SolarCity : Celebrities Taking a Stand for the Environment

Calling climate change 'the most urgent threat facing our entire species,' Leonardo DiCaprio cited the global plight while accepting his first Oscar for 'The Revenant' at Sunday's Academy Awards ceremony.

'Climate change is real. It is happening right now,' said the actor, noting that 2015 was the hottest year in reported history. Research further substantiates DiCaprio's statement: 2014 was our planet's second hottest year on record, and the top 10 warmest years have all occurred since 1998.

DiCaprio has become one of the world's most visible environmental activists, whether by participating in New York's 2014 climate march, speaking to hundreds of electeds at last fall's U.N. Climate Change Conference in Paris, receiving an award for his climate change work at the World Economic Forum in January in Davos, Switzerland, or pledging to divest from fossil fuels personally and on behalf of his environmental foundation.

Still, he is certainly not the only famous figure to take a stand for the environment. These celebrities are also doing their part to protect our planet:

Mark Ruffalo, another 2016 Oscar nominee, is co-founder of The Solutions Project, which seeks to transition the world to 100% renewable energy, and founder of Water Defense, a non-profit dedicated to clean water. Last November he helped launch Hollywood United for a Healthy California, a campaign to end oil and gas development in California by 2030. Ruffalo is also a solar supporter; he recently worked to retain key net energy metering policies in the state of Nevada.

Author Van Jones is arguably best known for his environmental justice work. He wrote the best seller, 'The Green Collar Economy,' and is president and founder of Green for All, which works to build an inclusive green economy strong enough to lift people out of poverty. Jones was the main advocate for the Green Jobs Act, which was the first piece of federal legislation to codify the term 'green jobs'. He recently spoke out in favor of President Obama's Clean Power Plan, which seeks to reduce carbon pollution from power plants.

In 2006, former Vice President Al Gore sounded the alarm over global warming with the documentary, 'An Inconvenient Truth.' He won a 2007 Nobel Prize for this activism (which he shared with the Intergovernmental Panel on Climate Change). Still on the climate campaign, Gore's TED Talk earlier this year, 'The case for optimism on climate change', highlighted decreasing costs for renewable energy among numerous positive developments. He is co-founder and chairman of the Climate Reality Project, which trains volunteers to inspire others to take climate action.

Alice Waters is renowned for her Northern California restaurant, Chez Panisse, and her pioneering advocacy for fresh seasonal ingredients produced sustainably and locally. She was honored with a Global Environmental Citizen Award (along with Kofi Annan) in 2008 by the Center for Health and the Global Environment at Harvard Medical School. Her non-profit organization allows middle school students to 'participate in all aspects of tending the land, harvesting their crops, and preparing and sharing fresh food.'

Robert Redford has been a prominent environmental activist for some four decades, and long-time trustee of the Natural Resources Defense Council. Like his fellow environmental champions, he has spoken out against an array of issues, from tar sands oil to energy waste in large urban buildings. Most recently, Redford narrated 'National Parks Adventure,' an IMAX film that debuted last month for the 100 anniversary of the National Park Service, and is slated to be shown in 60 countries.