that address both the pandemic and the climate crisis, highlighting the need for sustainable recovery efforts.

In 2015, the Sierra Club strongly supported the Paris Climate Agreement, a landmark international accord aimed at combating climate change and limiting global warming. The organization advocated for the United States to take a leadership role in the agreement and implement policies to meet its commitments.

The Sierra Club's Beyond Coal Campaign, launched in 2012, aimed to phase out coal-fired power plants in the United States and replace them with clean energy sources. The campaign has been credited with helping to retire hundreds of coal plants and significantly reduce carbon emissions.

In 2005, the Sierra Club launched the Climate Recovery Partnership, an initiative aimed at addressing climate change through advocacy, education, and grassroots organizing. The partnership focuses on reducing carbon emissions, promoting renewable energy, and encouraging sustainable practices.

In 1992, the Sierra Club celebrated its 100th anniversary. Over the century, the organization had grown significantly, with a membership of over 600,000 people. The centennial was marked by reflections on the club's achievements and a renewed commitment to environmental advocacy and conservation.

The Sierra Club played a significant role in the passage of the Wilderness Act of 1964, which was signed into law by President Lyndon B. Johnson. The act created the legal definition of wilderness in the United States and protected millions of acres of federal land from development.

In 1971, the Sierra Club opposed the construction of the Trans-Alaska Pipeline System, citing environmental concerns about the potential impact on Alaska's wilderness and wildlife. This opposition was part of a broader environmental movement that sought to balance energy development with environmental protection.

In 1969, the Sierra Club established the Sierra Club Legal Defense Fund, later known as Earthjustice. This organization was created to provide legal support for environmental causes, using the power of the law to protect the environment and ensure that environmental laws are enforced.

In 1960, the Sierra Club published 'This is the American Earth,' a groundbreaking book featuring photographs by Ansel Adams and text by Nancy Newhall. The book was influential in the environmental movement, using powerful imagery to convey the beauty and fragility of the American landscape.

In the mid-20th century, the Sierra Club played a crucial role in the establishment of Kings Canyon National Park in California. The club's advocacy and public campaigns were instrumental in protecting this area of the Sierra Nevada mountains, which is known for its deep valleys, rugged peaks, and diverse ecosystems.

In 1908, the Sierra Club launched a campaign to protect the Hetch Hetchy Valley in Yosemite National Park from being dammed for water supply. Despite the campaign's eventual failure, it marked one of the first major national environmental campaigns and helped raise awareness about the importance of preserving natural landscapes.

In 1901, John Muir published 'Our National Parks,' a book that played a significant role in the conservation movement. The book's vivid descriptions of the beauty of America's wilderness areas helped to inspire public support for the creation and protection of national parks.

In 1894, John Muir became the first president of the Sierra Club, a position he held until his death in 1914. Muir was a prominent naturalist and advocate for the preservation of wilderness in the United States, and his leadership helped establish the Sierra Club as a key player in the conservation movement.

The Sierra Club was founded on May 28, 1892, in San Francisco, California, by John Muir and a group of 182 other conservationists. The organization was established to explore, enjoy, and protect the wild places of the Earth, and to practice and promote the responsible use of the Earth's ecosystems and resources.