When you look at your planet from space, it's beautiful, fragile, and there's this little thin layer all the way around: our atmosphere. And that's the only thing that protects us from the really bad vacuum in outer space. This little fragile layer, the atmosphere, is part of our life support system. We need to be really careful with it. —Mary Cleave Our atmosphere connects us all. What happens in Africa affects North America. What happens in North America affects Asia. —Dan Barry, American astronaut Less than 550 humans have orbited the Earth. Those of us lucky enough to have done so more than once have not only heard about the negative impact that the industrial age has had on our planet, we've seen it with our own eyes. —Michael López-Alegría, American astronaut The view from space is just breathtaking. And at the same time we recognize deforestation and wildfires, and so on, which are related to climate change. —Naoko Yamazaki, Japanese astronaut We astronauts have been witnessing the continued shrinking of the Aral Sea, the burning rain forests along the Amazon and in Indonesia, the polluted air over industrial zones, and the dirty water at the river deltas. —Ernst Messerschmid, German astronaut This is the biggest problem the world has to face right now. And we're at a point now where we really have to take action and make the changes to try to ward off the worst effects which might come down the pipe. —Greg Linteris, American astronaut To make the changes we need to make and to reach a safer future, we will need the resources of everybody here — the scientists, the policy makers, and the industrialists — all working together towards a common goal. And that goal is a planet that can continue to support life. —Piers Sellers, American astronaut Our course would be better served if in addition to what [the Paris climate change] conference seeks to achieve, this world body focuses also equally on educating the next generation so that it grows up with the understanding that sustainable development is impossible if it is accompanied by non-sustainable consumption. —Rakesh Sharma, Indian cosmonaut We are citizens of space, and stewards of Earth. We need to take actions to build [a] global climate alliance in order to protect our environment. —Soichi Noguchi, Japanese astronaut Suppose I can transfer the experience which I have to you. Then you would go out and see the Earth. And when you have let's say the spirit and the insight and the attitude of an astronaut, you start to love the Earth. And if you really love something, you don't want to lose it. Our Earth has cancer. I have cancer, too. —Wubbo Ockels You can watch the astronauts' entire video below. Kelly Dickerson wrote a previous version of this post.