When asked about industrial agriculture's impact on the environment, Al Gore actually said:
Industrial agriculture is a part of the problem. Organic farming, relying on more productive, safer methods that put carbon back in the soil, produce safer and better food, that's a big part of it. The shift toward a more meat-intensive diet is also part of the problem. The clearing of forest areas in many parts of the world in order to raise more cattle, that's a part of it. The reliance on synthetic nitrogen fertilizer as a Faustian bargain, it's kind of like steroids, it gives a pop but then the soil degrades. So yeah, agriculture is a significant part of this. We have to change it.
It is well documented that increasing global demand for meat has environmental consequences. To characterize Gore's acknowledgment of this fact as a call for everyone to become vegetarian is simply a distortion.