I noticed there was some mention of planetary boundaries in the "Climate Change and You" topic in the controversies section, but I find it's something that's frequently overlooked in debates concerning our climate. I thought, for that reason, I would bring this to your attention: The nine planetary boundaries
In the media, in politics, and in debates, the focus is very often on climate change - global warming, if you prefer. That's only part of the picture, however. The link provides a brief introduction to the research of Rockström et al.
If you have access to academic journals, you can find the full paper "Planetary Boundaries: Exploring the Safe Operating Space for Humanity ( 2009 )", if you like.
What they have attempted to do is identify and quantify nine 'boundaries', which if crossed could have serious negative impact on Earth's environment. Climate change, which is commonly discussed, is just one of them. The other eight are: The stratospheric ozone layer; biodiversity loss; chemical pollution; ocean acidification; freshwater consumption; land use; the nitrogen cycle; and atmospheric aerosol loading. These are all connected, too, and so they can't really be seen in isolation from one another.
I find that this is useful ( and more than a little daunting ) to keep in mind, as it seems like climate change is getting all the attention, and often it seems like we get nowhere with that. Basically, it seems to me like it's easier to ignore climate change than any of the others: It's easy for people to laugh off 'global warming' on cold winter days ( though right now it feels like Spring here, when we should have plenty of snow ), but less so things like freshwater consumption and the nitrogen cycle. It may just be interesting and useful to keep in mind - or at best it may make people more aware of the effect human activity is having on Earth's climate, and what's really going on, and that what we're facing is not just milder winters and longer summers ( never mind the lethal droughts and floods and hurricanes ).