In 2013, The Intergovernmental Panel on Climate Change (IPCC) identified the world's "carbon budget" and defined it as "the estimated amount of carbon dioxide the world can emit while still having a likely chance of limiting global temperature rise to 2 degrees Celcius above pre-industrial levels. That budget is estimated to be around 1 trillion tonnes of carbon, or 1,000 PgC (PgC = Petagram of Carbon with 1 PgC equalling to 1 billion metric tonnes) according to consensus from the scientific community.
This infographic, published by the World Resources Institute in Washington, D.C. explains the carbon budget and what the ramifications to our planet might be if we exceed that budget. It also lists out ways we might be able to keep within our budget, like increasing the amount and types of renewable resources, and keeping fossil fuels in the ground.