Dr Jeffrey Sachs, Director of The Earth Institute at Columbia University and Special Advisor to the United Nations Secretary‐General on the Millennium Development Goals (2013): “The hydrofracking revolution that is bringing shale oil and shale gas to many parts of the world is very profitable, but it is not putting the world on a trajectory that is sustainable by any stretch of the imagination…while we are in the middle of our new ‘gold rush’ of hydrofracking, and we tell ourselves conveniently that natural gas is clean, it is cleaner than coal, but it is absolutely not clean enough to divert us from a trajectory of grave damage on the environment — let’s be clear about that. We use rhetoric, which lulls us to complacency, to say that natural gas is a clean energy source. It is not a low-carbon energy source. It’s low-carbon only in comparison to coal. But it is high-carbon in comparison to what our climate can take” (Zachary Shahan, “Jeffrey Sachs: Naturl agas is “absolutely not clean enough”, Clean Technica, 23 January 2013: http://cleantechnica.com/2013/01/23/jeffrey-sachs/ ).