Enlarge / This refinery would be replaced by a green alternative once it reaches the end of its lifetime. (credit: Eni An Energy Company) Because climate change is such a complex, globe-spanning problem, it’s hard to really wrap your head around possible future scenarios. A future where no action is taken to slow greenhouse gas emissions is easy enough to grok, but what exactly does a “middle-of-the-road emissions world” entail? These scenarios work well for outlining the range of futures available to us, but it can be hard to understand the steps necessary to get to that future.