To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Share Embed Share URL Video File Node URL Embed Code <iframe title="MRC TV video player" width="640" height="360" src="https://www.mrctv.org/embed/113976" allowfullscreen></iframe> In MSNBC's latest Lean Forward ad military bashing Chris Hayes claims the world's greatest challenge is 'climate change.'