Hmm, cutting sulfur dioxide emissions for health reasons is bad for global warming because sulfur dioxide clouds have a net cooling effect with reflection.
This is surprisingly often the case. At a short term scale, improvements in the local environment are at odds with improvements towards preventing climate change (hydropower is the poster child for this). Long term though, it's almost always better to prioritize the large scale, as failing to limit climate change will ultimately make any efforts to protect local environments futile.
Usually, for a hydro power plant to be effective they require a dam to be built. This significantly changes the surrounding landscape by flooding large areas of land and also reduces the ability of fish to travel through whichever waterway is dammed up.
Enviromental activists often decry and try to prevent these types of developments because of this - they consider these changes to ruin the local environment.
On the other hand, hydropower is possibly the most useful source of renewable electricity, having a large implicit storage capacity that can be released at any moment.
Same with trains, in the UK swampy famously protested the building of a high speed rail line because it's construction resulted in the destruction of an old growth forrest