Not a vulcanologist but, the hawaiian volcanoes largely erupt low viscosity (low silica) basalt lavas. Consequently they are not generally explosive in the way volcanoes with higher viscosity lavas (higher silica content) like andesite or dacite are. They don’t produce ash in a way that could have a major effect on the global climate.
Happy to be corrected by someone more in the know, but I think the main risk to the wider pacific would be a flank collapse and associated tsunami but the probabilities of this are very low.
When I was there in 1998, there was a little river of lava that reached the Pacific. You couldn't get anywhere near it, but you could see the steam rising up.
Happy to be corrected by someone more in the know, but I think the main risk to the wider pacific would be a flank collapse and associated tsunami but the probabilities of this are very low.
There is evidence of previous such events: https://en.m.wikipedia.org/wiki/Hilina_Slump