While this is a good development, hydrogen based planes would not be climate neutral. Unfortunately a large and often overlooked part of planes’ climate impact stems not from their carbon emissions but from the water vapor they produce [1]. Contrails reflect heat and thereby contribute to global warming. If we want planes to actually be harmless to the climate, we should probably be looking at electric planes.

[1] https://www.transportenvironment.org/news/aviation-2-3-times...