I reviewed the rules, just in case. This is not a political post. It's a technical discussion prompted by a statement from the CEO of a major US airline. I got an e-mail today (April 13, 2021) from United Airlines. Here is an excerpt: "A note from our CEO, Scott Kirby. This Earth Month, we have a lot to celebrate at United. We've committed to being 100% green by reducing our carbon emissions 100% by 2050 and have invested in ground-breaking technology to make our goal a reality. But there's still a long way to go. And today, we're launching an industry-first effort that has the potential to play a significant role in the global fight against climate change." Reducing something by 100% eliminates it completely, so United is committed to eliminating all carbon emissions by 2050. My questions are: 1. Is a 100% reduction in carbon emissions possible for a major airline (assuming they don't shut down)? 2. If so, how?