Javier Sierra

Media consultant and Sierra Club columnist

This 90-percent Latino community is literally surrounded by petrochemical facilities that spew at least eight carcinogens into the air. The levels of one of them, benzene, are so high that living in Manchester is tantamount to being stuck in traffic 24/7.

Kumi Naidoo

Executive Director, Greenpeace International / directeur général de Greenpeace International

Thriving, healthy oceans are essential, not only to the wonderful array of corals, fish, squid, sharks and whales, but for all of us. They provide us with the food we eat. They provide us with half of the oxygen we breathe.

Alan H. Lockwood, M.D.

Professor emeritus of neurology and nuclear medicine, University at Buffalo

Natural gas, whose principal constituent is methane, is touted as a "bridge fuel" to be used in a transition from fossil fuels to renewable sources of energy. Switching would theoretically combat global warming by decreasing carbon dioxide emissions. It is not that simple.

Bill McKibben

Author of a dozen books, including 'The End of Nature' and 'Deep Economy'

We may not need capital-L Leaders, but we certainly need small-l leaders by the tens of thousands. You could say that, instead of a leaderless movement, we need a leader-full one.

Steven Cohen

Executive Director, Columbia University's Earth Institute

At the present time we do not know how to develop a sustainable economy or a sustainable city, but we need to figure out how to do it. In my view, it begins with the basics and the development of less destructive ways to build our settlements, grow our food, supply our water and generate our energy.

Francesca Vietor

Environment Program Officer, The San Francisco Foundation, and Member of The San Francisco Public Utilities Commission

Maybe you are a physician who has read the alarming studies on dehydration, sugary beverages, and children's health, or a concerned resident reading here for the first time that our kids are not getting the water they need to reach their full potential.

Dan Chu

Director, Sierra Club 'Our Wild America' campaign

Promises from dirty energy companies to homeowners of easy money are quickly replaced by a nightmare of drinking water contaminated with toxic fracking chemicals and giant gas flares spewing toxins into the air next to houses and schools.

Niel Makinuddin

Senior Manager for governance and partnership, East Kalimantan program at The Nature Conservancy

Love orangutans? Then today -- World Orangutan Day, Aug. 19 -- is a day for you to celebrate.

Shai Agassi

Founder, Better Place, Inc.

The entire car industry should probably study Tesla, to understand if and how it plans to take such market share from all current incumbents. Assuming they will all learn the same underlying secret, what car will they make after they finished their collective hypothetical study?

Josh Burstein

Founder, the Millennial Youth Professionals Initiative

This land is not Susan's estate -- it is her duty. To leave this "little piece of heaven" in better standing than her family found it, for future generations and the native life that benefits.

Michael Rosenblum

Video producer, Founder of Current TV

Sometimes you get a confluence of things you read that give you a new insight into the way things work.

Quentin James

National Director, Sierra Club Sierra Student Coalition

This week, Sierra magazine released its seventh annual ranking of America's greenest schools, a salute to colleges that are helping to solve climate problems and making significant efforts to operate sustainably.

Rebecca Solnit

Author, 'A Paradise Built in Hell'

All through my activist life, I've seen police looking for leaders to negotiate with or suppress. A body with a head can be decapitated, but headless organisms charge on as long as some of us remain.

Natalie Lapides

Student, Yale University

Anti-poaching units that protect the world's remaining rhinos often spend 20 to 25 days at a time in the bush, return briefly to restock their supplies, then head back out, year-round.

Heather Taylor-Miesle

Director, NRDC Action Fund

Rush Limbaugh has sunk to new lows. I usually dismiss his incendiary comments, but I can't ignore them when he takes on two things that matter deeply to me: Christianity and climate change.

Danny Kennedy

Founder, Sungevity

Mr. President, you are finally doing it, and in the process you are making a strong statement to the world. But even as I applaud you, I present you with a question: Why the heck did it take you so long? And more importantly, cannot you do more?

Steve Horn

Research Fellow, DeSmogBlog

Pennsylvania Democratic Party gubernatorial candidate and former head of the PA Department of Environmental Protection, Kathleen "Katie" McGinty, has hired powerful PR firm SKDKnickerbocker for her campaign's communications efforts.