Carbon countdown clock: how much of the world's carbon budget have we spent?

The clock marks how long it will take, if the rate of greenhouse gas emissions stays the same, before 2 degrees celsius of warming is likely. The 2015 Paris climate accord seeks to keep warming well below 2 degrees above pre-industrial levels, to prevent the worst effects of climate change.

Here's how The Guardian built the clock. Here's more on Pennsylvania's response to climate change.